Possible involvement of infection with human coronavirus 229E, but not NL63, in Kawasaki disease

Indomethacin inhibits human seasonal coronaviruses at late stages of viral replication in lung cells: Impact on virus-induced COX-2 expression

Coronaviruses (CoV), zoonotic viruses periodically emerging worldwide, represent a constant potential threat to humans. To date, seven human coronaviruses (HCoV) have been identified: HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, globally circulating in the human population (seasonal coronaviruses, sHCoV), and three highly-pathogenic coronaviruses, SARS-CoV, MERS-CoV and SARS-CoV-2. Although sHCoV generally cause only mild respiratory diseases, severe complications may occur in specific populations, highlighting the need for broad-spectrum anti-coronavirus drugs. Herein we show that indomethacin (INDO), a non-steroidal anti-inflammatory drug widely used in the clinic for its potent anti-inflammatory and analgesic properties, effectively inhibits the replication of Alpha-coronavirus HCoV-229E and Beta-coronavirus HCoV-OC43 in human lung-derived cells. Indomethacin does not interfere with HCoV binding or entry into target cells, but acts at late stages of the virus life cycle, inhibiting viral RNA synthesis and infectious viral particles production. Although INDO anti-inflammatory action is mediated by blocking cyclooxygenase-1 and -2 (COX-1/2) enzymatic activity, the antiviral effect appears to be cyclooxygenase-independent and is not mimicked by the potent COX-1/2 inhibitor aspirin. Interestingly we found that both seasonal HCoVs markedly (>100 fold) induce the expression of the pro-inflammatory mediator COX-2 in lung cells; notably, INDO-treatment was found to effectively inhibit virus-induced COX-2 expression at the transcriptional level, revealing an additional mechanism to prevent COX-2-mediated inflammatory reactions in HCoV-infected lung cells, besides COX activity inhibition. Altogether the results indicate that indomethacin, possessing both potent anti-inflammatory properties and a direct antiviral activity against HCoV, could be effective in the treatment of Alpha- and Beta-coronavirus infections.

Kawasaki Disease-Associated Cytokine Storm Syndrome

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

Emerging evidence of microbial infection in causing systematic immune vasculitis in Kawasaki disease

Kawasaki disease (KD) is a systematic vasculitis that is often complicated by coronary artery lesions and is a leading cause of acquired heart disease in developed countries. Previous studies have suggested that genetic susceptibility, together with an inducing infectious agent, could be involved in KD pathogenesis; however, the precise causative agent of this disease remains unknown. Moreover, there are still debates concerning whether KD is an infectious disease or an autoimmune disease, although many studies have begun to show that various pathogens functioning as critical inducers could activate different kinds of immune cells, consequently leading to the dysfunction of endothelial cells and systematic vasculitis. Here in this review, we attempt to summarize all the available evidence concerning pathogen infections associated with KD pathogenesis. We also discuss the related mechanisms, present a future perspective, and identify the open questions that remain to be investigated, thereby providing a comprehensive description of pathogen infections and their correlations with the host immune system in leading to KD.

The FDA-approved drug nitazoxanide is a potent inhibitor of human seasonal coronaviruses acting at postentry level: effect on the viral spike glycoprotein

Coronaviridae is recognized as one of the most rapidly evolving virus family as a consequence of the high genomic nucleotide substitution rates and recombination. The family comprises a large number of enveloped, positive-sense single-stranded RNA viruses, causing an array of diseases of varying severity in animals and humans. To date, seven human coronaviruses (HCoV) have been identified, namely HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, which are globally circulating in the human population (seasonal HCoV, sHCoV), and the highly pathogenic SARS-CoV, MERS-CoV and SARS-CoV-2. Seasonal HCoV are estimated to contribute to 15-30% of common cold cases in humans; although diseases are generally self-limiting, sHCoV can sometimes cause severe lower respiratory infections and life-threatening diseases in a subset of patients. No specific treatment is presently available for sHCoV infections. Herein we show that the anti-infective drug nitazoxanide has a potent antiviral activity against three human endemic coronaviruses, the Alpha-coronaviruses HCoV-229E and HCoV-NL63, and the Beta-coronavirus HCoV-OC43 in cell culture with IC50 ranging between 0.05 and 0.15 μg/mL and high selectivity indexes. We found that nitazoxanide does not affect HCoV adsorption, entry or uncoating, but acts at postentry level and interferes with the spike glycoprotein maturation, hampering its terminal glycosylation at an endoglycosidase H-sensitive stage. Altogether the results indicate that nitazoxanide, due to its broad-spectrum anti-coronavirus activity, may represent a readily available useful tool in the treatment of seasonal coronavirus infections.

From Co-Infections to Autoimmune Disease via Hyperactivated Innate Immunity: COVID-19 Autoimmune Coagulopathies, Autoimmune Myocarditis and Multisystem Inflammatory Syndrome in Children

Neutrophilia and the production of neutrophil extracellular traps (NETs) are two of many measures of increased inflammation in severe COVID-19 that also accompany its autoimmune complications, including coagulopathies, myocarditis and multisystem inflammatory syndrome in children (MIS-C). This paper integrates currently disparate measures of innate hyperactivation in severe COVID-19 and its autoimmune complications, and relates these to SARS-CoV-2 activation of innate immunity. Aggregated data include activation of Toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD) receptors, NOD leucine-rich repeat and pyrin-domain-containing receptors (NLRPs), retinoic acid-inducible gene I (RIG-I) and melanoma-differentiation-associated gene 5 (MDA-5). SARS-CoV-2 mainly activates the virus-associated innate receptors TLR3, TLR7, TLR8, NLRP3, RIG-1 and MDA-5. Severe COVID-19, however, is characterized by additional activation of TLR1, TLR2, TLR4, TLR5, TLR6, NOD1 and NOD2, which are primarily responsive to bacterial antigens. The innate activation patterns in autoimmune coagulopathies, myocarditis and Kawasaki disease, or MIS-C, mimic those of severe COVID-19 rather than SARS-CoV-2 alone suggesting that autoimmunity follows combined SARS-CoV-2-bacterial infections. Viral and bacterial receptors are known to synergize to produce the increased inflammation required to support autoimmune disease pathology. Additional studies demonstrate that anti-bacterial antibodies are also required to account for known autoantigen targets in COVID-19 autoimmune complications.

T Cell Receptor Sequences Amplified during Severe COVID-19 and Multisystem Inflammatory Syndrome in Children Mimic SARS-CoV-2, Its Bacterial Co-Infections and Host Autoantigens

Published hypervariable region V-beta T cell receptor (TCR) sequences were collected from people with severe COVID-19 characterized by having various autoimmune complications, including blood coagulopathies and cardiac autoimmunity, as well as from patients diagnosed with the Kawasaki disease (KD)-like multisystem inflammatory syndrome in children (MIS-C). These were compared with comparable published v-beta TCR sequences from people diagnosed with KD and from healthy individuals. Since TCR V-beta sequences are supposed to be complementary to antigens that induce clonal expansion, it was surprising that only a quarter of the TCR sequences derived from severe COVID-19 and MIS-C patients mimicked SARS-CoV-2 proteins. Thirty percent of the KD-derived TCR mimicked coronaviruses other than SARS-CoV-2. In contrast, only three percent of the TCR sequences from healthy individuals and those diagnosed with autoimmune myocarditis displayed similarities to any coronavirus. In each disease, significant increases were found in the amount of TCRs from healthy individuals mimicking specific bacterial co-infections (especially Enterococcus faecium, Staphylococcal and Streptococcal antigens) and host autoantigens targeted by autoimmune diseases (especially myosin, collagen, phospholipid-associated proteins, and blood coagulation proteins). Theoretical explanations for these surprising observations and implications to unravel the causes of autoimmune diseases are explored.

Research trends on causes of Kawasaki disease in the COVID-19 era: focus on viral infections

Despite studies on the etiology of Kawasaki disease (KD) ongoing for half a century since its discovery, its cause has not yet been clearly identified. Although the clinical, epidemiological, and pathophysiological characteristics of KD are presumed to be closely related to infectious diseases, studies of various pathogens to identify its etiology have been actively conducted. To date, bacteria, fungi, and viruses have been investigated to determine the relationship between KD and infection, among which viruses have attracted the most attention. In particular, during the coronavirus disease 2019 pandemic, there were many reports in Europe of a sharp increase in cases of Kawasaki-like disease (KLD), while conflicting reports that the prevalence of KD decreased due to thorough "social distancing" or "wearing mask" in Asian countries drew more attention regarding the association between KD and viral infection. Therefore, the differential diagnosis of KD from KLD with these similar spectra has become a very important issue; simultaneously, research to solve questions about the association between KD and viral infections, including sudden acute respiratory syndrome coronavirus 2, is drawing attention again. Moreover, a new concept has emerged that immune responses occurring in patients with KD can be caused by the pathogen itself as well as host cells damaged by infection. This paper summarizes the research trends into KD etiology and related pathophysiology, especially its association with viral infections, and present future research tasks to increase our understanding of KD.

Plasma cytokine levels reveal deficiencies in IL-8 and gamma interferon in Long-COVID

Up to half of individuals who contract SARS-CoV-2 develop symptoms of long-COVID approximately three months after initial infection. These symptoms are highly variable, and the mechanisms inducing them are yet to be understood. We compared plasma cytokine levels from individuals with long-COVID to healthy individuals and found that those with long-COVID had 100% reductions in circulating levels of interferon gamma (IFNγ) and interleukin-8 (IL-8). Additionally, we found significant reductions in levels of IL-6, IL-2, IL-17, IL-13, and IL-4 in individuals with long-COVID. We propose immune exhaustion as the driver of long-COVID, with the complete absence of IFNγ and IL-8 preventing the lungs and other organs from healing after acute infection, and reducing the ability to fight off subsequent infections, both contributing to the myriad of symptoms suffered by those with long-COVID.

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.

A Review of Coronaviruses Associated With Kawasaki Disease: Possible Implications for Pathogenesis of the Multisystem Inflammatory Syndrome Associated With COVID-19

Multisystem Inflammatory Syndrome in Children (MIS-C), representing a new entity in the spectrum of manifestations of COVID-19, bears symptomatic resemblance with Kawasaki Disease (KD). This review explores the possible associations between KD and the human coronaviruses and discusses the pathophysiological similarities between KD and MIS-C and proposes implications for the pathogenesis of MIS-C in COVID-19. Since 2005, when a case-control study demonstrated the association of a strain of human coronavirus with KD, several studies have provided evidence regarding the association of different strains of the human coronaviruses with KD. Thus, the emergence of the KD-like disease MIS-C in COVID-19 may not be an unprecedented phenomenon. KD and MIS-C share a range of similarities in pathophysiology and possibly even genetics. Both share features of a cytokine storm, leading to a systemic inflammatory response and oxidative stress that may cause vasculitis and precipitate multi-organ failure. Moreover, antibody-dependent enhancement, a phenomenon demonstrated in previous coronaviruses, and the possible superantigenic behavior of SARS-CoV-2, possibly may also contribute toward the pathogenesis of MIS-C. Lastly, there is some evidence of complement-mediated microvascular injury in COVID-19, as well as of endotheliitis. Genetics may also represent a possible link between MIS-C and KD, with variations in FcγRII and IL-6 genes potentially increasing susceptibility to both conditions. Early detection and treatment are essential for the management of MIS-C in COVID-19. By highlighting the potential pathophysiological mechanisms that contribute to MIS-C, our review holds important implications for diagnostics, management, and further research of this rare manifestation of COVID-19.

Cytokine Deficiencies in Patients with Long-COVID

Up to half of individuals who contract SARS-CoV-2 develop symptoms of long-COVID approximately three months after initial infection. These symptoms are highly variable, and the mechanisms inducing them are yet to be understood. We compared plasma cytokine levels from individuals with long-COVID to healthy individuals and found that those with long-COVID had 100% reductions in circulating levels of Interferon Gamma (IFNγ) and Interleukin-8 (IL-8). Additionally, we found significant reductions in levels of IL-6, IL-2, IL-17, IL-13, and IL-4 in individuals with long-COVID. We propose immune exhaustion as the driver of long-COVID, with the complete absence of IFNγ and IL-8preventing the lungs and other organs from healing after acute infection, and reducing the ability to fight off subsequent infections, both contributing to the myriad of symptoms suffered by those with long-COVID.

Non-SARS, non-MERS human coronavirus infections and risk of Kawasaki disease: a meta-analysis

Aim: To study the association between non-SARS, non-MERS human coronavirus (HCoV) infections and Kawasaki disease (KD). Methods: Meta-analysis of observational studies published until 1 May 2021. Results: Out of 571 papers retrieved through database search, 10 provided data of 17,732 children. Age ranged from 2 months-14.9 years with 66% being male and 71% being complete KD. Compared with controls, there was an increased risk of developing KD in those detected to have HCoV infection (OR: 2.3 [95% CI: 1.06-4.99]; p = 0.03). The GRADE evidence for all outcomes was of 'low-certainty'. Conclusion: A 'low certainty' of evidence suggests an increased risk of KD in children infected with HCoV. We need multi-center, prospective studies to support or refute this finding. PROSPERO protocol registration: CRD42021251582.

COVID-19 and Its Repercussions on Oral Health: A Review

In 2019, a new type of coronavirus, SARS-CoV-2, the causing agent of COVID-19, was first detected in Wuhan, China. On 11 March 2020, the World Health Organization declared a pandemic. The manifestations of COVID-19 are mostly age-dependent and potentially more severe in cases with involved co-morbidities. The gravity of the symptoms depends on the clinical stage of the infection. The most common symptoms include runny nose and nasal congestion, anosmia, dysgeusia or hypogeusia, diarrhea, nausea/vomiting, respiratory distress, fatigue, ocular symptoms, diarrhea, vomiting, and abdominal pain. These systemic conditions are often accompanied by skin and mucosal lesions. Oral lesions reported in patients with COVID-19 include: herpex simplex, candidiasis, geographic tongue, aphthous-like ulcers, hemorrhagic ulcerations, necrotic ulcerations, white hairy tongue, reddish macules, erythematous surfaces, petechiae, and pustular enanthema. It is still unclear if these manifestations are a direct result of the viral infection, a consequence of systemic deterioration, or adverse reactions to treatments. Poor oral hygiene in hospitalized or quarantined COVID-19 patients should also be considered as an aggravating condition. This narrative review is focused on presenting the most relevant data from the literature regarding oral manifestations related to SARS-CoV-2, as well as the challenges faced by the dental system during this pandemic. A routine intraoral examination is recommended in COVID-19 patients, either suspected or confirmed, as, in certain cases, oral manifestations represent a sign of severe infection or even of a life-threatening condition. It is our belief that extensive knowledge of all possible manifestations, including oral lesions, in cases of COVID-19 is of great importance in the present uncertain context, including new, currently emerging viral variants with unknown future impact.

Kawasaki Disease Shock Syndrome vs Classical Kawasaki Disease: A Meta-analysis and Comparison With SARS-CoV-2 Multisystem Inflammatory Syndrome

BACKGROUND

The emergence of increasing reports worldwide of a severe inflammatory process and shock in pediatric patients resembling Kawasaki disease (KD)-and, more specifically, Kawasaki disease shock syndrome (KDSS)-prompted us to explore KDSS in a preamble of a systematic comparison between the 2 conditions.

METHODS

We completed a systematic review of KDSS and performed a meta-analysis comparison between reported KDSS cases and KD controls.

RESULTS

A total of 10 case-control series were included in the meta-analysis. Patients with KDSS were older (38.4 ± 30.6 vs 21.9 ± 19.5 months; P < 0.001) compared with standard KD with equal sex distribution and completeness of clinical diagnostic criteria. KDSS present higher C-reactive protein (59.4 ± 29.2 mg/dL vs 20.8 ± 14.8 mg/dL; P < 0.001), lower albumin (2.7 ± 0.5 g/dL vs 3.3 ± 0.5 g/dL; P < 0.01), and lower platelets (255 ± 149 109/L vs 394 ± 132 109/L; P < 0.001) but only borderline higher white blood cells (P = 0.06). Differences in alanine transaminase, aspartate aminotransferase, and erythrocyte sedimentation rate were nonsignificant. The odds of intravenous immunoglobulin resistance (44.4% vs 9.6%; (P < 0.001) and the hospital length of stay (10.9 ± 5.8 vs 5.0 ± 3.0 days; P < 0.001) were higher in KDSS, as were the odds of coronary-artery abnormalities (33.9% vs 8.6%; P < 0.001).

CONCLUSIONS

This first meta-analysis on KDSS vs KD represents a basis for future works on KDSS and opens the opportunity for future multicentre studies in the search of causal relationships between presenting elements and the eventual complications of KDSS. The similarities between SARS-CoV-2 multisystem inflammatory syndrome in children and KDSS open new horizons to the understanding of the etiology and pathophysiology related to KDSS.

An overview on the seven pathogenic human coronaviruses

To date, seven human coronaviruses (HCoVs) have been detected: HCoV-NL63, HCoV-229E, HCoV-HKU1, HCoV-OC43, severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and SARS-CoV-2. Four of these viruses, including HCoV-NL63, -229E, -HKU1 and -OC43, usually cause mild-to-moderate respiratory diseases with a seasonal pattern. Since 2000, three new HCoVs have emerged with a significant mortality rate. Although SARS-CoV and MERS-CoV caused an epidemic in some countries, SARS-CoV-2 escalated into a pandemic. All HCoVs can cause severe complications in the elderly and immunocompromised individuals. The bat origin of HCoVs, the presence of intermediate hosts and the nature of their viral replication suggest that other new coronaviruses may emerge in the future. Despite the fact that all HCoVs share similarities in viral replication, they differ in their accessory proteins, incubation period and pathogenicity. This study aims to review these differences between the seven HCoVs.

Pathogens in Vasculitis: Is It Really Idiopathic?

Vasculitis is an autoimmune disease characterized by the infiltration of leukocytes in blood vessels. An increasing number of studies on human and animal models have implicated various microorganisms in the pathogenesis of vasculitis. Previous studies have shown the presence of infectious agents, including viruses, bacteria, and fungi, in diseased vessels. However, despite continued research, the link between infection and vasculitis is not fully understood, possibly owing to the lack of appropriate animal models that mirror human disease and the technical limitations of pathogen detection in blood vessels. Among the pathogen-induced animal models, Candida albicans water-soluble fraction (CAWS)-induced coronary arteritis is currently considered one of the representative models of Kawasaki (KD) disease. Advances in metagenomic next-generation sequencing have enabled the detection of all nucleic acids in tissue, which can help identify candidate pathogens, including previously unidentified viruses. In this review, we discuss the findings from reports on pathogen-associated vasculitis in animal models and humans, with a specific focus on the investigation of the pathogenesis of vasculitis. Further studies on animal models and microbes in diseased vessels may provide important insights into the pathogenesis of vasculitis, which is often considered an idiopathic disease.

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.

Coronary artery ectasia in a child after arterial switch operation for transposition of the great arteries and suspected multisystem inflammatory syndrome in children associated with COVID-19: a case report

Background

Multisystem inflammatory syndrome in children (MIS-C) with features resembling Kawasaki disease has been reported in association with coronavirus disease 2019 (COVID-19).

Case summary

We report the rare case of a 22 months old boy with a history of operated simple transposition of the great arteries (TGA), who developed features of MIS-C likely to be associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection and involving the coronary arteries. Cardiovascular magnetic resonance imaging and cardiac catheterization showed long-distance ectasia of both coronary arteries after their origins and an origin stenosis of the right coronary artery with a perfusion defect. The patient was treated with oral anticoagulation together with antiplatelet therapy and remains under careful monitoring.

Discussion

This rare case demonstrates that also patients with TGA after the arterial switch operation (ASO) can develop coronary artery dilatation in association with MIS-C. The most interesting finding in this patient was that the origins of the reimplanted coronary arteries were not dilated. We speculate that scar tissue formation in the area of coronary artery transfer after ASO has prevented proximal coronary artery dilation.

COVID-19 in Immunosuppressed Children

Following the spread of the SARS-CoV-2 infection and coronavirus disease 2019 (COVID-19) to a global pandemic, concerns have arisen for the disease impact in at-risk populations, especially in immunocompromised hosts. On the other hand, clinical studies have clarified that the COVID-19 clinical burden is mostly due to over-inflammation and immune-mediated multiorgan injury. This has led to downsizing the role of immunosuppression as a determinant of outcome, and early reports confirm the hypothesis that patients undergoing immunosuppressive treatments do not have an increased risk of severe COVID-19 with respect to the general population. Intriguingly, SARS-CoV-2 natural reservoirs, such as bats and mice, have evolved mechanisms of tolerance involving selection of genes optimizing viral clearance through interferon type I and III responses and also dampening inflammasome response and cytokine expression. Children exhibit resistance to COVID-19 severe manifestations, and age-related features in innate and adaptive response possibly explaining this difference are discussed. A competent recognition by the innate immune system and controlled pro-inflammatory signaling seem to be the pillars of an effective response and the premise for pathogen clearance in SARS-CoV-2 infection. Immunosuppression-if not associated with other elements of fragility-do not represent per se an obstacle to this competent/tolerant phenotype in children. Several reports confirm that children receiving immunosuppressive medications have similar clinical involvement and outcomes as the pediatric general population, indicating that maintenance treatments should not be interrupted in suspect or confirmed SARS-CoV-2 infection.

Kawasaki disease recurrence in the COVID-19 era: a systematic review of the literature

Kawasaki disease (KD) is a vasculitis of unknown origin of small and medium caliber blood vessels, especially involving coronary arteries and is the leading cause of acquired heart disease in childhood in developed countries. Although rarely, it can recur: most recurrences occur within 2 years of the initial episode. No data are available on incidence of recurrent KD in Europe and multiple recurrences are rarely seen. We reviewed the medical literature on Kawasaki disease recurrence and reported a new case of Kawasaki disease recurrence in a child with SARS-CoV-2 infection. We believe that in our case SARS Cov2 acted as a trigger capable to determine, in a genetically susceptible individual, a second recurrence of the disease. In the Covid-19 era we affirm the importance for Kawasaki disease to be tested for SARS Cov2 infection.

The Blood Gene Expression Signature for Kawasaki Disease in Children Identified with Advanced Feature Selection Methods

Kawasaki disease (KD) is an acute vasculitis, accompanied by coronary artery aneurysm, coronary artery dilatation, arrhythmia, and other serious cardiovascular diseases. So far, the etiology of KD is unclear; it is necessary to study the molecular mechanism and related factors of KD. In this study, we analyzed the expression profiles of 75 DB (identifying bacteria), 122 DV (identifying virus), 71 HC (healthy control), and 311 KD (Kawasaki disease) samples. 332 key genes related to KD and pathogen infections were identified using a combination of advanced feature selection methods: (1) Boruta, (2) Monte-Carlo Feature Selection (MCFS), and (3) Incremental Feature Selection (IFS). The number of signature genes was narrowed down step by step. Subsequently, their functions were revealed by KEGG and GO enrichment analyses. Our results provided clues of potential molecular mechanisms of KD and were helpful for KD detection and treatment.

Skin manifestations of COVID-19 in children: Part 2

The current COVID-19 pandemic is caused by the SARS-CoV-2 coronavirus. The initial recognized symptoms were respiratory, sometimes culminating in severe respiratory distress requiring ventilation, and causing death in a percentage of those infected. As time has passed, other symptoms have been recognized. The initial reports of cutaneous manifestations were from Italian dermatologists, probably because Italy was the first European country to be heavily affected by the pandemic. The overall clinical presentation, course and outcome of SARS-CoV-2 infection in children differ from those in adults, as do the cutaneous manifestations of childhood. In this review, we summarize the current knowledge on the cutaneous manifestations of COVID-19 in children after thorough and critical review of articles published in the literature and from the personal experience of a large panel of paediatric dermatologists in Europe. In Part 1, we discussed one of the first and most widespread cutaneous manifestations of COVID-19, chilblain-like lesions. In this part of the review, we describe other manifestations, including erythema multiforme, urticaria and Kawasaki disease-like inflammatory multisystemic syndrome. In Part 3, we discuss the histological findings of COVID-19 manifestations, and the testing and management of infected children for both COVID-19 and any other pre-existing conditions.

Multisystem inflammatory syndrome in pediatric COVID-19 patients: a meta-analysis

BACKGROUND

We aimed to systematically review the clinical and laboratory features of patients with the multisystem inflammatory syndrome in pediatrics diagnosed during the COVID-19 pandemic.

DATA SOURCES

A literature search in Web of Science, PubMed, Scopus, and Science Direct was made up to June 29, 2020.

RESULTS

Analysis of 15 articles (318 COVID-19 patients) revealed that although many patients presented with the typical multisystem inflammatory syndrome in pediatrics, Kawasaki-like features as fever (82.4%), polymorphous maculopapular exanthema (63.7%), oral mucosal changes (58.1%), conjunctival injections (56.0%), edematous extremities (40.7%), and cervical lymphadenopathy (28.5%), atypical gastrointestinal (79.4%) and neurocognitive symptoms (31.8%) were also common. They had elevated serum lactic acid dehydrogenase, D-dimer, C-reactive protein, procalcitonin, interleukin-6, troponin I levels, and lymphopenia. Nearly 77.0% developed hypotension, and 68.1% went into shock, while 41.1% had acute kidney injury. Intensive care was needed in 73.7% of cases; 13.2% were intubated, and 37.9% required mechanical ventilation. Intravenous immunoglobulins and steroids were given in 87.7% and 56.9% of the patients, respectively, and anticoagulants were utilized in 67.0%. Pediatric patients were discharged after a hospital stay of 6.77 days on average (95% CI 4.93-8.6).

CONCLUSIONS

Recognizing the typical and atypical presentation of the multisystem inflammatory syndrome in pediatric COVID-19 patients has important implications in identifying children at risk. Monitoring cardiac and renal decompensation and early interventions in patients with multisystem inflammatory syndrome is critical to prevent further morbidity.

Coronavirus Infections in the Nervous System of Children: A Scoping Review Making the Case for Long-Term Neurodevelopmental Surveillance

BACKGROUND

The objective of this study was to describe the case literature of human coronavirus infections in the nervous system of children, including from SARS-CoV-2, and to provide guidance to pediatric providers for managing the potential long-term effects on neurodevelopment of human coronavirus infections in the nervous system.

METHODS

Using a structured strategy, the PubMed and Ovid:Embase databases were queried for articles about the clinical presentation and pathophysiology of coronavirus infections in the nervous system of children and young adults, aged 0 to 24 years.

RESULTS

Of 2302 articles reviewed, 31 described SARS-CoV-2 infections in the nervous system of children and 21 described other human coronaviruses: HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1, MERS-CoV, SARS-CoV-1. Excepting MERS-CoV, we found cases of neurological disease in children from each human coronavirus. Children with non-SARS-CoV-2 infections have suffered acute flaccid paralysis, acute disseminated encephalomyelitis, encephalitis, and seizures. In addition, cases of ischemic, hemorrhagic, and microvascular strokes have occurred in children with SARS-CoV-2. Patients with multisystem inflammatory syndrome in children have suffered encephalitis, stroke, pseudotumor cerebri syndrome, and cytotoxic lesions of deep brain structures. Despite these reports, few articles evaluated the impact of human coronavirus infections on long-term neurodevelopmental domains including cognitive, language, academic, motor, and psychosocial outcomes.

CONCLUSIONS

Neurological manifestations of human coronavirus infections can cause severe disease in children. The case literature suggests a critical gap in knowledge of the long-term effects on child neurodevelopment of these infections. As the current SARS-CoV-2 pandemic continues, this gap must be filled to facilitate optimal outcomes in recovering children.

Human and novel coronavirus infections in children: a review

Coronaviruses, seven of which are known to infect humans, can cause a spectrum of clinical presentations ranging from asymptomatic infection to severe illness and death. Four human coronaviruses (hCoVs)-229E, HKU1, NL63 and OC43-circulate globally, commonly infect children and typically cause mild upper respiratory tract infections. Three novel coronaviruses of zoonotic origin have emerged during the past two decades: severe acute respiratory syndrome coronavirus (SARS-CoV-1), Middle East respiratory syndrome coronavirus (MERS-CoV) and the recently discovered severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which is the cause of the ongoing coronavirus disease 2019 (COVID-19) pandemic. These novel coronaviruses are known to cause severe illness and death predominantly in older adults and those with underlying comorbidities. Consistent with what has been observed during the outbreaks of SARS and MERS, children with COVID-19 are more likely to be asymptomatic or to have mild-to-moderate illness, with few deaths reported in children globally thus far. Clinical symptoms and laboratory and radiological abnormalities in children have been similar to those reported in adults but are generally less severe. A rare multisystem inflammatory syndrome in children (MIS-C) which has resulted in critical illness and some deaths has recently been described. Clinical trials for therapeutics and vaccine development should include paediatric considerations. Children may play an important role in the transmission of infection and outbreak dynamics and could be a key target population for effective measures to control outbreaks. The unintended consequences of the unprecedented scale and duration of pandemic control measures for children and families around the world should be carefully examined.Abbreviations: 2019-nCoV, 2019 novel coronavirus; ADEM, acute demyelinating encephalomyelitis; AAP, American Academy of Pediatrics; ACE-2, angiotensin-converting enzyme 2; ARDS, acute respiratory distress syndrome; BCG, bacillus Calmette-Guérin; BNP, brain natriuretic peptide; CDC, Centers for Disease Control and Prevention; CRP, C-reactive protein; CSF, cerebrospinal fluid; COVID-19, coronavirus disease 2019; CT, computed tomography; CXR, chest X-ray; DOL, day of life; hCoV, human coronavirus; ICU, intensive care unit; IL, interleukin; IVIG, intravenous immunoglobulin; KD, Kawasaki disease; LDH, lactate dehydrogenase; MERS, Middle East respiratory syndrome; MERS-CoV, Middle East respiratory syndrome coronavirus; MEURI, monitored emergency use of unregistered and experimental interventions; MIS-C, multi-system inflammatory syndrome in children; PCR, polymerase chain reaction; PICU, paediatric intensive care unit; RNA, ribonucleic acid; RCT, randomised-controlled trial; RSV, respiratory syncytial virus; SARS, severe acute respiratory syndrome; SARS-CoV-1, severe acute respiratory syndrome coronavirus 1; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TNF-alpha, tumour necrosis factor alpha; UK United Kingdom; UNICEF, United Nations Children's Fund; USA, United States of America; WHO, World Health Organization.

Severe SARS-CoV-2 Infection: A Multisystem Inflammatory Syndrome in Moroccan Children

Until October 2020, children seem to have a mild form of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Morocco. Since April 2020, a new entity of multisystem inflammatory syndrome in children associated with SARS-CoV-2 infection was reported in England, Italy, France, and the United States. This syndrome has similarities with the most frequent vasculitis in children, Kawasaki disease. Here, we describe the features and outcome of the first five cases of Kawasaki-like multisystem inflammatory syndrome in Moroccan children triggered by the SARS-CoV-2. The median age of the children was 7.8 years; three of them were boys. Criteria for Kawasaki disease were met in all of them with a complete presentation. Three patients required admission to a critical care unit with multi-organ failure in one of them, but no mortality occurred. They all received intravenous immunoglobulin (IVIG), a high dose of aspirin, methylprednisolone, and supportive therapy. Coronavirus 2019 disease (COVID-19) infection in children may be life-threatening; rigorous monitoring for several weeks is required in any positive child or living in a family cluster.

COVID-19 and Pediatric Asthma: Clinical and Management Challenges

Asthma is the most frequent chronic condition in childhood and a current concern exists about asthma in the pediatric population and its risk for severe SARS-CoV-2 infection. Although all ages can be affected, SARS-CoV-2 infection has lower clinical impact on children and adolescents than on adults. Fever, cough and shortness of breath are the most common symptoms and signs in children; wheezing has not been frequently reported. Published studies suggest that children with asthma do not appear to be disproportionately more affected by COVID-19. This hypothesis raises two issues: is asthma (and/or atopy) an independent protective factor for COVID-19? If yes, why? Explanations for this could include the lower IFN-α production, protective role of eosinophils in the airway, and antiviral and immunomodulatory proprieties of inhaled steroids. Additionally, recent evidence supports that allergic sensitization is inversely related to ACE2 expression. Obesity is a known risk factor for COVID-19 in adults. However, in the childhood asthma–obesity phenotype, the classic atopic Th2 pattern seems to predominate, which could hypothetically be a protective factor for severe SARS-CoV-2 infection in children with both conditions. Finally, the return to school activities raises concerns, as asymptomatic children could act as vectors for the spread of the disease. Although this is still a controversial topic, the identification and management of asymptomatic children is an important approach during the SARS-CoV-2 epidemic. Focus on asthma control, risk stratification, and medication adherence will be essential to allow children with asthma to return safely to school.

COVID-19-Related Giant Coronary Aneurysms in an Infant with Multisystem Inflammatory Disorder in Children: The First Case Report from the United Arab Emirates and the Arab Region

BACKGROUND

Multisystem inflammatory disorder in children and adolescents is a relatively new and rare complication of COVID-19. This complication seems to develop after the infection rather than during the acute phase of COVID-19. The clinical features are similar to a well-known inflammatory syndrome in children, Kawasaki disease, and it can lead to collapse and multiple organ failure requiring intensive care. The COVID-19-associated multisystem inflammatory syndrome in children and adolescents is referred to mutually as pediatric inflammatory multisystem syndrome temporally linked with SARS-CoV-2 (PIMS-TS) or multisystem inflammatory syndrome in children (MIS-C) correlated with COVID-19, and here, it is referred to as MIS-C. Case Presentation. This report describes a nine-month-old Asian infant presented with a two-week history of fever with nonspecific signs of viral illness and erythematous rash. The clinical and biochemical findings were compatible with complicated typical Kawasaki disease (KD). The infant fulfilled the World Health Organization criteria for MIS-C and was treated with intravenous immunoglobulin and anticoagulation, which he responded well to. He was discharged home in good condition after almost 3 weeks of treatment.

CONCLUSION

This case highlights a rare but new phenomenon attributed to severe acute respiratory syndrome coronavirus 2 infection. We report the first case report of MIS-C in the United Arab Emirates and Arab region. Among KD's complications, massive aneurysm with thrombosis is rare and usually will have deleterious results if not diagnosed and managed promptly.

Prevalence and Clinical Characteristics of SARS-CoV-2 Confirmed and Negative Kawasaki Disease Patients During the Pandemic in Spain

Introduction: COVID-19 has a less severe course in children. In April 2020, some children presented with signs of multisystem inflammation with clinical signs overlapping with Kawasaki disease (KD), most of them requiring admission to the pediatric intensive care unit (PICU). This study aimed to describe the prevalence and clinical characteristics of KD SARS-CoV-2 confirmed and negative patients during the pandemic in Spain. Material and Methods: Medical data of KD patients from January 1, 2018 until May 30, 2020 was collected from the KAWA-RACE study group. We compared the KD cases diagnosed during the COVID-19 period (March 1-May 30, 2020) that were either SARS-CoV-2 confirmed (CoV+) or negative (CoV-) to those from the same period during 2018 and 2019 (PreCoV). Results: One hundred and twenty-four cases were collected. There was a significant increase in cases and PICU admissions in 2020 (P-trend = 0.001 and 0.0004, respectively). CoV+ patients were significantly older (7.5 vs. 2.5 yr) and mainly non-Caucasian (64 vs. 29%), had incomplete KD presentation (73 vs. 32%), lower leucocyte (9.5 vs. 15.5 × 109) and platelet count (174 vs. 423 × 109/L), higher inflammatory markers (C-Reactive Protein 18.5vs. 10.9 mg/dl) and terminal segment of the natriuretic atrial peptide (4,766 vs. 505 pg/ml), less aneurysm development (3.8 vs. 11.1%), and more myocardial dysfunction (30.8 vs. 1.6%) than PreCoV patients. Respiratory symptoms were not increased during the COVID-19 period. Conclusion: The KD CoV+ patients mostly meet pediatric inflammatory multisystem syndrome temporally associated with COVID-19/multisystem inflammatory syndrome in children criteria. Whether this is a novel entity or the same disease on different ends of the spectrum is yet to be clarified.

Distinguishing Between Multisystem Inflammatory Syndrome, Associated With COVID-19 in Children and the Kawasaki Disease: Development of Preliminary Criteria Based on the Data of the Retrospective Multicenter Cohort Study

Objectives: Diagnostic between multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C) and Kawasaki disease (KD) can make difficulties due to many similarities. Our study aimed to create a Kawasaki/MIS-C differentiation score (KMDscore) allowing discrimination of MIS-C and KD. Study design: The retrospective multicenter cohort study included clinical, laboratory, and instrumental information about MIS-C (n = 72) and KD (n = 147). The variables allowed to discriminate both conditions used to construct and validate the diagnostic score called the KMDscore. Results: Patients with MIS-C were older, had earlier admission to the hospital, had a shorter time before fever resolution, two times frequently had signs of GI and CNS involvement observed, and had more impressive thrombocytopenia, higher level of CRP, ferritin, ALT, AST, LDH, creatinine, triglycerides, troponin, and D-dimer compared to KD patients. Respiratory signs in MIS-C were presented with pleuritis, acute respiratory distress syndrome, oxygen dependency, lung infiltration, and ground-glass opacities in CT. The heart involvement with fast progression of myocarditis provided the severity of MIS-C and ICU admission due to 12 times higher arterial hypotension or shock and required cardiotonic. No differences in the frequency of CA lesions were seen in the majority of cases. Five criteria, CRP >11 mg/dl (18 points), D-dimer >607 ng/ml (27 points), age >5 years (30 points), thrombocytopenia (25 points), and GI involvement (28 points), were included in the KMDscore. The summa >55 points allowed to discriminate MIS-C from KD with a sensitivity of 87.5% and specificity of 89.1%. Conclusion: The KMDscore can be used to differentiate the diagnostic of MIS-C from KD.

A meta-analysis on association between viral infections and Kawasaki disease in children

Aim: To investigate the association between different viral infections and the development of Kawasaki disease (KD) in children. Materials & methods: Electronic databases were searched for relevant studies published from inception to May 2020. The pooled odds ratios (ORs) of the association of different viral pathogens with KD were estimated using a random-effects model weighted by the inverse variance method. Results: The strongest associations were found between KD and human parvovirus B19 viremia (OR = 41.05; 95% CI: 5.13–328.28; I-square = 0%), EBV IgM seropositivity (OR = 7.18; 95% CI: 3.65–14.12, I-square = 0%) and human herpesvirus-6 IgG seropositivity (OR = 5.83; 95% CI: 1.06–32.01). Conclusion: Human parvovirus B19, EBV and human herpesvirus-6 are highly suspected to be key contributors to the development of KD.

Multisystem Inflammatory Syndrome in Children: Unique Disease or Part of the Kawasaki Disease Spectrum?

One of the most intriguing and mysterious phenomena observed during the COVID-19 pandemic has been represented by the occurrence of the multisystem inflammatory syndrome in children and adolescents (MIS-C). Patients with this condition have some overlapping signs and symptoms with those of Kawasaki disease (KD), but also display clinical features that are uncommon or less frequent in this illness, such as diarrhea, abdominal pain and myocardial involvement. The sickest patients may develop multiorgan failure and shock, usually due to myocarditis. Management is based on the administration of intravenous immunoglobulin, glucocorticoids and, in the most severe instances, anakinra. It is still debated whether MIS-C and KD represent different illnesses or are part of the same disease spectrum. The aim of the present review is to analyze critically the evidence in favor of the latter hypothesis and to provide the authors' personal interpretation of the relationship between the two conditions.

Paediatric multisystem inflammatory syndrome associated with COVID-19: filling the gap between myocarditis and Kawasaki?

Myocarditis and Kawasaki disease are common but usually distinct diseases in children. During the coronavirus pandemic (COVID-19), reports of a new form of myocarditis with clinical features of Kawasaki appeared. We investigated the place of this new disease in the spectrum encompassing Kawasaki disease and myocarditis.Thirty two consecutive children referred to our centre for a suspicion of Kawasaki or a diagnosis of myocarditis were included and eventually divided into four groups: 11 Kawasaki diseases, 6 Kawasaki syndromes (children with another diagnosis), 7 myocarditis without Kawasaki clinical feature and 7 myocarditis with incomplete Kawasaki clinical features. All were treated with immunoglobulins except those of the myocarditis group. The survival rate was 91%. The 7 children with myocarditis and clinical features of incomplete Kawasaki were all positive for SARS-CoV-2. They had a transient myocardial failure with a favourable course and none had coronary artery disease.Conclusion: Every COVID-19 child within our population had a mild to severe myocarditis and presented with fever plus two or three Kawasaki clinical features. Short-term evolution was good for these children. This new disease seems to fill the gap between isolated myocarditis and Kawasaki disease. What is Known: • A new paediatric disease close to Kawasaki disease appeared during the COVID-19 pandemic What is New: • In our population, children presented with fever, vivid Kawasaki clinical features (although the Kawasaki syndrome was always incomplete) and a myocarditis without coronary abnormalities. • The new disease fills the gap between paediatric myocarditis and Kawasaki disease but its prognosis is much better.

Vascular Endothelial Glycocalyx Damage in COVID-19

The new coronavirus disease-2019 (COVID-19), which is spreading around the world and threatening people, is easily infecting a large number of people through airborne droplets; moreover, patients with hypertension, diabetes, obesity, and cardiovascular disease are more likely to experience severe conditions. Vascular endothelial dysfunction has been suggested as a common feature of high-risk patients prone to severe COVID-19, and measurement of vascular endothelial function may be recommended for predicting severe conditions in high-risk patients with COVID-19. However, fragmented vascular endothelial glycocalyx (VEGLX) is elevated in COVID-19 patients, suggesting that it may be useful as a prognostic indicator. Although the relationship between VEGLX and severe acute respiratory syndrome coronavirus 2 infections has not been well studied, some investigations into COVID-19 have clarified the relationship between VEGLX and the mechanism that leads to severe conditions. Clarifying the usefulness of VEGLX assessment as a predictive indicator of the development of severe complications is important as a strategy for confronting pandemics caused by new viruses with a high affinity for the vascular endothelium that may recur in the future.

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.

Severe COVID-19, multisystem inflammatory syndrome in children, and Kawasaki disease: immunological mechanisms, clinical manifestations and management

Multisystem inflammatory syndrome (MIS-C) is a pediatric hyperinflammation disorder caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). It has now been reported from several countries the world over. Some of the clinical manifestations of MIS-C mimic Kawasaki disease (KD) shock syndrome. MIS-C develops 4–6 weeks following SARS-CoV-2 infection, and is presumably initiated by adaptive immune response. Though it has multisystem involvement, it is the cardiovascular manifestations that are most prominent. High titres of anti-SARS-CoV-2 antibodies are seen in these patients. As this is a new disease entity, its immunopathogenesis is not fully elucidated. Whether it has some overlap with KD is still unclear. Current treatment guidelines recommend use of intravenous immunoglobulin and high-dose corticosteroids as first-line treatment. Mortality rates of MIS-C are lower compared to adult forms of severe COVID-19 disease.

Multisystem inflammatory syndrome in children and COVID-19 are distinct presentations of SARS-CoV-2

BACKGROUNDInitial reports from the severe acute respiratory coronavirus 2 (SARS-CoV-2) pandemic described children as being less susceptible to coronavirus disease 2019 (COVID-19) than adults. Subsequently, a severe and novel pediatric disorder termed multisystem inflammatory syndrome in children (MIS-C) emerged. We report on unique hematologic and immunologic parameters that distinguish between COVID-19 and MIS-C and provide insight into pathophysiology.METHODSWe prospectively enrolled hospitalized patients with evidence of SARS-CoV-2 infection and classified them as having MIS-C or COVID-19. Patients with COVID-19 were classified as having either minimal or severe disease. Cytokine profiles, viral cycle thresholds (Cts), blood smears, and soluble C5b-9 values were analyzed with clinical data.RESULTSTwenty patients were enrolled (9 severe COVID-19, 5 minimal COVID-19, and 6 MIS-C). Five cytokines (IFN-γ, IL-10, IL-6, IL-8, and TNF-α) contributed to the analysis. TNF-α and IL-10 discriminated between patients with MIS-C and severe COVID-19. The presence of burr cells on blood smears, as well as Cts, differentiated between patients with severe COVID-19 and those with MIS-C.CONCLUSIONPediatric patients with SARS-CoV-2 are at risk for critical illness with severe COVID-19 and MIS-C. Cytokine profiling and examination of peripheral blood smears may distinguish between patients with MIS-C and those with severe COVID-19.FUNDINGFinancial support for this project was provided by CHOP Frontiers Program Immune Dysregulation Team; National Institute of Allergy and Infectious Diseases; National Cancer Institute; the Leukemia and Lymphoma Society; Cookies for Kids Cancer; Alex's Lemonade Stand Foundation for Childhood Cancer; Children's Oncology Group; Stand UP 2 Cancer; Team Connor; the Kate Amato Foundations; Burroughs Wellcome Fund CAMS; the Clinical Immunology Society; the American Academy of Allergy, Asthma, and Immunology; and the Institute for Translational Medicine and Therapeutics.

Is multisystem inflammatory syndrome in children on the Kawasaki syndrome spectrum?

An alarming increase in children presenting with fever, hyperinflammation, and multiorgan dysfunction frequently requiring intensive care has been observed after severe acute respiratory syndrome coronavirus 2 infection. The illness resembles Kawasaki disease (KD), with coronary dilatation and aneurysm occurring in some. However, the cardiovascular manifestations were typically on the severe end of the KD spectrum, with cardiogenic shock a common presentation together with other features. This led to defining a unique syndrome named multisystem inflammatory syndrome in children (MIS-C). In this issue of the JCI, Lee and Day-Lewis et al. and Diorio et al. explored the clinical profiles associated with coronavirus disease 2019 in children. We posit that while splitting MIS-C into a separate disease may aid clinical management decisions, lumping it into the KD pot may better serve to understand pathobiology.

Host-pathogen interaction in COVID-19: Pathogenesis, potential therapeutics and vaccination strategies

The current coronavirus pandemic, COVID-19, is the third outbreak of disease caused by the coronavirus family, after Severe Acute Respiratory Syndrome and Middle East Respiratory Syndrome. It is an acute infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This severe disease is characterised by acute respiratory distress syndrome, septic shock, metabolic acidosis, coagulation dysfunction, and multiple organ dysfunction syndromes. Currently, no drugs or vaccines exist against the disease and the only course of treatment is symptom management involving mechanical ventilation, immune suppressants, and repurposed drugs. The severe form of the disease has a relatively high mortality rate. The last six months have seen an explosion of information related to the host receptors, virus transmission, virus structure-function relationships, pathophysiology, co-morbidities, immune response, treatment and the most promising vaccines. This review takes a critically comprehensive look at various aspects of the host-pathogen interaction in COVID-19. We examine the genomic aspects of SARS-CoV-2, modulation of innate and adaptive immunity, complement-triggered microangiopathy, and host transmission modalities. We also examine its pathophysiological impact during pregnancy, in addition to emphasizing various gaps in our knowledge. The lessons learnt from various clinical trials involving repurposed drugs have been summarised. We also highlight the rationale and likely success of the most promising vaccine candidates.

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.

Serum Responses of Children With Kawasaki Disease Against Severe Acute Respiratory Syndrome Coronavirus 2 Proteins

With recent reports showing clinical and laboratory overlap of multisystem inflammatory syndrome in children and Kawasaki disease (KD), we addressed the hypothesis that cross coronavirus humoral immunity leads to a parallel postinfectious phenomenon explaining similar pathologic findings in KD and multisystem inflammatory syndrome in children. We demonstrated no cross-reactivity in children with KD but observed some nonspecific interactions postintravenous immunoglobulin infusion.

Kawasaki Disease-Like Features in 10 Pediatric COVID-19 Cases: A Retrospective Study

Children with coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), usually present with symptoms of mild upper respiratory tract infection without developing any significant complications. However, this observation has been rendered incautious by hundreds of clinical cases from around the world that have depicted a less benign multisystem inflammatory illness mimicking Kawasaki disease in COVID-positive pediatric patients. Our study aimed at retrospectively reviewing the different features of Kawasaki disease-like illness in children suffering from COVID-19, including the complications, laboratory investigations, treatment strategies used during their hospital stay, and outcomes. We searched the electronic database of the two pediatric units of Mayo Hospital, Lahore, Pakistan, for children who had been admitted to the ward between April 2020 and July 2020 and were diagnosed with COVID-19. A total of 10 such pediatric cases were found, whose clinical details were then reviewed and the obtained data were presented in the form of tables and percentages. The median age was between 4 months to 11 years (mean: 6 years). Of the 10 patients, 8 (80%) were boys. Criteria for Kawasaki disease were met in all of them (100%), with a complete presentation in five (50%). Fever (100%), conjunctival and oral cavity changes (90%), and rash (80%) were the most common features. Seven (70%) patients required admission to a critical care unit, but no mortality occurred. This article can assist in understanding and dealing with Kawasaki disease-like manifestation of pediatric COVID-19 infection, especially in critical care settings, and its possible complications. It will help in a timely and appropriate decision-making regarding treatment and management of such cases.

Comprehensive pathogen detection in sera of Kawasaki disease patients by high-throughput sequencing: a retrospective exploratory study

Background

Kawasaki disease (KD) is an idiopathic systemic vasculitis that predominantly damages coronary arteries in children. Various pathogens have been investigated as triggers for KD, but no definitive causative pathogen has been determined. As KD is diagnosed by symptoms, several days are needed for diagnosis. Therefore, at the time of diagnosis of KD, the pathogen of the trigger may already be diminished. The aim of this study was to explore comprehensive pathogens in the sera at the acute stage of KD using high-throughput sequencing (HTS).

Methods

Sera of 12 patients at an extremely early stage of KD and 12 controls were investigated. DNA and RNA sequences were read separately using HTS. Sequence data were imported into the home-brew meta-genomic analysis pipeline, PATHDET, to identify the pathogen sequences.

Results

No RNA virus reads were detected in any KD case except for that of equine infectious anemia, which is known as a contaminant of commercial reverse transcriptase. Concerning DNA viruses, human herpesvirus 6B (HHV-6B, two cases) and Anelloviridae (eight cases) were detected among KD cases as well as controls. Multiple bacterial reads were obtained from KD and controls. Bacteria of the genera Acinetobacter, Pseudomonas, Delfita, Roseomonas, and Rhodocyclaceae appeared to be more common in KD sera than in the controls.

Conclusion

No single pathogen was identified in serum samples of patients at the acute phase of KD. With multiple bacteria detected in the serum samples, it is difficult to exclude the possibility of contamination; however, it is possible that these bacteria might stimulate the immune system and induce KD.

Pathophysiology of Cardiovascular Complications in COVID-19

Numerous recent studies have shown that patients with underlying cardiovascular disease (CVD) are at increased risk of more severe clinical course as well as mortality of COVID-19. Also, the available data suggests that COVID-19 is related to numerous de novo cardiovascular complications especially in the older population and those with pre-existing chronic cardiometabolic conditions. SARS-CoV-2 virus can cause acute cardiovascular injury, as well as increase the risk of chronic cardiovascular damage. As CVD seem to be the major comorbidity in critically unwell patients with COVID-19 and patients often die of cardiovascular complications, we review the literature and discuss the possible pathophysiology and molecular pathways driving these disease processes: cytokine release syndrome, RAAS system dysregulation, plaque destabilization and coagulation disorders with the aim to identify novel treatment targets. In addition, we review the pediatric population, the major cause of the cardiovascular complications is pediatric inflammatory multisystem syndrome that is believed to be associated with COVID-19 infection. Due to the increasingly recognized CVD damage in COVID-19, there is a need to establish clear clinical and follow-up protocols and to identify and treat possible comorbidities that may be risk factors for the development of cardiovascular complications.

The Wide Spectrum of COVID-19 Clinical Presentation in Children

Background: Ten months after its appearance in December 2019, SARS-CoV-2 has infected more than 25 million patients worldwide. Because children were first identified as potential spreaders of the virus, schools were closed in several countries. However, it rapidly became evident that the number of hospitalized children infected by SARS-CoV-2 was dramatically lower than that of adults. To date, only hypotheses have been raised to explain this difference, so it is of great importance to describe the presentation of this disease among children. Here, we describe a wide spectrum of COVID-19 manifestation in children in a dedicated pediatric unit in France. Methods: Patients hospitalized with COVID-19 who were diagnosed on the basis of either positive SARS-CoV-2 RT-PCR in nasopharyngeal swabs and/or typical aspects in chest-computed tomography (CT) were included between March and May 2020 in Paris. Results: Twenty-three patients were included on the basis of positive RT-PCR (n = 20) and/or typical aspects in CT (n = 4). The median age was 4.9 years [0.1–17.6]. Patients were grouped by age (<2 years old: n = 14, 61%; 2–10 years old: n = 2, 9%; >10 years old: n = 7, 30%). Overweight or obesity was reported in only three patients. At presentation, the most frequent symptom in the overall cohort was fever (n = 18, 78%), followed by acute rhinitis (n = 9, 64%) and cough (n = 7, 50%) in the under 2-year-old group and cough (n = 4, 57%), fatigue, dyspnea and abdominal pain (n = 3, 43% each) in the over 10-year-old group. Five patients required ICU treatment, four of whom were aged >10 years, two presented with acute myocarditis, and two were sickle cell disease patients who presented with acute chest syndrome. Discussion and conclusion: The youngest patients seem to present milder forms of COVID-19 without the need for ICU treatment and with a shorter length of hospitalization. More severe evolutions were observed in teenagers, with, however, favorable outcomes. Given the context of closed schools and confinement, the infection of these children suggests intra-familial transmission that needs to be further assessed. This description might help to understand the intriguing differences in COVID-19 severity across age-classes.

COVID-19 Inflammatory Syndrome With Clinical Features Resembling Kawasaki Disease

We describe 2 patients with coronavirus disease who had multiple clinical features suggestive of Kawasaki disease (KD). Both patients presented with fever lasting >5 days and were found to have rash, conjunctival injection, and swollen lips. One patient also had extremity swelling, whereas the other developed desquamation of the fingers. In both cases, laboratory results were similar to those seen in KD. These patients had highly unusual but similar features, and both appeared to respond favorably to treatment. It remains unclear whether these patients had true KD or manifestations of coronavirus disease that resembled KD.

Age-Related Differences in Immunological Responses to SARS-CoV-2

There is a striking age-related disparity in the prevalence and severity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced coronavirus disease 2019 infections, which might be explained by age-dependent immunological mechanisms. These include age-related physiological differences in immunological responses, cross-neutralizing antibodies, and differences in levels and binding affinity of angiotensin-converting enzyme 2, the SARS-CoV-2 target receptor; antibody-dependent enhancement in adults manifesting with an overexuberant systemic inflammation in response to infection; and the increased likelihood of comorbidities in adults and the elderly. Emerging immunological phenomena such as Pediatric Multi-System Inflammatory Disorder Temporally associated with SARS-CoV-2 or Multisystem Inflammatory Syndrome in Children are now being observed, though the underlying mechanisms are still unclear. Understanding the mechanisms through which pediatric patients are protected from severe novel coronaviruses infections will provide critical clues to the pathophysiology of coronavirus disease 2019 infection and inform future therapeutic and prophylactic interventions. Asymptomatic carriage in children may have major public health implications, which will have an impact on social and health care policies on screening and isolation practices, school reopening, and safe distancing requirements in the community.

Endothelial glycocalyx damage as a systemic inflammatory microvascular endotheliopathy in COVID-19

In atherosclerosis patients, vascular endothelial dysfunction is commonly observed alongside damage of the vascular endothelial glycocalyx, an extracellular matrix bound to and encapsulating the endothelial cells lining the blood vessel wall. Although atherosclerotic risk factors have been reported in severe patients with coronavirus disease 2019 (COVID-19), the exact mechanisms are unclear. The mortality associated with the COVID-19 outbreak is increased by comorbidities, including hypertension, diabetes, obesity, chronic obstructive pulmonary disease (COPD), and cardiovascular disease. Besides, older individuals and smokers have significantly worse outcomes. Interestingly, these comorbidities and risk factors are consistent with the pathophysiology that causes vascular endothelial glycocalyx damage. Moreover, vascular glycocalyx dysfunction causes microvascular leakage, which results in interstitial pulmonary abnormal shadows (multiple patchy shadows with a ground glass inter-pneumonic appearance). This is frequently followed by severe acute respiratory distress syndrome (ARDS), closely related to coagulo-fibrinolytic changes contributing to disseminated intravascular coagulation (DIC) and Kawasaki disease shock syndrome, as well as inducing activation of the coagulation cascade, leading to thromboembolism and multiple organ failure. Notably, SARS-CoV-2, the causative virus of COVID-19, binds to ACE2, which is abundantly present not only in human epithelia of the lung and the small intestine, but also in vascular endothelial cells and arterial smooth muscle cells. Moreover, COVID-19 can induce severe septic shock, and sepsis can easily lead to systemic degradation of the vascular endothelial glycocalyx. In the current review, we propose new concepts and therapeutic goals for COVID-19-related vascular endothelial glycocalyx damage, based on previous vascular endothelial medicine research.