MIS-C: A COVID-19-as sociated condition between hypoimmunity and hyperimmunity.

Multisystem inflammatory syndrome in children (MIS-C) is a rare, severe complication of COVID-19. A better knowledge of immunological, cellular, and genetic characteristics of MIS-C could help better understand the pathogenesis of the disease and contribute to identifying specific diagnostic biomarkers and develop targeted therapies. We studied 37 MIS-C children at hospital admission and 24 healthy controls analyzing serum cytokines (IFN-α, IFN-ß, IFN-γ, IL-6, IL-10, IL-17A, IL-12p70 and TNF), lymphocyte populations by flow cytometry and 386 genes related to autoimmune diseases, autoinflammation and primary immunodeficiencies by NGS. MIS-C patients showed a significant increase of serum IFNγ (despite a significant reduction of activated Th1) and ILs, even if with a great heterogeneity among patients, revealing different pathways involved in MIS-C pathogenesis and suggesting that serum cytokines at admission may help to select the inflammatory pathways to target in each patient. Flow cytometry demonstrated a relevant reduction of T populations while the percentage of B cell was increased in agreement with an autoimmune pathogenesis of MIS-C. Genetic analysis identified variants in 34 genes and 83.3% of patients had at least one gene variant. Among these, 9 were mutated in more patients. Most genes are related to autoimmune diseases like ATM, NCF1, MCM4, FCN3, and DOCK8 or to autoinflammatory diseases associated to the release of IFNγ like PRF1, NOD2, and MEF. Thus, an incomplete clearance of the Sars-CoV2 during the acute phase may induce tissue damage and self-antigen exposure and genetic variants can predispose to hyper-reactive immune dysregulation events of MIS-C-syndrome. Type II IFN activation and cytokine responses (mainly IL-6 and IL-10) may cause a cytokine storm in some patients with a more severe acute phase of the disease, lymphopenia and multisystemic organ involvement. The timely identification of such patients with an immunocytometric panel might be critical for targeted therapeutic management.

Immunophenotyping of peripheral blood cells allows to discriminate MIS-C and Kawasaki disease.

Background: The pathogenesis of the novel described multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) is still debated as it is not clear if they are the same or different nosological entities. However, for both the diseases a rapid and unequivocal diagnosis is mandatory to start the therapy before the onset of severe complications. In this study, we aimed to evaluate the white cell populations in MIS-C and KD as potential markers to discriminate between the two diseases. Methods: We studied white cell populations by flow cytometry in 46 MIS-C and 28 KD patients in comparison to 70 age-matched healthy children. Results: MIS-C patients had a significant lymphopenia that involved both B and T populations while KD patients showed a significant neutrophilia and thrombocythemia. Granulocyte/lymphocyte ratio helped to diagnose both MIS-C and KD with a high diagnostic sensitivity, while a multivariate analysis of granulocyte and T lymphocyte number contributed to discriminate between the two diseases. Conclusions: The relevant lymphopenia observed in MIS-C patients suggests that the disease would be a post-infectious sequel of COVID-19 immunologically amplified by a massive cytokine release, while the significant neutrophilia and thrombocythemia observed in KD confirmed that the disorder has the genesis of a systemic vasculitis. The analysis of a panel of circulating cells may help to early diagnose and to discriminate between the two diseases. Supplementary Information: The online version contains supplementary material available at 10.1186/s41231-022-00128-2.

Biomarkers of Endothelial Damage in Distinct Phases of Multisystem Inflammatory Syndrome in Children.

Endothelial hyperinflammation and vasculitis are known hallmarks of acute COVID-19 and multisystem inflammatory syndrome in children (MIS-C). They are due to the direct effect of the virus on endothelial cells enhanced by pro-inflammatory modulators and may cause venous/arterial thrombosis. Therefore, it is essential to identify patients with endothelial damage early in order to establish specific therapies. We studied the monocyte chemoattractant protein 1 (MCP-1), the perinuclear anti-neutrophil cytoplasmic antibodies (pANCA), and the vascular endothelial growth factor A (VEGF-A) in serum from 45 MIS-C patients at hospital admission and 24 healthy controls (HC). For 13/45 MIS-C patients, we measured the three serum biomarkers also after one week from hospitalization. At admission, MIS-C patients had significantly higher levels of MCP-1 and VEGF-A than the HC, but no significant differences were observed for pANCA. While after one week, MCP-1 was significantly lower, pANCA was higher and VEGF-A levels were not significantly different from the admission values. These findings suggest an involvement of epithelium in MIS-C with an acute phase, showing high MCP-1 and VEGF-A, followed by an increase in pANCA that suggests a vasculitis development. The serum biomarker levels may help to drive personalized therapies in these phases with anticoagulant prophylaxis, immunomodulators, and/or anti-angiogenic drugs.

Distinctive Phenotype of Multisystem Inflammatory Syndrome in Children Associated with SARS-CoV-2 According to Patients' Age: A Monocentric Experience.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a disease temporally related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it is characterized by fever, conjunctival injections, rash, gastrointestinal symptoms, and cardiovascular complications. We evaluated the clinical presentation, laboratory findings, imaging features, therapeutic interventions, and hospital course of a monocentric cohort, and we analyzed these findings according to two age groups. METHODS: Patients with MIS-C admitted to a Tertiary Care Pediatric Hospital from November 2020 to November 2021 were considered for the enrollment. RESULTS: Overall, 35 consecutive patients were included. Most of the children did not require intensive care unit at the admission. The clinical presentation of MIS-C slightly differs according to age groups. Mucocutaneus involvement was more frequent in younger patients, while abdominal symptoms were present in 54% of patients aged less than 5 years and in 95% of patients aged more than 5 years (p < 0.05). In addition, the number of cases with troponin above the normal reference value was significantly higher in older patients (77%) compared to younger cases (15%) (p < 0.01). CONCLUSIONS: MIS-C is a new emerging condition and represents a challenge to pediatricians due to the severity of presentation. Further studies to better characterize the long-term outcome of MIS-C patients are mandatory.

Liver and Pancreatic Involvement in Children with Multisystem Inflammatory Syndrome Related to SARS-CoV-2: A Monocentric Study.

Liver and pancreatic involvement in children with Multisystem Inflammatory Syndrome related to SARS-CoV-2 (MIS-C) has been poorly investigated so far. We reviewed a cohort of MIS-C patients to analyze the prevalence of acute liver injury (ALI) and pancreatic injury and their correlation with clinical outcomes. Demographic, clinical, laboratory and imaging features of children with MIS-C at admission and during hospital stay were prospectively collected. Fifty-five patients (mean age 6.5 ± 3.7 years) were included. At admission, 16 patients showed ALI and 5 had increased total serum lipase. During observation, 10 more patients developed ALI and 19 more subjects presented raised pancreatic enzymes. In comparison to those with normal ALT, subjects with ALI were significantly older (p = 0.0004), whereas pancreatic involvement was associated to a longer duration of hospital stay compared with patients with normal pancreatic enzymes (p = 0.004). Time between hospital admission and onset of ALI was shorter compared to the onset of raised pancreatic enzymes (3.2 ± 3.9 versus 5.3 ± 2.7 days, respectively; p = 0.035). Abdominal ultrasound showed liver steatosis in 3/26 (12%) and hepatomegaly in 6/26 (16%) patients with ALI; 2 patients presented enlarged pancreas. Although liver and pancreatic involvement is commonly observed in MIS-C patients, it is mild in most cases with a complete recovery.

Distinctive Phenotype of Multisystem Inflammatory Syndrome in Children Associated with SARS-CoV-2 According to Patients' Age: A Monocentric Experience

Background: Multisystem inflammatory syndrome in children (MIS-C) is a disease temporally related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it is characterized by fever, conjunctival injections, rash, gastrointestinal symptoms, and cardiovascular complications. We evaluated the clinical presentation, laboratory findings, imaging features, therapeutic interventions, and hospital course of a monocentric cohort, and we analyzed these findings according to two age groups. Methods: Patients with MIS-C admitted to a Tertiary Care Pediatric Hospital from November 2020 to November 2021 were considered for the enrollment. Results: Overall, 35 consecutive patients were included. Most of the children did not require intensive care unit at the admission. The clinical presentation of MIS-C slightly differs according to age groups. Mucocutaneus involvement was more frequent in younger patients, while abdominal symptoms were present in 54% of patients aged less than 5 years and in 95% of patients aged more than 5 years (p < 0.05). In addition, the number of cases with troponin above the normal reference value was significantly higher in older patients (77%) compared to younger cases (15%) (p < 0.01). Conclusions: MIS-C is a new emerging condition and represents a challenge to pediatricians due to the severity of presentation. Further studies to better characterize the long-term outcome of MIS-C patients are mandatory.

Brugada Pattern in a Child with Severe SARS-CoV-2 Related Multisystem Inflammatory Syndrome.

This report presents the first case of Brugada pattern complicated by a supraventricular arrhythmia in a child with SARS-CoV-2 related Multisystem Inflammatory Syndrome in Children (MIS-C). A 7-year-old boy came to our Emergency Department with 7 days of abdominal pain and fever. MIS-C was diagnosed on the basis of the clinical, laboratory and instrumental tests. On admission, ECG showed type 1 Brugada pattern in the right precordial leads. During hospitalization the onset of supraventricular arrhythmias complicated the clinical picture. This case underlines management complexity of supraventricular arrhythmic events, different from atrial fibrillation, in patients with Brugada pattern in the context of a systemic inflammatory condition with significant cardiac involvement. All potential therapeutic choices should be considered to ensure the best outcomes.

Effect of Population Lockdown on Pediatric Emergency Room Demands in the Era of COVID-19.

Objectives: The aim of this study was to assess the impact of the COVID-19 pandemic and population lockdown on pediatric ED consultations. Methods: A cross-sectional study on pediatric emergency department consultations before and during the current COVID-19 pandemic (March-May 2019 vs. March-May 2020) was performed in two hospitals in the Campania region (Southern Italy) [i.e., Salerno University Hospital (Salerno) and Pediatric Regional Referral Emergency Hub "AORN Santobono-Pausillipon" (Naples)]. Results: 29,368 consecutive ED pediatric patients (13,430 females; mean age ± SD = 5.4 ± 4.7 years) were seen in March-May 2019 and 9,133 (4,494 females; mean age ± SD = 5.9 ± 4.2 years) in March-May 2020. Resuscitation/emergency and urgent care pediatric ED consultations were 1,388 (4.7%, 95% CI 4.5-4.9) in the 2019 trimester, while they were 648 (7.1%, 95% CI 6.6-7.6) in the 2020 trimester (p < 0.01). Mean pediatric ED daily consultations were 326.3 (95% CI 299.9-352.7) in the considered period of 2019 and 101.4 (95%CI 77.9-124.9) in the same period of 2020 (p < 0.001). COVID-19 nasal swabs were performed for 385 children; of those, six resulted positive and four of them were hospitalized. Conclusions: This work provides a unique snapshot of the pediatric EDs demands in the era of COVID-19. We witnessed a significant reduction of non-urgent health care demands during the pandemic but an increase of more severe urgent cases. The COVID-19 pandemic and the following lockdown unveiled the inappropriateness of the majority of pediatric ED consultations. Nevertheless, the current scenario highlighted the need for appropriate and timely clinical evaluations in the pediatric primary care to tackle late and more severe diagnoses in EDs.