Distinct clinical and immunological features of SARS-CoV-2-induced multisystem inflammatory syndrome in children

The Intricate Dance of Infections and Autoimmunity: An Interesting Paradox

Besides genetic susceptibility, infections due to viruses, bacteria and protozoa have been implicated in the development of autoimmune diseases (AD). AD can be triggered in a genetically susceptible individual by infections that disrupt immunological tolerance towards self-antigens. Pathogens can initiate autoimmunity by way of molecular mimicry, bystander activation, epitope spreading or persistent infection with polyclonal activation. This review covers two main topics: (i) the mechanisms by which an infectious agent can trigger or worsen autoimmunity; and (ii) the correlation between specific infectious agents and AD in humans with special emphasis on multisystem inflammatory syndrome in children (MIS-C).

The changes of coagulation profiles in Kawasaki disease and its associations with clinical classification, intravenous immunoglobulin responsiveness and coronary artery involvement

Coagulation disorders are common in Kawasaki disease (KD). The main objectives of the present study were to probe the associations of coagulation profiles with clinical classification, IVIG responsiveness, coronary artery abnormalities (CAAs) in the acute episode of KD. A total of 313 KD children were recruited and divided into six subgroups, including complete KD (n = 217), incomplete KD (n = 96), IVIG-responsive KD (n = 293), IVIG-nonresponsive KD (n = 20), coronary artery noninvolvement KD (n = 284) and coronary artery involvement KD (n = 29). Blood samples were collected within 24-h pre-IVIG therapy and 48-h post-IVIG therapy. Coagulation profiles, conventional inflammatory mediators and blood cell counts were detected. Echocardiography was performed during the period from 2- to 14-day post-IVIG infusion. In addition, 315 sex- and age-matched healthy children were enrolled as the controls. (1) Before IVIG therapy, coagulation disorders were more prone to appear in KD patients than in healthy controls, and could be overcome by IVIG therapy. FIB and DD significantly increased in the acute phase of KD, whereas reduced to normal levels after IVIG therapy. (2) PT and APTT were significantly longer in patients with complete KD when compared with their incomplete counterparts after IVIG therapy. (3) The larger δDD, δFDP and the smaller δPT, δINR predicted IVIG nonresponsiveness. (4) The higher δDD and δFDP correlated with a higher risk for CAAs (DD: r = -0.72, FDP: r = -0.54). Coagulation disorders are correlated with complete phenotype, IVIG nonresponsiveness and CAA occurrence in the acute episode of KD, and can be rectified by synergistic effects of IVIG and aspirin.

Describing Elephants: An Update on the Immunopathology of Multisystem Inflammatory Syndrome in Children

First described in 2020, multi-system inflammatory syndrome in children (MIS-C) is an, initially life-threatening, disease characterised by severe inflammation and following exposure to SARS-CoV-2. The immunopathology of MIS-C involves a hyperinflammation characterised by a cytokine storm and activation of both the innate and adaptive immune system, eventually leading to multi-organ failure. Several etiological theories are described in literature. Firstly, it is suggested that the gut plays an important role in the translocation of microbial products to the systemic circulation. Additionally, the production of autoantibodies that develop after the initial infection with SARS-CoV-2 might lead to many of its broad clinical symptoms. Finally, the superantigen theory where non-specific binding of the SARS-CoV-2 spike glycoprotein to the T-cell receptor leads to a subsequent activation of T cells, generating a powerful immune response. Despite the sudden outbreak of MIS-C and alarming messages, as of 2024, cases have declined drastically and subsequently show a less severe clinical spectrum. However, subacute cases not meeting current diagnostic criteria might be overlooked even though they represent a valuable research population. In the future, research should focus on adjusting these criteria to better understand the broad pathophysiology of MIS-C, aiding early detection, therapy, and prediction.

Should aortic stiffness parameters be used in MIS-C patient follow-up?

We evaluated the short- and long-term effects of multisystem inflammatory syndrome in children (MIS-C) on their cardiovascular system. The study population consisted of 38 MIS-C patients and 55 control patients. Standard echocardiographic measurements and aortic stiffness parameters were compared between the two groups at different time points. During the standard echocardiographic examination at the time of diagnosis, mitral valve insufficiency was detected in 42% of the cases, left ventricular systolic dysfunction in 36%, aortic valve insufficiency in 3%, tricuspid valve insufficiency in 13%, and coronary artery dilatation in 31%. The ejection fraction, pulse pressure of the experimental group were significantly lower than the control group (p < 0.01, p = 0.045, respectively). When aortic stiffness parameters were compared, it was seen that the parameters increased in the experimental group and the difference was significant for aortic distensibility. (p = 0.105, p = 0.029 respectively). When comparing the experimental group's results at diagnosis and at the sixth month, there was a decrease in aortic stiffness parameters at the sixth month compared to the time of diagnosis, but the difference wasn't significant (p = 0.514, p = 0.334). However, no statistically significant difference was detected when comparing the aortic distensibility results of the experimental group with the control group at the sixth month (p = 0.667). Our results showed that many pathological echocardiographic findings detected at diagnosis in MIS-C patients returned to normal within six months. Therefore, we believe that the cardiovascular follow-up period of MIS-C cases should be at least six months.

Pathologic Analysis of Twenty-one Appendices From Children With Multisystem Inflammatory Syndrome Compared to Specimens of Acute Appendicitis: A Cross-sectional Study

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a rare, severe complication of coronavirus disease 2019, commonly involving the gastrointestinal tract. Some children with MIS-C undergo appendectomy before the final diagnosis. There are several hypotheses explaining the pathomechanism of MIS-C, including the central role of the viral antigen persistence in the gut, associated with lymphocyte exhaustion. We aimed to examine appendectomy specimens from MIS-C patients and assess their pathologic features, as well as the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens.

METHODS

In this cross-sectional study we included 21 children with MIS-C who underwent appendectomy. The control group included 21 sex- and age-matched children with acute appendicitis (AA) unrelated to SARS-CoV-2 infection. Histologic evaluation of appendiceal specimens included hematoxylin and eosin staining and immunohistochemical identification of lymphocyte subpopulations, programmed cell death protein-1 (PD-1) and SARS-CoV-2 nucleocapsid antigen.

RESULTS

Appendices of MIS-C patients lacked neutrophilic infiltrate of muscularis propria typical for AA (14% vs. 95%, P < 0.001). The proportion of CD20+ to CD5+ cells was higher in patients with MIS-C (P = 0.04), as was the proportion of CD4+ to CD8+ (P < 0.001). We found no proof of SARS-CoV-2 antigen presence, nor lymphocyte exhaustion, in the appendices of MIS-C patients.

CONCLUSIONS

The appendiceal muscularis of patients with MIS-C lack edema and neutrophilic infiltration typical for AA. SARS-CoV-2 antigens and PD-1 are absent in the appendices of children with MIS-C. These findings argue against the central role of SARS-CoV-2 persistence in the gut and lymphocyte exhaustion as the major triggers of MIS-C.

Gastrointestinal and Hepatic Manifestations of COVID-19 in Children: A Systematic Review and Meta-analysis

Background

Children with COVID-19 may present with gastrointestinal (GI) symptoms and liver dysfunction.

Objective

To determine the type and prevalence of gastrointestinal (GI) and hepatic manifestations of COVID-19 in children and its association with severity of illness.

Methods

A systematic literature search was done from inception until January 4, 2021 using PubMed, Cochrane Library, Google Scholar and prepublication repositories with no language restrictions. Studies that reported the demographic and clinical features of children with COVID-19 and provided data on their GI and hepatic signs and symptoms were included. Prevalence of GI and hepatic manifestations were pooled using Stata14.

Results

We included 58 studies with total of 4497 participants. Overall, one-third of children with COVID-19 presented with at least one GI symptom (33.8%; 95% confidence interval (CI) 23.0, 45.4; I2 97.5%; 42 studies, 3327 participants) with abdominal pain, nausea or vomiting, and diarrhea each occurring in approximately 20%. Children with severe COVID-19 were more likely to present with GI symptoms (odds ratio 2.59; 95% CI 1.35, 4.99; I2 24%; 4 studies, 773 participants). The pooled prevalence of elevated transaminases was 11% for both AST (11.3%, 95% CI 4.9, 19.3; I2 74.7%; 11 studies, 447 participants) and ALT (11.2%, 95% CI 7.1, 16.0; I2 40.8%; 15 studies, 513 participants). Hepatic findings such as jaundice (2-17%), hepatomegaly (2%) or behavioral changes (2%) from hepatic encephalopathy were variably reported by a few studies.The degree of heterogeneity was not improved on exclusion of studies with poor quality, but markedly improved on subgroup analysis according to geographical region and presence of MIS-C. Studies from China showed that children with COVID-19 had significantly lower pooled prevalence for any of the GI symptoms with low degree of heterogeneity, particularly for diarrhea, nausea/vomiting, and abdominal pain, all of which had I2 of 0%. Those with multisystem inflammatory syndrome in children (MIS-C) had significantly more common GI symptoms and increased transaminases than those without.

Conclusion

One-third of children with COVID-19 exhibit at least one GI symptom and more likely present in those with severe disease. Elevated transaminases were present in 10%. Prevalence of GI and hepatic manifestations were higher among children with MIS-C.

Long-term global longitudinal strain abnormalities in paediatric patients after multisystem inflammatory syndrome in children correlate with cardiac troponin T: a single-centre cohort study

BACKGROUND

Multisystem inflammatory syndrome in children is an inflammatory syndrome related to severe acute respiratory syndrome coronavirus 2 with a high risk of cardiovascular complications (vasoplegia, cardiac shock). We investigated the cardiac outcomes in multisystem inflammatory syndrome in children, focusing on the identification of predictors for late cardiac function impairment.

METHODS

Clinical characteristics, conventional echocardiography (left ventricle ejection fraction, fractional shortening), 4-chamber left ventricular global longitudinal strain, and cardiac MRI of multisystem inflammatory syndrome in children patients (n = 48) were collected during admission, 6 weeks, 6 months, >12-≤18 months, and >18-≤24 months post-onset. Paired over-time patterns were assessed and multivariable regression analyses were performed to identify predictors for late global longitudinal strain impairment.

RESULTS

In total, 81.3% of patients had acute cardiac dysfunction (left ventricle ejection fraction <50% and/or fractional shortening <28%). The left ventricle ejection fraction and fractional shortening reached a plateau level ≤6 weeks, while the global longitudinal strain continued to decrease in the first 6 months post-onset (median -17.3%, P < 0.001 [versus acute]). At 6 months, 35.7% of the patients still had an abnormal global longitudinal strain, which persisted in 5/9 patients that underwent echocardiography >12-≤18 months post-onset and in 3/3 patients >18-≤24 months post-onset. In a multivariable analysis, soluble troponin T (>62.0 ng/L [median]) was associated with reduced global longitudinal strain at 6 months. Our cardiac MRI findings indicated acute myocardial involvement (increased T1/T2 value) in 77.8% (7/9), which recovered quickly without signs of fibrosis on convalescent cardiac MRIs.

CONCLUSIONS

Late global longitudinal strain impairment is seen in some multisystem inflammatory syndrome in children patients up to one-year post-onset. Careful cardiac follow-up in patients with elevated troponin in the acute phase and patients with persistent abnormal global longitudinal strain is warranted until resolution of the global longitudinal strain since the long-term implications of such abnormalities are still unclear.

Treatment of multisystem inflammatory syndrome in children

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C), a relatively uncommon but severe pediatric complication, is associated with coronavirus disease 2019 (COVID-19). A variety of treatment approaches, including intravenous immunoglobulins (IVIGs), glucocorticoids (GCs) and biologic agents, such as anakinra and infliximab, have been described for the management of COVID-19-related MIS-C. Anticoagulant therapy is also important. However, a well-developed treatment system has not been established, and many issues remain controversial. Several recently published articles related to the treatment of MIS-C have been released. Hence, in this review, we identified relevant articles published recently and summarized the treatment of MIS-C more comprehensively and systematically.

DATA SOURCES

We reviewed the literature on the treatment of MIS-C through 20 September 2023. The PubMed/Medline, Web of Science, EMBASE, and Cochrane Library databases were searched with the combination of the terms "multisystem inflammatory syndrome", "MIS-C", "PIMS-TS", "therapy", "treatment", "drug", "IVIG", "GCs", "intravenous immunoglobulin", "corticosteroids", "biological agent", and "aspirin".

RESULTS

The severity of MIS-C varies, and different treatment schemes should be used according to the specific condition. Ongoing research and data collection are vital to better understand the pathophysiology and optimal management of MIS-C.

CONCLUSIONS

MIS-C is a disease involving multiple systems and has great heterogeneity. With the accumulation of additional experience, we have garnered fresh insights into its treatment strategies. However, there remains a critical need for greater standardization in treatment protocols, alongside the pressing necessity for more robust and meticulously conducted studies to deepen our understanding of these protocols. Supplementary file1 (MP4 208044 kb).

NT-proBNP cardiac value in COVID-19: a focus on the paediatric population

NT-proBNP is a peptide related to brain natriuretic peptide, a cardiac biomarker and a member of the natriuretic family of peptides. NT-proBNP has demonstrated its clinical utility in the assessment of a wide spectrum of cardiac manifestations. It is also considered a more precise diagnostic and prognostic cardiac biomarker than brain natriuretic peptide. With the appearance of the Severe Acute Respiratory Syndrome Coronavirus 2 virus and the subsequent COVID-19 pandemic, diagnosis of heart implications began to pose an increasing struggle for the physician. Echocardiography is considered a central means of evaluating cardiac disorders like heart failure, and it is considered a reliable method. However, other diagnostic methods are currently being explored, one of which involves the assessment of NT-proBNP levels. In the literature that involves the adult population, significant positive correlations were drawn between the levels of NT-proBNP and COVID-19 outcomes such as high severity and fatality. In the paediatric population, however, the literature is scarce, and most of the investigations assess NT-proBNP in the context of Multiple Inflammatory Syndrome in Children, where studies have shown that cohorts with this syndrome had elevated levels of NT-proBNP when compared to non-syndromic cohorts. Thus, more large-scale studies on existing COVID-19 data should be carried out in the paediatric population to further understand the prognostic and diagnostic roles of NT-proBNP.

Cardiac injury progression in children with multisystem inflammatory syndrome associated with SARS-CoV-2 infection: a review

The symptoms and signs of infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are milder in children than in adults. However, in April 2020, British pediatricians first reported that coronavirus disease 2019 (COVID-19) may present as multisystem inflammatory syndrome in children and adolescents (MIS-C), similar to that observed in Kawasaki disease. MIS-C can be associated with multiple systemic injuries and even death in children. In addition to digestive system involvement, cardiac injury is prominent. This article reviews the pathogenesis, clinical manifestations, and treatment of cardiac injury caused by MIS-C, which may help clinicians in early diagnosis and timely commencement of treatment.

Children with severe neurological symptoms associated with SARS-CoV-2 infection during Omicron pandemic in China

BACKGROUND

To analyze the clinical characteristics and outcomes of children with severe neurological symptoms associated with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection during the Omicron pandemic in China.

METHODS

This study used a questionnaire to obtain data from pediatric intensive care unit (PICU) centers in seven tertiary hospitals in Northeast China from December 1, 2022, to January 31, 2023.

RESULTS

A total of 255 patients were confirmed to have SARS-CoV-2 infection, and 45 patients (17.65 %) were included in this study. Of these, seven (15.6%) patients died, and the median time from admission to death was 35 h (IQR, 14-120 h). Twenty (52.6%) survivors experienced neurological sequelae. Patients with platelet counts lower than 100 × 109/L had a higher incidence of complications such as multiple organ dysfunction, mechanical ventilation rate, and mortality. Cranial magnetic resonance imaging (MRI) always reveals cerebral tissue edema, with some severe lesions forming a softening site.

CONCLUSION

Children infected with SARS-CoV-2 often exhibit severe neurological symptoms, and in some cases, they may rapidly develop malignant cerebral edema or herniation, leading to a fatal outcome. An early decrease in platelet count may associated with an unfavorable prognosis.

IMPACT

Since early December 2022, China has gradually adjusted its prevention and control policy of SARS-CoV-2; Omicron outbreaks have occurred in some areas for a relatively short period. Due to the differences in ethnicity, endemic strains and vaccination status, there was a little difference from what has been reported about children with SARS-CoV-2 infection with severe neurological symptoms in abroad. This is the first multicenter clinical study in children with nervous system involvement after acute SARS-CoV-2 infection in China, and helpful for pediatricians to have a more comprehensive understanding of the clinical symptoms and prognosis of such disease.

Clinical prediction model: Multisystem inflammatory syndrome in children versus Kawasaki disease

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious complication of severe acute respiratory syndrome coronavirus 2 infection. Features of MIS-C overlap with those of Kawasaki disease (KD).

OBJECTIVE

The study objective was to develop a prediction model to assist with this diagnostic dilemma.

METHODS

Data from a retrospective cohort of children hospitalized with KD before the coronavirus disease 2019 pandemic were compared to a prospective cohort of children hospitalized with MIS-C. A bootstrapped backwards selection process was used to develop a logistic regression model predicting the probability of MIS-C diagnosis. A nomogram was created for application to individual patients.

RESULTS

Compared to children with incomplete and complete KD (N = 602), children with MIS-C (N = 105) were older and had longer hospitalizations; more frequent intensive care unit admissions and vasopressor use; lower white blood cell count, lymphocyte count, erythrocyte sedimentation rate, platelet count, sodium, and alanine aminotransferase; and higher hemoglobin and C-reactive protein (CRP) at admission. Left ventricular dysfunction was more frequent in patients with MIS-C, whereas coronary abnormalities were more common in those with KD. The final prediction model included age, sodium, platelet count, alanine aminotransferase, reduction in left ventricular ejection fraction, and CRP. The model exhibited good discrimination with AUC 0.96 (95% confidence interval: [0.94-0.98]) and was well calibrated (optimism-corrected intercept of -0.020 and slope of 0.99).

CONCLUSIONS

A diagnostic prediction model utilizing admission information provides excellent discrimination between MIS-C and KD. This model may be useful for diagnosis of MIS-C but requires external validation.

Assessment of the Choroidal Vascular Structure in Multisystem Inflammatory Syndrome in Children

PURPOSE

To evaluate the choroidal vascular structure in cases of multisystem inflammatory syndrome in children (MIS-C).

METHODS

This prospective study included 38 eyes of 19 patients with MIS-C and 60 eyes of 30 healthy participants. Optical coherence tomography (OCT) imaging was performed at 1 month after diagnosis in the MIS-C group. Using enhanced depth imaging OCT, choroidal thickness was measured in the subfoveal, nasal, and temporal quadrants at 500 and 1,500 µm distances from the fovea (SCT, N500CT, T500CT, N1500CT, and T1500CT, respectively). The luminal, stromal, and total choroidal areas were evaluated with the binarization method in ImageJ software (National Institutes of Health). The ratio of the luminal area to the total choroidal area was determined as the choroidal vascular index (CVI).

RESULTS

The age and sex distributions of the two groups without any ophthalmologic pathology were similar (P > .05). The choroidal thickness values in all quadrants except for T1500CT were similar between the two groups (P > .05). T1500CT was significantly lower in the MIS-C group (P = .02). The luminal choroidal area was 1.04 ± 0.10 mm2 in the MIS-C group and 1.26 ± 0.24 mm2 in the healthy control group (P < .001), and the CVI values were 0.52 ± 0.04 and 0.57 ± 0.09, respectively (P = .01). The stromal and total choroidal area values did not significantly differ between the two groups (P > .05).

CONCLUSIONS

This is the first study to evaluate CVI in patients with MIS-C. It was observed that the choroidal vascular structure could be affected in the early period of MIS-C, as shown by a decrease in the CVI value and luminal vascular area. OCT can be used to monitor ocular vascular changes in these patients. [J Pediatr Ophthalmol Strabismus. 2024;61(2):120-126.].

A genetically modulated Toll-like-receptor-tolerant phenotype in peripheral blood cells of children with multisystem inflammatory syndrome

Dysregulated innate immune responses contribute to multisystem inflammatory syndrome in children (MIS-C), characterized by gastrointestinal, mucocutaneous, and/or cardiovascular injury occurring weeks after SARS-CoV-2 exposure. To investigate innate immune functions in MIS-C, we stimulated ex vivo peripheral blood cells from MIS-C patients with agonists of Toll-like receptors (TLR), key innate immune response initiators. We found severely dampened cytokine responses and elevated gene expression of negative regulators of TLR signaling. Increased plasma levels of zonulin, a gut leakage marker, were also detected. These effects were also observed in children enrolled months after MIS-C recovery. Moreover, cells from MIS-C children carrying rare genetic variants of lysosomal trafficking regulator (LYST) were less refractory to TLR stimulation and exhibited lysosomal and mitochondrial abnormalities with altered energy metabolism. Our results strongly suggest that MIS-C hyperinflammation and/or excessive or prolonged stimulation with gut-originated TLR ligands drive immune cells to a lasting refractory state. TLR hyporesponsiveness is likely beneficial, as suggested by excess lymphopenia among rare LYST variant carriers. Our findings point to cellular mechanisms underlying TLR hyporesponsiveness; identify genetic determinants that may explain the MIS-C clinical spectrum; suggest potential associations between innate refractory states and long COVID; and highlight the need to monitor long-term consequences of MIS-C.

Evaluation of acute terminal ileitis in children before and during the COVID-19 pandemic

OBJECTIVES

The aim of this study was to examine the clinical features of acute terminal ileitis in children and evaluate its rate before and during the COVID-19 pandemic.

METHODS

This retrospective study was performed in our pediatric emergency department between 2018 and 2022. The records of 5363 patients who required abdominal imaging due to acute abdomen were analyzed, and 143 patients with terminal ileitis were included. The rate and etiological causes were compared during and before the COVID-19 pandemic.

RESULTS

The rate of acute terminal ileitis has increased over the years. The fastest increase was in 2021, when the COVID-19 pandemic was experienced. While 59 (41.2%) patients showed acute nonspecific ileitis, the most common etiologic cause that could be identified was acute gastroenteritis. It was determined that multisystem inflammatory syndrome in children was among the causes of ileitis after the COVID-19 pandemic and was one of the top three causes.

CONCLUSIONS

Acute terminal ileitis, which has many etiologies, is one of the rare radiological findings in acute abdominal pain. Examination and laboratory findings are not specific. Guidelines are needed for the investigation of the underlying etiology of acute terminal ileitis in children. The incidence of acute terminal ileitis is increasing, and the increase has been found to be faster after the COVID-19 pandemic.

Comparing the immune abnormalities in MIS-C to healthy children and those with inflammatory disease reveals distinct inflammatory cytokine production and a monofunctional T cell response

Multisystem inflammatory syndrome in children (MIS-C) is a severe, hyperinflammatory disease that occurs after exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying immune pathology of MIS-C is incompletely understood, with limited data comparing MIS-C to clinically similar paediatric febrile diseases at presentation. SARS-CoV-2-specific T cell responses have not been compared in these groups to assess whether there is a T cell profile unique to MIS-C. In this study, we measured inflammatory cytokine concentration and SARS-CoV-2-specific humoral immunity and T cell responses in children with fever and suspected MIS-C at presentation (n = 83) where MIS-C was ultimately confirmed (n = 58) or another diagnosis was made (n = 25) and healthy children (n = 91). Children with confirmed MIS-C exhibited distinctly elevated serum IL-10, IL-6, and CRP at presentation. No differences were detected in SARS-CoV-2 spike IgG serum concentration, neutralisation capacity, antibody dependant cellular phagocytosis, antibody dependant cellular cytotoxicity or SARS-CoV-2-specific T cell frequency between the groups. Healthy SARS-CoV-2 seropositive children had a higher proportion of polyfunctional SARS-CoV-2-specific CD4+ T cells compared to children with MIS-C and those with other inflammatory or infectious diagnoses, who both presented a largely monofunctional SARS-CoV-2-specific CD4+ T cell profile. Treatment with steroids and/or intravenous immunoglobulins resulted in rapid reduction of inflammatory cytokines but did not affect the SARS-CoV-2-specific IgG or CD4+ T cell responses in MIS-C. In these data, MIS-C had a unique cytokine profile but not a unique SARS-CoV-2 specific humoral or T cell cytokine response.

Elevation of IL-17 Cytokines Distinguishes Kawasaki Disease From Other Pediatric Inflammatory Disorders

OBJECTIVE

Kawasaki disease (KD) is a systemic vasculitis of young children that can lead to development of coronary artery aneurysms. We aimed to identify diagnostic markers to distinguish KD from other pediatric inflammatory diseases.

METHODS

We used the proximity extension assay to profile proinflammatory mediators in plasma samples from healthy pediatric controls (n = 30), febrile controls (n = 26), and patients with KD (n = 23), multisystem inflammatory syndrome in children (MIS-C; n = 25), macrophage activation syndrome (n = 13), systemic and nonsystemic juvenile idiopathic arthritis (n = 14 and n = 10, respectively), and juvenile dermatomyositis (n = 9). We validated the key findings using serum samples from additional patients with KD (n = 37) and febrile controls (n = 28).

RESULTS

High-fidelity proteomic profiling revealed distinct patterns of cytokine and chemokine expression across pediatric inflammatory diseases. Although KD and MIS-C exhibited many similarities, KD differed from MIS-C and other febrile diseases in that most patients exhibited elevation in one or more members of the interleukin-17 (IL-17) cytokine family, IL-17A, IL-17C, and IL-17F. IL-17A was particularly sensitive and specific, discriminating KD from febrile controls with an area under the receiver operator characteristic curve of 0.95 (95% confidence interval 0.89-1.00) in the derivation set and 0.91 (0.85-0.98) in the validation set. Elevation of all three IL-17-family cytokines was observed in over 50% of KD patients, including 19 of 20 with coronary artery aneurysms, but was rare in all other comparator groups.

CONCLUSION

Elevation of IL-17 family cytokines is a hallmark of KD and may help distinguish KD from its clinical mimics.

Using HScore for Evaluation of Hemophagocytosis in Multisystem Inflammatory Syndrome Associated with COVID-19 in Children

Hemophagocytic syndrome is a key point in the pathogenesis of severe forms of multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C). The factors associated with hemophagocytosis in patients with MIS-C were assessed in the present study of 94 boys and 64 girls ranging in age from 4 months to 17 years, each of whose HScore was calculated. In accordance with a previous analysis, patients with HScore ≤ 91 (n = 79) and HScore > 91 (n = 79) were compared. Patients with HScore > 91 had a higher frequency of symptoms such as cervical lymphadenopathy, dry cracked lips, bright mucous, erythema/swelling of hands and feet, peeling of fingers, edematous syndrome, hepatomegaly, splenomegaly, and hypotension/shock. They also had a higher erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and D-dimer levels, and a tendency to anemia, thrombocytopenia, and hypofibrinogenemia. They more often needed acetylsalicylic acid and biological treatment and were admitted to ICU in 70.9% of cases. Conclusion: The following signs of severe MIS-C were associated with HScore > 91: myocardial involvement, pericarditis, hypotension/shock, and ICU admission.

Sex-specific differences in systemic immune responses in MIS-C children

Multisystem Inflammatory Syndrome in Children (MIS-C) is a rare manifestation of Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2) infection that can result in increased morbidity and mortality. Mounting evidence describes sex disparities in the clinical outcomes of coronavirus disease 2019 (COVID-19). However, there is a lack of information on sex-specific differences in immune responses in MIS-C. This study is an observational and cross-sectional study and we wanted to examine immune parameters such as cytokines, chemokines, acute phase proteins (APPs), growth factors, microbial translocation markers (MTMs), complement components and matrix metalloproteinases (MMPs) in MIS-C children, based on sex. Male children were associated with heightened levels of pro-inflammatory cytokines-IFNγ, IL-2, TNFα, IL-1α, IL-1β, IL-6, IL-12, G-CSF and GM-CSF, chemokines-CCL2, CCL11, CXCL1, CXCL8 and CXCL10, acute phase proteins-α-2M, CRP, growth factors VEGF and TGFα, microbial translocation markers- iFABP, LBP, EndoCAb, complement components-C1q, MBL and C3 and matrix metalloproteinases MMP-8 and MMP-9 compared to female children with MIS-C. These results indicate that the heightened immune response in males is a characteristic feature of MIS-C. These findings might explain the differential disease pathogenesis in males compared to females with MIS-C and facilitate a deeper understanding of this disease.

Metabolomic and Immunologic Discriminators of MIS-C at Emergency Room Presentation

Multisystem Inflammatory Syndrome in Childhood (MIS-C) follows SARS-CoV-2 infection and frequently leads to intensive care unit admission. The inability to rapidly discriminate MIS-C from similar febrile illnesses delays treatment and leads to misdiagnosis. To identify diagnostic discriminators at the time of emergency department presentation, we enrolled 104 children who met MIS-C screening criteria, 14 of whom were eventually diagnosed with MIS-C. Before treatment, we collected breath samples for volatiles and peripheral blood for measurement of plasma proteins and immune cell features. Clinical and laboratory features were used as inputs for a machine learning model to determine diagnostic importance. MIS-C was associated with significant changes in breath volatile organic compound (VOC) composition as well as increased plasma levels of secretory phospholipase A2 (PLA2G2A) and lipopolysaccharide binding protein (LBP). In an integrated model of all analytes, the proportion of TCRVβ21.3+ non-naive CD4 T cells expressing Ki-67 had a high sensitivity and specificity for MIS-C, with diagnostic accuracy further enhanced by low sodium and high PLA2G2A. We anticipate that accurate diagnosis will become increasingly difficult as MIS-C becomes less common. Clinical validation and application of this diagnostic model may improve outcomes in children presenting with multisystem febrile illnesses.

COVID-19-Related Multi-systemic Inflammatory Syndrome in Children (MIS-C)

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infections in children. This syndrome manifests about a month after the initial viral infection and is characterized by fever, multiorgan dysfunction, and systemic inflammation. This chapter will review the emergence, epidemiology, clinical characteristics, diagnosis, pathophysiology, immunomodulatory treatment, prognosis, outcomes, and prevention of MIS-C. While the pathophysiology of MIS-C remains to be defined, it is a post-infection, hyperinflammatory syndrome of childhood with elevated inflammatory cytokines.

Multisystem Inflammatory Syndrome in Children (MIS-C) in a Low-income Country: What Treatment Should be Adopted in Case of a Lack of Immunoglobulin?

INTRODUCTION

In multisystem inflammatory syndrome (MIS-C), children typically present high-grade fever, gastrointestinal symptoms, Kawasaki-like symptoms, and even a toxic shock-like syndrome days to weeks after recovering from SARS-CoV-2 infection. It is important to raise awareness of this condition in order to have early diagnosis and immediate treatment of patients. We have, herein, reported 44 cases of MIS-C with various risk factors and symptoms. Furthermore, we have emphasized the efficacy of experience in treating children with MIS-C with high-dose corticosteroids as an alternative to immunoglobulin in low-income countries.

METHODS

We conducted a targeted survey of MIS-C from early May 2020 to October 2022 on 44 children and adolescents with characteristics of multisystem inflammatory syndrome admitted to the pediatric department of the university hospital center in Oujda, Morocco, to which patients diagnosed with MIS-C were referred. The case definition included six criteria: serious illness leading to hospitalization, age under 18 years, fever of at least 24 hours, laboratory evidence of inflammation, multi-organ involvement, biological inflammatory syndrome, and evidence of coronavirus infection based on polymerase chain reaction, antibody testing or exposure to people with COVID-19 in the past month. The criteria used to diagnose myocarditis were impaired left ventricular function, central mitral leak, and elevation of BNP or pro-BNP. Coronary involvement was assessed by the z-score and the criteria for its presence was a z-score equal to or greater than 2.5.

RESULTS

Our study included 44 children and adolescents with MIS-C in our hospital, with male predominance (79%) and a median age of six years. Cardiovascular involvement was present in 91%, mucocutaneous in 78%, gastrointestinal in 70%, hematologic in 84%, and respiratory in 2% of patients. Coronary abnormalities (z-score ≥ 2.5) were documented in 21 cases (48%). Glucocorticoids were frequently used in comparison to immunoglobulin, which were uncommonly available and expensive.

CONCLUSION

The therapeutic protocol that was adopted was high doses of short-term prednisone (Cortancyl) at 4mg/kg/day for 4 days. Favorable outcome was noted in all patients over a 2-year period.

Criteria for Cytokine Storm Syndromes

In the past two decades, there has been a great deal of work aimed to devise diagnostic guidelines, classification criteria, and diagnostic scores for cytokine storm syndromes (CSSs). The most notable effort has been the large-scale multinational study that led to the development of the 2016 classification criteria for macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (JIA). Future studies should scrutinize the validity of the proposed criteria, particularly in systemic JIA patients treated with biologics, in children with subtle or incomplete forms of MAS, and in patients with MAS complicating other rheumatologic disorders. More generic CSS criteria are also available but often lack sensitivity and specificity in a wide variety of patient populations and CSSs of different etiologies. The coronavirus disease 2019 (COVID-19)-related lung disease led to an evolution of the concept of a "cytokine storm." Emerging and unsolved challenges in the diagnosis of the different forms of CSSs highlight the need for diagnostic tools and well-established classification criteria to enable timely recognition and correct classification of patients.

Multisystem inflammatory syndrome in children with COVID-19 in a multitransfused patient

Multi-system inflammatory syndrome in children associated with COVID19 (MIS-C) is a unique clinical syndrome characterised by fever, gastrointestinal symptoms, skin and oral rash and or neurological symptoms in the presence of raised acute phase reactants and coagulopathy. Ferritin is an acute phase reactant which is used as a marker of inflammation. Diagnosis of MIS-C in the background of transfusion dependent thalassemia with iron overload needs a strong clinical suspicion. Early diagnosis and prompt treatment are necessary to ensure a rapid uneventful recovery. A three-year-old male child born to non-consanguineously related parents reported to pediatric emergency with difficulty breathing and pain abdomen for one day. The child was a diagnosed case of Beta thalassemia major since the age of one year and was on regular transfusions and was on iron chelation for past eleven months with deferrasirox. Initial clinical examination showed a sick and irritable child with tachypnea tachycardia and hypoxia. Initial investigations showed raised acute phase reactants along with severe anemia. The child was investigated for MIS-C because of unexpected rise of serum ferritin from 1980 ng/mL (October 2020) to 6686 ng/mL (in January 2021) despite being on regular chelation. Antibody titre for SARS COVID-19 was positive. The patient was treated with intravenous corticosteroids and improved with the same. The advent of COVID19 pandemic saw most children having a mild disease with no or minimal symptoms. Some kids however presented with more serious delayed symptoms of MIS-C. To diagnose same in multi transfused patients a strong clinical suspicion and just judgement based on the clinical and laboratory findings should be done. Unexplained rise in ferritin levels, typical symptoms and high probability of exposure to COVID19 helped in clinching diagnosis.

Updated Case Definition of MIS-C and Implications for Clinical Care

OBJECTIVES

A broad, surveillance case definition was implemented when multisystem inflammatory syndrome in children (MIS-C) emerged in 2020. In 2023, a revised MIS-C case definition was constructed to improve specificity and reduce misclassification with other pediatric inflammatory conditions. This study aims to describe the impact of the updated definition on the classification of patients with MIS-C and Kawasaki Disease (KD).

METHODS

Patients hospitalized from March 2020 to November 2022 with clinician-diagnosed KD and MIS-C at a single center were studied retrospectively. Specificity and positive predictive value were assessed; McNemar test was used to compare specificity.

RESULTS

Among 119 patients with MIS-C per the 2020 definition, 20 (17%) did not fulfill the 2023 definition. Six of these 20 (30%) had shock or cardiac involvement. Of 59 KD patients, 10 (17%) met the 2020 MIS-C definition. Five patients (8%) met the 2023 MIS-C definition. Specificity for the 2020 and 2023 MIS-C definitions among KD patients were 83.1% and 91.5% respectively (McNemar, P = .0736). Positive predictive value was higher for the 2023 MIS-C case definition compared with the 2020 MIS-C case definition (95.2% vs 92.2%).

CONCLUSIONS

Approximately 1 in 5 patients diagnosed with MIS-C using the 2020 case definition did not meet the 2023 definition, including patients with cardiovascular dysfunction. Overlap persisted between patients meeting KD and 2023 MIS-C case definitions, with a false positive rate of 8%. Implications for treatment should be considered, particularly in settings where presumed MIS-C may be treated with corticosteroid monotherapy.

Monocytic Phagocytes in the Immunopathogenesis of Cytokine Storm Syndromes

Cytokine storm syndromes (CSSs) are caused by a dysregulated host immune response to an inciting systemic inflammatory trigger. This maladaptive and harmful immune response culminates in collateral damage to host tissues resulting in life-threatening multisystem organ failure. Knowledge of the various immune cells that contribute to CSS pathogenesis has improved dramatically in the past decade. Monocytes, dendritic cells, and macrophages, collective known as monocytic phagocytes, are well-positioned within the immune system hierarchy to make key contributions to the initiation, propagation, and amplification of the hyperinflammatory response in CSS. The plasticity of monocytic phagocytes also makes them prime candidates for mediating immunoregulatory and tissue-healing functions in patients who recover from cytokine storm-mediated immunopathology. Therefore, approaches to manipulate the myriad functions of monocytic phagocytes may improve the clinical outcome of CSS.

Impact of anakinra use on clinical outcomes in children with moderate or severe multisystem inflammatory syndrome in children: a propensity score matched retrospective cohort study

BACKGROUND

The treatment of children with multisystem inflammatory syndrome in children (MIS-C) related to SARS-CoV-2 infection involves immunomodulatory therapies such as IVIG and steroids. Anakinra, an interleukin-1 receptor inhibitor, has also been used, but its effectiveness is not established yet. As optimal regimens for MIS-C remain unknown, we aimed to assess the effect of anakinra in reducing hospital stay in patients with MIS-C.

METHODS

We included children admitted from May 2020 to May 2021 diagnosed with MIS-C based on CDC criteria. The exposure of interest was anakinra use at any point during admission. The anakinra exposed group and the anakinra unexposed group were propensity score matched based on demographic and clinical severity indicators at initial presentation. Our primary outcome was length of hospital stay. Secondary outcomes were duration of vasoactive support, vasoactive inotropic score (VIS), level of respiratory support, time to fever resolution, reduction of CRP levels, and length of ICU stay. We used Wilcoxon rank sum, t-test, Chi square and Fisher's exact tests.

RESULTS

Of 138 children diagnosed with MIS-C, 79% had moderate or severe illness and 41% received anakinra. Of those, 31 patients who received anakinra were propensity score matched to 31 who did not. The length of stay in the hospital but not in the ICU was longer in the anakinra group. There were no differences in median duration of vasoactive support, fever resolution, CRP reduction, or VIS.

CONCLUSIONS

In patients with moderate to severe MIS-C, use of anakinra was associated with longer duration of hospital stay.

Type I interferon signature and cycling lymphocytes in macrophage activation syndrome

BACKGROUNDMacrophage activation syndrome (MAS) is a life-threatening complication of Still's disease (SD) characterized by overt immune cell activation and cytokine storm. We aimed to further understand the immunologic landscape of SD and MAS.METHODWe profiled PBMCs from people in a healthy control group and patients with SD with or without MAS using bulk RNA-Seq and single-cell RNA-Seq (scRNA-Seq). We validated and expanded the findings by mass cytometry, flow cytometry, and in vitro studies.RESULTSBulk RNA-Seq of PBMCs from patients with SD-associated MAS revealed strong expression of genes associated with type I interferon (IFN-I) signaling and cell proliferation, in addition to the expected IFN-γ signal, compared with people in the healthy control group and patients with SD without MAS. scRNA-Seq analysis of more than 65,000 total PBMCs confirmed IFN-I and IFN-γ signatures and localized the cell proliferation signature to cycling CD38+HLA-DR+ cells within CD4+ T cell, CD8+ T cell, and NK cell populations. CD38+HLA-DR+ lymphocytes exhibited prominent IFN-γ production, glycolysis, and mTOR signaling. Cell-cell interaction modeling suggested a network linking CD38+HLA-DR+ lymphocytes with monocytes through IFN-γ signaling. Notably, the expansion of CD38+HLA-DR+ lymphocytes in MAS was greater than in other systemic inflammatory conditions in children. In vitro stimulation of PBMCs demonstrated that IFN-I and IL-15 - both elevated in MAS patients - synergistically augmented the generation of CD38+HLA-DR+ lymphocytes, while Janus kinase inhibition mitigated this response.CONCLUSIONMAS associated with SD is characterized by overproduction of IFN-I, which may act in synergy with IL-15 to generate CD38+HLA-DR+ cycling lymphocytes that produce IFN-γ.

Cardiac manifestations of multisystem inflammatory syndrome of children after SARS-CoV-2 infection: a systematic review and meta-analysis

This systematic review and meta-analysis were conducted to evaluate the prevalence of cardiac manifestations associated with multisystem inflammatory syndrome in children worldwide. We conducted electronic searches in Ovid MEDLINE, Ovid EMBASE, and the World Health Organization COVID-19 Literature Database from the inception of the SARS-CoV-2 pandemic to 1 January, 2022. Three authors independently screened the abstracts to determine eligibility, assessed methodology in the full texts, and extracted the data.We identified 2848 citations; 94 studies (14,932 patients) were included. The prevalence of vasopressors was 48.2% (95% CI 45.1%, 51.3%), left ventricular systolic dysfunction occurred in 37.2% (95% CI 34.1%, 40.3%), myocarditis in 34.1% (95% CI 30.5%, 37.8%), electrocardiographic dysrhythmias and abnormalities detected in 23.1% (95% CI 18.8%, 27.6%), coronary abnormalities identified in 18% (95% CI 16%, 20%), extracorporeal membrane oxygenation deployed in 2.2% (95% CI 1.7%, 2.8%), and mortality rate of 2.2% (95% CI 1.7%, 2.7%). A sensitivity analysis was performed after removing eleven studies with high bias, and the adjusted prevalence was not different than the original evaluation.In this meta-analysis of the largest cohort of multisystem inflammatory syndrome in children patients to date, we established the most accurate prevalence of the most common cardiac manifestations. Providers will subsequently have more precise data to anticipate patient outcomes and approach discussions concerning the frequency of monitoring outside the acute hospital period.

Clinical Utility of SARS-CoV-2 Serological Testing and Defining a Correlate of Protection

Herein, we review established clinical use cases for SARS-CoV-2 antibody measures, which include diagnosis of recent prior infection, isolating high titer convalescent plasma, diagnosing multisystem inflammatory syndrome in children (MIS-C), and booster dosing in the immunosuppressed and other populations. We then address whether an antibody correlate of protection (CoP) for SARS-CoV-2 has been successfully defined with the following considerations: Antibody responses in the immunocompetent, vaccine type, variants, use of binding antibody tests vs. neutralization tests, and endpoint measures. In the transition from the COVID-19 pandemic to endemic, there has been much interest in defining an antibody CoP. Due to the high mutability of respiratory viruses and our current knowledge of SARS-CoV-2 variants defining a CoP for prevention of infection is unrealistic. However, a CoP may be defined for prevention of severe disease requiring hospitalization and/or death. Most SARS-CoV-2 CoP research has focused on neutralization measurements. However, there can be significant differences in neutralization test methods, and disparate responses to new variants depending on format. Furthermore, neutralization assays are often impractical for high throughput applications (e.g., assessing humoral immune response in populations or large cohorts). Nevertheless, CoP studies using neutralization measures are reviewed to determine where there is consensus. Alternatively, binding antibody tests could be used to define a CoP. Binding antibody assays tend to be highly automatable, high throughput, and therefore practical for large population applications. Again, we review studies for consensus on binding antibody responses to vaccines, focusing on standardized results. Binding antibodies directed against the S1 receptor binding domain (S1-RBD) of the viral spike protein can provide a practical, indirect measure of neutralization. Initially, a response for S1-RBD antibodies may be selected that reflects the peak response in immunocompetent populations and may serve as a target for booster dosing in the immunocompromised. From existing studies reporting peak S1-RBD responses in standardized units, an approximate range of 1372-2744 BAU/mL for mRNA and recombinant protein vaccines was extracted that could serve as an initial CoP target. This target would need to be confirmed and potentially adjusted for updated vaccines, and almost certainly for other vaccine formats (i.e., viral vector). Alternatively, a threshold or response could be defined based on outcomes over time (i.e., prevention of severe disease). We also discuss the precedent for clinical measurement of antibodies for vaccine-preventable diseases (e.g., hepatitis B). Lastly, cellular immunity is briefly addressed for its importance in the nature and durability of protection.

Anti-Inflammatory and Immunomodulatory Effect of High-Dose Immunoglobulins in Children: From Approved Indications to Off-Label Use

BACKGROUND

The large-scale utilization of immunoglobulins in patients with inborn errors of immunity (IEIs) since 1952 prompted the discovery of their key role at high doses as immunomodulatory and anti-inflammatory therapy, in the treatment of IEI-related immune dysregulation disorders, according to labelled and off-label indications. Recent years have been dominated by a progressive imbalance between the gradual but constant increase in the use of immunoglobulins and their availability, exacerbated by the SARS-CoV-2 pandemic.

OBJECTIVES

To provide pragmatic indications for a need-based application of high-dose immunoglobulins in the pediatric context.

SOURCES

A literature search was performed using PubMed, from inception until 1st August 2023, including the following keywords: anti-inflammatory; children; high dose gammaglobulin; high dose immunoglobulin; immune dysregulation; immunomodulation; immunomodulatory; inflammation; intravenous gammaglobulin; intravenous immunoglobulin; off-label; pediatric; subcutaneous gammaglobulin; subcutaneous immunoglobulin. All article types were considered.

IMPLICATIONS

In the light of the current imbalance between gammaglobulins' demand and availability, this review advocates the urgency of a more conscious utilization of this medical product, giving indications about benefits, risks, cost-effectiveness, and administration routes of high-dose immunoglobulins in children with hematologic, neurologic, and inflammatory immune dysregulation disorders, prompting further research towards a responsible employment of gammaglobulins and improving the therapeutical decisional process.

Acute kidney injury in critically ill children with COVID-19 and MIS-C

BACKGROUND

This study's objective was to investigate the incidence of acute kidney injury (AKI) in children with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and multisystem inflammatory syndrome (MIS-C) and to report our clinical experience.

METHODS

Acute COVID-19 and MIS-C-diagnosed patients observed in two pediatric intensive care units (PICUs) between 2019 and 2021 were examined for AKI and retrospectively compared to children with AKI.

RESULTS

The study comprised 163 children, of whom 98 (60.1%) were diagnosed with acute COVID-19 and 65 (39.9%) with MIS-C. AKI was observed in 40 (40.8%) of the acute COVID-19 patients and 18 (27.7%) of the MIS-C patients. Low calcium level and hypotension were linked with AKI at initial presentation (OR: 0.56, 95% CI: 0.369-0.560, p = 0.006 and OR: 3.64, 95% CI: 1.885-7.152, p = 0.001, respectively). A history of nephrotoxic medication usage played an essential role in the development of AKI in patients who acquired AKI after hospitalization (p = 0.001, odds ratio: 9.32, confidence interval: 3.106-27.973). In clinical practice, individuals with respiratory distress and cough had a high chance of having AKI (OR: 4.47, 95% confidence interval: 2.25-8,892 and OR: 3.48, 95% confidence interval: 1.76-6.88). AKI patients had a greater demand for respiratory assistance and a longer period of stay in the PICU.

CONCLUSIONS

AKI in the COVID-19 and MIS-C patient groups is related with increased mortality and extended hospitalization, according to the findings. These statistics imply that identifying and preventing risk factors is necessary. A higher resolution version of the Graphical abstract is available as Supplementary information.

Distinguishing Incomplete Kawasaki and Nonsevere Multisystem Inflammatory Syndrome in Children

OBJECTIVES

Characterizing inflammatory syndromes during the coronavirus disease 2019 pandemic was complicated by recognition of multisystem inflammatory syndrome in children (MIS-C), contemporaneous with episodes of Kawasaki disease. We hypothesized a substantial overlap between the 2 and assessed the performance of an MIS-C likelihood score in differentiating inpatients with nonsevere MIS-C from prepandemic incomplete Kawasaki disease (iKD) without coronary involvement.

METHODS

A retrospective review of inpatient records was conducted; the nonsevere MIS-C cohort (March 2020-February 2021) met the 2023 definition for MIS-C; the iKD cohort (January 2018-January 2019) met the American Heart Association criteria for iKD without coronary involvement. We applied the likelihood score to both cohorts. We estimated the percent of children with iKD who could have met the clinical criteria of the MIS-C, had they presented in 2023.

RESULTS

The 68 children in the nonsevere MIS-C cohort were older (8 vs 4 years, P < .001) than the 28 children in the iKD cohort. Those in the nonsevere MIS-C cohort had higher rates of thrombocytopenia (P < .001) and lymphopenia (P = .021); those in the iKD cohort had higher rates of pyuria (P < .001). Twenty-four (86%) children in the iKD cohort met the 2023 MIS-C definition. The scoring system correctly predicted 71% to 74% children with their respective clinical diagnoses.

CONCLUSIONS

Though there was considerable clinical overlap, thrombocytopenia, lymphopenia, and the absence of pyuria were the most helpful parameters to distinguish children with nonsevere MIS-C from those with iKD.

Innate immune dysregulation in multisystem inflammatory syndrome in children (MIS-C)

MIS-C is a systemic inflammation disorder with poorly characterised immunopathological mechanisms. We compared changes in the systemic immune response in children with MIS-C (n = 12, 5-13 years) to healthy controls (n = 14, 5-15 years). Analysis was done in whole blood treated with LPS. Expression of CD11b and Toll-like receptor-4 (TLR4) in neutrophils and monocytes were analysed by flow cytometry. Serum cytokines (IL-1β, IL-2, IL-6, IL-8, IL-10, IL-Ira, TNF-α, TNF-β, IFN-Υ, VEGF, EPO and GM-CSF) and mRNA levels of inflammasome molecules (NLRP3, ASC and IL-1β) were evaluated. Subpopulations of lymphocytes (CD3+, CD19+, CD56+, CD4+, CD8+, TCR Vδ1+, TCR Vδ2+) were assessed at basal levels. Absolute counts of neutrophils and NLR were high in children with MIS-C while absolute counts of lymphocytes were low. Children with MIS-C had increased levels of IL-6, IL-10, TNF-β and VEGF serum cytokines at the basal level, and significantly increased TNF-β post-LPS, compared to controls. IL-1RA and EPO decreased at baseline and post-LPS in MIS-C patients compared to controls. The percentage of CD3+ cells, NK cells and Vδ1 was lower while B cells were higher in children with MIS-C than in controls. Dysregulated immune response in children with MIS-C was evident and may be amenable to immunomodulation.

The Local Anaesthetic Procaine Prodrugs ProcCluster® and Procaine Hydrochloride Impair SARS-CoV-2 Replication and Egress In Vitro

As vaccination efforts against SARS-CoV-2 progress in many countries, there is still an urgent need for efficient antiviral treatment strategies for those with severer disease courses, and lately, considerable efforts have been undertaken to repurpose existing drugs as antivirals. The local anaesthetic procaine has been investigated for antiviral properties against several viruses over the past decades. Here, we present data on the inhibitory effect of the procaine prodrugs ProcCluster® and procaine hydrochloride on SARS-CoV-2 infection in vitro. Both procaine prodrugs limit SARS-CoV-2 progeny virus titres as well as reduce interferon and cytokine responses in a proportional manner to the virus load. The addition of procaine during the early stages of the SARS-CoV-2 replication cycle in a cell culture first limits the production of subgenomic RNA transcripts, and later affects the replication of the viral genomic RNA. Interestingly, procaine additionally exerts a prominent effect on SARS-CoV-2 progeny virus release when added late during the replication cycle, when viral RNA production and protein production are already largely completed.

Stratification of Pediatric COVID-19 Cases Using Inflammatory Biomarker Profiling and Machine Learning

While pediatric COVID-19 is rarely severe, a small fraction of children infected with SARS-CoV-2 go on to develop multisystem inflammatory syndrome (MIS-C), with substantial morbidity. An objective method with high specificity and high sensitivity to identify current or imminent MIS-C in children infected with SARS-CoV-2 is highly desirable. The aim was to learn about an interpretable novel cytokine/chemokine assay panel providing such an objective classification. This retrospective study was conducted on four groups of pediatric patients seen at multiple sites of Texas Children's Hospital, Houston, TX who consented to provide blood samples to our COVID-19 Biorepository. Standard laboratory markers of inflammation and a novel cytokine/chemokine array were measured in blood samples of all patients. Group 1 consisted of 72 COVID-19, 70 MIS-C and 63 uninfected control patients seen between May 2020 and January 2021 and predominantly infected with pre-alpha variants. Group 2 consisted of 29 COVID-19 and 43 MIS-C patients seen between January and May 2021 infected predominantly with the alpha variant. Group 3 consisted of 30 COVID-19 and 32 MIS-C patients seen between August and October 2021 infected with alpha and/or delta variants. Group 4 consisted of 20 COVID-19 and 46 MIS-C patients seen between October 2021 andJanuary 2022 infected with delta and/or omicron variants. Group 1 was used to train an L1-regularized logistic regression model which was tested using five-fold cross validation, and then separately validated against the remaining naïve groups. The area under receiver operating curve (AUROC) and F1-score were used to quantify the performance of the cytokine/chemokine assay-based classifier. Standard laboratory markers predict MIS-C with a five-fold cross-validated AUROC of 0.86 ± 0.05 and an F1 score of 0.78 ± 0.07, while the cytokine/chemokine panel predicted MIS-C with a five-fold cross-validated AUROC of 0.95 ± 0.02 and an F1 score of 0.91 ± 0.04, with only sixteen of the forty-five cytokines/chemokines sufficient to achieve this performance. Tested on Group 2 the cytokine/chemokine panel yielded AUROC = 0.98 and F1 = 0.93, on Group 3 it yielded AUROC = 0.89 and F1 = 0.89, and on Group 4 AUROC = 0.99 and F1 = 0.97. Adding standard laboratory markers to the cytokine/chemokine panel did not improve performance. A top-10 subset of these 16 cytokines achieves equivalent performance on the validation data sets. Our findings demonstrate that a sixteen-cytokine/chemokine panel as well as the top ten subset provides a highly sensitive, and specific method to identify MIS-C in patients infected with SARS-CoV-2 of all the major variants identified to date.

Determination of Risk Factors for Severe Life-Threatening Course of Multisystem Inflammatory Syndrome Associated with COVID-19 in Children

Multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C) is a life-threatening condition that often requires intensive care unit (ICU) admission. The aim of this study was to determine risk factors for severe/life-threatening course of MIS-C. The study included 166 patients (99 boys, 67 girls) aged 4 months-17 years (median 8.2 years). The criterion of severity was the fact of ICU admission. To conduct a comparative analysis, MIS-C patients were divided into two groups: patients hospitalized in the ICU (n = 84, 50.6%) and those who did not need ICU admission (n = 82, 49.4%). Patients with a more severe course of MIS-C were significantly older. They had a higher frequency of signs such as rash, swelling, hepatomegaly, splenomegaly, and neurological and respiratory symptoms. Hypotension/shock and myocardial involvement were much more common in patients with severe MIS-C. These patients had a more significant increase in CRP, creatinine, troponin, and D-dimer levels. Additionally, the presence of macrophage activation syndrome was higher in patients admitted to the ICU. Conclusion: Nineteen predictors of severe course of MIS-C were found, out of which hepatomegaly, splenomegaly, D-dimer > 2568 ng/mL, troponin > 10 pg/mL were mainly associated with the probability of being classified as early predictors of severe MIS-C requiring ICU admission.

SARS-CoV-2 infection and recovery in children: Distinct T cell responses in MIS-C compared to COVID-19

SARS-CoV-2 infection for most children results in mild or minimal symptoms, though in rare cases severe disease can develop, including a multisystem inflammatory syndrome (MIS-C) with myocarditis. Here, we present longitudinal profiling of immune responses during acute disease and following recovery in children who developed MIS-C, relative to children who experienced more typical symptoms of COVID-19. T cells in acute MIS-C exhibited transient signatures of activation, inflammation, and tissue residency which correlated with cardiac disease severity, while T cells in acute COVID-19 upregulated markers of follicular helper T cells for promoting antibody production. The resultant memory immune response in recovery showed increased frequencies of virus-specific memory T cells with pro-inflammatory functions in children with prior MIS-C compared to COVID-19 while both cohorts generated comparable antibody responses. Together our results reveal distinct effector and memory T cell responses in pediatric SARS-CoV-2 infection delineated by clinical syndrome, and a potential role for tissue-derived T cells in the immune pathology of systemic disease.

Variation in Early Anakinra Use and Short-Term Outcomes in Multisystem Inflammatory Syndrome in Children

OBJECTIVE

Evidence regarding effectiveness of interleukin-1 receptor antagonism in multisystem inflammatory syndrome in children (MIS-C) is lacking. We characterized variation in initial treatment with anakinra and evaluated cardiovascular outcomes associated with adding anakinra to standard initial therapy.

METHODS

We conducted a retrospective cohort study of MIS-C cases in a US surveillance registry from November 2020 to December 2021. Day 0 was the first calendar day of immunomodulatory treatment. Factors associated with initial anakinra use (days 0-1) were identified. We compared cases in patients ages 2-20 years receiving intravenous immunoglobulin (IVIG) and glucocorticoids versus anakinra plus IVIG and/or glucocorticoids on days 0-1, using inverse probability weighting to balance disease severity. Primary outcomes were vasopressor requirement on day 3 and impaired left ventricular ejection fraction on days 3-4. The secondary outcome was 50% reduction in C-reactive protein on day 3.

RESULTS

Among 1,516 MIS-C cases at 44 sites, 193 (13%) patients received anakinra alone or with other immunomodulators as initial treatment (range 0-74% by site). Site accounted for 59% of residual variance in anakinra use. After balancing disease severity, initial treatment with anakinra plus IVIG and/or glucocorticoids (n = 121) versus IVIG plus glucocorticoids (n = 389) was not associated with significant differences in vasopressor requirement (25.6% versus 20.1%, respectively; risk ratio [RR] 1.27 [95% confidence interval (95% CI) 0.88-1.84]), ventricular dysfunction (33.7% versus 25.7%, respectively; RR 1.31 [95% CI 0.98-1.75]), or C-reactive protein reduction.

CONCLUSION

We identified substantial variation in initial anakinra use in a real-world population of children with MIS-C, but no average short-term improvement in cardiovascular outcomes associated with early addition of anakinra to IVIG and/or glucocorticoids compared to IVIG and glucocorticoids alone.

Multisystem inflammatory syndrome in children: another COVID-19 sequel

With the rapid expansion of the COVID-19 pandemic, the disease burden and its consequences on the paediatric population has been progressively recognised. Although COVID-19 infection in children presents as asymptomatic to mild illness, instances of hyperinflammation and multi-organ involvement following the viral infection have been described. This condition, known as the multisystem inflammatory syndrome in children (MIS-C), has gained a wide global attention. Despite the global efforts to uncover the disease characteristics and management, a clear pathogenesis and a unified treatment regimen have not been reached yet. This paper tackles the epidemiology of the MIS-C, discusses its suggested pathogenesis, drives through its varying clinical presentations, and evaluates the different treatment regimens employed in managing MIS-C.

Multisystem inflammatory syndrome in children and Kawasaki disease; comparison of their clinical findings and one-year follow-up-a cross-sectional study

BACKGROUND

Studies on Multisystem Inflammatory Syndrome in Children (MIS-C) and Kawasaki Disease (KD) have yielded inconsistent results and are lacking in Asian and African countries. This study aimed to compare the laboratory and clinical features, short-term outcomes, and one-year follow-ups of a large cohort of MIS-C and KD patients.

METHODS

Data from 176 MIS-C and 56 KD patients admitted to Tehran Children's Medical Center between January 2021 and January 2022 were collected. Patients were followed up until January 2023.

RESULTS

While lymphopenia and thrombocytopenia were more prevalent in MIS-C (73.2% vs. 20% in KD, p < 0.001), KD patients exhibited a higher median white blood cell count and prevalence of anemia, along with higher fibrinogen and erythrocyte sedimentation rate levels (p < 0.001, p < 0.001, p = 0.005, p < 0.001, respectively). MIS-C patients also exhibited lower ejection fraction, a greater occurrence of pericardial effusion, and a higher incidence of coronary aneurysms and ectasia, and ascites. Echocardiography after seven days of treatment showed a reduction in pathologies for both groups, but it was significant only for MIS-C. After one year, coronary artery abnormalities remained in only six cases.

CONCLUSIONS

In conclusion, this study highlights differences between MIS-C and KD, including laboratory indices as well as echocardiographic and abdominal ultrasound findings. These findings contribute valuable data on Iranian patients to the existing literature on this topic and have significant implications for accurate diagnosis and improved management of pediatric patients presenting with these conditions.

Cardiac involvement in multisystem inflammatory syndrome in children: single-centre experience

BACKGROUND

This study aimed to evaluate electrocardiographic and echocardiographic findings, Holter recordings of the multisystem inflammatory syndrome in children, and to identify prognostic factors for cardiac involvement.

METHODS

We retrospectively reviewed demographic characteristics, medical data, laboratory findings, electrocardiogram and echocardiographic findings, 24-hour Holter recordings, need for an ICU, and extracorporeal membrane oxygenation in multisystem inflammatory syndrome in children. Acute left ventricular systolic dysfunction was defined as left ventricular ejection fraction (EF) ≤%55 on echocardiography.

RESULTS

Sixty-seven children were included in the study. 24-hour Holters were recorded in 61.2% of the patients and 49.2% were normal. On echocardiographic examination, 14.9% of the patients had systolic dysfunction (EF ≤ 55%). While 32.8% of patients had mild mitral regurgitation, 3% had moderate mitral regurgitation, and 6% had mild aortic regurgitation. There was no statistically significant difference in EF values between the group with arrhythmia in Holter and the group with normal Holter results (p ≥ 0.05). B-type natriuretic peptide was positively correlated with C-reactive protein, ferritin, and fibrinogen. Significant effectivity of the B-type natriuretic peptide value was observed in the differentiation of those with EF ≤ and > 55%. Extracorporeal membrane oxygenation support was needed for three (4.5%) patients. One patient who died had systemic juvenile idiopathic arthritis.

CONCLUSIONS

Neutrophil/lymphocyte ratio, C-reactive protein, D-dimer, ferritin, troponin, and B-type natriuretic peptide were found to be significantly higher in patients with systolic dysfunction. Also, the cut-off value of 1700 pg/ml for B-type natriuretic peptide was significantly effective. These parameters may indicate the severity of the disease but should be supported by prospective studies.

[Kawasaki disease and multisystem inflammatory syndrome in children. Differences, and similarities in a pediatric center in Mexico]

OBJECTIVE

To evaluate the differences and similarities in clinical picture, laboratory findings and outcomes between children's with Kawasaki Disease (KD) versus multisystem inflammatory syndrome (MIS-C).

METHODS

We conducted a retrospective, comparative study from children with Kawasaki Disease (KD) hospi-talized in Sinaloa Pediatric Hospital from January 1, 2004, to March 31, 2020, and patients with multisystem inflammatory syndrome (MIS-C) according with World Health Organization (WHO) case definition criteria be-tween May 1, 2020 and May 31, 2021. Demographic characteristics, epidemiological data, clinical features, laboratory findings, type of treatment and clinical outcomes were compared among both groups.

RESULTS

Eighty-one patients were included (62 patients with KD and 19 with MIS-C). several clinical and lab-oratory differences were found among these two entities. Median age was lower in KD vs. MIS-C (25 vs 79 months). Those finding more frequent in KD were male gender (64.5 vs. 47.4%), Mucocutaneous features (93.5 vs. 63.2%): Oral changes (83.9 vs. 63.2%) and extremity changes (77.4 vs. 57.9%); complete form of KD was (75.8 vs. 47.4%), Coronary artery aneurysm (16.1 vs. 11.8%). Secondly, findings that were more frequent in MIS-C than KD were Gastrointestinal involvement (89.4 vs. 9.6%), shock (57.9 vs. 3.2%), neurological symp-toms (63.1 vs. 11.2%), kidney involvement (52.6 vs. 16.1%), heart disease in general (52.9% vs 29%): Myocardial dysfunction (23.5 vs. 11.3%) and pericardial effusion (17.6 vs. 2.9%). Lymphocyte count (2.07 + 2.03 vs. 4.28 + 3.01/mm3), platelet count (197.89 + 187.51 vs. 420.37 + 200.08/mm3); serum albumin (2.29 + 0.65 vs. 3.33 + 0.06g/dL), and CPR (21.4 + 11.23 vs. 14.26 + 12.37 mg/dL). KD vs. MIS-C types of Treatment: IVIG (96.8 vs. 94.7%), systemic steroids (4.82 vs. 94.7%), IVIG resistance (19.4 vs. 15.8). Finally, mortality in KD was 0% and 5.3% in MIS-C.

CONCLUSIONS

Similarities were found in both groups such as fever, rash, and conjunctivitis. Nevertheless, signifi-cant differences such as severity of clinical presentation with multi-organ involvement and worst inflammato-ry response were found more frequently in MIS-C group than KD group, requiring more fluid replacement, use of inotropic agents and higher steroids dosages. Also, mortality rate was higher in patients with MIS-C thanpatients with KD. Similar results have been observed in other studies where both disorders were compared.

Comparison of Clinical Manifestations of Kawasaki Disease According to SARS-CoV-2 Antibody Positivity

BACKGROUND

Kawasaki disease (KD) is the most common cause of acquired heart disease in paediatric patients, with infectious agents being the main cause. This study aimed to determine whether there are differences in the clinical manifestations of KD between patients with and without severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies.

METHODS

From January 1, 2021 to August 15, 2022, 82 patients with analysable echocardiographic data were diagnosed with KD. Twelve patients with multisystem inflammatory syndrome in children were excluded. Serologic tests were performed by chemiluminescence immunoassay for both the nucleocapsid (N) and the spike (S) proteins in blood samples. Among the 70 patients diagnosed with KD at Jeonbuk University Children's Hospital, the SARS-CoV-2 antibody test was performed in 41 patients.

RESULTS

The SARS-CoV-2 antibody test results for the N antigen were positive in 12 patients, while those for S protein were positive in 14 patients. N antigen SARS-CoV-2 antibody-positive KD was different from N antigen SARS-CoV-2 antibody-negative KD in terms of sex (male predominance in the positive group, 83.3% vs. female predominance in the negative group 62.1%, P = 0.008) and the incidence of refractory KD (41.7% vs. 10.3%, P = 0.034). The pro-B-type natriuretic peptide level was lower in the N-antigen SARS-CoV-2 antibody-positive KD group than that in the negative group (518.9 ± 382.6, 1,467.0 ± 2,417.6, P = 0.049). No significant differences in the echocardiographic findings between both groups were noted. In the multi-variable analysis, SARS-CoV-2 antibody (N antigen) was the only predictor of refractory KD (odds ratio, 13.70; 95% confidence interval, 1.63-115.44; P = 0.016).

CONCLUSION

High incidence of intravenous immunoglobulin-refractory KD may occur in up to 40% of the patients having recent history of coronavirus disease 2019. For patients having KD with N-type SARS-CoV-2 antibody positivity, adjunctive treatment, such as corticosteroids, can be considered as the first line of treatment.

COVID-19-induced liver injury in infants, children, and adolescents

Coronavirus disease 2019 (COVID-19) typically presents with fever and respiratory symptoms in children. Most children develop an asymptomatic and mild illness, with a minority requiring specialist medical care. Gastrointestinal manifestations and liver injury can also occur in children following infection. The mechanisms of liver injury may include infection following direct viral hepatic tissue invasion, immune response, or medication effects. Affected children might develop mild liver dysfunction which has a benign course in most children with no pre-existing liver disease. However, the presence of non-alcoholic fatty liver disease or other pre-existing chronic liver disorders is associated with a higher risk of developing severe COVID-19 illness with poor outcomes. On the other hand, the presence of liver manifestations is associated with the severity of COVID-19 disease and is considered an independent prognostic factor. Respiratory, hemodynamic, and nutritional supportive therapies are the mainstay of management. Vaccination of children at increased risk of developing severe COVID-19 disease is indicated. This review describes the liver manifestations in children with COVID-19, detailing its epidemiology, basic mechanisms, clinical expression, management, and prognosis in those with and without pre-existing liver disease and also children who have had earlier liver transplantation.

Cytokine Storm Syndromes in Pediatric Patients

Cytokine storm syndromes (CSS) represent a diverse group of disorders characterized by severe overactivation of the immune system. In the majority of patients, CSS arise from a combination of host factors, including genetic risk and predisposing conditions, and acute triggers such as infections. CSS present differently in adults than in children, who are more likely to present with monogenic forms of these disorders. Individual CSS are rare, but in aggregate represent an important cause of severe illness in both children and adults. We present 3 rare, illustrative cases of CSS in pediatric patients that describe the spectrum of CSS.

Case report: Fatal lung hyperinflammation in a preterm newborn with SARS-CoV-2 infection

Vertical transmission of SARS-CoV-2 from mother to fetus is widely accepted. Whereas most infected neonates present with mild symptoms or are asymptomatic, respiratory distress syndrome (RDS) and abnormal lung images are significantly more frequent in COVID-19 positive neonates than in non-infected newborns. Fatality is rare and discordant meta-analyses of case reports and series relating perinatal maternal COVID-19 status to neonatal disease severity complicate their extrapolation as prognostic indicators. A larger database of detailed case reports from more extreme cases will be required to establish therapeutic guidelines and allow informed decision making. Here we report an unusual case of a 28 weeks' gestation infant with perinatally acquired SARS-CoV-2, who developed severe protracted respiratory failure. Despite intensive care from birth with first line anti-viral and anti-inflammatory therapy, respiratory failure persisted, and death ensued at 5 months. Lung histopathology showed severe diffuse bronchopneumonia, and heart and lung immunohistochemistry confirmed macrophage infiltration, platelet activation and neutrophil extracellular trap formation consistent with late multisystem inflammation. To our knowledge, this is the first report of SARS CoV-2 pulmonary hyperinflammation in a preterm newborn with fatal outcome.

Evaluation of Autoantibody Binding to Cardiac Tissue in Multisystem Inflammatory Syndrome in Children and COVID-19 Vaccination-Induced Myocarditis

Importance

Cardiac dysfunction and myocarditis have emerged as serious complications of multisystem inflammatory syndrome in children (MIS-C) and vaccines against SARS-CoV-2. Understanding the role of autoantibodies in these conditions is essential for guiding MIS-C management and vaccination strategies in children.

Objective

To investigate the presence of anticardiac autoantibodies in MIS-C or COVID-19 vaccine-induced myocarditis.

Design, Setting, and Participants

This diagnostic study included children with acute MIS-C or acute vaccine myocarditis, adults with myocarditis or inflammatory cardiomyopathy, healthy children prior to the COVID-19 pandemic, and healthy COVID-19 vaccinated adults. Participants were recruited into research studies in the US, United Kingdom, and Austria starting January 2021. Immunoglobulin G (IgG), IgM, and IgA anticardiac autoantibodies were identified with immunofluorescence staining of left ventricular myocardial tissue from 2 human donors treated with sera from patients and controls. Secondary antibodies were fluorescein isothiocyanate-conjugated antihuman IgG, IgM, and IgA. Images were taken for detection of specific IgG, IgM, and IgA deposits and measurement of fluorescein isothiocyanate fluorescence intensity. Data were analyzed through March 10, 2023.

Main Outcomes and Measures

IgG, IgM and IgA antibody binding to cardiac tissue.

Results

By cohort, there were a total of 10 children with MIS-C (median [IQR] age, 10 [13-14] years; 6 male), 10 with vaccine myocarditis (median age, 15 [14-16] years; 10 male), 8 adults with myocarditis or inflammatory cardiomyopathy (median age, 55 [46-63] years; 6 male), 10 healthy pediatric controls (median age, 8 [13-14] years; 5 male), and 10 healthy vaccinated adults (all older than 21 years, 5 male). No antibody binding above background was observed in human cardiac tissue treated with sera from pediatric patients with MIS-C or vaccine myocarditis. One of the 8 adult patients with myocarditis or cardiomyopathy had positive IgG staining with raised fluorescence intensity (median [IQR] intensity, 11 060 [10 223-11 858] AU). There were no significant differences in median fluorescence intensity in all other patient cohorts compared with controls for IgG (MIS-C, 6033 [5834-6756] AU; vaccine myocarditis, 6392 [5710-6836] AU; adult myocarditis or inflammatory cardiomyopathy, 5688 [5277-5990] AU; healthy pediatric controls, 6235 [5924-6708] AU; healthy vaccinated adults, 7000 [6423-7739] AU), IgM (MIS-C, 3354 [3110-4043] AU; vaccine myocarditis, 3843 [3288-4748] AU; healthy pediatric controls, 3436 [3313-4237] AU; healthy vaccinated adults, 3543 [2997-4607] AU) and IgA (MIS-C, 3559 [2788-4466] AU; vaccine myocarditis, 4389 [2393-4780] AU; healthy pediatric controls, 3436 [2425-4077] AU; healthy vaccinated adults, 4561 [3164-6309] AU).

Conclusions and Relevance

This etiological diagnostic study found no evidence of antibodies from MIS-C and COVID-19 vaccine myocarditis serum binding cardiac tissue, suggesting that the cardiac pathology in both conditions is unlikely to be driven by direct anticardiac antibody-mediated mechanisms.

Incidence and Prevalence of Multisystem Inflammatory Syndrome in Children (MIS-C) in Southern Italy

Multisystem inflammatory syndrome in children (MIS-C) is a pediatric hyperinflammatory syndrome related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection whose epidemiology is not very well known at present. The objective of the study was to better understand the incidence of MIS-C in the Apulia region in southern Italy. Our primary goal was to estimate the incidence of newly identified cases of MIS-C in children aged 0-18 years, during a period of six months, encompassing the second pandemic wave. We also analyzed the characteristics of our cohort in terms of clinical features, treatment, and outcomes. The cumulative incidence of MIS-C was 3.27 per 100,000 residents between 0 and 18 years of age. In our cohort, gastrointestinal, mucocutaneous, and cardiac involvement were the most common clinical features. With our step-up approach to therapy, no patients required intensive care unit (ICU) admission and no cardiac sequelae after 6 months of onset were found in echocardiograms. Conclusion: Our epidemiological study of MIS-C in southern Italy showed unexpectedly overlapping figures with other US studies.

Stratification of Pediatric COVID-19 cases by inflammatory biomarker profiling and machine learning

An objective method to identify imminent or current Multi-Inflammatory Syndrome in Children (MIS-C) infected with SARS-CoV-2 is highly desirable. The aims was to define an algorithmically interpreted novel cytokine/chemokine assay panel providing such an objective classification. This study was conducted on 4 groups of patients seen at multiple sites of Texas Children's Hospital, Houston, TX who consented to provide blood samples to our COVID-19 Biorepository. Standard laboratory markers of inflammation and a novel cytokine/chemokine array were measured in blood samples of all patients. Group 1 consisted of 72 COVID-19, 66 MIS-C and 63 uninfected control patients seen between May 2020 and January 2021 and predominantly infected with pre-alpha variants. Group 2 consisted of 29 COVID-19 and 43 MIS-C patients seen between January-May 2021 infected predominantly with the alpha variant. Group 3 consisted of 30 COVID-19 and 32 MIS-C patients seen between August-October 2021 infected with alpha and/or delta variants. Group 4 consisted of 20 COVID-19 and 46 MIS-C patients seen between October 2021-January 2022 infected with delta and/or omicron variants. Group 1 was used to train a L1-regularized logistic regression model which was validated using 5-fold cross validation, and then separately validated against the remaining naïve groups. The area under receiver operating curve (AUROC) and F1-score were used to quantify the performance of the algorithmically interpreted cytokine/chemokine assay panel. Standard laboratory markers predict MIS-C with a 5-fold cross-validated AUROC of 0.86 ± 0.05 and an F1 score of 0.78 ± 0.07, while the cytokine/chemokine panel predicted MIS-C with a 5-fold cross-validated AUROC of 0.95 ± 0.02 and an F1 score of 0.91 ± 0.04, with only sixteen of the forty-five cytokines/chemokines sufficient to achieve this performance. Tested on Group 2 the cytokine/chemokine panel yielded AUROC =0.98, F1=0.93, on Group 3 it yielded AUROC=0.89, F1 = 0.89, and on Group 4 AUROC= 0.99, F1= 0.97). Adding standard laboratory markers to the cytokine/chemokine panel did not improve performance. A top-10 subset of these 16 cytokines achieves equivalent performance on the validation data sets. Our findings demonstrate that a sixteen-cytokine/chemokine panel as well as the top ten subset provides a sensitive, specific method to identify MIS-C in patients infected with SARS-CoV-2 of all the major variants identified to date.