Multisystem Inflammatory Syndrome (MIS-C) Could Be Triggered By High Antiviral Antibody Levels In COVID-19 Infected Children

Multisystem Inflammatory Syndrome or MIS-C could be triggered by high antiviral antibody levels in COVID-19 Infected Children according to researchers from at Emory University School of Medicine and Children's Healthcare of Atlanta.


 
The study team said that measuring blood antibody levels against SARS-CoV-2 may distinguish children with multisystem inflammatory syndrome (MIS-C), which appears to be a serious but growing complication of viral infection.
 
The study findings are published in the journal: Pediatrics, the official journal of the American Academy of Pediatrics. https://pediatrics.aappublications.org/content/early/2020/08/31/peds.2020-018242
 
The study team found that children with MIS-C had significantly higher levels of antiviral antibodies ie more than 10 times higher compared to children with milder symptoms of COVID-19.
 
The research findings could help doctors establish the diagnosis of MIS-C and figure out which children are likely to need extra anti-inflammatory treatments.
 
It should be noted that children with MIS-C often develop cardiac problems and low blood pressure requiring intensive care.
 
According to Dr Christina Rostad, MD, assistant professor of pediatrics at Emory University School of Medicine and an infectious disease specialist at Children's Healthcare of Atlanta and senior author Dr Preeti Jaggi, MD, associate professor of pediatrics (infectious disease) at Emory University School of Medicine and Children's Healthcare of Atlanta, the high antibody levels may represent an exaggerated immune response or a delayed complication of COVID-19 or a combination of both.
 
Dr Jaggi told Thailand Medical News, "One of the challenges in interpreting these findings in children with MIS-C is that we do not know when they were actually infected with the virus. The rapid emergence of MIS-C has required both physicians at Children's and researchers at Emory to work collaboratively to quickly understand the clinical course of the disease, treatments, and pathophysiology and has required a huge team effort from clinicians and basic scientists."
 
Children's physicians have continued to see cases of COVID-19, and more than 50 cases of MIS-C have met the definition of MIS-C requiring hospitalization in the Children's Healthcare system. These figures are growing each week.
 
Dr Rostad said, "These cases underscore the importance of all the efforts we are taking as a community to decrease transmission of this virus. By wearing a mask, washing your hands, and avoiding large gatherings, you may be saving someone's life.”
 
According to the U.S. Centers for Disease Control and Prevention, patients with MIS-C usually present with persistent fever, abdominal pain, vomiting, diarrhea, skin rashes, and severe cases have low blood pressure and shock.
 
The manner to how MIS-C develops remains mysterious.
 
Emerging studies have suggested that it arrives in a second wave of inflammation, after initial viral infecti on.
 
Interestingly none of the children with MIS-C studied by the Emory and Children's researchers recalled having a previous fever or respiratory illness, even though they had high levels of antiviral antibodies. However, the majority tested negative for an active infection (by RT-PCR) at the point of their hospitalization.
 
The study team says that it "seems paradoxical" that children without preceding symptoms of SARS-CoV-2 infection develop such robust immune responses. It may hint that although some children with active infections lack symptoms, they are still capable of developing robust and aberrant immune responses associated with MIS-C.
 
Dr Rostad added, "These studies provide supportive evidence that MIS-C represents an aberrant immune response to SARS-CoV-2 infection in children. However, the mechanisms of this disease process and the reasons why some children develop symptoms while others do not remain areas of active research."
Initially when they first came to the hospital, children with MIS-C mainly displayed gastrointestinal and respiratory symptoms.
 
However several of them developed myocardial dysfunction with decreased ejection fraction, which is a measure of the heart's ability to pump blood. All patients with MIS-C needed to be hospitalized in intensive care because of low blood pressure.
 
The research team studied 10 children hospitalized with MIS-C between March and May 2020 of which 10 with symptomatic COVID-19, five with Kawasaki disease and four hospitalized controls. Kawasaki disease is a pediatric inflammatory disease affecting blood vessels, including the coronary arteries, which shares some features with MIS-C. The average age of the children with MIS-C was 8.5 years.
 
Importantly, the time elapsed between symptom onset and the time antibody samples were taken varied, generally between 0 and 20 days, with a few in the MIS-C group later than 20 days.
 
The study team used tests for antibodies against the receptor binding-domain of the viral spike protein and the viral nucleocapsid protein using assays developed in the laboratory of co-author Dr Jens Wrammert, Ph.D. They also performed live-virus neutralization assays in the laboratory of co-author Dr Mehul Suthar, Ph.D.


 
Infographic showing CDC criteria for MIS-C diagnosis. Combination of fever, inflammation, involvement of at least two organ systems and prior evidence of SARS-CoV-2 infection required. Credit: Nakra et al Children (2020) via Creative Commons.

In the study all the children with MIS-C were treated with intravenous immunoglobulin (a mixture of donated antibodies) and half received corticosteroids, a common anti-inflammatory medication.
 
However some of the COVID-19 group was treated with antiviral or immunomodulatory drugs such as remdesivir (4 children) and convalescent plasma (2).
 
A t the end of the study, all the children with MIS-C eventually returned home.
 
However two of the patients with symptomatic COVID-19 were being treated for leukemia and died due to their underlying disease processes.

For more about Multisystem Inflammatory Syndrome or MIS-C, keep on logging to Thailand Medical News.