A new study has been conducted by researchers from the Mount Sinai Health System in New York to investigate the cause of a rare but severe inflammatory syndrome in children after getting infected by the COVID virus.
According to the research, RNA sequencing of blood samples showed that some cells of the immune system were at lower levels in kids who developed multisystem inflammatory syndrome after the coronavirus infection. Experts say that the results show that lower levels of specific types of natural killer (NK) cells and “exhausted cytotoxic T cells” may be key to treat multisystem inflammatory syndrome in children (MIS-C). NK cells are cells that attack and kill viral cells.
Findings show that exposing cytotoxic cells to a pathogen for a longer period caused the cells to become “exhausted”. This result means that they are less effective in destroying pathogens and can no longer thrive, Medical News Today reported.
Dr. Noam D. Beckmann, a corresponding author in this study shared that “follow-up studies could identify drug targets that could prevent COVID-19 from progressing into MIS-C.”
MIS-C is a pediatric inflammatory multisystem syndrome, also known as Kawasaki-like disease. A very dangerous but rare condition that affects almost 11.4 of 100,000 people who are younger than 20 years. There had been 4,404 reported cases in the U.S. as of June 2021.
Symptoms of MIS-C include pain, fever, and inflammation in various areas of the body such as the heart, lungs, brain, eyes, skin, and gastrointestinal organs.
Scientists also suggest that MIS-C can be an autoimmune condition, but the exact mechanisms involved are yet to be determined. The study makes it more difficult because it is rare.
In recent studies, researchers found a reduction in the production of both the NK cells and exhausted T cells in children with multisystem inflammatory syndrome after contracting covid19 infection. They also saw the impact of a subset of T cells called cytotoxic T cells, or CD8 + T cells, cells that are essential in defending the body against viruses.
Researchers further investigated the pathway and found that NK cells and CD8+ T cells control each other. Depletion of NK cells also disturbed the CD8+ T- cell exhaustion. Authors said that “Disruption in CD8+ T-cell exhaustion can lead to severe and even fatal T-cell immunopathology after viral infection, whereas its presence can improve inflammatory disease symptoms.”
The well-detailed gene expression study also discovered nine key regulators connected with the cytotoxic cells. The expression of these nine regulators is high in the CD8+ T cells but observed that they are downregulated in children with MIS-C. the researchers pointed out that the regulator TBX21 is important because it is involved in the differentiation of exhausted cytotoxic cells. BX21 might be an essential therapeutic target in MIS-C after COVID-19.
On the limitations of this study, Dr. Danelle Fisher, FAAP, a pediatrician and chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, CA, said to Medical News Today.
“This study was a retrospective review of inflammatory markers in children with MIS-C, with a very small number of children studied. This minimizes the power of the study, and it would be important to look at larger numbers of children with MIS-C in future studies.”