Mount Sinai researchers have found an important clue to a rare but serious aftereffect of COVID-19 in children, known as multisystem inflammatory syndrome in children or MIS-C, according to a news release.
The researchers reported that RNA sequencing of blood samples from the Mount Sinai COVID-19 Biobank led to the discovery that specific infection-fighting cells of the immune system are downregulated in children with MIS-C, and that this is associated with a sustained inflammatory response, a hallmark of infection with SARS-CoV-2, the virus that causes COVID-19. The study was published in Nature Communications.
MIS-C is characterized by fever, pain and inflammation of multiple organs including the heart, lungs, kidneys, skin, eyes or gastrointestinal tract. More than 2,600 cases of MIS-C have been reported in the United States since the COVID-19 pandemic began. While an autoimmune condition has been suggested as an underlying cause, specific genes, pathways and cell types remain unknown.
One of the more significant gene networks implicated the suppression of two types of immune cells: natural killer (NK) cells and CD8+ T cells. Previous research has shown that when CD8+ T cells are persistently exposed to pathogens, they enter a state of “exhaustion,” resulting in a loss of their effectiveness and ability to proliferate. The researchers in the new study specifically pointed to the CD8+ T cells being in this exhausted state, thus, potentially weakening the inflammatory immune response. An increase in NK cells is also associated with exhausted CD8+ T cells.
