MAIT cell activation and dynamics studied in relation to COVID-19 disease severity
Since the start of the COVID-19 pandemic almost a year ago the COVID-19 research efforts have been unprecedented. However, COVID-19 immunopathogenesis is still relatively poorly understood.
Recently, researchers from several departments at the Karolinska Institute and Karolinska University Hospital (first authors: Tiphaine Parrot, Jean-Baptiste Gorin; PI and corresponding author: Johan K. Sandberg) published a study focused on the balance between protective and pathological immune responses in COVID-19.
Mucosa-associated invariant T (MAIT) cells that recognize bacterial metabolites and may function as innate-like sensors and mediators of antiviral responses represent between 1 to 10% of T cells in the circulation. The broad effector profile of MAIT cells is important for protection against pulmonary infections and helps recruit adaptive T cells to the lung. The aim of the study was to study changes in conventional and unconventional T cell subsets in patients with moderate or severe COVID-19 disease (N=24) compared to healthy donors (N=14) using flow cytometry.
The researchers found a profound and preferential decline in MAIT cells in the circulation in patients with active disease paired with strong activation. In addition, the researchers showed MAIT cell enrichment and pro-inflammatory IL-17A bias in the airways. In addition, they found that MAIT cell levels normalized in the convalescent phase. In summary, Parrot and Gorin and colleagues (2020) suggest that MAIT cells may be important to the immune response against SARS-CoV-2 and further indicate that they play a role in COVID-19 immunopathogenesis.
The researchers shared their findings early in a preprint on medRxiv (first version published on 01.09.2020) and has gained attention and citations. The data from the article is available from the article page on the Science Immunology website. This project is part of the Karolinska KI/K COVID-19 Immune Atlas.
The project is funded by grants to J.K.S. from the Swedish Research Council (2016-03052), the Swedish Cancer Society (CAN 2017/777), the Swedish Heart-Lung Foundation (20180675), the Center for Innovative Medicine (20190732), and Karolinska Institutet. K.S. was supported by the Center for Innovative Medicine (20180864). H.-G.L. and the Karolinska COVID-19 Study Group were supported by the Knut and Alice Wallenberg foundation and Nordstjernan AB.
Parrot T., Gorin J-B., Ponzetta A, Maleki K.T., Kammann T., Emgård J., Perez-Potti A., Sekine T., Rivera-Ballesteros O., The Karolinska COVID-19 Study Group, Gredmark-Russ S., Rooyackers O., Folkesson E., Eriksson L. I., Norrby-Teglund A., Ljunggren H-G., Björkström N. K., Aleman S., Buggert M., Klingström J., Strålin K., Sandberg J. K. Science Immunology, 5 (51), eabe1670 (2020).