S100A9 and myalgic encephalomeyelitis/chronic fatigue syndrome: S100-A9 promotes a proinflammatory and prothrombotic phenotype in endothelial cells, impairs cell-adhesion processes of the endothelium (thereby increasing vascular permeability, which coincides with the function of leukocyte recruitment and migration), and upregulates endothelial TSP-1 expression [143, 161] – a phenomenon which perhaps underlies the increase in TSP-1 exhibited by the ME/CFS group in this study.