FIS1 and Sepsis: It has been proved that the expression of Fis1, Mfn2, parkin and PGC-1α in peripheral blood mononuclear cells (PBMCs) could give us some information about the mitochondrial quality control status (15–19), and considering the immune cell death during sepsis (20, 21), MQC-related proteins in the immune cells could continuously release into circulation, making the detection of these proteins in serum possible.