For example, although it may be beneficial to administer recombinant TSG-6 as treatment for LPS-induced lung injury in mice [38], TSG-6 treatment for severe influenza may be detrimental due to its ability to upregulate cyclooxygenase-2 (COX-2), as COX-2 upregulation has been associated with increased morbidity and mortality in severe influenza [3], [55], [56]. This evidence concerns the gene PTGS2 and influenza.