This anti-tumor effect relies on IL-9-mediated tumor cytotoxicity and activation of CD8+ T cells (93, 94).In children with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia, miR-155 promotes Th9 cell differentiation by silencing the deacetylase Sirtuin 1 (SIRT1), exacerbating pulmonary inflammation (95). Here, SIRT1 is linked to inflammation.