IL10 and infection: The high levels of ISG15 induced locally in the FGT in response to Ct infection in WT mice, the exacerbated pathology and lower IL-10 levels observed in the FGT of infected ISG15−/− mice, and the evidence that ISG15 not only promotes an M2-like phenotype in macrophages but also counteracts the enhanced inflammatory response of polarized M1 macrophages in vitro, support the critical role of ISG15 in regulating inflammatory responses during chlamydial infection.