Tailored inflammation control is badly needed for the treatment of kinds of inflammatory diseases, such as atherosclerosis. IL-10 is a potent anti-inflammatory cytokine, while systemic and repeated delivery could cause detrimental side-effects due to immune repression. In this study, we have developed a nano-system to deliver inflammation-responsive mRNA preferentially into macrophages for tailored inflammation control. was engineered to harbor a modified HCV-IRES (hepatitis C virus internal ribosome entry site), in which the two miR-122 recognition sites were replaced by two miR-155 recognition sites. The translational responsiveness of the engineered mRNA to miR-155 was tested by Western blot or ELISA. Moreover, the engineered mRNA was passively encapsulated into exosomes by forced expression in donor cells. Therapeutic effects on atherosclerosis and the systemic leaky expression effects of the functionalized exosomes were analyzed in ApoE (Apolipoprotein E-deficient) mice. The engineered IRES- mRNA could be translationally activated in cells when miR-155 was forced expressed or in M1 polarized macrophages with endogenous miR-155 induced. In addition, the engineered IRES- mRNA, when encapsulated into the exosomes, could be efficiently delivered into macrophages and some other cell types in the plaque in ApoE mice. In the recipient cells of the plaque, the encapsulated mRNA was functionally translated into protein, with relatively low leaky in other tissues/organs without obvious inflammation. Consistent with the robust induction in the plaque, exosome-based delivery of the engineered could alleviate the atherosclerosis in ApoE mice. Our study established a potent platform for controlled inflammation control via exosome-based systemic and repeated delivery of engineered mRNA, which could be a promising strategy for atherosclerosis treatment.