Identification of 14-series sulfido-conjugated mediators that promote resolution of infection and organ protection

Abstract

Upon infection and inflammation, tissue repair and regeneration are essential in reestablishing function. Here we identified potent molecules present in self-limited infectious murine exudates, regenerating planaria, and human milk as well as macrophages that stimulate tissue regeneration in planaria and are proresolving. Characterization of their physical properties and isotope tracking indicated that the bioactive structures contained docosahexaenoic acid and sulfido-conjugate (SC) of triene double bonds that proved to be 13-glutathionyl, 14-hydroxy-docosahexaenoic acid (SCI) and 13-cysteinylglycinyl, 14-hydroxy-docosahexaenoic acid (SCII). These molecules rescued Escherichia coli infection-mediated delay in tissue regeneration in planaria, improving regeneration intervals from similar to 4.2 to similar to 3.7 d. Administration of SCs protected mice from second-organ reflow injury, promoting repair via limiting neutrophil infiltration, up-regulating Ki67, and Roof plate-specific spondin 3. At nanomolar potencies these conjugates also resolved E. coli infections by limiting neutrophil infiltration and stimulating bacterial phagocytosis and clearance as well as efferocytosis of apoptotic cells. Together, these findings identify previously undescribed conserved chemical signals and pathways in planaria, mouse, and human tissues that enhance host responses to contain infections, stimulate resolution of inflammation, and promote the restoration of function.