The AvrA protein is produced by Salmonella typhimurium, a pathogen that is a major cause of human gastroenteritis. It inhibits the NF-kappaB and JNK MAPK pathways, thereby suppressing inflammatory and apoptotic responses. We have formulated AvrA protein nanoparticles with diameters of ~100 nm. Therefore these AvrA protein nanoparticles can serve as both the therapeutic and the delivery vehicle. Initial in vivo studies show that AvrA nanoparticles reduce inflammation in mouse models of acute inflammation and colitis.