Therapeutic Induction of Endogenous Antibiotics for Improved Recovery in Shigellosis

Shigellosis is one of the major causes of morbidity and mortality in many developing countries. The continued emergence of antibiotic resistant strains has complicated the treatment of shigellosis and has increased the cost of treatment markedly. Antimicrobial peptides are considered as endogenous antibiotic. A mixture of these antimicrobial peptides (LL-37 and beta-defensin) drenches the mucosal epithelial surfaces forming a barrier for invading microorganisms. Recently, we found that Shigella down-regulates the expression of LL-37 and beta-defensin 1 (HBD-1) in the colon of patients during acute shigellosis thereby facilitating bacterial invasion. Both LL-37 and HBD-1 could inhibit the growth of various microbes e.g. S. dysenteriae type 1, S. flexneri, and S. boydii. Our study indicated that bacterial DNA might be a potential mediator for the down- regulation in vitro. Down-regulation of LL-37 and HBD-1 was also seen in watery diarrhea caused by other pathogens. Thus, bacteria-mediated down-regulation of our front line defenses could be one strategy evolved by the pathogens to subvert this host-defense mechanism. gene encoding LL-37 in cultured epithelial cell lines were up-regulated when treated with butyrate; butyrate decreased the severity of Shigella infections in rabbit model. We could reproduce our findings from human i.e. downregulation of CAP-18 (the rabbit homologue to human LL-37) in colon epithelia after infection with Shigella flexneri. CAP-18 reappeared after treatment of the infected rabbits with sodium butyrate. Thus, the rabbit model demonstrated the proof of principal. In this study, we aim to assess the efficacy of sodium butyrate enema in reduction of clinical symptoms and / severity, reduction of inflammatory responses and induction of endogenous antibiotic activity in the rectum in adult patients with shigellosis.