Inflammatory bactericidal lectin RegIIIβ: Friend or foe for the host?

In the inflamed gut, the bactericidal lectin RegIII beta is massively produced by intestinal mucosa. RegIIIb binds peptidoglycan and lipid A respectively, and thus can kill certain Gram-positive and Gram-negative bacteria, including the gut commensal microbiota and enteropathogenic bacteria. Considering the expression pattern and bactericidal activity, RegIIIb is believed to be a host defense factor for protecting against the infection with enteropathogenic bacteria. However, it was poorly understood how RegIIIb recognizes the target bacteria and kill them, and how RegIIIb plays role(s) in infectious diarrhea. Therefore, our recent study has focused on RegIII beta-target recognition, killing of Gram-negative bacteria, and host protective functions of RegIIIb for infectious diarrhea inflicted by Salmonella Typhimurium. Here, we discuss novel insights into the protective role of RegIIIb in infectious diarrhea, and propose avenues towards novel therapeutic interventions for Salmonella diarrhea.