Bacteroides fragilis strain ZY-312 promotes intestinal barrier integrity via upregulating the STAT3 pathway in a radiation-induced intestinal injury mouse model

Abstract

Radiation-induced intestinal injury is characterized by intestinal barrier impairment. However, the therapeutic effects of probiotics for intestinal epithelial barrier repair in a mouse model of radiation-induced intestinal injury remain unclear. Previously, we isolated a strain of <i>Bacteroides fragilis</i> from the feces of a healthy infant and named it as <i>B. fragilis</i> strain ZY-312 (<i>B. fragilis</i>). In this study, we showed that <i>B. fragilis</i> can ameliorate radiation-induced intestinal injury in mice, manifested by decreased weight loss, intestinal length shortening, and intestinal epithelial cell (IEC) shedding. Moreover, we found that <i>B. fragilis</i> promoted IEC proliferation, stem cell regeneration, mucus secretion, and tight junction integrity by upregulating the STAT3 signaling pathway, through an experimental verification in <i>Stat3</i> ^△IEC mice (STAT3 defects in intestinal epithelial cells). Thus, the underlying protective mechanism of <i>B. fragilis</i> in radiation-induced intestinal injury is related to IEC proliferation, stem cell regeneration, goblet cell secretion, and tight junction repair <i>via</i> activation of the STAT3 signaling pathway. In addition, the therapeutic effects of <i>B. fragilis</i> were studied to provide new insights into its application as a functional and clinical drug for radiation-induced intestinal injury after radiotherapy.