Dietary genistein supplementation improves intestinal mucosal barrier function in Escherichia coli O78-challenged broilers

Genistein has multiple biological activities in both humans and animals. However, a protective effect of genistein on Escherichia coli (E. coli)-induced intestinal mucosal barrier dysfunction remains unknown. In the present study, a total of 288 1-day-old male Arbor Acre broilers fed a corn-soybean basal diet unsupplemented or supplemented with 20 mg genistein/kg diet were subjected to E. coli serotype O78 (10⁸ cfu per bird) infection or equal volume of sodium chloride at 19 days of age. Sera and tissue samples were collected 2 days after E. coli infection. Growth performance, index of immune-related organs, intestinal barrier permeability, protein level of inflammatory cytokines, sIgA, tight junction protein, and mRNA level of apoptotic genes in jejunum were determined. Mortality rate at 7 days post infection was recorded. The results showed that E. coli challenge led to a reduced average daily gain, a decreased thymus index, and bursal index in broilers, an increase of fluorescein isothiocyanate (FITC)-dextran in serum, and a decreased sIgA in jejunum. These effects were abrogated by genistein administration. Western blot results showed that E. coli infection led to increased protein level of claudin-1 and zonula occludens (ZO)-1, which was largely abolished by genistein. Moreover, E. coli infection resulted increased protein level of TNF-α and IL-6, enhanced mRNA level of Bax and caspase-3, as well as decreased mRNA level of Bcl-2 were abrogated by genistein in jujunum of broilers. In conclusion, the results indicate that genistein supplementation improves intestinal mucosal barrier function which is associated with a regulatory effect on tight junction proteins, sIgA, apoptosis, and secretion of inflammatory cytokines in jejunum of E. coli-challenged broilers.