Effects of E. Coli Infection on the Expressions of TGF-β/Smads Signaling Pathway in Broiler Intestine

ABSTRACT This experiment aimed to investigate whether Escherichia coli (E. coli) infection could affect the TGF-β/smads signaling pathway in the jejunal tissue of chickens. One-day-old Cobb 500 broilers were randomly divided into 2 groups and treated with intraperitoneal E. coli or broth injection. Clinical signs of the birds were assessed every day. Spleen and bursa of Fabricius of the birds, post-infection (pi), were collected to evaluate immune organ index. Jejunal tissues were collected to ascertain the expression of TGF-βs, TβRs, and Smads. The results showed that the infected birds had significantly higher index of the spleen (24hrs and 48hrs pi) compared with birds in the control group (p<0.05). The relative gene expression of TGF-β4 increased (p<0.05), while the expression of Smad7 down-regulated in the E. coli group (p<0.01). There was no significant difference in TGF-β2, TGF-β3, TβR I, TβR II, Smad2, Smad3 expression (p>0.05). In conclusion, TGF-β/Smad signaling pathway was associated with the immune response of broilers in E. coli infection and TGF-β4 was the main subtype interacting with E. coli infection.