in Pigs Challenged with Escherichia coli Production and Intestinal T-Cell Responses rhamnosus on Serum Interleukin-17 Dose-Dependent Effects of Lactobacillus

(ETEC) strains are not only acommon cause of postweaning diarrhea in piglets (1) but arealso associated with children’s and traveler’s diarrhea (2, 3). Themost prevalent ETEC strains implicated in postweaning diarrheaexpress F4 (K88) fimbriae (4). Adaptive immune responses relyon differentiation of CD4 T-helper cells into subsets with dis-tinct effector functions best suited for host defense against invad-ingpathogens(5).Dependingonthecytokinemilieu,naiveCD4T-helpercellsdevelopintoTh1,Th2,Th17,orregulatoryT(Treg)cells (6). Th17 cells are characterized by the expression of inter-leukin-17 (IL-17) and IL-22 and reside primarily at barrier sur-faces, particularly the gut mucosa. In humans and mice, interleu-kin-17 is a cytokine with pleiotropic functions, including therecruitment and activation of neutrophils, which in turn orches-trate inflammatory responses (7–9). In humans, expression ofIL-17 mRNA increases in inflamed intestinal mucosa after