The invention relates to a transgenic probiotic E. coli cell genetically engineered to express and secrete a nematode-derived immunomodulator. The cell comprises chromosomal E. coli DNA, wherein the genetic information for expression and secretion of the nematode-derived immunomodulator is integrated into the chromosomal E. coli DNA and wherein the E. coli cell is an auxotrophic cell lacking genetic information necessary for synthesizing a compound required for the growth of the E. coli cell.