An Escherichia coli strain expressing the
ovalbumin (OVA) 323-329 allergenic
peptide on the bacterial surface was evaluated for its ability to reduce the lung inflammatory response in mice allergic to OVA. BALB/c mice were rendered allergic by means of two
intraperitoneal injections of OVA suspended in
alum 5 days apart, and one intratracheal boost 1 week later. The mice were then treated with two intranasal, 1 week apart, doses of 4x10(9) E. coli-UH302 transformed with plasmids pST13 or pST13-OVA(323-339), which bear the OmpC
porin from Salmonella enterica serovar Typhi or the OmpC with the OVA allergenic 323-339 amino acid sequence inserted in the external loop 5. The allergic inflammatory reaction was evaluated on day 31, finding that mice treated with E. coli-UH302-pST13-OVA reduced four to seven times perivascular and peribronchial infiltrates, mucus production, goblet cell
hyperplasia and eosinophils when compared with mice treated with E. coli-UH302-pST13 or
saline solution. These results were consistent with a significant decrease of
IL-5 mRNA and induction of IFN-gamma
mRNA in cells from bronchio-alveolar lavages (BAL). Specific serum
IgE anti-OVA was also reduced, although the decrease did not reach statistical significance. These results demonstrate that the bacterial live vector bearing an allergenic
peptide successfully moderated two important components of
allergy,
pulmonary inflammation and mucus overproduction.