Immunization with a Pseudomonas aeruginosa elastase peptide reduces severity of experimental lung infections due to P-aeruginosa or Burkholderia cepacia

Pseudomonas aeruginosa and Burkholderia cepacia produce metalloproteases that effect lung injury. Two epitopes (peptides 15 and 42) previously identified on P. aeruginosa elastase induce the production of antibodies that neutralize protease activity, The effects of immunization with synthetic peptides based on these epitopes on experimental lung infections due to P. aeruginosa or B, cepacia were examined. Rats were immunized with peptides conjugated to keyhole limpet hemocyanin or tetanus toroid before infection. Immunization with peptide 15 (pep15) resulted in a decrease in total cells and polymorphonuclear leukocytes in bronchoalveolar lavage (BAL) fluid and a 50%-70% decrease in lung histopathologic changes, compared with findings in controls. Immunization with peptide 42 decreased cells in BAL fluid but did not decrease lung pathologic changes. Immunization with pep15 alone was just as effective in protecting against lung injury as immunization with a combination of both peptides. These studies suggest that immunization with pep15 can reduce the severity of lung infections due to P. aeruginosa or B, cepacia.