Silber-resistente Pseudomonas aerug/nosa-Bakterien werden durch lokale LBP (Lipopolysaccharid binding protein) exprimierende Gentherapie in infizierten Verbrennungswunden reduziert

Introduction: LPS-Binding-Protein (LBP), a class I acute phase protein, is capable of enhancing inflammatory cytokine production in response to LPS (lipopolysaccharide, endotoxin). It also functions as an opsonin for Gram-negative bacteria and reduces by 10,000-fold the concentration of neutrophil derived BPI (bactericidal permeability increasing protein) necessary to kill Gram-negative bacteria. Wound infection after thermal injury is a major source of morbidity and mortality. By increasing LBP at the site of burn injury we anticipate increased wound bactericidal activity by potentiating neutrophil and macrophage recruitment, activation and bactericidal killing, therefore we hypothesize that increasing levels of LBP by means of local gene therapy leads to decreased bacterial infection in burn injury. Materials and Methods: 13 female inbred LBP-knockout (LBPko) mice and 13 age- and weight-matched pathogen-free C57b wild-type (C57BL6) mice received a 25% body surface partial thickness (IIb) burn wound. Postb the burn area received intradermal injection of 1010 pfu of designed adenoviral constructs expressing either rat-LBP or beta-galactosidase (control). After 72 hrs 105 Silvadene®-resistant P. aeruginosa were topically applied and occlusively covered. Another 72 hrs later, animals were sacrificed, the treated skin was harvested for histology and quantitative bacterial cultures. Results: In wild-type animals (C57BL6), treatment with LBP-adenovirus resulted in significantly lower bacterial counts than animals treated with the control adenovirus (p < 0.04). Overall, bacterial counts were reduced 44.3 fold. Histology, Western blotting and X-gal staining revealed efficacy of the experimental design and viral expression. Conclusions: Our findings demonstrate for the first time that local gene therapy-driven over-expression of LPS-binding-protein (LBP) can suppress bacterial infection within burn wounds. These findings confirm LBP’s importance in host immune defense against Gram-negative infection and support a possible feasibility of local gene therapy for the treatment of burn injuries.