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A mouse model of lung injury induced by microbial products: implication of tumor necrosis factor
1Pulmonary Research Unit, Faculty of Medicine, University of Sherbrooke, Quebec, Canada.
Abstract:
Mice of the C57BL/6 strain were injected with bacterial lipopolysaccharide (LPS) followed by formylnorleucyl-leucyl-phenylalanine (FNLP) by the intraperitoneal route; markers of acute lung injury were examined in mice given a fusion protein of soluble human tumor necrosis factor-alpha (TNF-alpha) receptor (p80) linked to the Fc portion of human IgG (TNFR:Fc) or excipient. Challenge with LPS/FNLP elicited an adult respiratory distress syndrome-like pathology characterized by sharp increases in levels of lactate dehydrogenase (LDH) and total proteins in bronchoalveolar lavage as well as in lung myeloperoxidase (MPO) content at 16 and 20 h after challenge. Infusion of 1 mg of TNFR:Fc 2 h before challenge very significantly abrogated the increases in LDH, protein levels, and MPO. Histologic analysis revealed that LPS/FNLP infusion resulted in an intravascular neutrophil agglomerate and perivascular/peribronchial damage; the extent of tissue lesions was significantly reduced, but not abrogated, by TNF-alpha depletion. There were moderate levels of antigenic TNF-alpha in lung homogenates at 16 and 20 h after challenge, not affected by infusion with TNFR:Fc. No bioactive TNF-alpha was detected in lung homogenates of challenged mice given TNFR:Fc. High levels of antigenic interleukin-6 (IL-6) were found in lung homogenates of challenged mice treated with TNFR:Fc or with diluent. Elevated levels of antigenic IL-6 and TNF-alpha were found in sera of challenged mice at 16 and 20 h after injection; TNFR:Fc-treated mice had a higher level of antigenic TNF-alpha than did challenged mice given diluent, but it was not bioactive.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Tumor necrosis factor-alpha (TNF-alpha) receptor fusion protein (TNFR:Fc) significantly reduced acute lung injury markers in mice challenged with lipopolysaccharide (LPS) and formylnorleucyl-leucyl-phenylalanine (FNLP). This treatment mitigated neutrophil infiltration and tissue damage, indicating TNFR:Fc
Area of Science:
- Immunology
- Pulmonary Medicine
- Pharmacology
Background:
- Bacterial lipopolysaccharide (LPS) and formylnorleucyl-leucyl-phenylalanine (FNLP) induce acute lung injury (ALI) with adult respiratory distress syndrome (ARDS)-like pathology.
- Tumor necrosis factor-alpha (TNF-alpha) is implicated in ALI pathogenesis.
- Soluble TNF-alpha receptor fusion proteins offer potential therapeutic strategies for inflammatory lung diseases.
Purpose of the Study:
- To evaluate the efficacy of a soluble human TNF-alpha receptor (TNFR:Fc) fusion protein in mitigating LPS/FNLP-induced acute lung injury in a murine model.
- To assess the impact of TNFR:Fc on key markers of lung injury, including lactate dehydrogenase (LDH), total protein, and myeloperoxidase (MPO) levels.
- To investigate the histological changes and inflammatory mediator profiles following TNFR:Fc administration.
Main Methods:
- C57BL/6 mice were challenged with LPS/FNLP via intraperitoneal injection.
- Mice received either TNFR:Fc (1 mg) or excipient 2 hours prior to challenge.
- Markers of lung injury (LDH, total protein, MPO) were measured in bronchoalveolar lavage fluid and lung homogenates at 16 and 20 hours post-challenge.
- Histological analysis assessed neutrophil infiltration and tissue damage.
- Antigenic and bioactive levels of TNF-alpha and interleukin-6 (IL-6) were quantified.
Main Results:
- LPS/FNLP challenge significantly increased LDH, total protein, and MPO levels, indicative of ALI.
- Pre-treatment with TNFR:Fc significantly abrogated these increases in lung injury markers.
- Histological examination showed reduced neutrophil agglomerates and tissue lesions in TNFR:Fc treated mice, although not completely abrogated.
- While antigenic TNF-alpha was present, bioactive TNF-alpha was undetectable in TNFR:Fc treated mice.
- Elevated levels of antigenic IL-6 were observed in both TNFR:Fc treated and control groups.
Conclusions:
- The soluble TNF-alpha receptor fusion protein (TNFR:Fc) effectively ameliorates LPS/FNLP-induced acute lung injury in mice.
- TNFR:Fc treatment significantly reduces key biochemical markers and histological evidence of lung damage.
- The therapeutic effect is associated with the neutralization of bioactive TNF-alpha, suggesting its critical role in this ALI model.