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Intraductal Injection of LPS as a Mouse Model of Mastitis: Signaling Visualized via an NF-κB Reporter Transgenic
Published on: September 4, 2012
Recombinant bovine soluble CD14 reduces severity of experimental Escherichia coli mastitis in mice
Jai-Wei Lee1, Max J Paape, Xin Zhao
1Department of Animal Science, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada.
Abstract:
Endotoxin, or lipopolysaccharide (LPS), is responsible for pathogenesis of infections induced by Gram-negative bacteria, such as E. coli. The cellular response to LPS is modulated by interactions among LPS, LPS-binding protein (LBP) and CD14. Accumulated evidence shows that the soluble form of CD14 (sCD14) competes with membrane-bound CD14 (mCD14) for LPS and plays a pivotal role in regulating bacterial infection and septic shock caused by Gram-negative bacteria. Recombinant bovine sCD14 (rbosCD14) was produced by transfected insect sf/9 cells and its biological function was evaluated in mice. Eighty-one 8-week old BALB/cj female mice were randomly assigned to two groups, and injected intraperitoneally with either LPS (8 microg/g of body weight, n = 41) or LPS plus rbosCD14 (6.8 microg/g of body weight, n = 40). Survival rate at 24 h after injection for mice injected with either LPS or LPS plus rbosCD14 was 30 and 72%, respectively (P < 0.01). At 48 h survival rate was 7 and 37%, respectively (P < 0.01). To investigate the protective effect of rbosCD14 on experimentally induced mastitis in mice, two abdominal contralateral mammary glands of 7 lactating BALB/cj mice were injected through the teat canal with 10-20 colony-forming units (CFU) of Escherichia coli. One gland simultaneously received rbosCD14 (6 microg) and the other saline. At 24 h after challenge, glands that received rbosCD14 had less swelling and hemorrhaging, significantly lower bacterial counts (P < 0.05) and lower concentrations of TNF-alpha (P < 0.05). Results indicate that rbosCD14 is biologically functional and reduces mortality in mice from endotoxin shock and severity of intramammary infection by E. coli.
Insights
Recombinant bovine soluble CD14 (rbosCD14) significantly improved survival rates in mice challenged with lipopolysaccharide (LPS) and reduced the severity of E. coli-induced mastitis, demonstrating its protective potential.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- Endotoxin (lipopolysaccharide, LPS) from Gram-negative bacteria drives infection pathogenesis.
- Soluble CD14 (sCD14) modulates cellular responses to LPS, competing with membrane-bound CD14 (mCD14).
- sCD14 plays a critical role in regulating bacterial infections and septic shock.
Purpose of the Study:
- To produce recombinant bovine sCD14 (rbosCD14) in insect cells.
- To evaluate the biological function and protective effects of rbosCD14 in mouse models of endotoxin shock and E. coli mastitis.
Main Methods:
- rbosCD14 was produced using transfected insect sf/9 cells.
- Mice were injected with LPS or LPS plus rbosCD14 to assess endotoxin shock survival.
- Experimental mastitis was induced in mice by intramammary E. coli challenge, with or without rbosCD14 treatment.
Main Results:
- rbosCD14 administration significantly increased 24-h and 48-h survival rates in mice challenged with LPS (72% vs 30% at 24h, 37% vs 7% at 48h).
- In E. coli-induced mastitis, rbosCD14 treatment led to reduced gland swelling, hemorrhaging, bacterial counts, and TNF-alpha concentrations.
- P-values indicated statistical significance for survival rates (P < 0.01) and mastitis parameters (P < 0.05).
Conclusions:
- rbosCD14 is biologically functional and demonstrates efficacy in vivo.
- rbosCD14 effectively reduces mortality associated with endotoxin shock.
- rbosCD14 mitigates the severity of intramammary infections caused by E. coli.
