LPS induced PCT production via TLR-4/NF-кB passway:it is the difference of G−/G+ bacteremia rats

Abstract

Sepsis by Gram-negative bacteria infection leads to further increase in procalcitonin (PCT). Herein, we examined the expression of PCT after 24 h in rats by injecting Escherichia coli (E. coli) or Staphylococcus aureus (SA). Healthy male SD rats were divided into six groups (n = 8): (1) Control group: no treatment; (2) SA group: injected with 106CFU/ml SA suspension 0.1 ml in the tail vein; (3) SA and antibiotics group: injected with 106/ml SA bacterial suspension 0.1 ml and 4 mg/kg Cefotaxime sodium, q8h in the tail vein; (4) E. coli group: injected with 106CFU/ml E. coli suspension 0.1 ml in the tail vein; (5) E. coli and antibiotics group: injected with 106/ml E. coli bacterial suspension 0.1 ml and 4 mg/kg Cefotaxime sodium, q8h in the tail vein; and (6) Endotoxin group: injected with 5 mg/kg endotoxin in the tail vein. Expression of PCT was significantly increased in the E. coli, SA or endotoxin-induced bacteremia rats than in the control rats. Compared with SA, PCT was more significantly increased in E. coli rats. NF-κB changes were in line with PCT. Next, we investigated whether the expression of PCT decreased when TLR4 or NF-κB were inhibited after injecting E. coli in rats. A total of 40 healthy male SD rats were divided into five groups (n = 8): (1) Control group: no treatment; (2) E. coli group: injected with 106CFU/ml E. coli suspension 0.1 ml in the tail vein. (3) E. coli and PBS group: injected with 106CFU/ml E. coli suspension 0.1 ml and PBS 0.1 ml in the tail vein. (4) E. coli and TAK242: injected with 106CFU/ml E. coli suspension 0.1 ml and 3 mg/kg TAK242 in the tail vein. (5) E. coli and BAY-11–7082: injected with 106/ml E. coli suspension 0.1 ml and 25 mg/kg BAY-11–7082 in the tail vein. A marked increase of TLR4, NF-κB, LPS and PCT expression was observed in the lungs after E. coli induced bacteremia. Expressions of TLR4, NF-κB, and PCT proteins were decreased in the lungs at 24 h after injection of TAK-242 or BAY-11–7082. In summary, this study suggested that LPS is the key factor for differential expression of PCT between E. coli and SA bacteremia. E. coli induces PCT elevation via the TLR4/NF-κB pathway.