Tissue coexpression of LBP and CD14 mRNA in a mouse model of sepsis

Lipopolysaccharide binding protein (LBP) markedly increases the sensitivity of immune cells to LPS and CD14 expression correlates with cellular responsiveness to LPS. LBP gene expression can be induced in multiple organs following injury and CD14 upregulation on monocytes correlates with the infection and mortality rates in severely injured patients. We sought to determine the time-course induction of LBP and CD14 gene expression following experimental peritonitis.

BALB/c mice were subjected to laparotomy alone or laparotomy with cecal ligation and puncture and treated with Imipenem. At serial time points, animals were sacrificed and tissues harvested for isolation of RNA and protein. LBP, CD14, and cytokine mRNAs were analyzed by Northern blot analysis and TaqMan fluorescent quantitative RT-PCR.

LBP and CD14 mRNA levels were significantly increased in all three organs from CLP mice compared to sham-operated mice. IL-1 mRNA levels increased in all three organs following CLP with significantly higher levels found in the lungs compared to the kidney and liver. No significant differences were noted in local TNF mRNA levels.

LBP, CD14, and IL-1 mRNA levels are induced concurrently in the lung, kidney, and liver after cecal ligation and puncture. Given the synergistic affect of LBP and CD14 in potentiating LPS-induced production of inflammatory cytokines and the hypothesized role of such cytokines in the etiology of MSOF following injury and sepsis, our findings suggest a mechanism by which these organs may be rendered more susceptible to a "second hit" from endotoxemia after initial injury.