Michael A West1, Ann Koons. 1. Department of Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA. mwest@northwestern.edu
Abstract
BACKGROUND: We previously showed that macrophages (MPhi) pretreated with bacterial endotoxin (lipopolysaccharide [LPS]) develop an altered state of LPS-responsiveness--"LPS tolerance": LPS tolerance was associated with inhibition of tumor necrosis factor (TNF) release and decreased extracellular signal-regulated kinase and p38 kinase activation when MPhi were restimulated with LPS. However, the concentration of LPS used for pretreatment (most frequently 10 ng/mL) may be much higher than LPS concentrations observed in patients. Therefore, in the current study we examined the effect of lower and higher pretreatment LPS concentrations on subsequent LPS-stimulated MPhi responses. METHODS: RAW 264.7 MPhi-like cells were pretreated in vitro (PreRx) for 24 hours in medium or a range of LPS concentrations (0 ng/mL, 1 ng/mL, 10 ng/mL, or 100 ng/mL of E. coli 0111B4 LPS). Culture medium was discarded after 24 hours and MPhi were restimulated with LPS (0 ng/mL, 1 ng/mL, 10 ng/mL or 100 ng/mL). Three different lots of LPS (Sigma) were used. Supernatant TNF secretion at 3 hour was measured using enzyme-linked immunosorbent assay (pg/mL +/- SEM). Statistics by Chi-square and student's t test. RESULTS: Pretreatment with 100 ng/mL of LPS profoundly inhibited TNF release at all LPS restimulation concentrations (p < 0.05 vs. Medium PreRx). In contrast, very low dose LPS pretreatment (1 ng/mL) significantly augmented TNF release versus medium (p < 0.05). There was no further augmentation observed when even lower doses of LPS (0.1 ng/mL) were used for pretreatment. Similar results were obtained with three different lots E. coli 0111B4 LPS or using LPS from E. coli 0127B8. CONCLUSION: Prior exposure of MPhi to bacterial ligands alters MPhi cytokine production in response to subsequent LPS-stimulated activation. This modulated MPhi response is critically dependent on the concentration of LPS pretreatment.
BACKGROUND: We previously showed that macrophages (MPhi) pretreated with bacterial endotoxin (lipopolysaccharide [LPS]) develop an altered state of LPS-responsiveness--"LPS tolerance": LPS tolerance was associated with inhibition of tumor necrosis factor (TNF) release and decreased extracellular signal-regulated kinase and p38 kinase activation when MPhi were restimulated with LPS. However, the concentration of LPS used for pretreatment (most frequently 10 ng/mL) may be much higher than LPS concentrations observed in patients. Therefore, in the current study we examined the effect of lower and higher pretreatment LPS concentrations on subsequent LPS-stimulated MPhi responses. METHODS: RAW 264.7 MPhi-like cells were pretreated in vitro (PreRx) for 24 hours in medium or a range of LPS concentrations (0 ng/mL, 1 ng/mL, 10 ng/mL, or 100 ng/mL of E. coli 0111B4 LPS). Culture medium was discarded after 24 hours and MPhi were restimulated with LPS (0 ng/mL, 1 ng/mL, 10 ng/mL or 100 ng/mL). Three different lots of LPS (Sigma) were used. Supernatant TNF secretion at 3 hour was measured using enzyme-linked immunosorbent assay (pg/mL +/- SEM). Statistics by Chi-square and student's t test. RESULTS: Pretreatment with 100 ng/mL of LPS profoundly inhibited TNF release at all LPS restimulation concentrations (p < 0.05 vs. Medium PreRx). In contrast, very low dose LPS pretreatment (1 ng/mL) significantly augmented TNF release versus medium (p < 0.05). There was no further augmentation observed when even lower doses of LPS (0.1 ng/mL) were used for pretreatment. Similar results were obtained with three different lots E. coli 0111B4 LPS or using LPS from E. coli 0127B8. CONCLUSION: Prior exposure of MPhi to bacterial ligands alters MPhi cytokine production in response to subsequent LPS-stimulated activation. This modulated MPhi response is critically dependent on the concentration of LPS pretreatment.
Authors: Christopher D Romero; Tushar K Varma; Jason B Hobbs; Aimee Reyes; Brandon Driver; Edward R Sherwood Journal: Infect Immun Date: 2011-06-06 Impact factor: 3.441
Authors: Matthew J Delano; Terri Thayer; Sonia Gabrilovich; Kindra M Kelly-Scumpia; Robert D Winfield; Philip O Scumpia; Alex G Cuenca; Elizabeth Warner; Shannon M Wallet; Mark A Wallet; Kerri A O'Malley; Reuben Ramphal; Michael Clare-Salzer; Philip A Efron; Clayton E Mathews; Lyle L Moldawer Journal: J Immunol Date: 2010-11-24 Impact factor: 5.422