Background: Hypertonic saline (HS) and pentoxifylline (PTX) have been shown to modulate polymorphonuclear neutrophil (PMN) functions after shock and sepsis. We hypothesized that a combination of HS and PTX (HSPTX) would down-regulate PMN functions and inflammatory mediator synthesis more effectively than each alone, possibly by acting at different steps of the signaling pathways, ultimately leading to an enhanced effect.
Methods: Whole blood from healthy volunteers was stimulated with lipopolysaccharide (LPS) (100 microg/mL), f-methionyl-leucyl-phenylalanine (1 micromol/L), and phorbol 12-myristate 13-acetate (1 microg/mL). Baseline oxidative burst was measured by flow cytometry. Two different concentrations of NaCl to achieve increases of 10 mmol/L (HS10) and 40 mmol/L (HS40) above isotonicity, simulating increases in sodium levels seen after infusion of 3% HS and 7.5% HS, were used. PTX (2 mmol/L), HS10, HS40, HSPTX10, and HSPTX40 were added to whole blood concomitantly to the activators. PMN CD14 and CD11b expression were measured by flow cytometry and tumor necrosis factor-alpha levels by enzyme-linked immunosorbent assay in LPS-stimulated whole blood.
Results: The combination of PTX with HS10 and with HS40 markedly decreased LPS- (27 +/- 7 and 23 +/- 6 vs. 100; p < 0.01), f-methionyl-leucyl-phenylalanine- (54 +/- 11 and 55 +/- 8 vs. 100; p < 0.05), and phorbol 12-myristate 13-acetate- (30 +/- 4 and 54 +/- 9 vs. 100; p < 0.01 and p < 0.05, respectively) induced PMN oxidative burst. Furthermore, a significant decrease in LPS-induced neutrophil CD11b expression after PTX treatment (79 +/- 5 vs. 100; p < 0.05) and HSPTX40 (68 +/- 7 vs. 100; p < 0.05) was observed. HSPTX10 (7 +/- 0.6; p < 0.001) or HSPTX40 (6 +/- 1.4; p < 0.001) markedly decreased tumor necrosis factor-alpha production to levels similar to those observed with PTX alone (6.5 +/- 0.5; p < 0.001) and significantly lower than HS10 (110 +/- 4.9; p < 0.001) and HS40 alone (83 +/- 1.5; p < 0.001)
Conclusion: HSPTX down-regulates neutrophil activation and proinflammatory mediator synthesis more effectively that HS alone. HSPTX may have significant applications as a novel fluid resuscitation strategy in hemorrhagic shock.