Protective Effects of Sphingosine 1-Phosphate in Murine Endotoxin-induced Inflammatory Lung Injury

Abstract

Our prior in vitro studies indicate that sphingosine 1-phosphate (S1P), a phospholipid angiogenic factor, produces endothelial cell barrier enhancement through ligation of endothelial differentiation gene family receptors. We hypothesized that S1P may reduce the vascular leak associated with acute lung injury and found that S1P infusion produced a rapid and significant reduction in lung weight gain (more than 50%) in the isolated perfused murine lung. The effect of S1P was next assessed in a murine model of LPS-mediated microvascular permeability and inflammation with marked increases in parameters of lung injury at both 6 and 24 hours after intratracheal LPS. Each parameter assessed was significantly reduced by intravenous S1P (1 microM final) and in selected experiments by the S1P analogue FTY720 (0.1 mg/kg, intraperitoneally) delivered 1 hour after LPS. S1P produced an approximately 40-50% reduction in LPS-mediated extravasation of Evans blue dye albumin, bronchoalveolar lavage protein content, and lung tissue myeloperoxidase activity (reflecting phagocyte infiltration). Consistent with systemic barrier enhancement, S1P significantly decreased Evans blue dye albumin extravasation and myeloperoxidase content in renal tissues of LPS-treated mice. These studies indicate that S1P significantly decreases pulmonary/renal vascular leakage and inflammation in a murine model of LPS-mediated acute lung injury and may represent a novel therapeutic strategy for vascular barrier dysfunction.

A transgenic mouse with vascular endothelial over-expression of the non-muscle myosin light chain kinase-2 isoform is susceptible to inflammatory lung injury: role of sexual dimorphism and age

“…Such mechanical ventilation is often combined together with an infectious injury to mimic clinical sepsis-induced ALI, [ 12 ], [ 40 ], [ 42 ], [ 63 ] and [ 64 ] although the direct effect of each challenge is difficult to dissociate. We assumed that high-volume ventilation will cause mechanical stress-related injury and hypothesized that the resulting barrier dysfunction [ 65 ] and [ 66 ] will be exacerbated by increases in EC paracellular gap formation in nmMLCK2 transgenic mice.…”

“…Despite the high success rate of embryo survival in hybrid strains, 39 we chose the B6 strain rather than a hybrid strain primarily because inbred strains eliminate ambiguity caused by different genetic backgrounds and segregating markers in the progeny, and secondarily because we are familiar with this strain in terms of their ALI/VALI responses. [ 40 ], [ 41 ] and [ 42 ] The transgene specific primers were J9 (forward; 5′-GTGGCTCCCCTCTCCCCTCCTG-3′) and J30 (reverse; 5′-CTTGGCGGTGGCTCCTTCTTTGAT-3′), which gave a 319-bp product. Mouse β-globin gene-specific primers J18 (forward; 5′-GGCAGCTCACAAGAAGAAGTTGGG-3′) and J19 (reverse; 5′-ATCAAAGTACCGCTGGGTCCAAGG-3′) that amplify a 138-bp band were included in all reactions as positive control.…”

“…The LPS-induced ALI model has been described previously. [ 40 ] and [ 41 ] Briefly, mice were anesthetized with intraperitoneal ketamine (150 mg/kg) and acetylpromazine (15 mg/kg) before the exposure of the trachea and the right internal jugular vein via neck incision. Sterile water (pH 7.0) or LPS (2.5 mg/kg in 50 μL of the same vehicle) were instilled intratracheally via a 20-gauge catheter.…”

Functional Genomic Insights into Acute Lung Injury: Role of Ventilators and Mechanical Stress

“…Next, we filtered the expression data by selecting those genes with significant (p Ͻ 0.05) unidirectional expression in response to mechanical stress across species, thereby further narrowing the list of potential targets to 141 genes. Finally, we excluded all genes that did not achieve at least a 1.35-fold change in expression, a filtering event which resulted in a final list of 69 VALI candidate genes (19). Figure 2 depicts this filtering approach used for the generation of a robust candidate gene list, which included data derived from a total of 25 Affymetrix chips.…”

“…Two canine models of ALI were used: a model of unilateral saline lavage-induced lung injury with subsequent high-volume mechanical ventilation (17), and a model of intrabronchially delivered endotoxin (LPS) followed by conventional mechanical ventilation (18). Two murine ALI models were also used: a model of intratracheal LPS alone and a second model with 2 h of high-volume mechanical ventilation (17 ml/kg) as the primary insult as we recently described (18,19). Control groups for canine and murine models were allowed to ventilate spontaneously.…”