The Effects of Prone Position Ventilation on Experimental Mild Acute Lung Injury Induced by Intraperitoneal Lipopolysaccharide Injection in Rats

Suppressive Effects of GSS on Lipopolysaccharide-Induced Endothelial Cell Injury and ALI via TNF-α and IL-6

Background. Under septic conditions, LPS induced lung vascular endothelial cell (EC) injury, and the release of inflammatory mediator launches and aggravates acute lung injury (ALI). There are no effective therapeutic options for ALI. Genistein-3'-sodium sulfonate (GSS) is a derivative of native soy isoflavone, which exhibits neuroprotective effects via its antiapoptosis property. However, whether GSS protect against sepsis-induced EC injury and release of inflammatory mediators has not been determined. In this study, we found that GSS not only downregulated the levels of TNF-α and IL-6 in the lung and serum of mice in vivo but also inhibited the expression and secretion of TNF-α and IL-6 in ECs. Importantly, we also found that GSS blocked LPS-induced TNF-α and IL-6 expression in ECs via the Myd88/NF-κB signaling pathway. Taken together, our results demonstrated that GSS might be a promising candidate for sepsis-induced ALI via its regulating effects on inflammatory response in lung ECs.

Immediate Prone Positioning After Massive Gastric Aspiration Reduces Lung Injury Possibly by Attenuating Interleukin-6-Mediated Lung-Tissue Inflammation in Pigs

Gastric aspiration, which can cause acute, diffuse, inflammatory lung injury, is of particular concern in critically ill patients. This study aimed to determine the effects of immediate prone positioning on the degree of lung injury and inflammatory response induced by gastric aspiration. Following induction of gastric aspiration by injection of gastric fluid, 16 healthy pigs were randomized to one of two groups: supine position (SP) or prone position (PP). After ventilation and monitoring for 6 hr, all pigs were euthanized. The ratio of the partial pressure of arterial oxygen/fraction of inspired oxygen (P_aO2/F_IO2) and the partial pressure of arterial carbon dioxide (P_aCO2) were recorded during the 6-hr study period. Serum levels of interleukin (IL)-6 were measured every 2 hr, and the mean optical density (MOD) of IL-6 in lung tissues and lung-injury scores were measured at the end of the experiment. The PP group showed a significantly higher P_aO2/F_IO2 ratio, lower serum IL-6 concentration (p = .015), lower lung-injury scores (p = .012), and lower IL-6 concentration and MOD of IL-6 in lung tissue, especially in dorsal (p = .001, p = .021, respectively) and nondependent regions (p = .005, p = .035, respectively) than the SP group. There were no statistically significant differences in P_aCO2 between the groups. Lung-injury severity was positively correlated with the IL-6 concentration and MOD of IL-6 in lung tissues (p < .05). These results suggest that immediate prone positioning alleviated the degree of aspiration-induced lung injury, possibly through mitigating IL-6-mediated lung inflammation.

Unfractionated heparin ameliorates pulmonary microvascular endothelial barrier dysfunction via microtubule stabilization in acute lung injury

Background

Endothelial barrier dysfunction is central to the pathogenesis of sepsis-associated acute lung injury (ALI). Microtubule (MT) dynamics in vascular endothelium are crucial for the regulation of endothelial barrier function. Unfractionated heparin (UFH) possesses various biological activities, such as anti-inflammatory activity and endothelial barrier protection during sepsis.

Methods

Here, we investigated the effects and underlying mechanisms of UFH on lipopolysaccharide (LPS)-induced endothelial barrier dysfunction. C57BL/6 J mice were randomized into vehicle, UFH, LPS and LPS + UFH groups. Intraperitoneal injection of 30 mg/kg LPS was used to induce sepsis. Mice in the LPS + UFH group received intravenous UFH 0.5 h prior to LPS injection. Human pulmonary microvascular endothelial cells (HPMECs) were cultured for analyzing the effects of UFH on LPS-induced and nocodazole-induced hyperpermeability, F-actin remodeling, and LPS-induced p38 MAPK activation.

Results

UFH pretreatment significantly attenuated LPS-induced pulmonary histopathological changes, and increased the lung W/D ratio and Evans blue accumulation in vivo. Both in vivo and in vitro studies showed that UFH pretreatment blocked the LPS-induced increase in guanine nucleotide exchange factor (GEF-H1) expression and myosin phosphatase target subunit 1 (MYPT1) phosphorylation, and microtubule (MT) disassembly in LPS-induced ALI mouse model and human pulmonary microvascular endothelial cells (HPMECs). These results suggested that UFH ameliorated LPS-induced endothelial barrier dysfunction by inhibiting MT disassembly and GEF-H1 expression. In addition, UFH attenuated LPS-induced hyperpermeability of HPMECs and F-actin remodeling. In vitro, UFH pretreatment inhibited LPS-induced increase in monomeric tubulin expression and decrease in tubulin polymerization and acetylation. Meanwhile, UFH ameliorates nocodazole-induced MTs disassembly and endothelial barrier dysfunction.Additionally, UFH decreased p38 phosphorylation and activation, which was similar to the effect of the p38 MAPK inhibitor, SB203580.

Conclusions

UFH exert its protective effects on pulmonary microvascular endothelial barrier dysfunction via microtubule stabilization and is associated with the p38 MAPK pathway.

Anti-Semaphorin-7A single chain antibody demonstrates beneficial effects on pulmonary inflammation during acute lung injury

Pulmonary inflammation is a primary characteristic of lung injury initiated by the accession of immune cells into the alveolar space. Neutrophil migration serves an important role in pulmonary inflammation mediated by the migration of neutrophils into hypoxic tissue sites. The elimination of pulmonary inflammation is directly associated with rehabilitation in patients with lung injury. Anti-inflammatory treatment is essential following lung injury and ultimately determines patient outcomes. Semaphorin-7A (SEMA-7A) is a member of the Semaphorin family that influences the migration of neutrophils into hypoxic tissue sites, thus promoting inflammation. However, understanding of the role of SEMA-7A serves during lung injury is limited and the immunological function of SEMA-7A during the migration of neutrophils into acute injury sites remains unknown. The present study investigated SEMA-7A expression and constructed a single chain antibody for SEMA-7A (Anti-SEMA-7A) to study its therapeutic efficacy against pulmonary inflammation in a mouse model of acute injury sites. The data indicated that the expression of SEMA-7A was upregulated due to induction by pro-inflammatory cytokines and demonstrated that Anti-SEMA-7A inhibited SEMA-7A expression in vitro and in vivo. The current study also indicated that the production of pro-inflammatory cytokines induced by SEMA-7A in endothelial and epithelial cells enhanced pulmonary inflammation. Anti-SEMA-7A suppressed the transendothelial migration of neutrophils mediated by SEMA-7A. Anti-SEMA-7A treatment neutralized SEMA-7A expression and reduced signs of pulmonary inflammation, leading to the elimination of pulmonary inflammation in rat with acute lung injury. The current study identified Anti-SEMA-7A as a potential agent to interfere with the inflammatory pathway during acute lung injury, which may be the basis for anti-inflammatory strategies to treat lung injuries in the future.