Vascular endothelial growth factor increased the permeability of respiratory barrier in acute respiratory distress syndrome model in mice

Comparison of metabolic rates of ropivacaine in cerebrospinal fluid as inferred from plasma concentrations between elderly patients and young patients

BACKGROUND

With the aging of human society, more and more elderly patients have to undergo surgery and anesthesia. Clinical observations have indicated from time to time that spinal anesthesia in the elderly appears to last longer than in young people, although there is limited research in this area and the mechanism is unclear at present time. This research work is expected to help understand the decline of local anesthetic metabolism in cerebrospinal fluid of elderly patients so as to help them with precise anesthesia and rapid rehabilitation.

METHODS

Twenty patients with spinal anesthesia in orthopedic lower limb surgery were selected to study the rate of drug metabolism in cerebrospinal fluid in two age groups, i.e.,18-30 years old and 75-90 years old. Ropivacaine in peripheral blood is used as a probe to reflect the speed of drug metabolism in cerebrospinal fluid. The contents of total Aβ protein and hyaluronic acid in the cerebrospinal fluid were investigated as well.

RESULTS

The equivalent dose of ropivacaine anesthetizes the elderly group for a longer time. The metabolism rate of ropivacaine in an elderly patient was slower than that of a young patient. No significant difference in total Aβ protein between the two groups was observed while hyaluronic acid in the elderly group was significantly higher than that in the young group.

CONCLUSIONS

This study shows that the dose of ropivacaine should be reduced when used for anesthesia in elderly patients. The cumulation of ropivacaine and HA appears to imitate the degeneration of central lymphatic circulation metabolism in elderly people.

Plasma microRNA and metabolic changes associated with pediatric acute respiratory distress syndrome: a prospective cohort study

Acute respiratory distress syndrome is a heterogeneous pathophysiological process responsible for significant morbidity and mortality in pediatric intensive care patients. Diagnosis is defined by clinical characteristics that identify the syndrome after development. Subphenotyping patients at risk of progression to ARDS could provide the opportunity for therapeutic intervention. microRNAs, non-coding RNAs stable in circulation, are a promising biomarker candidate. We conducted a single-center prospective cohort study to evaluate random forest classification of microarray-quantified circulating microRNAs in critically ill pediatric patients. We additionally selected a sub-cohort for parallel metabolomics profiling as a pilot study for concurrent use of miRNAs and metabolites as circulating biomarkers. In 35 patients (n = 21 acute respiratory distress, n = 14 control) 15 microRNAs were differentially expressed. Unsupervised random forest classification accurately grouped ARDS and control patients with an area under the curve of 0.762, which was improved to 0.839 when subset to only patients with bacterial infection. Nine metabolites were differentially abundant between acute respiratory distress and control patients (n = 4, both groups) and abundance was highly correlated with miRNA expression. Random forest classification of microRNAs differentiated critically ill pediatric patients who developed acute respiratory distress relative to those who do not. The differential expression of microRNAs and metabolites provides a strong foundation for further work to validate their use as a prognostic biomarker.

N-acetylcysteine alleviates fine particulate matter (PM2.5)-induced lung injury by attenuation of ROS-mediated recruitment of neutrophils and Ly6Chigh monocytes and lung inflammation

BACKGROUND

Exposure to particulate matter (PM) may contribute to lung inflammation and injury. The therapeutic effect of N-acetylcysteine (NAC), a well-known antioxidant, with regards to the prevention and treatment of fine PM (PM2.5)-induced lung injury is poorly understood. This study aimed to determine the effect of PM2.5 on the recruitment of neutrophils and Ly6C^high monocytes into lung alveoli and the production of proinflammatory proteins by stimulating the generation of reactive oxygen species (ROS), and to investigate the therapeutic effect of NAC on PM2.5-induced lung injury.

METHODS

C57BL/6 mice were exposed to a single administration of PM2.5 (200 μg/100 μl/mouse) or phosphate-buffered saline (control) via intratracheal instillation. The mice were injected intratracheally via a microsprayer aerosolizer with NAC (20 or 40 mg/kg) 1 h before PM2.5 instillation and 24 h after PM2.5 instillation. Total protein, VEGF, IL-6, and TNF-α in bronchoalveolar lavage fluid (BALF) were measured. Oxidative stress was evaluated by determining levels of malondialdehyde (MDA) and nitrite in BALF. Flow cytometric analysis was used to identify and quantify neutrophils and Ly6C^high and Ly6C_low monocyte subsets.

RESULTS

Neutrophil count, total protein, and VEGF content in BALF significantly increased after PM2.5 exposure and reached the highest level on day 2. Increased levels of TNF-alpha, IL-6, nitrite, and MDA in BALF were also noted. Flow cytometric analysis showed increased recruitment of neutrophils and Ly6C^high, but not Ly6C^low monocytes, into lung alveoli. Treatment with NAC via the intratracheal spray significantly attenuated the recruitment of neutrophils and Ly6C^high monocytes into lung alveoli in PM2.5-treated mice in a dose-dependent manner. Furthermore, NAC significantly attenuated the production of total protein, VEGF, nitrite, and MDA in the mice with PM2.5-induced lung injury in a dose-dependent manner.

CONCLUSION

PM2.5-induced lung injury caused by the generation of oxidative stress led to the recruitment of neutrophils and Ly6C^high monocytes, and production of inflammatory proteins. NAC treatment alleviated PM2.5-induced lung injury by attenuating the ROS-mediated recruitment of neutrophils and Ly6C^high monocytes and lung inflammation.

Targeted Antagonism of Vascular Endothelial Growth Factor Reduces Mortality of Mice with Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is associated with a mortality of 45%. Our previous research indicated that anti-vascular endothelial growth factor (VEGF) could maintain the normal structure and function of the respiratory barrier. However, systemic application of VEGF antagonists would lead to animal death. This study attempts to study the targeted drug delivery for ARDS. In this study, we used soluble fms-like tyrosine kinase-1 (sFlt)-targeted ultrasound microbubbles to antagonize the effect of VEGF on lung tissue. Ninety male BALB/c mice were randomly assigned to 6 groups: phosphate buffer saline (PBS) group (PBS+PBS); blank group (PBS+empty microbubbles); lipopolysaccharide (LPS) group (LPS+PBS); ARDS group (LPS+empty microbubbles); control group (PBS+sFlt microbubbles); and treatment group (LPS+sFlt microbubbles). After administration of LPS or PBS in the corresponding groups, the sFlt-targeted microbubbles or empty microbubbles were injected into the blood circulation. Then the lungs were irradiated with ultrasound, which ruptured the drug-loaded microbubbles and helped release drugs to the lung tissues targeted. The lung injury score, lung wet/dry ratio (W/D), liver and kidney functions, and the mortality of the mice in all groups were investigated at the predetermined time point. The difference in mortality between groups was examined by Fisher test. Other data were analyzed by one-way analysis of variance (ANOVA). A value of P<0.05 indicates that the difference was significant. The results showed that the PaO₂ levels were normal in the PBS group, the blank group, and the control group. The LPS group and ARDS group showed significant hypoxia. PaO₂ was improved significantly in the treatment group. The lung injury score and W/D were normal in the PBS group, the blank group, and the control group. The lung injury score and W/D increased significantly in the LPS group and ARDS group and decreased in the treatment group (P<0.05). The mortality rate of the ARDS model was 60% (95% confidence interval 47.5%–72.5%), and that with sFlt-targeted microbubbles was significantly lower at only 40% (95% confidence interval 27.5%–52.5%, P<0.05). It was concluded that anti-VEGF with sFlt targeted ultrasound microbubbles attenuated the lung injury and ultimately reduced the 7-day mortality effectively. It might be a suitable therapeutic tool for the treatment of ARDS.

[Effect of human placental mesenchymal stem cells transplantation on pulmonary vascular endothelial permeability and lung injury repair in mice with acute lung injury]

OBJECTIVE

To investigate the effects of human placental mesenchymal stem cells (hPMSCs) transplantation on pulmonary vascular endothelial permeability and lung injury repair in mice with lipopolysaccharide (LPS)-induced acute lung injury (ALI).

METHODS

The hPMSCs were isolated from the human placental tissue by enzyme digestion and passaged. The cell phenotype of the 3rd generation hPMSCs was detected by flow cytometry. Twenty-four 6-week-old healthy male C57BL/6 mice were randomly divided into 3 groups ( n=8). The mice were instilled with LPS in the airway to prepare an ALI model in the ALI model group and the hPMSCs treatment group, and with saline in the control group. At 12 hours after LPS infusion, the mice were injected with 3rd generation hPMSCs via the tail vein in hPMSCs treatment group and with saline in the ALI model group and the control group. At 24 hours after injection, the lung tissues of all mice were taken. The pathological changes were observed by HE staining. The wet/dry mass ratio (W/D) of lung tissue was measured. The Evans blue leak test was used to detect the pulmonary vascular endothelial permea bility in mice. The expression of lung tissue permeability-related protein (VE-cadherin) was detected by Western blot.

RESULTS

Flow cytometry examination showed that the isolated cells had typical MSCs phenotypic characteristics. Mice in each group survived. The alveolar structure of the ALI model group significantly collapsed, a large number of inflammatory cells infiltrated, and local alveolar hemorrhage occurred; while the alveolar structure collapse of the hPMSCs treatment group significantly improved, inflammatory cells infiltration significantly reduced, and a few red blood cells were in the interstitial lung. W/D and exudation volume of Evans blue stain were significantly higher in the ALI model group than in the control group and the hPMSCs treatment group ( P<0.05), in the hPMSCs treatment group than in the control group ( P<0.05). The relative protein expression of VE-cadherin was significantly lower in the ALI model group than in the control group and the hPMSCs treatment group ( P<0.05), and in the hPMSCs treatment group than in the control group ( P<0.05).

CONCLUSION

Intravenous injection of hPMSCs can effectively reduce the increased pulmonary vascular endothelial permeability mediated by LPS, relieve the degree of lung tissue damage, and play a therapeutic role in ALI mice.

BMX Represses Thrombin-PAR1-Mediated Endothelial Permeability and Vascular Leakage During Early Sepsis

RATIONALE

BMX (bone marrow kinase on the X chromosome) is highly expressed in the arterial endothelium from the embryonic stage to the adult stage in mice. It is also expressed in microvessels and the lymphatics in response to pathological stimuli. However, its role in endothelial permeability and sepsis remains unknown.

OBJECTIVE

We aimed to delineate the function of BMX in thrombin-mediated endothelial permeability and the vascular leakage that occurs with sepsis in cecal ligation and puncture models.

METHODS AND RESULTS

The cecal ligation and puncture model was applied to WT (wild type) and BMX-KO (BMX global knockout) mice to induce sepsis. Meanwhile, the electric cell-substrate impedance sensing assay was used to detect transendothelial electrical resistance in vitro and, the modified Miles assay was used to evaluate vascular leakage in vivo. We showed that BMX loss caused lung injury and inflammation in early cecal ligation and puncture-induced sepsis. Disruption of BMX increased thrombin-mediated permeability in mice and cultured endothelial cells by 2- to 3-fold. The expression of BMX in macrophages, neutrophils, platelets, and lung epithelial cells was undetectable compared with that in endothelial cells, indicating that endothelium dysfunction, rather than leukocyte and platelet dysfunction, was involved in vascular permeability and sepsis. Mechanistically, biochemical and cellular analyses demonstrated that BMX specifically repressed thrombin-PAR1 (protease-activated receptor-1) signaling in endothelial cells by directly phosphorylating PAR1 and promoting its internalization and deactivation. Importantly, pretreatment with the selective PAR1 antagonist SCH79797 rescued BMX loss-mediated endothelial permeability and pulmonary leakage in early cecal ligation and puncture-induced sepsis.

CONCLUSIONS

Acting as a negative regulator of PAR1, BMX promotes PAR1 internalization and signal inactivation through PAR1 phosphorylation. Moreover, BMX-mediated PAR1 internalization attenuates endothelial permeability to protect vascular leakage during early sepsis.