RvD1 accelerates the resolution of inflammation by promoting apoptosis of the recruited macrophages via the ALX/FasL-FasR/caspase-3 signaling pathway.

The uncontrolled inflammatory response caused by a disorder in inflammation resolution is one of the reasons for acute respiratory distress syndrome (ARDS). The macrophage pool markedly expands when inflammatory monocytes, known as recruited macrophages, migrate from the circulation to the lung. The persistent presence of recruited macrophages leads to chronic inflammation in the resolution phase of inflammation. On the contrary, elimination of the recruited macrophages at the injury site leads to the rapid resolution of inflammation. Resolvin D1 (RvD1) is an endogenous lipid mediator derived from docosahexaenoic acid. Mice were administered RvD1 via the tail vein 3 and 4 days after stimulation with lipopolysaccharide. RvD1 reduced the levels of the inflammatory factors in the lung tissue, promoted the anti-inflammatory M2 phenotype, and enhanced the phagocytic function of recruited macrophages to alleviate acute lung injury. We also found that the number of macrophages was decreased in BAL fluid after treatment with RvD1. RvD1 increased the apoptosis of recruited macrophages partly via the FasL-FasR/caspase-3 signaling pathway, and this effect could be blocked by Boc-2, an ALX/PRP2 inhibitor. Taken together, our findings reinforce the concept of therapeutic targeting leading to the apoptosis of recruited macrophages. Thus, RvD1 may provide a new therapy for the resolution of ARDS.

Resolvin Conjugates in Tissue Regeneration 1 Promote Alveolar Fluid Clearance by Activating Alveolar Epithelial Sodium Channels and Na, K-ATPase in Lipopolysaccharide-Induced Acute Lung Injury.

Acute respiratory distress syndrome (ARDS), a common and fatal clinical condition, is characterized by the destruction of epithelium and augmented permeability of the alveolar-capillary barrier. Resolvin conjugates in tissue regeneration 1 (RCTR1) is an endogenous lipid mediator derived from docosahexaenoic acid , exerting proresolution effects in the process of inflammation. In our research, we evaluated the role of RCTR1 in alveolar fluid clearance (AFC) in lipopolysaccharide-induced ARDS/acute lung injury (ALI) rat model. Rats were injected with RCTR1 (5 µg/kg) via caudal veins 8 hours after lipopolysaccharide (LPS) (14 mg/kg) treatment, and then AFC was estimated after 1 hour of ventilation. Primary type II alveolar epithelial cells were incubated with LPS (1 ug/ml) with or without RCTR1 (10 nM) for 8 hours. Our results showed that RCTR1 significantly enhanced the survival rate, promoted the AFC, and alleviated LPS-induced ARDS/ALI in vivo. Furthermore, RCTR1 remarkably elevated the protein expression of sodium channels and Na, K-ATPase and the activity of Na, K-ATPase in vivo and in vitro. Additionally, RCTR1 also decreased neural precursor cell expressed developmentally downregulated 4-2 (Nedd4-2) level via upregulating Ser473-phosphorylated-Akt expression. Besides this, inhibitors of receptor for lipoxin A4 (ALX), cAMP, and phosphatidylinositol 3-kinase (PI3K) (BOC-2, KH-7, and LY294002) notably inhibited the effects of RCTR1 on AFC. In summary, RCTR1 enhances the protein levels of sodium channels and Na, K-ATPase and the Na, K-ATPase activity to improve AFC in ALI through ALX/cAMP/PI3K/Nedd4-2 pathway, suggesting that RCTR1 may become a therapeutic drug for ARDS/ALI. SIGNIFICANCE STATEMENT: RCTR1, an endogenous lipid mediator, enhanced the rate of AFC to accelerate the resolution of inflammation in the LPS-induced murine lung injury model. RCTR1 upregulates the expression of epithelial sodium channels (ENaCs) and Na, K-ATPase in vivo and in vitro to accelerate the AFC. The efficacy of RCTR1 on the ENaC and Na, K-ATPase level was in an ALX/cAMP/PI3K/Nedd4-2-dependent manner.

Rosuvastatin Enhances Alveolar Fluid Clearance in Lipopolysaccharide-Induced Acute Lung Injury by Activating the Expression of Sodium Channel and Na,K-ATPase via the PI3K/AKT/Nedd4-2 Pathway.

BACKGROUND: Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are devastating clinical conditions characterized by pulmonary epithelial damage and protein-rich fluid accumulation in the alveolar spaces. Statins are a class of HMG-CoA reductase inhibitors, which exert cholesterol-lowering and anti-inflammatory effects. METHODS: Rosuvastatin (1 mg/kg) was injected intravenously in rats 12 h before lipopolysaccharide (LPS, 10 mg/kg) administration. Eight hours later after LPS challenge, alveolar fluid clearance (AFC) was detected in rats (n = 6-8). Rosuvastatin (0.3 µmol/mL) and LPS were cultured with primary rat alveolar type II epithelial cells for 8 h. RESULTS: Rosuvastatin obviously improved AFC and attenuated lung-tissue damage in ALI model. Moreover, it enhanced AFC by increasing sodium channel and Na,K-ATPase protein expression. It also up-regulated P-Akt via reducing Nedd4-2 in vivo and in vitro. Furthermore, LY294002 blocked the increase in AFC in response to rosuvastatin. Rosuvastatin-induced AFC was found to be partly rely on sodium channel and Na,K-ATPase expression via the PI3K/AKT/Nedd4-2 pathway. CONCLUSION: In summary, the findings of our study revealed the potential role of rosuvastatin in the management of ALI/ARDS.

Determination of five neurotransmitters in the rat brain for the study of the hypnotic effects of Ziziphi Spinosae Semen aqueous extract on insomnia rat model by UPLC-MS/MS.

Ziziphi Spinosae Semen (ZSS) has been used for treatment of insomnia in China for centuries. To reveal the influence of insomnia on the levels of the neurotransmitters including serotonin (5-HT), glutamic acid (Glu), γ-aminobutyric acid (GABA), noradrenaline (NE) and dopamine (DA), and to study the role of ZSS aqueous extract in the treatment of insomnia, an UPLC-ESI- MS/MS method was developed and validated for simultaneous determination of five neurotransmitters in the rat brain. The brain samples were pretreated by one-step direct protein precipitation with acetonitrile. The analytes were detected in positive mode with multiple reaction monitoring (MRM) and the procedure was completed in less than 10 min. The method showed a good linearity (R2 > 0.9967) with the other validation parameters were within acceptance range. The results indicated that the concentration of 5-HT, GABA and DA is significantly lower (P < 0.01) in para-chlorophenylalanine (PCPA)-induced insomnia rat model group, while Glu and NE significantly higher than those in control group (P < 0.01). Treatment with ZSS aqueous extract (4 or 8 g·kg-1·d-1 for seven days) could ameliorate the symptoms of insomnia by significantly changing the levels of the neurotransmitter parameters mentioned above. The data obtained in this study demonstrate that ZSS aqueous extract could ameliorate the symptoms of insomnia by modulating the levels of monoamines and amino acid neurotransmitters in the brain.