Effects of prostaglandin E2 receptor on the activation of inflammasomes and cell damage in human retinal microvascular endothelial cells in a high-glucose environment / 中华眼底病杂志

Objective:To observe the effects of four prostaglandin E2 (PGE2) receptors (EP 1-4R) on the activation of inflammasomes and cell damage in human retinal microvascular endothelial cells (hRMEC) in a high glucose environment. Methods:The hRMEC were divided into normal group and high glucose group, and they were cultured in Dulbecco modified Eagle medium containing 5.5 and 30.0 mmol/L glucose, respectively. Flow cytometry was used to observe the apoptosis rate of the high glucose group and the normal group; enzyme chain immunosorbent assay (ELISA) was used to detect the level of PGE2 in the culture supernatant of hRMEC cells. Western blot was used to detect the protein expression of cyclooxyganese (COX2) and EP 1-4R in hRMEC. Real-time fluorescent quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of EP 1-4R mRNA in hRMEC. After 72 h of culture, the cells in the high glucose group were divided into control group, PGE2 group, EP 1-4R agonist group, PGE2+EP 1-4R inhibitor group, and dimethylsulfoxide group. According to the group, each group was given the corresponding agonist or inhibitor to continue the culture for 24 h. QRT-PCR was used to detect the expression of nucleotide-binding oligomerization structure-like receptor protein (NLRP3) and pro-interleukin (IL)-1β mRNA in each group of cells. ELISA was used to detect the content of IL-1β and lactic dehydrogenase (LDH) in the cell culture supernatant. Western blot was used to detect the expression of cleaved Caspase-1 in each group of cells. At the same time, hRMEC in a high glucose environment was given IL-1β stimulation for 24 h, and the activity of LDH in the supernatant of the cell culture medium was detected. Results:The apoptotic rate, COX2 protein expression, and PGE2 protein content in hRMEC in the high glucose group were significantly higher than those in the normal group, and they were time-dependent. Compared with the normal group, the expression levels of EP 1R, EP 2R, EP 4R protein and mRNA in hRMEC in the high glucose group were higher than those in the normal group ( P<0.05). Compared with the control group, PGE2 group ( t=4.627, P<0.01), EP 1-4R agonist group ( t=3.889, 3.583, 2.445, 3.216; P<0.05) hRMEC NLRP3 mRNA expression level was significantly increased; the expression level of pro-IL-1β mRNA increased, however the difference was not statistically significant (PGE2 group: t=1.807, P>0.05; EP 1-4R agonist group: t=1.807, 1.477, 0.302, 1.926, P>0.05). Compared with the PGE2 group, the expression of NLRP3 mRNA in hRMEC in the PGE2+EP 2R inhibitor group was significantly reduced ( t=2.812, P<0.05); the expression of pro-IL-1β mRNA in hRMEC in the PGE2+EP 3R inhibitor group was significantly increased ( t=4.113, P<0.01). The protein content of IL-1β in the cell culture supernatant of the PGE2 group, EP 1R agonist group and EP 2R agonist group was significantly higher than that of the control group ( t=5.155, 4.136, 4.817; P<0.01). Compared with PGE2 group, the protein content of IL-1β in the cell culture supernatant of the PGE2+EP 2R inhibitor group and the PGE2+EP 4R inhibitor group were significantly lower than that of the PGE2 group ( t=1.964, 4.765; P<0.05). The expression of cleaved Caspase-1 in hRMEC in the PGE2 group and EP 2R agonist group was significantly higher than that in the control group ( t=5.332, 4.889; P<0.05). The expression of cleaved Caspase-1 in hRMEC in the PGE2+EP 2R inhibitor group was significantly lower than that of the PGE2 group ( t=6.699, P<0.01). The LDH activity in the cell culture supernatant of the PGE2 group and the EP 2R agonist group was significantly higher than that of the control group ( t=4.908, 4.225; P<0.05). The activity of LDH in the cell culture supernatant of the PGE2+EP 2R inhibitor group was significantly lower than that of the PGE2 group ( t=5.301, P<0.01). Compared with the control group, the LDH activity in the culture supernatant of hRMEC cells in the high glucose environment was significantly increased ( t=3.499, P<0.05). Conclusions:The four receptors of PGE2 can activate NLRP3 and its effector molecules to varying degrees. EP 2R mainly mediates hRMEC damage under high glucose environment.

Effects of alprostadil in β-aminopropanitrile induced aortic dissection in a murine model / 中华心血管病杂志

Objective: To investigate the protective role of alprostadil on aortic dissection. Methods: 26 C57BL6 male mice were divided into control group (normal drinking water, n=13) and model group (1 g·kg-1·d-1 BAPN via drinking water, n=13). On day 14, mRNA expression of inflammatory-related genes as well as EP receptor families were detected by RT-PCR (n=6 each) and EP4 protein levels were determined by Western blot (n=7 each). Another 88 mice were divided into 3 groups: control group (n=22), model group (n=33) and treatment group (n=33). The mice in model group and treatment group were applied with BAPN (1 g·kg-1·d-1) via drinking water. The mice in treatment group received additional intraperitoneal injection with alprostadil (80 μg·kg-1·d-1) for 28 days. The mice in the control and model group received equal volume intraperitoneal injection with 0.9% saline respectively. The body weight and systolic blood pressure, the mortality and morbidity were monitored from the beginning until the designed end of the study. On day 28, the mice were sacrificed and aorta were fixed, embedded and sliced, followed by staining with HE and Victoria Blue. The distribution of EP4 was determined by immunohistochemistry in control (n=6) and model group (n=6). Furthermore, the concentration of PGE1 were tested among model (n=3) and treatment group (n=4). EP4 protein expression was determined in model group (n=7) and treatment group (n=6). Results: On day 14, mRNA expression level of MCP-1 ((2.74±1.55) vs. (1.00±0.49),<0.05) and MMP2((1.38±0.42) vs. (1.00±0.27), P<0.05) was significantly upregulated in model group compared with control group. Protein expression of EP4 receptor also increased in aorta in model group compared with control group (1.48±0.51 vs. 1.00±0.19, P<0.05). In the dissection area, the EP4 expression was also enriched compared with non-dissection area, particularly in endothelial cells and inflammatory cells on day 28. BAPN applied in drinking water (model and treatment groups) successfully induced the aortic dissection in mice, some mice died of the rupture. The elastic fibers were fractured, and the infiltrated immune cells were visible in dissected tissue. False lumen was formed. There was no dissection and death in the control group. Compared with control group, the morbidity and mortality rates were significantly increased in the model group (60.6%, 20/33, 30.3%, 10/33) and the treatment group (72.7%, 24/33, 24.2%, 8/33). The mortality and morbidity rates were similar between model and treatment groups. There is no difference in terms of SBP among three groups (P>0.05). Further study showed that after alprostadil injection, the blood concentration of PGE1 was increased in treatment group ((0.540±0.041 vs. 0.436±0.012)μmol/L, P<0.05). Besides, the EP4 receptor expression was downregulated in the treatment group compared to model group (0.60±0.30 vs. 1.00±0.20, P<0.05). Conclusion: EP4 expression is upregulated in BAPN induced aortic dissection mouse model. No protective effects are observed post alprostadil treatment in this model probably due to the reduced expression of EP4.

Prostaglandin E2 receptor 1 antagonist attenuates mesangial cell lesion induced by TGF-β1 in mice through inhibiting ERK signal pathway / 中华肾脏病杂志

Objective To explore the effects and mechanisms of prostaglandin E2 (PGE2) receptor 1 antagonist (SC-19220) on proliferation,prostaglandin synthase and extracellular regulated protein kinases (ERK) signal pathway induced by transforming growth factor β1(TGF-β1) in glomerular mesangial cells.Methods Mouse glomerular mesangial cells (GMCs) were divided into 5 groups:control group,TGF-β1 (10 μg/L) group,TGF-β1 (10 μg/L) plus SC-19220 group (0.1,0.5,1.0 μmol/L).The proliferation of GMCs was measured by CCK-8.The PGE2 in supernatant was measured by ELISA.The expression of connective tissue growth factor (CTGF),laminin (LN),cyclooxygenase 2(COX2),membrane-bound prostaglandin E2 synthase 1 (mPGES1) protein and mRNA was examined by Westem blotting and real-time quantitative PCR,ERK1/2 or phospho-ERK1/2 was measured by Western blotting as well.Results TGF-β1 induced the proliferation of GMCs and increased the secretion of PGE2.Besides,TGF-β1 significantly up-regulated the expression of CTGF,LN,COX2 and mPGES1 mRNA and protein (P ＜ 0.05),and increased the expression of phospho-ERK1/2 protein (P ＜ 0.05).However,SC-19220 significantly attenuated the changes of above-mentioned parameters and their activities (P ＜ 0.05).All the effects of SC-19220 were in dose-dependent manner.Conclusions SC19220 may reduce TGF-β1-induced cell damage by suppressing the activity of ERK1/2,and feedback inhibition of COX2,mPGES1 and PGE2,thus decreases the expression of LN and CTGF.

Lubiprostone Increases Small Intestinal Smooth Muscle Contractions Through a Prostaglandin E Receptor 1 (EP1)-mediated Pathway

BACKGROUND/AIMS: Lubiprostone, a chloride channel type 2 (ClC-2) activator, was thought to treat constipation by enhancing intestinal secretion. It has been associated with increased intestinal transit and delayed gastric emptying. Structurally similar to prostones with up to 54% prostaglandin E2 activity on prostaglandin E receptor 1 (EP1), lubiprostone may also exert EP1-mediated procontractile effect on intestinal smooth muscles. We investigated lubiprostone's effects on intestinal smooth muscle contractions and pyloric sphincter tone. METHODS: Isolated murine small intestinal (longitudinal and circular) and pyloric tissues were mounted in organ baths with modified Krebs solution for isometric recording. Basal muscle tension and response to electrical field stimulation (EFS; 2 ms pulses/10 V/6 Hz/30 sec train) were measured with lubiprostone (10(-10)-10(-5) M) +/- EP1 antagonist. Significance was established using Student t test and P < 0.05. RESULTS: Lubiprostone had no effect on the basal tension or EFS-induced contractions of longitudinal muscles. With circular muscles, lubiprostone caused a dose-dependent increase in EFS-induced contractions (2.11 +/- 0.88 to 4.43 +/- 1.38 N/g, P = 0.020) that was inhibited by pretreatment with EP1 antagonist (1.69 +/- 0.70 vs. 4.43 +/- 1.38 N/g, P = 0.030). Lubiprostone had no effect on circular muscle basal tension, but it induced a dose-dependent increase in pyloric basal tone (1.07 +/- 0.01 to 1.97 +/- 0.86 fold increase, P < 0.05) that was inhibited by EP1 antagonist. CONCLUSIONS: In mice, lubiprostone caused a dose-dependent and EP1-mediated increase in contractility of circular but not longitudinal small intestinal smooth muscles, and in basal tone of the pylorus. These findings suggest another mechanism for lubiprostone's observed clinical effects on gastrointestinal motility.

Role of prostaglandin E_2 receptor 1 in neuronal cell death induced by hypoxia on rat cortical neurocytes / 中国病理生理杂志

AIM:To observe the effects of prostaglandin E2 receptor1 (EP1) in neuronal cell death induced by hypoxia/reoxygenation and ischemia/reperfusion. METHODS:The cortical neurocytes of neonatal Wistar rats were cultured for 12 days and exposed to hypoxia/re-oxygenation to establish a hypoxia/re-oxygenation model. Another set of cultured primary neonatal cortical neurocytes of rats were pretreated with 17-pt (an antagonist of EP1),then underwent hypoxia for 3 h,re-oxygenated for 21 h. MTT reagent was added 1 h before measuring the cell viability. Neuron apoptosis was determined by flow cytometry. The protein expression was examined by Western blotting. RESULTS:Compared to the control cells (only underwent hypoxia /re -oxygenation and without any pretreatment),the neurons pretreated with 17-pt and then underwent hypoxia/re-oxygenation showed significantly lower survival rate (P