[Endothelial dysfunction--assessment of current status and approaches to therapy]

CRISPR-Cas9 mediated gene knockout in human coronary artery endothelial cells reveals a pro-inflammatory role of TLR2

Endothelial inflammatory responses promote the development and progression of atherosclerosis. It was reported that Toll-like receptors 2 (TLR2) is associated with endothelial inflammation. However, the effect of TLR2 on inflammatory responses in human coronary artery endothelial cells (HCAECs) remains largely unknown. Here, we tested the hypothesis that TLR2 can enhance inflammatory reactions in HCAECs after stimulated by TLR2 agonist. First, we used CRISPR-Cas9 technology to knockout TLR2 gene in HCAECs. Then, TLR2-KO and wild type HCAECs were treated with TLR2 agonist peptidoglycan (PGN). The expression levels of intercellular cell adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), and interleukin-8 (IL-8) were analyzed by real-time PCR, Western blot, and ELISA. The expression status of myeloid differentiation primary response gene 88 (MyD88), phosphorylated IRAK-1 (pIRAK-1) and phosphorylated NF-κB (pNF-κB) were detected by Western blot. Our results show that after treated with TLR2 agonist, the expression levels of ICAM-1, IL-6, and IL-8 were downregulated in TLR2-KO cells compared to those of wild type cells. Further, Western blots of MyD88, pIRAK-1, and pNF-κB show that the expression levels of these pro-inflammatory molecules were much lower in TLR2-KO cells compared to that of wild type cells by stimulating with TLR2 agonist. We suggest that TLR2 may affect inflammatory reaction in HCAECs by introducing pro-inflammatory molecules like MyD88, pIRAK-1, and pNF-κB.

TGF-beta and TNF-alpha producing effects of losartan and amlodipine on human mononuclear cell culture

AIM

The modulation of cytokine release, which affects adhesion of leucocytes to endothelial cells, and proliferation of peripheral blood mononuclear cells with antihypertensive drugs was explored.

METHOD

In the present study, mononuclear cells were incubated with losartan and amlodipine at concentrations of 10(-6), 10(-5) and 10(-4) mol/L for 6 h. Transforming growth factor (TGF)-beta and tumour necrosis factor (TNF)-alpha levels were measured. Proliferation of mononuclear cells were assessed at the same concentrations of amlodipine and losartan with the methylthiazoletetrazolium (MTT) test.

RESULTS

Amlodipine was found to induce TGF-beta synthesis from mononuclear cells with increasing concentrations, while it was found to inhibit TNF-alpha secretion with increasing concentrations. In contrast, losartan was found to induce TGF-beta and TNF-alpha secretion with increasing concentrations.

CONCLUSION

Anti-atherosclerotic effects of amlodipine and losartan might be through increased secretion of TGF-beta from mononuclear cells. Different results at different concentrations might be due to the pharmocokinetic differences of these drugs.

Different antioxidative potencies of dihydropyridine calcium channel modulators in various models

There is evidence that dihydropyridine calcium antagonists (DHP) play a beneficial role during the development of atherosclerosis. Since antioxidative properties of this substance class may be important, we investigated the antioxidative potency of the DHP prototype calcium channel antagonist nifedipine, the long acting calcium channel antagonist lacidipine, the DHP calcium channel agonist Bay K 8644 and the bulky DHP derivate Bay O 5572 (negligible effects on L-type calcium channels) in three different models. Additionally, we examined the potential correlation between lipophilic and antioxidative properties. In an in vitro model, Bay K 8644 was significantly more effective in scavenging superoxide anions (hypoxanthine/xanthine-oxidase-assay) than lacidipine, Bay O 5572 or nifedipine (micro- to millimolar concentration range). Addition of artificial membrane preparations (dimyristoylphosphatidylcholine) to mimic a physiological environment resulted in an enhanced antioxidative effect, with lacidipine being the most effective DHP to quench radicals (low micromolar concentration range). Thirdly, in a more physiological model of hyperglycemia (30 mmol/l) induced release of reactive oxygen species (ROS) from native endothelial cells of porcine coronary arteries, we showed that nifedipine was a significantly more potent antioxidant (therapeutical nanomolar concentration range) than the other DHP. Calculation of the lipophilicity of the four substances (lacidipine>Bay O 5572>Bay K 8644>nifedipine) showed a positive correlation between the antioxidative potency and the lipophilicity in the model with the artificial membranes but not in the other models. We conclude that it seems necessary to access antioxidative properties of substances in physiological models in which we could demonstrate that nifedipine exhibits ROS-quenching properties in a therapeutic concentration range.

The Aqueous Outflow System as a Mechanical Pump

PURPOSE

To describe a new aqueous outflow model involving a mechanical pump.

MATERIALS AND METHODS

Laboratory materials include human and monkey eyes; methods include the dissecting microscope, light microscopy, scanning electron microscopy, transmission electron microscopy, and tracer studies. Clinical methods involve human subject slit lamp, gonioscopy, and operating microscope examination.

RESULTS

Laboratory evidence demonstrates that aqueous outflow tissues are responsive to intraocular pressure induced deformation. Deformation occurs in response to small pressure gradients. Laboratory evidence also demonstrates the presence of valves discharging aqueous to Schlemm's canal. The laboratory model predicts pulsatile aqueous discharge in vivo. Clinical in vivo evidence demonstrates pulsatile aqueous flow from the anterior chamber into Schlemm's canal, from Schlemm's canal into collector channels, and from Schlemm's canal into aqueous and episcleral veins, all synchronous with the ocular pulse.

CONCLUSIONS

Aqueous outflow tissue deformation caused by normal intraocular pressure transients induces pulsatile one-way discharge of aqueous to the vascular system. The model identifies biomechanical coupling of intraocular pressure with aqueous outflow tissue deformation and also sites of high flow capable of inducing shear stress. These mechanotransduction mechanisms, well characterized as a means of controlling pressure and flow in the vascular system, also provide a means of regulatory feedback to control intraocular pressure and aqueous flow.

Nutrition and the endothelium

Growing evidence suggests that dietary factors play an important role in modulating endothelial function. Epidemiologic and clinical studies have related intake of alpha-linolenic acid and long-chain n-3 fatty acids to lower plasma concentrations of inflammatory cytokines and endothelial adhesion molecules, both of which are considered markers of endothelial dysfunction. In contrast, trans fatty acid intake and a higher dietary glycemic load have been associated with increased plasma concentrations of these biomarkers. Recently, several epidemiologic and intervention studies have examined the relationship between overall dietary patterns and endothelial dysfunction. In general, a "prudent diet," characterized by higher intake of fruits, vegetables, legumes, fish, poultry, and whole grains, is associated with a beneficial effect on the endothelium. Conversely, a "Western diet," characterized by higher intake of red and processed meats, sweets, desserts, French fries, and refined grains, is associated with an impairment of the endothelial function. These findings provide additional biological mechanisms through which dietary factors influence the risk of cardiovascular diseases.

Fetal plasma stimulates endothelial cell production of cytokines and the family of suppressor of cytokine signaling in umbilical placental vascular disease

OBJECTIVE

We have shown that fetal plasma from pregnancies with placental vascular disease that were identified by an abnormal umbilical artery Doppler study causes endothelial cell activation. We investigated the hypothesis that this would be associated with endothelial cell production of cytokines and their natural regulators, the suppressor of cytokine signaling family. Activation of suppressor of cytokine signaling at the time of cytokine release confirms the fact that cytokine production is occurring in a stimulated cell.

STUDY DESIGN

Aliquots from a common culture of human umbilical vein endothelial cells were incubated with fetal plasma from normal pregnancy (n = 29 pregnancies), from umbilical placental vascular disease defined by abnormal umbilical artery Doppler waveforms (n = 38 pregnancies), and from preeclampsia with normal umbilical artery Doppler scans (n = 10 pregnancies). The expression of messenger RNA for the cytokines interleukin-6 and interleukin-8 and the members of suppressor of cytokine signaling family (cytokine-inducible SH2-containing protein, suppressor of cytokine signaling 1, 2, and 3) were assessed by reverse transcriptase-polymerase chain reaction.

RESULTS

Endothelial cell expression of interleukin-6 messenger RNA (1.94 +/- 0.24 vs 1.31 +/- 0.16) and interleukin-8 messenger RNA (2.62 +/- 0.33 vs 1.64 +/- 0.22) were enhanced in response to incubation with fetal plasma from placental vascular disease in comparison to incubation with fetal plasma from normal pregnancy. The messenger RNA expression of suppressor of cytokine signaling-2 (2.03 +/- 0.23 vs 1.37 +/- 0.16) was up-regulated significantly in placental vascular disease. Differences for cytokine-inducible SH2-containing protein, suppressor of cytokine signaling-1, and suppressor of cytokine signaling-3 were not significant. The expression of cytokines and the suppressor of cytokine signaling family did not differ from normal in the group with maternal preeclampsia and a normal umbilical study. Interestingly, in the umbilical placental vascular disease group, the results were similar in the subgroups, with or without preeclampsia in the mother.

CONCLUSION

We have shown that factors that cause endothelial cell injury are present in the fetal circulation in umbilical placental vascular disease. This study is the first report of cytokine production and release and activation of the suppressor of cytokine signaling family by endothelial cells in response to fetal plasma in placental vascular disease. The role of all members of the suppressor of cytokine signaling family in this process must be investigated further. The fact that both the agonist (cytokines) and the antagonist (suppressor of cytokine signaling-2) are produced points to a significant role of endothelial cells in this disease.

Endothelial cell expression of adhesion molecules is induced by fetal plasma from pregnancies with umbilical placental vascular disease

OBJECTIVE

To test the hypothesis that local production with spill into the fetal circulation of factor(s) injurious to endothelium is responsible for the vascular pathology present when the umbilical artery Doppler study is abnormal. Expression of adhesion molecules is a feature of endothelial cell activation.

DESIGN

Case-control study.

SETTING

University teaching hospital.

SAMPLES

Fetal plasma was collected from 27 normal pregnancies, 39 pregnancies with umbilical placental vascular disease defined by abnormal umbilical artery Doppler and 11 pregnancies with pre-eclampsia and normal umbilical artery Doppler.

METHODS

Isolated and cultured human umbilical vein endothelial cells from normal pregnancies were incubated with fetal plasma from three study groups. mRNA expression of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) were assessed by reverse transcription-polymerase chain reaction. To confirm the occurrence of this in vivo, we measured the levels of soluble fractions of sICAM-1, sVCAM-1 and sPECAM-1 in the fetal circulation in the fetal plasma used for endothelial cell incubation.

RESULTS

The mRNA expression of ICAM-1 [median 1.1 (interquartile range 0.5-1.9) vs 0.7 (0.3-1.2), P < 0.05] and PECAM-1 [2.1 (1.2-3.0) vs 1.5 (0.7-2.1), P < 0.05] was significantly higher following incubation with fetal plasma from umbilical placental vascular disease compared with the normal group. There was no difference in the expression of VCAM-1 [1.2 (0.9-1.8) vs 1.1 (0.8-1.6), ns]. The group with maternal pre-eclampsia and normal umbilical artery Doppler did not differ from the normal group. In the umbilical placental vascular disease group, the results were similar in the presence or absence of pre-eclampsia. For soluble fractions of the adhesion molecules released into the fetal circulation, we found the levels (ng/mL) of sICAM- I [median 248.5 (interquartile range 197.3-315.7) vs 174.2 (144.5-212.9), P < 0.05] and sPECAM-1 [9.3 (6.2-11.1) vs 6.1 (5.4-7.7), P < 0.05] in fetal plasma to be significantly increased in the presence of umbilical placental vascular disease compared with the normal.

CONCLUSIONS

Vascular disease in the fetal umbilical placental circulation is associated with an elevation in mRNA expression by endothelial cells of ICAM-1 and PECAM-1. Our study provides evidence for endothelial cell activation and dysfunction in umbilical placental vascular disease. We speculate that the plasma factor(s) affecting the vessels of the umbilical villous tree is locally released by the trophoblast. The occurrence of the maternal syndrome of pre-eclampsia appears to be independent of this.