Endothelial phosphodiesterase 4B inactivation ameliorates endothelial-to-mesenchymal transition and pulmonary hypertension

Pulmonary hypertension (PH) is a fatal disorder characterized by pulmonary vascular remodeling and obstruction. The phosphodiesterase 4 (PDE4) family hydrolyzes cyclic AMP (cAMP) and is comprised of four subtypes (PDE4A–D). Previous studies have shown the beneficial effects of pan-PDE4 inhibitors in rodent PH;however, this class of drugs is associated with side effects owing to the broad inhibition of all four PDE4 isozymes. Here, we demonstrate that PDE4B is the predominant PDE isozyme in lungs and that it was upregulated in rodent and human PH lung tissues. We also confirmed that PDE4B is mainly expressed in the lung endothelial cells (ECs). Evaluation of PH in Pde4b wild type and knockout mice confirmed that Pde4b is important for the vascular remodeling associated with PH. In vivo EC lineage tracing demonstrated that Pde4b induces PH development by driving endothelial-to-mesenchymal transition (EndMT), and mechanistic studies showed that Pde4b regulates EndMT by antagonizing the cAMP-dependent PKA–CREB–BMPRII axis. Finally, treating PH rats with a PDE4B-specific inhibitor validated that PDE4B inhibition has a significant pharmacological effect in the alleviation of PH. Collectively, our findings indicate a critical role for PDE4B in EndMT and PH, prompting further studies of PDE4B-specific inhibitors as a therapeutic strategy for PH.

Yes-associated protein promotes endothelial-tomesenchymal transition of endothelial cells in choroidal neovascularization fibrosis

AIM:To reveal whether and how Yes-associated protein(YAP)promotes the occurrence of subretinal fibrosis in agerelated macular degeneration(AMD).METHODS:Cobalt chloride(Co Cl2)was used in primary human umbilical vein endothelial cells(HUVECs)to induce hypoxia in vitro.Eight-week-old male C57 BL/6 J mice weighing 19-25 g were used for a choroidal neovascularization(CNV)model induced by laser photocoagulation in vivo.Expression levels of YAP,phosphorylated YAP,mesenchymal markers[αsmooth muscle actin(α-SMA),vimentin,and Snail],and endothelial cell markers(CD31 and zonula occludens 1)were measured by Western blotting,quantitative real-time PCR,and immunofluorescence microscopy.Small molecules YC-1(Lificiguat,a specific inhibitor of hypoxia-inducible factor 1α),CA3(CIL56,an inhibitor of YAP),and XMU-MP-1(an inhibitor of Hippo kinase MST1/2,which activates YAP)were used to explore the underlying mechanism.RESULTS:Co Cl2 increased expression of mesenchymal markers,decreased expression of endothelial cell markers,and enhanced the ability of primary HUVECs to proliferate and migrate.YC-1 suppressed hypoxia-induced endothelialto-mesenchymal transition(End MT).Moreover,hypoxia promoted total expression,inhibited phosphorylation,and enhanced the transcriptional activity of YAP.XMU-MP-1 enhanced hypoxia-induced End MT,whereas CA3 elicited the opposite effect.Expression of YAP,α-SMA,and vimentin were upregulated in the laser-induced CNV model.However,silencing of YAP by vitreous injection of small interfering RNA targeting YAP could reverse these changes.CONCLUSION:The findings reveal a critical role of the hypoxia-inducible factor-1α(HIF-1α)/YAP signaling axis in End MT and provide a new therapeutic target for treatment of subretinal fibrosis in AMD.

Oxidative stress mediates glycidol-induced endothelial injury and its protection by 6-C-(E-2-fluorostyryl)naringenin

Glycidol is a common lipid-derived foodborne toxicant mainly presents in refined oils and related foodstuffs.Vascular endothelial cells may be potential targets of the deleterious effects associated with glycidol exposure.In human umbilical vein endothelial cells(HUVECs),we found that glycidol treatment promoted endothelialto-mesenchymal transition(EndMT)at a lower concentration(0.5 mmol/L),while induced apoptosis and inflammation at a higher concentration(1 mmol/L).These harmful effects were achieved by the activation of NF-κB/MAPK signaling pathway and were mediated by reactive oxygen species(ROS).In addition,the protective potential of 6-C-(E-2-fluorostyryl)naringenin(6-CEFN)against glycidol was evaluated and compared with naringenin.HUVECs pre-treated with 6-CEFN,but not naringenin,displayed resistance to endothelial dysfunction caused by glycidol.

Leech-Centipede Granules Suppress EndMT to Improve Erectile Dysfunction in Rats with Diabetes Mellitus via TGF-β/Smad Pathway

Objective:To investigate whether Leech-Centipede(LC) Granules can improve erectile function in rats with diabetes mellitus-associated erectile dysfunction(DMED) through endothelial-to-mesenchymal transition(EndMT) inhibition.Methods:Components of LC Granules were identified via ultra-high-performance liquid chromatography.Thirty male Sprague Dawley rats were injected with streptozotocin and fed continuously for 8weeks to establish the DMED rat model.Rats with erectile dysfunction symptoms diagnosed using apomorphine were divided into DMED and low-,medium-,and high-doses LC groups(n=6 in each).The negative control(NC, n=6) and DMED groups were given 5 mL of deionized water via intragastric gavage,and the low-,mediumand the high-doses LC groups were administered LC at 1.6,3.2,and 6.4 g/kg,respectively,via intragastric gavage for 4 weeks.The intracavernous pressure(ICP),mean arterial pressure(MAP),and nitric oxide(NO) levels in cavernous tissue were measured for each group.Quantitative reverse transcription-polymerase chain reaction and Western blot were used to detect mRNA and protein expressions of endothelial and mesenchymal markers.Immunofluorescence staining was used to observe α-SMA, and Masson’s trichrome staining was performed to determine the myofiber/collagen ratio.Results:A total of 474 active components were identified.After treatment,the ICP/MAP value and NO level were significantly higher in the medium-and high-dose LC groups than in the DMED group(P<0.05).Compared with the DMED groups,the medium-and high-dose groups LC significantly increased and decreased endothelial and mesenchymal markers expression,respectively(P<0.05).Tumor growth factor(TGF) β RⅡ,p-Smad2, and p-Smad3 levels were considerably higher following diabetes onset but reduced following LC intervention(P<0.05),except for TGF β 1(P>0.05).α-SMA expression was significantly higher in the DMED group and was reduced in all LC intervention groups(P>0.05).The myofiber/collagen ratio in the LC groups was higher than that in the DMED group but lower than that in the NC group(all P<0.05).Conclusions:LC Granules may improve the erectile function of DMED rats by suppressing TGF-β/Smad pathway to reverse EndMT.

Notch信号与卡波西肉瘤相关疱疹病毒关系的研究进展

卡波西肉瘤相关疱疹病毒(Kaposi's sarcoma-associated herpesvirus,KSHV)是卡波西肉瘤(Kaposi′s sarcoma,KS)等肿瘤的病因。一系列研究显示KSHV病毒基因与Notch信号通路分子的交互作用在调控KSHV复制以及促进肿瘤发生中发挥了重要作用。Notch信号传导通路由配体、受体、转录因子、效应分子等组成,相邻细胞间通过Notch信号调节细胞分化、增殖和凋亡、器官形成和形态发生等过程。本文就KSHV对Notch信号的调控以及Notch信号在KSHV复制及肿瘤形成中的作用作一综述。