Endothelial extracellular vesicles induce acute lung injury via follistatin-like protein 1

Cardiopulmonary bypass has been speculated to elicit systemic inflammation to initiate acute lung injury(ALI), including acute respiratory distress syndrome(ARDS), in patients after cardiac surgery. We previously found that post-operative patients showed an increase in endothelial cell-derived extracellular vesicles(eEVs) with components of coagulation and acute inflammatory responses. However, the mechanism underlying the onset of ALI owing to the release of e EVs after cardiopulmonary bypass, remains unclear. Plasma plasminogenactivated inhibitor-1(PAI-1) and eEV levels were measured in patients with cardiopulmonary bypass. Endothelial cells and mice(C57BL/6,Toll-like receptor 4 knockout(TLR4^(-/-))) and inducible nitric oxide synthase knockout(iNOS^(-/-)) were challenged with eEVs isolated from PAI-1-stimulated endothelial cells. Plasma PAI-1 and eEVs were remarkably enhanced after cardiopulmonary bypass. Plasma PAI-1 elevation was positively correlated with the increase in eEVs. The increase in plasma PAI-1 and eEV levels was associated with post-operative ARDS. The eEVs derived from PAI-1-stimulated endothelial cells could recognize TLR4 to stimulate a downstream signaling cascade identified as the Janus kinase 2/3(JAK2/3)-signal transducer and activator of transcription 3(STAT3)-interferon regulatory factor 1(IRF-1)pathway, along with i NOS induction, and cytokine/chemokine production in vascular endothelial cells and C57BL/6 mice, ultimately contributing to ALI. ALI could be attenuated by JAK2/3 or STAT3 inhibitors(AG490 or S3I-201, respectively), and was relieved in TLR4-/-and iNOS-/-mice. eEVs activate the TLR4/JAK3/STAT3/IRF-1 signaling pathway to induce ALI/ARDS by delivering follistatin-like protein 1(FSTL1), and FSTL1 knockdown in eEVs alleviates eEV-induced ALI/ARDS. Our data thus demonstrate that cardiopulmonary bypass may increase plasma PAI-1 levels to induce FSTL1-enriched eEVs, which target the TLR4-mediated JAK2/3/STAT3/IRF-1 signaling cascade and form a positive feedback loop, leading to ALI/ARDS after cardiac surgery. Our findings provide new insight into the molecular mechanisms and therapeutic targets for ALI/ARDS after cardiac surgery.

High-density lipoprotein regulates angiogenesis by affecting autophagy via miRNA-181a-5p

We previously demonstrated that normal high-density lipoprotein(nHDL)can promote angiogenesis,whereas HDL from patients with coronary artery disease(d HDL)is dysfunctional and impairs angiogenesis.Autophagy plays a critical role in angiogenesis,and HDL regulates autophagy.However,it is unclear whether n HDL and d HDL regulate angiogenesis by affecting autophagy.Endothelial cells(ECs)were treated with n HDL and d HDL with or without an autophagy inhibitor.Autophagy,endothelial nitric oxide synthase(e NOS)expression,miRNA expression,nitric oxide(NO)production,superoxide anion(O2^(·-))generation,EC migration,and tube formation were evaluated.n HDL suppressed the expression of miR-181a-5p,which promotes autophagy and the expression of e NOS,resulting in NO production and the inhibition of O2^(·-)generation,and ultimately increasing in EC migration and tube formation.d HDL showed opposite effects compared to n HDL and ultimately inhibited EC migration and tube formation.We found that autophagy-related protein 5(ATG5)was a direct target of miR-181a-5p.ATG5 silencing or miR-181a-5p mimic inhibited n HDL-induced autophagy,e NOS expression,NO production,EC migration,tube formation,and enhanced O2^(·-)generation,whereas overexpression of ATG5 or miR-181a-5p inhibitor reversed the above effects of d HDL.ATG5 expression and angiogenesis were decreased in the ischemic lower limbs of hypercholesterolemic low-density lipoprotein receptor null(LDLr^(-/-))mice when compared to C57BL/6 mice.ATG5 overexpression improved angiogenesis in ischemic hypercholesterolemic LDLr^(-/-)mice.Taken together,nHDL was able to stimulate autophagy by suppressing miR-181a-5p,subsequently increasing e NOS expression,which generated NO and promoted angiogenesis.In contrast,d HDL inhibited angiogenesis,at least partially,by increasing miR-181a-5p expression,which decreased autophagy and e NOS expression,resulting in a decrease in NO production and an increase in O2^(·-)generation.Our findings reveal a novel mechanism by which HDL affects angiogenesis by regulating autophagy and provide a therapeutic target for d HDL-impaired angiogenesis.

L-GrAFT_(7) has High Accuracy in Predicting Early Allograft Failure after Liver Transplantation: A Multicenter Cohort Study in China

Background and Aims:Increasing utilization of extended criteria donor leads to an increasing rate of early allograft failure after liver transplantation.However,consensus of definition of early allograft failure is lacking.Methods:A retrospective,multicenter study was performed to validate the Liver Graft Assessment Following Transplantation(L-GrAFT)risk model in a Chinese cohort of 942 adult patients undergoing primary liver transplantation at three Chinese centers.L-GrAFT(L-GrAFT7 and L-GrAFT10)was compared with existing models:the Early Allograft Failure Simplified Estimation(EASE)score,the model of early allograft function(MEAF),and the Early Allograft Dysfunction(EAD)model.Univariate and multivariate logistic regression were used to find risk factors of L-GrAFT high-risk group.Results:L-GrAFT7 had an area under the curve of 0.85 in predicting 90-day graft survival,significantly superior to MEAF[area under the curve(AUC=0.78,p=0.044)]and EAD(AUC=0.78,p=0.006),while there was no statistical significance between the predicting abilities of L-GrAFT7 and EASE(AUC=0.84,p>0.05).Furthermore,L-GrAFT7 maintains good predicting ability in the subgroup of high-donor risk index(DRI)cases(AUC=0.83 vs.MEAF,p=0.007 vs.EAD,p=0.014)and recipients of donors after cardiac death(AUC=0.92 vs.EAD,p<0.001).Through multivariate analysis,pretransplant bilirubin level,units of packed red blood cells,and the DRI score were selected as independent risk factors of a L-GrAFT7 high-risk group.Conclusions:The accuracy of L-GrAFT7 in predicting early allograft failure was validated in a Chinese multicenter cohort,indicating that it has the potential to become an accurate endpoint of clinical practice and transitional study of machine perfusion.

Signaling cascades in the failing heart and emerging therapeutic strategies

Chronic heart failure is the end stage of cardiac diseases.With a high prevalence and a high mortality rate worldwide,chronic heart failure is one of the heaviest health-related burdens.In addition to the standard neurohormonal blockade therapy,several medications have been developed for chronic heart failure treatment,but the population-wide improvement in chronic heart failure prognosis over time has been modest,and novel therapies are still needed.

Electrospinning nanofibers to ID,2D,and 3D scaffolds and their biomedical applications

Electrospinning is a popular and effective method of producing porous nanofibers with a large surface area,superior physical and chemical properties,and a controllable pore size.Owing to these properties,electrospun nanofibers can mimic the extracellular matrix and some human tissue structures,based on the fiber configuration.Consequently,the application of electrospun nanofibers as biomaterials,varying from two-dimensional(2D)wound dressings to three-dimensional(3D)tissue engineering scaffolds,has increased rapidly in recent years.Nanofibers can either be uniform fiber strands or coaxial drug carriers,and their overall structure varies from random mesh-like mats to aligned or gradient scaffolds.In addition,the pore size of the fibers can be adjusted or the fibers can be loaded with disparate medicines to provide different functions.This review discusses the various structures and applications of 2D fiber mats and 3D nanofibrous scaffolds made up of different one-dimensional(1D)fibers in tissue engineering.In particular,we focus on the improvements made in recent years,especially in the fields of wound healing,angiogenesis,and tissue regeneration.

VEGF-B prevents excessive angiogenesis by inhibiting FGF2/FGFR1 pathway

Although VEGF-B was discovered as a VEGF-A homolog a long time ago,the angiogenic effect of VEGF-B remains poorly understood with limited and diverse findings from different groups.Notwithstanding,drugs that inhibit VEGF-B together with other VEGF family members are being used to treat patients with various neovascular diseases.It is therefore critical to have a better understanding of the angiogenic effect of VEGF-B and the underlying mechanisms.Using comprehensive in vitro and in vivo methods and models,we reveal here for the first time an unexpected and surprising function of VEGF-B as an endogenous inhibitor of angiogenesis by inhibiting the FGF2/FGFR1 pathway when the latter is abundantly expressed.Mechanistically,we unveil that VEGF-B binds to FGFR1,induces FGFR1/VEGFR1 complex formation,and suppresses FGF2-induced Erk activation,and inhibits FGF2-driven angiogenesis and tumor growth.Our work uncovers a previously unrecognized novel function of VEGF-B in tethering the FGF2/FGFR1 pathway.Given the anti-angiogenic nature of VEGF-B under conditions of high FGF2/FGFR1 levels,caution is warranted when modulating VEGF-B activity to treat neovascular diseases.

High-density lipoprotein regulates angiogenesis by long non-coding RNA HDRACA

Normal high-density lipoprotein(nHDL)can induce angiogenesis in healthy individuals.However,HDL from patients with coronary artery disease undergoes various modifications,becomes dysfunctional(dHDL),and loses its ability to promote angiogenesis.Here,we identified a long non-coding RNA,HDRACA,that is involved in the regulation of angiogenesis by HDL.In this study,we showed that nHDL downregulates the expression of HDRACA in endothelial cells by activating WW domain-containing E3 ubiquitin protein ligase 2,which catalyzes the ubiquitination and subsequent degradation of its transcription factor,Kruppel-like factor 5,via sphingosine 1-phosphate(S1P)receptor 1.In contrast,dHDL with lower levels of S1P than nHDL were much less effective in decreasing the expression of HDRACA.HDRACA was able to bind to Ras-interacting protein 1(RAIN)to hinder the interaction between RAIN and vigilin,which led to an increase in the binding between the vigilin protein and proliferating cell nuclear antigen(PCNA)mRNA,resulting in a decrease in the expression of PCNA and inhibition of angiogenesis.The expression of human HDRACA in a hindlimb ischemia mouse model inhibited the recovery of angiogenesis.Taken together,these findings suggest that HDRACA is involved in the HDL regulation of angiogenesis,which nHDL inhibits the expression of HDRACA to induce angiogenesis,and that dHDL is much less effective in inhibiting HDRACA expression,which provides an explanation for the decreased ability of dHDL to stimulate angiogenesis.

Harnessing stem cell and lineage reprogramming technology to treat cardiac fibrosis

Cardiac fibrosis is a pathological response characterized by excessive deposition of fibrous connective tissue within the heart.It typically occurs following cardiac injuries or diseases.However,the lack of suitable models for disease modeling and high-throughput drug discovery has hindered the establishment of an effective treatments for cardiac fibrosis.The emergence and rapid progress of stem-cell and lineage reprogramming technology offer an unprecedented opportunity to develop an improved humanized and patient-specific model for studying cardiac fibrosis,providing a platform for screening potential drugs and synchronously elucidating the underlying molecular mechanisms.Furthermore,reprogramming cardiac fibroblasts into cardiomyocyte-like cells to reduce scar volume and induce myocardial tissue regeneration is a promising approach in treating cardiac fibrosis.In this review,we summarize the current advancements in stem cell technologies applied to study cardiac fibrosis and provide insights for future investigations into its mechanisms,drug discovery as well as therapy method.