Annexin A5 therapy attenuates vascular inflammation and remodeling and improves endothelial function in mice

LncRNA MIR4697HG Alleviates Endothelial Cell Injury and Atherosclerosis Progression in Mice via the FUS/ANXA5 Axis

Atherosclerosis (AS) manifests with arterial intimal injury, lipid deposition and chronic inflammation, which is a key pathogenic cause of cardio-cerebrovascular disorders. LncRNA MIR4697HG was downregulated in human advanced atherosclerotic plaques. This study probed the precise biological functions and downstream regulatory mechanisms of MIR4697HG during AS progression. MIR4697HG levels in atherosclerotic plaque tissues and normal arterial intima were measured by RT-qPCR. An injury model of human umbilical vein endothelial cells (HUVECs) was induced through treating with oxidative low-density lipoprotein (ox-LDL). MIR4697HG overexpression plasmids (pcDNA-MIR4697HG) was transfected into ox-LDL-treated HUVECs, and then cell viability, apoptosis, reactive oxygen species (ROS) level, oxidative stress marker protein malondialdehyde (MDA) level and superoxide dismutase (SOD) activity, and adhesion molecule intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels in HUVECs were determined. Moreover, the binding between MIR4697HG and fused in sarcoma (FUS) was checked with RNA pull-down assay. The interaction between FUS and annexin A5 (ANXA5) was gauged with Co-immunoprecipitation. Then MIR4697HG/FUS/ANXA5 axis mediated HUVEC functions were accessed with rescue experiments. Additionally, an AS model was established via feeding a high-fat diet for ApoE-/- mice, and lentivirus MIR4697HG overexpression vector (Lv-MIR4697HG) was injected into AS mice followed by detection of atherosclerotic plaque area in mice. MIR4697HG was downregulated in atherosclerotic plaque tissues and HUVECs stimulated by ox-LDL. MIR4697HG overexpression attenuated ox-LDL-induced HUVEC viability inhibition, apoptosis, oxidative stress and adhesion molecule release. Moreover, MIR4697HG bound with FUS and facilitated FUS expression in HUVECs. FUS knockdown abrogated the functions of lncRNA MIR4697HG overexpression in ox-LDL induced HUVEC injury. Besides, FUS could bind with ANXA5. FUS overexpression inhibited ox-LDL induced HUVEC injury, while ANXA5 knockdown reversed these effects. Additionally, Lv-MIR4697HG reduced atherosclerotic plaque area in ApoE-/- mice. LncRNA MIR4697HG mitigated ox-LDL-induced apoptosis, oxidative stress and adhesion molecule release in HUVECs and alleviated AS progression in mice through the FUS/ANXA5 axis.

New Therapeutic Strategies in Retinal Vascular Diseases: A Lipid Target, Phosphatidylserine, and Annexin A5-A Future Theranostic Pairing in Ophthalmology

Despite progress in the management of patients with retinal vascular and degenerative diseases, there is still an unmet clinical need for safe and effective therapeutic options with novel mechanisms of action. Recent mechanistic insights into the pathogenesis of retinal diseases with a prominent vascular component, such as retinal vein occlusion (RVO), diabetic retinopathy (DR) and wet age-related macular degeneration (AMD), may open up new treatment paradigms that reach beyond the inhibition of vascular endothelial growth factor (VEGF). Phosphatidylserine (PS) is a novel lipid target that is linked to the pathophysiology of several human diseases, including retinal diseases. PS acts upstream of VEGF and complement signaling pathways. Annexin A5 is a protein that targets PS and inhibits PS signaling. This review explores the current understanding of the potential roles of PS as a target and Annexin A5 as a therapeutic. The clinical development status of Annexin A5 as a therapeutic and the potential utility of PS-Annexin A5 as a theranostic pairing in retinal vascular conditions in particular is described.

The Relevance, Predictability, and Utility of Annexin A5 for Human Physiopathology

As an important functional protein molecule in the human body, human annexin A5 (hAnxA5) is widely found in human cells and body fluids. hAnxA5, the smallest type of annexin, performs a variety of biological functions by reversibly and specifically binding phosphatidylserine (PS) in a calcium-dependent manner and plays an important role in many human physiological and pathological processes. The free state hAnxA5 exists in the form of monomers and usually forms a polymer in a specific self-assembly manner when exerting biological activity. This review systematically discusses the current knowledge and understanding of hAnxA5 from three perspectives: physiopathological relevance, diagnostic value, and therapeutic utility. hAnxA5 affects the occurrence and development of many physiopathological processes. Moreover, hAnxA5 can be used independently or in combination as a biomarker of physiopathological phenomena for the diagnosis of certain diseases. Importantly, based on the properties of hAnxA5, many novel drug candidates have been designed and prepared for application in actual medical practice. However, there are also some gaps and shortcomings in hAnxA5 research. This in-depth study will not only expand the understanding of structural and functional relationships but also promote the application of hAnxA5 in the field of biomedicine.

Pharmacokinetics of recombinant human annexin A5 (SY-005) in patients with severe COVID-19

Objective: Annexin A5 is a phosphatidylserine binding protein with anti-inflammatory, anticoagulant and anti-apoptotic properties. Preclinical studies have shown that annexin A5 inhibits pro-inflammatory responses and improves organ function and survival in rodent models of sepsis. This clinical trial aimed to evaluate the pharmacokinetic (PK) properties of the recombinant human annexin A5 (SY-005) in severe COVID-19. Methods: This was a pilot randomized, double-blind, placebo-controlled trial. Severe COVID-19 patients were randomly assigned to receive intravenous 50 μg/kg (low dose, n = 3), 100 μg/kg (high dose, n = 5) of SY-005 or placebo (n = 5) every 12 h for 7 days. Plasma SY-005 levels were assessed using enzyme-linked immunosorbent assay (ELISA) and the PK parameters were determined using non-compartmental analysis. Results: All patients treated with SY-005 had a normal baseline estimated glomerular filtration rate (eGFR, 104-125 mL/min/1.73 m2). Both low and high doses of SY-005 were cleared within 6 h after intravenous administration. Plasma maximum concentrations (Cmax), half-life, clearance and volume distribution of low and high doses of SY-005 were 402.4 and 848.9 ng/mL, 0.92 and 0.96 h, 7.52 and 15.19 L/h, and 9.98 and 20.79 L, respectively. Daily pre-dose circulating annexin A5 levels were not significantly different when SY-005 was administered at the low or the high dose 12-h intervals. There was no significant effect on activated partial thromboplastin time (aPTT) or INR (international normalized ratio of prothrombin time) during 7 days of SY-005 treatment. Conclusion: SY-005 doses of 50 and 100 μg/kg were detectable and subsequently cleared from the plasma in severe COVID-19 patients with normal baseline renal function. There was no significant plasma SY-005 accumulation 6 h after drug administration and coagulation was not altered during 7 days of treatment. Clinical trials Registration: This study was registered with ClinicalTrials.gov (NCT04748757, first posted on 10 February 2021).

Annexin A5 in Patients With Severe COVID-19 Disease: A Single-Center, Randomized, Double-Blind, Placebo-Controlled Feasibility Trial

OBJECTIVES

To evaluate the study design and feasibility of drug administration and safety in a randomized clinical trial of recombinant human annexin A5 (SY-005), a constitutively expressed protein with anti-inflammatory, antiapoptotic, and anticoagulant properties, in patients with severe coronavirus disease 2019 (COVID-19).

DESIGN

Double-blind, randomized clinical trial.

SETTING

Two ICUs at an academic medical center.

PATIENTS/SUBJECTS

Adults admitted to the ICU with a confirmed diagnosis of COVID-19 and requiring ventilatory or vasopressor support.

INTERVENTIONS

SY-005, a recombinant human annexin A5, at 50 or 100 µg/kg IV every 12 hours for 7 days.

MEASUREMENTS AND MAIN RESULTS

We enrolled 18 of the 55 eligible patients (33%) between April 21, 2021, and February 3, 2022. We administered 82% (196/238) of the anticipated doses of study medication and 86% (169/196) were given within 1 hour of the scheduled time. There were no drug-related serious adverse events. We captured 100% of the data that would be required for measuring clinical outcomes in a phase 2 or 3 trial.

LIMITATIONS

The small sample size was a result of decreasing admissions of patients with COVID-19, which triggered a stopping rule for the trial.

CONCLUSIONS

Although enrollment was low, administration of SY-005 to critically ill patients with COVID-19 every 12 hours for up to 7 days was feasible and safe. Further clinical trials of annexin A5 for the treatment of COVID-19 are warranted. Given reduction of severe COVID-19 disease, future studies should explore the safety and effectiveness of SY-005 use in non-COVID-related sepsis.

Prevention of atrial fibrillation after open-chest surgery with extracellular vesicle therapy

Almost half of patients recovering from open-chest surgery experience atrial fibrillation (AF) that results principally from inflammation in the pericardial space surrounding the heart. Given that postoperative AF is associated with increased mortality, effective measures to prevent AF after open-chest surgery are highly desirable. In this study, we tested the concept that extracellular vesicles (EVs) isolated from human atrial explant-derived cells can prevent postoperative AF. Middle-aged female and male rats were randomized to undergo sham operation or induction of sterile pericarditis followed by trans-epicardial injection of human EVs or vehicle into the atrial tissue. Pericarditis increased the probability of inducing AF while EV treatment abrogated this effect in a sex-independent manner. EV treatment reduced infiltration of inflammatory cells and production of pro-inflammatory cytokines. Atrial fibrosis and hypertrophy seen after pericarditis were markedly attenuated by EV pretreatment, an effect attributable to suppression of fibroblast proliferation by EVs. Our study demonstrates that injection of EVs at the time of open-chest surgery shows prominent antiinflammatory effects and prevents AF due to sterile pericarditis. Translation of this finding to patients might provide an effective new strategy to prevent postoperative AF by reducing atrial inflammation and fibrosis.

Systemic lupus erythematosus and cardiovascular disease

The prognosis in systemic lupus erythematosus (SLE) has improved due to better treatment and care, but cardiovascular disease (CVD) still remains an important clinical problem, since the risk of CVD in SLE is much higher than among controls. Atherosclerosis is the main cause of CVD in the general population, and in SLE, increased atherosclerosis, especially the prevalence of atherosclerotic plaques, has been demonstrated. Atherosclerosis is an inflammatory condition, where immunity plays an important role. Interestingly, oxidized low-density lipoprotein, defective clearance of dead cells, and inflammation, with a pro-inflammatory T-cell profile are characteristics of both atherosclerosis and SLE. In addition to atherosclerosis as an underlying cause of CVD in SLE, there are also other non-mutually exclusive mechanisms, and the most important of these are antiphospholipid antibodies (aPL) leading to the antiphospholipid antibody syndrome with both arterial and venous thrombosis. aPL can cause direct pro-inflammatory and prothrombotic effects on endothelial and other cells and also interfere with the coagulation, for example, by inhibiting annexin A5 from its antithrombotic and protective effects. Antibodies against phosphorylcholine (anti-PC) and other small lipid-related epitopes, sometimes called natural antibodies, are negatively associated with CVD and atherosclerosis in SLE. Taken together, a combination of traditional risk factors such as hypertension and dyslipidemia, and nontraditional ones, especially aPL, inflammation, and low anti-PC are implicated in the increased risk of CVD in SLE. Close monitoring of both traditional risk factors and nontraditional ones, including treatment of disease manifestations, not lest renal disease in SLE, is warranted.

Annexin A5 ameliorates traumatic brain injury-induced neuroinflammation and neuronal ferroptosis by modulating the NF-ĸB/HMGB1 and Nrf2/HO-1 pathways

Traumatic brain injury often causes poor outcomes and has few established treatments. Neuroinflammation and ferroptosis hinder therapeutic progress in this domain. Annexin A5 (A5) has anticoagulant, anti-apoptotic and anti-inflammatory bioactivities. However, its protective effects on traumatic brain injury remain unclear. Thus, we explored whether inhibiting ferroptosis and neuroinflammation using A5 could ameliorate traumatic brain injury. We injected recombinant A5 (50 µg/kg) in the tail vein of mice 30 min after fluid percussion injury. We then assessed modified neurologic severity scores, Morris water maze performance, rotarod test performance, brain water content, and blood-brain barrier permeability to document the neuroprotective effects of A5. Two days after the traumatic brain injury, we collected injured cortex tissues for western blot, Perl's staining, apoptosis staining, Nissl staining, immunofluorescence/immunohistochemistry, and enzyme-linked immunosorbent assay. We also quantified superoxide dismutase and glutathione peroxidase activity and glutathione and malondialdehyde levels. A5 improved neurological deficits, weight loss, cerebral hypoperfusion, brain edema, blood-brain barrier disruption, neuronal apoptosis, and ferroptosis. It also increased the ratio of M2/M1 phenotype microglia, reduced interleukin 1β and 6 levels, decreased peripheral immune cell infiltration, and increased interleukin 10 levels. A5 reduced neuronal iron accumulation, p53-related cell death, and oxidative stress damage. Finally, A5 downregulated HMGB1 and NF-ĸB pathways and upregulated the nuclear erythroid 2-related factor (Nrf2) and HO-1 pathways. These results suggest that A5 exerts neuroprotection in traumatic brain injury mice and ameliorates neuroinflammation, oxidative stress, and ferroptosis by regulating the NF-kB/HMGB1 pathway and the Nrf2/HO-1 antioxidant system.

Fluid Shear Stress Regulates Osteogenic Differentiation via AnnexinA6-Mediated Autophagy in MC3T3-E1 Cells

Fluid shear stress (FSS) facilitates bone remodeling by regulating osteogenic differentiation, and extracellular matrix maturation and mineralization. However, the underlying molecular mechanisms of how mechanical stimuli from FSS are converted into osteogenesis remain largely unexplored. Here, we exposed MC3T3-E1 cells to FSS with different intensities (1 h FSS with 0, 5, 10, and 20 dyn/cm² intensities) and treatment durations (10 dyn/cm² FSS with 0, 0.5, 1, 2 and 4 h treatment). The results demonstrate that the 1 h of 10 dyn/cm² FSS treatment greatly upregulated the expression of osteogenic markers (Runx2, ALP, Col I), accompanied by AnxA6 activation. The genetic ablation of AnxA6 suppressed the autophagic process, demonstrating lowered autophagy markers (Beclin1, ATG5, ATG7, LC3) and decreased autophagosome formation, and strongly reduced osteogenic differentiation induced by FSS. Furthermore, the addition of autophagic activator rapamycin to AnxA6 knockdown cells stimulated autophagy process, and coincided with more expressions of osteogenic proteins ALP and Col I under both static and FSS conditions. In conclusion, the findings in this study reveal a hitherto unidentified relationship between FSS-induced osteogenic differentiation and autophagy, and point to AnxA6 as a key mediator of autophagy in response to FSS, which may provide a new target for the treatment of osteoporosis and other diseases.

Relationship between the Soluble F11 Receptor and Annexin A5 in African Americans Patients with Type-2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is characterized by endothelial dysfunction, increased thrombogenicity, and inflammation. The soluble human F11 receptor (sF11R) and annexin A5 (ANXA5) play crucial roles in inflammatory thrombosis and atherosclerosis. We examined the relationship between circulating sF11R and ANXA5 and their impact on endothelial function. The study included 125 patients with T2DM. Plasma levels of sF11R and ANXA5 were quantified by ELISA. Microvascular function was assessed using the vascular reactivity index (VRI). Large artery stiffness was assessed by carotid-femoral pulse wave velocity (PWV). Carotid intima-media thickness (CIMT) was assessed by B-mode ultrasound imaging. The mean age of patients in the study was 59.7 ± 7.8 years, 78% had hypertension, 76% had dyslipidemia, and 12% had CKD. sF11R correlated positively with ANXA5 levels (β = 0.250, p = 0.005), and correlated inversely with VRI and total nitic oxide (NO), (β = −0.201, p = 0.024; β = −0.357, p = 0.0001, respectively). Multivariate regression analysis revealed that sF11R was independently associated with ANXA5 in the total population and in patients with HbA1c > 6.5% (β = 0.366, p = 0.007; β = 0.425, p = 0.0001, respectively). sF11R and ANXA5 were not associated with vascular outcome, suggesting that they may not be reliable markers of vascular dysfunction in diabetes. The clinical significance of sF11R/ANXA5 association in diabetes warrants further investigation in a larger population.

Laminar shear stress alleviates monocyte adhesion and atherosclerosis development via miR-29b-3p/CX3CL1 axis regulation

Laminar shear stress (Lss) is an important anti-atherosclerosis (anti-AS) factor, but its mechanism network is not clear. Therefore, this study aimed to identify how Lss acts against AS formation from a new perspective. In this study, we analyzed high-throughput sequencing data from static and Lss-treated human aortic and human umbilical vein endothelial cells (HAECs and HUVECs, respectively) and found that the expression of CX3CL1, which is a target gene closely related to AS development, was lower in the Lss group. Lss alleviated the inflammatory response in TNF-α (also known as TNF)-activated HAECs by regulating the miR-29b-3p/CX3CL1 axis, and this was achieved by blocking nuclear factor (NF)-κB signaling. In complementary in vivo experiments, a high-fat diet (HFD) induced inflammatory infiltration and plaque formation in the aorta, both of which were significantly reduced after injection of agomir-miRNA-29b-3p via the tail vein into HFD-fed ApoE^−/− mice. In conclusion, this study reveals that the Lss-sensitive miR-29b-3p/CX3CL1 axis is an important regulatory target that affects vascular endothelial inflammation and AS development. Our study provides new insights into the prevention and treatment of AS.

Summary: The laminar shear stress-sensitive miR-29b-3p/CX3CL1 axis significantly inhibits monocyte adhesion to activated human aortic endothelial cells, and alleviates local inflammation and plaque formation in ApoE^−/− mice fed a high-fat diet.

Annexin A Protein Family in Atherosclerosis

Atherosclerosis, a silent chronic vascular pathology, is the cause of the majority of cardiovascular ischaemic events. Atherosclerosis is characterized by a series of deleterious changes in cellularity, including endothelial dysfunction, transmigration of circulating inflammatory cells into the arterial wall, pro-inflammatory cytokines production, lipid accumulation in the intima, vascular local inflammatory response, atherosclerosis-related cells apoptosis and autophagy. Proteins of Annexin A (AnxA) family, the well-known Ca²⁺ phospholipid-binding protein, have many functions in regulating inflammation-related enzymes and cell signaling transduction, thus influencing cell adhesion, migration, differentiation, proliferation and apoptosis. There is now accumulating evidence that some members of the AnxA family, such as AnxA1, AnxA2, AnxA5 and AnxA7, play major roles in the development of atherosclerosis. This article discusses the major roles of AnxA1, AnxA2, AnxA5 and AnxA7, and the multifaceted mechanisms of the main biological process in which they are involved in atherosclerosis. Considering these evidences, it has been proposed that AnxA are drivers- and not merely participator- on the road to atherosclerosis, thus the progression of atherosclerosis may be prevented by targeting the expression or function of the AnxA family proteins.

Therapeutic Potential of Annexins in Sepsis and COVID-19

Sepsis is a continuing problem in modern healthcare, with a relatively high prevalence, and a significant mortality rate worldwide. Currently, no specific anti-sepsis treatment exists despite decades of research on developing potential therapies. Annexins are molecules that show efficacy in preclinical models of sepsis but have not been investigated as a potential therapy in patients with sepsis. Human annexins play important roles in cell membrane dynamics, as well as mediation of systemic effects. Most notably, annexins are highly involved in anti-inflammatory processes, adaptive immunity, modulation of coagulation and fibrinolysis, as well as protective shielding of cells from phagocytosis. These discoveries led to the development of analogous peptides which mimic their physiological function, and investigation into the potential of using the annexins and their analogous peptides as therapeutic agents in conditions where inflammation and coagulation play a large role in the pathophysiology. In numerous studies, treatment with recombinant human annexins and annexin analogue peptides have consistently found positive outcomes in animal models of sepsis, myocardial infarction, and ischemia reperfusion injury. Annexins A1 and A5 improve organ function and reduce mortality in animal sepsis models, inhibit inflammatory processes, reduce inflammatory mediator release, and protect against ischemic injury. The mechanisms of action and demonstrated efficacy of annexins in animal models support development of annexins and their analogues for the treatment of sepsis. The effects of annexin A5 on inflammation and platelet activation may be particularly beneficial in disease caused by SARS-CoV-2 infection. Safety and efficacy of recombinant human annexin A5 are currently being studied in clinical trials in sepsis and severe COVID-19 patients.

Phosphatidylserine externalized on the colonic capillaries as a novel pharmacological target for IBD therapy

Inflammatory bowel disease (IBD) is a chronic and relapsing disorder for many people associated with poor health. Although there are some clinical drugs for IBD treatment, the development of effective therapeutics on IBD patients has always been necessary. Here, we show that externalized phosphatidylserine (PS) is observed on the surface of colonic capillaries. Annexin A5 (ANXA5) with high affinity for PS has a good targeting to the colon and effectively alleviates experimental colitis. In contrast, ANXA5 mutant (A5m) lacking the PS-binding ability, has no accumulation in the colon and no therapeutic effects on colitis. Mechanistic investigations indicate that ANXA5 reduces the inflammatory cell infiltration by inhibiting endothelial cell activation dependent on PS-binding ability. With the increasing of PS exposure on activated HUVECs (human umbilical vein endothelial cells), ANXA5 binding induces the internalization of TLR4 via PS-dependent endocytosis. We provide new insights on the molecular mechanism of ANXA5 for its anti-inflammatory effect. Our data suggest that PS-externalization is a potential target of ANXA5 aiming at targeted drug delivery (TDD) for IBD treatment.

Annexin Induces Cellular Uptake of Extracellular Vesicles and Delays Disease in Escherichia coli O157:H7 Infection

Enterohemorrhagic Escherichia coli secrete Shiga toxin and lead to hemolytic uremic syndrome. Patients have high levels of circulating prothrombotic extracellular vesicles (EVs) that expose phosphatidylserine and tissue factor and transfer Shiga toxin from the circulation into the kidney. Annexin A5 (AnxA5) binds to phosphatidylserine, affecting membrane dynamics. This study investigated the effect of anxA5 on EV uptake by human and murine phagocytes and used a mouse model of EHEC infection to study the effect of anxA5 on disease and systemic EV levels. EVs derived from human whole blood or HeLa cells were more readily taken up by THP-1 cells or RAW264.7 cells when the EVs were coated with anxA5. EVs from HeLa cells incubated with RAW264.7 cells induced phosphatidylserine exposure on the cells, suggesting a mechanism by which anxA5-coated EVs can bind to phagocytes before uptake. Mice treated with anxA5 for six days after inoculation with E. coli O157:H7 showed a dose-dependent delay in the development of clinical disease. Treated mice had lower levels of EVs in the circulation. In the presence of anxA5, EVs are taken up by phagocytes and their systemic levels are lower, and, as EVs transfer Shiga toxin to the kidney, this could postpone disease development.

Diannexin Can Ameliorate Acute Respiratory Distress Syndrome in Rats by Promoting Heme Oxygenase-1 Expression

Background

The recombinant protein diannexin can inhibit platelet-mediated events, which contribute to acute respiratory distress syndrome (ARDS). Here, we investigated the effect of diannexin and its effect on heme oxygenase-1 (HO-1) in ARDS.

Methods

A total of 32 rats were randomized into sham, ARDS, diannexin (D), and diannexin+HO-1 inhibitor (DH) groups. Alveolar-capillary permeability was evaluated by testing the partial pressure of oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratio, lung wet/dry weight ratio, and protein levels in the lung. Inflammation was assessed by measuring cytokine levels in the bronchial alveolar lavage fluid (BALF) and serum and nuclear factor-κB (NF-κB) in the lung tissue. Inducible nitric oxide synthase (iNOS), malondialdehyde (MDA), and myeloperoxidase (MPO) were measured to evaluate the oxidative stress response. Lung tissue pathology and apoptosis were also evaluated. We measured HO-1 expression in the lung tissue to investigate the effect of diannexin on HO-1 in ARDS.

Results

Compared with the ARDS group, diannexin improved PaO₂/FiO₂, lung wet/dry weight ratio, and protein levels in the BALF and decreased levels of cytokines and NF-κB in the lung and serum. Diannexin inhibited the oxidative stress response and significantly ameliorated pathological lung injury and apoptosis. The partial reversal of diannexin effects by a HO-1 inhibitor suggests that diannexin may promote HO-1 expression to ameliorate ARDS.

Conclusions

We showed that diannexin can improve alveolar-capillary permeability, inhibit the oxidative stress response and inflammation, and protect against ARDS-induced lung injury and apoptosis.

Annexins: Involvement in cholesterol homeostasis, inflammatory response and atherosclerosis

The annexin superfamily consists of 12 proteins with a highly structural homology that binds to phospholipids depending on the availability of Ca²⁺-dependent. Different studies of overexpression, inhibition, or using recombinant proteins have linked the main function of these proteins to their dynamic and reversible binding to membranes. Annexins are found in multiple cellular compartments, regulating different functions, such as membrane trafficking, anchoring to the cell cytoskeleton, ion channel regulation, as well as pro- or anti-inflammatory and anticoagulant activities. The use of animals deficient in any of these annexins has established their possible functions in vivo, demonstrating that annexins can participate in relevant functions independent of Ca²⁺ signalling. This review will focus mainly on the role of different annexins in the pathological vascular remodelling that underlies the formation of the atherosclerotic lesion, as well as in the control of cholesterol homeostasis.

Pre-Exposure to Defibrotide Prevents Endothelial Cell Activation by Lipopolysaccharide: An Ingenuity Pathway Analysis

Defibrotide (DFB) effects on different endothelial cell pathways have been investigated focusing on a limited number of genes or molecules. This study explored the modulation of the gene expression profile of steady-state or lipopolysaccharide (LPS)-activated endothelial cells, following the DFB exposure. Starting from differentially regulated gene expression datasets, we utilized the Ingenuity Pathway Analysis (IPA) to infer novel information about the activity of this drug. We found that effects elicited by LPS deeply differ depending on cells were exposed to DFB and LPS at the same time, or if the DFB priming occurs before the LPS exposure. Only in the second case, we observed a significant down-regulation of various pathways activated by LPS. In IPA, the pathways most affected by DFB were leukocyte migration and activation, vasculogenesis, and inflammatory response. Furthermore, the activity of DFB seemed to be associated with the modulation of six key genes, including matrix-metalloproteinases 2 and 9, thrombin receptor, sphingosine-kinase1, alpha subunit of collagen XVIII, and endothelial-protein C receptor. Overall, our findings support a role for DFB in a wide range of diseases associated with an exaggerated inflammatory response of endothelial cells.

Overexpression of miR-506-3p Aggravates DBP-Induced Testicular Oxidative Stress in Rats by Downregulating ANXA5 via Nrf2/HO-1 Signaling Pathway

Background

Di-N-butylphthalate (DBP) is a kind of unique endocrine toxicity linked to hormonal disruptions that affects the male reproductive system and has given rise to more and more attention. However, the mechanism of DBP-induced testicular injury remains unclear. Here, the objective of this study was to investigate the potential molecular mechanism of miR-506-3p in DBP-induced rat testicular oxidative stress injury via ANXA5 (Annexin A5)/Nrf2/HO-1 signaling pathway.

Methods

In vivo, a total of 40 adolescent male rats were treated from 2 weeks with 800 mg/kg/day of DBP in 1 mL/kg corn oil administered daily by oral gavage. Among them, some rats were also injected subcutaneously with 2 nmol agomir-506-3p and/or 10 nmol recombinant rat ANXA5. The pathomorphological changes of testicular tissue were assessed by histological examination, and the antioxidant factors were evaluated. Subsequently, ANXA5, Nrf2, and its dependent antioxidant enzymes, such as HO-1, NQO1, and GST, were detected by Western blotting or immunohistochemical staining. In vitro, TM3 cells (Leydig cells) were used to detect the cell activity by CCK-8 and the transfection in the DBP-treated group.

Results

Differentially expressed miRNAs between the DBP-treated and normal rats were analyzed, and qRT-PCR showed miR-506-3p was highly expressed in testicular tissues of the DBP-treated rats. DBP-treated rats presented severe inflammatory infiltration, increased abnormal germ cells, and missed cell layers frequently existed in seminiferous tubules, resulted in oxidative stress and decreased testicular function. Meanwhile, upregulation of miR-506-3p aggravated the above changes. In addition, miR-506-3p directly bound to ANXA5, and overexpression of miR-506-3p could reduce the ANXA5 expression and also decrease the protein levels of Nrf2/HO-1 signaling pathway. Additionally, we found that recombinant rat ANXA5 reversed the DBP-treated testicular oxidative stress promoting injury of miR-506-3p in rats. In vivo results were reproduced in in vitro experiments.

Conclusions

This study provided evidence that miR-506-3p could aggravate the DBP-treated testicular oxidative stress injury in vivo and in vitro by inhibiting ANXA5 expression and downregulating Nrf2/HO-1 signaling pathway, which might provide novel understanding in DBP-induced testicular injury therapy.

Annexin A5 regulates hepatic macrophage polarization via directly targeting PKM2 and ameliorates NASH

Nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease (NAFLD), is becoming a common chronic liver disease with the characteristics of steatosis, inflammation and fibrosis. Macrophage plays an important role in the development of NASH. In this study, Annexin A5 (Anx A5) is identified with the special effect on hepatic macrophage phenotype shift from M1 to M2. And it is further demonstrated that Anx A5 significantly switches metabolic reprogramming from glycolysis to oxidative phosphorylation in activated macrophages. Mechanistically, the main target of Anx A5 in energy metabolism is confirmed to be pyruvate kinase M2 (PKM2). And we following reveal that Anx A5 directly interacts with PKM2 at ASP101, LEU104 and ARG106, inhibits phosphorylation of Y105, and promotes PKM2 tetramer formation. In addition, based on the results of PKM2 inhibitor (compound 3k) and the phosphorylated mutation (PKM2 (Y105E)), it is proved that Anx A5 exhibits the function in macrophage polarization dependently on PKM2 activity. In vivo studies also show that Anx A5 improves steatosis, inflammation and fibrosis in NASH mice due to specially regulating hepatic macrophages via interaction with PKM2. Therefore, we have revealed a novel function of Anx A5 in hepatic macrophage polarization and HFD-induced NASH, providing important insights into the metabolic reprogramming, which is important for NASH therapy.

Annexin A5 prevents amyloid-β-induced toxicity in choroid plexus: implication for Alzheimer's disease

In Alzheimer’s disease (AD) amyloid-β (Aβ) deposits may cause impairments in choroid plexus, a specialised brain structure which forms the blood–cerebrospinal fluid (CSF) barrier. We previously carried out a mass proteomic-based study in choroid plexus from AD patients and we found several differentially regulated proteins compared with healthy subjects. One of these proteins, annexin A5, was previously demonstrated implicated in blocking Aβ-induced cytotoxicity in neuronal cell cultures. Here, we investigated the effects of annexin A5 on Aβ toxicity in choroid plexus. We used choroid plexus tissue samples and CSF from mild cognitive impairment (MCI) and AD patients to analyse Aβ accumulation, cell death and annexin A5 levels compared with control subjects. Choroid plexus cell cultures from rats were used to analyse annexin A5 effects on Aβ-induced cytotoxicity. AD choroid plexus exhibited progressive reduction of annexin A5 levels along with progressive increased Aβ accumulation and cell death as disease stage was higher. On the other hand, annexin A5 levels in CSF from patients were found progressively increased as the disease stage increased in severity. In choroid plexus primary cultures, Aβ administration reduced endogenous annexin A5 levels in a time-course dependent manner and simultaneously increased annexin A5 levels in extracellular medium. Annexin A5 addition to choroid plexus cell cultures restored the Aβ-induced impairments on autophagy flux and apoptosis in a calcium-dependent manner. We propose that annexin A5 would exert a protective role in choroid plexus and this protection is lost as Aβ accumulates with the disease progression. Then, brain protection against further toxic insults would be jeopardised.

Therapeutic Antibody Against Phosphorylcholine Preserves Coronary Function and Attenuates Vascular 18F-FDG Uptake in Atherosclerotic Mice

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Phosphorylcholine is a pro-inflammatory epitope in atherogenic oxidized phospholipids.

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This study investigated effects of a novel monoclonal IgG1 antibody against PC on vascular function and atherosclerotic inflammation.

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Treatment with phosphorylcholine antibody preserved coronary flow reserve and decreased uptake of ¹⁸F-FDG in atherosclerotic lesions in hypercholesterolemic mice.

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Noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis.

This study showed that treatment with a therapeutic monoclonal immunoglobulin-G1 antibody against phosphorylcholine on oxidized phospholipids preserves coronary flow reserve and attenuates atherosclerotic inflammation as determined by the uptake of ¹⁸F-fluorodeoxyglucose in atherosclerotic mice. The noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis in clinical studies.

The role of ANXA5 in DBP-induced oxidative stress through ERK/Nrf2 pathway

Di-N-butylphthalate (DBP) have given rise to more and more attention due to its unique endocrine toxicity to male reproductive system. Our previous studies have demonstrated antioxidative Nrf2 (nuclear factor erythroid related factor 2) pathway play a vital role in DBP induced oxidative stress injury. ANXA5 (annexin A5), which is highly expressed in testicular Leydig and Sertoli cells, was found upregulated after DBP stimulation. Mouse Leydig and Sertoli cells were exposed to different concentration of DBP for 24 h to examine the ROS (Reactive oxygen species), MDA (Malondialdehyde), SOD (superoxide dismutase) level and ANXA5, Nrf2, NQO1 (NAD(P)H-quinone oxidoreductase 1), HO-1 (heme oxygenase 1) and ERK/P-ERK protein expression by DHE (Dihydroethidium) staining, ELISA (enzyme-linked immunosorbent assay) and Western blot respectively. Firstly, the oxidative stress injury induced by DBP was re-validated. Then, we confirmed the change of Nrf2 pathway and ANXA5 level after DBP exposure to testicular cells. Additionally, overexpressed ANXA5 could activate Nrf2/HO-1/NQO1 antioxidant pathway and significantly attenuate DBP-induced oxidative stress. Ultimately, we demonstrated ANXA5 could increase ERK phosphorylated level and the activated role of ANXA5 on ERK/Nrf2 pathway could be reversed by ERK inhibitor. Overall, this study illuminated that ANXA5 could defend testicle Leydig and Sertoli cells against DBP-induced oxidative stress injury through ERK/Nrf2 pathway.

Loss of Annexin A5 expression attenuates the lipopolysaccharide-induced inflammatory response of rat alveolar macrophages

Acute lung injury (ALI) is a common respiratory syndrome accompanied with an inflammation response. Annexin A5 (AnxA5) has anti-thrombotic, anti-apoptotic, and anti-inflammatory properties. The current study aims to explore the potential effect of AnxA5 on lipopolysaccharide (LPS)-induced inflammatory response in alveolar macrophages (AMs). Rat AMs (NR8383) were used in this study, and the cell viabilities at 4, 8, and 16 h after LPS administration with gradient concentrations were determined using cell counting kit-8 assay. Cell apoptosis and expressions of messenger RNAs (mRNAs) and protein were determined by flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot, respectively. We found that LPS suppressed the viability of AMs in a dose-dependent manner, and it elevated the expression of AnxA5 in AMs. Inhibition of AnxA5 improved the cell viability compared with the LPS group and could reduce the apoptosis rate in comparison with LPS treatment. The knockdown of AnxA5 suppressed the expressions of tumor necrosis factor-α (TNF-α), interleukin (IL-1β), and IL-6 at both protein and mRNA levels and regulated the expressions of apoptosis-related molecules (Bax, Bcl-2, and caspase-3). Moreover, the knockdown of AnxA5 improved the expression levels of inhibitory κB (IκB) and nuclear factor E2-related factor 2 (Nrf2) but inhibited the expression of nuclear transcription factor κB (NF-κB), compared with the LPS group. SN50 and ML385 were used to validate this signaling, and the inhibition of AnxA5 suppressed the LPS-induced inflammation, indicating that AnxA5 may be a potential anti-inflammatory target. In addition, NF-κB/Nrf2 signaling pathway may also be involved in the LPS-induced inflammatory response of rat alveolar macrophages.

Annexin A5 Protein as a Potential Biomarker for the Diagnosis of Asthma

PURPOSE

Annexin A5 (ANXA5) has a potential role in cellular signal transduction, inflammation, and fibrosis. However, the exact role of ANXA5 in asthma remains to be clarified. The aims of the present study were to investigate ANXA5 protein expression in a mouse model of asthma and pollutant exposure and to elucidate the relationships between clinical variables and plasma ANXA5 levels in patients with asthma.

METHODS

A murine model of asthma induced by ovalbumin (OVA) and titanium dioxide (TiO₂) nanoparticles has been established using BALB/c mice, and we examined ANXA5 expression and lung fibrosis using this model. Moreover, we also compared ANXA5 plasma levels in patients with controlled vs. exacerbated asthma.

RESULTS

ANXA5 protein levels were lower in lung tissue from OVA + OVA mice than in control mice. Lung ANXA5, connective tissue growth factor (CTGF), and transforming growth factor β1 (TGF-β1) protein levels were higher in OVA + TiO₂-exposed mice than in control or OVA + OVA mice. Although Dermatophagoides pteronyssinus (Derp1) treatment increased lung ANXA5 protein levels in MRC-5 cells and A549 epithelial cells, it decreased lung ANXA5 levels in NHBE cells. Treatment with TiO₂ nanoparticles increased lung ANXA5, CTGF, and TGF-β1 protein levels in MRC-5 cells, A549 epithelial cells, and NHBE cells. Plasma ANXA5 levels were lower in asthmatic patients than in healthy controls, and they were significantly enriched in patients with exacerbated asthma compared with those with controlled asthma (P < 0.05). ANXA5 levels were correlated with pulmonary function as assessed by spirometry.

CONCLUSION

Our results imply that ANXA5 plays a potential role in asthma pathogenesis and may be a promising marker for exacerbated bronchial asthma and exposure to air pollutants.

Annexin A5 reduces infarct size and improves cardiac function after myocardial ischemia-reperfusion injury by suppression of the cardiac inflammatory response

Annexin A5 (AnxA5) is known to have anti-inflammatory and anti-apoptotic properties. Inflammation and apoptosis are key processes in post-ischemic cardiac remodeling. In this study, we investigated the effect of AnxA5 on left ventricular (LV) function and remodeling three weeks after myocardial ischemia-reperfusion (MI-R) injury in hypercholesterolemic ApoE*3-Leiden mice. Using a mouse model for MI-R injury, we demonstrate AnxA5 treatment resulted in a 27% reduction of contrast-enhanced MRI assessed infarct size (IS). End-diastolic and end-systolic volumes were decreased by 22% and 38%, respectively. LV ejection fraction was increased by 29% in the AnxA5 group compared to vehicle. Following AnxA5 treatment LV fibrous content after three weeks was reduced by 42%, which was accompanied by an increase in LV wall thickness of the infarcted area by 17%. Two days and three weeks after MI-R injury the number of cardiac macrophages was significantly reduced in both the infarct area and border zones following AnxA5 treatment compared to vehicle treatment. Finally, we found that AnxA5 stimulation leads to a reduction of IL-6 production in bone-marrow derived macrophages in vitro. AnxA5 treatment attenuates the post-ischemic inflammatory response and ameliorates LV remodeling which improves cardiac function three weeks after MI-R injury in hypercholesterolemic ApoE*3-Leiden mice.

Excipients for the lyoprotection of MAPKAP kinase 2 inhibitory peptide nano-polyplexes

Herein, excipients are investigated to ameliorate the deleterious effects of lyophilization on peptide-polymer nano-polyplex (NP) morphology, cellular uptake, and bioactivity. The NPs are a previously-described platform technology for intracellular peptide delivery and are formulated from a cationic therapeutic peptide and the anionic, pH-responsive, endosomolytic polymer poly(propylacrylic acid) (PPAA). These NPs are effective when formulated and immediately used for delivery into cells and tissue, but they are not amenable to reconstitution following storage as a lyophilized powder due to aggregation. To develop a lyophilized NP format that facilitates longer-term storage and ease of use, MAPKAP kinase 2 inhibitory peptide-based NPs (MK2i-NPs) were prepared in the presence of a range of concentrations of the excipients sucrose, trehalose, and lactosucrose prior to lyophilization and storage. All excipients improved particle morphology post-lyophilization and significantly improved MK2i-NP uptake in human coronary artery smooth muscle cells relative to lyophilized NPs without excipient. In particular, MK2i-NPs lyophilized with 300 mM lactosucrose as an excipient demonstrated a 5.23 fold increase in cellular uptake (p < 0.001), a 2.52 fold increase in endosomal disruption (p < 0.05), and a 2.39 fold increase in ex vivo bioactivity (p < 0.01) compared to MK2i-NPs lyophilized without excipients. In sum, these data suggest that addition of excipients, particularly lactosucrose, maintains and even improves the uptake and therapeutic efficacy of peptide-polymer NPs post-lyophilization relative to freshly-made formulations. Thus, the use of excipients as lyoprotectants is a promising approach for the long-term storage of biotherapeutic NPs and poises this NP platform for clinical translation.

Inflammation in Vein Graft Disease

Bypass surgery is one of the most frequently used strategies to revascularize tissues downstream occlusive atherosclerotic lesions. For venous bypass surgery the great saphenous vein is the most commonly used vessel. Unfortunately, graft efficacy is low due to the development of vascular inflammation, intimal hyperplasia and accelerated atherosclerosis. Moreover, failure of grafts leads to significant adverse outcomes and even mortality. The last couple of decades not much has changed in the treatment of vein graft disease (VGD). However, insight is the cellular and molecular mechanisms of VGD has increased. In this review, we discuss the latest insights on VGD and the role of inflammation in this. We discuss vein graft pathophysiology including hemodynamic changes, the role of vessel wall constitutions and vascular remodeling. We show that profound systemic and local inflammatory responses, including inflammation of the perivascular fat, involve both the innate and adaptive immune system.

Annexin A5 reduces early plaque formation in ApoE -/- mice

Annexin A5 (AnxA5) exerts anti-inflammatory, anticoagulant and anti-apoptotic effects through its binding to cell surface expressed phosphatidylserine. We previously showed that AnxA5 can stabilize advanced atherosclerotic plaques by reducing macrophage infiltration. We now investigated the effects of AnxA5 administration on the onset of atherosclerosis development. Eight-week-old ApoE-/-mice were fed a western diet while being administered AnxA5 or control (M1234) for a total of 6 weeks. AnxA5 administration reduced plaque size in the aortic root as well as the aortic arch by 36% and 55% respectively. As determined by immunohistochemistry, administration of AnxA5 further stabilized plaque by reducing macrophage content and increasing smooth muscle cell content. Furthermore, the pre-treatment of HUVEC's with AnxA5 reduced monocyte adhesion under flow-conditions. Finally, AnxA5 administration results in a trend to reduced cell death more pronounced in the aortic arch than the aortic root. In conclusion, treatment with AnxA5 before the onset of atherosclerosis reduces plaque formation in a murine model of atherosclerosis in part by reducing apoptotic rates further to its beneficial effect on macrophage infiltration and activation.

Induction of Dendritic Cell-Mediated Activation of T Cells From Atherosclerotic Plaques by Human Heat Shock Protein 60

BACKGROUND

Atherosclerosis is characterized by the presence of activated immune-competent cells including dendritic cells (DCs) and T cells, dead cells, and oxidized low-density lipoprotein. HSP60 (Heat shock protein 60) has been implicated in atherosclerosis. A plasma protein, Annexin A5, has atheroprotective properties.

METHODS AND RESULTS

Human DCs differentiated from peripheral blood monocytes were treated with human HSP60 or HSP90 and autologous T cells were cocultured with these pretreated DCs (mDCs). HSP60 induced mDCs and T-cell activation as determined by FACScan (Fluorescence associated cell scan), gene-activation, and cytokine production. HSP60-induced T-cell activation was partly major histocompatibility complex class II-dependent. T cells exposed to HSP60-treated mDCs produced interferon-γ, interleukin-17, but not transforming growth factor-β. HSP60 did not promote expression of Toll-like receptors 2 or 4. HSP90 promoted mDCs maturation but had no effect on T-cell activation. Annexin A5 inhibited HSP60-proinflammatory Th1/Th17 effects on mDCs and T cells, and partly bound HSP60. Further, Annexin A5 inhibited HSP-induced activation of mDCs and also oxidized low-density lipoprotein-induced HSP-production from mDCs. Experiments on mDCs and T cells derived from carotid atherosclerotic plaques from patients with symptomatic carotid disease gave similar results as from blood donors.

CONCLUSIONS

HSP60 induces mDCs activation and partly major histocompatibility complex class II-dependent activation of blood- and plaque-derived T cells, which is mostly of Th1/Th17 type. HSP60 could thus be an important T-cell antigen in plaques, and also mediate oxidized low-density lipoproteins immunogenic effects on DC-T-cell activation, promoting plaque rupture and clinical manifestations of cardiovascular disease. Annexin A5 inhibits both oxidized low-density lipoprotein-induced HSP60, and HSP60-mediated immune activation, which suggests a potential therapeutic role.

Upregulation of miR-126-3p promotes human saphenous vein endothelial cell proliferation in vitro and prevents vein graft neointimal formation ex vivo and in vivo

Poor long-term patency of vein grafts remains an obstacle in coronary artery bypass grafting (CABG) surgery using an autologous saphenous vein graft. Recent studies have revealed that miR-126-3p promotes vascular integrity and angiogenesis. We aimed to identify the role of miR-126-3p in the setting of vein graft disease and investigate the value of miR-126-3p agomir as a future gene therapy in vein graft failure. Expression analysis of circulating miR-126-3p in plasma from CABG patients established the basic clues that miR-126-3p participates in CABG. The in vitro results indicated that elevated miR-126-3p expression significantly improved proliferation and migration in human saphenous vein endothelial cells (HSVECs) by targeting sprouty-related protein-1 (SPRED-1) and phosphatidylinositol-3-kinase regulatory subunit 2 (PIK3R2), but not in human saphenous vein smooth muscle cells (HSVSMCs). Moreover, the therapeutic potential of miR-126-3p agomir was demonstrated in cultured human saphenous vein (HSV) ex vivo. Finally, local delivery of miR-126-3p agomir was confirmed to enhance reendothelialization and attenuate neointimal formation in a rat vein arterialization model. In conclusion, we provide evidence that upregulation of miR-126-3p by agomir possesses potential clinical value in the prevention and treatment of autologous vein graft restenosis in CABG.

Circulating annexin A5 levels are associated with carotid intima-media thickness but not coronary plaque composition

BACKGROUND

Annexin A5 (anxA5) is involved in processes which are crucial in atherogenesis. However, anxA5's relationship with atherosclerotic lesion extension and plaque composition in high-risk patients with type 2 diabetes remains unclear. Thus, we characterized the association between circulating anxA5 levels with atherosclerotic burden and coronary plaque composition in diabetes mellitus patients.

METHODS

Intima-media thickness was determined in 96 diabetes mellitus patients with stable coronary artery disease. Furthermore, intracoronary optical coherence tomography was performed in 106 lesions to determine plaque composition.

RESULTS

AnxA5 plasma levels of patients with intima-media thickening were higher (3.49 ± 2.19 ng/mL) compared to patients with normal intima-media thickness (2.24 ± 1.67 ng/mL, p = 0.002). Furthermore, anxA5 was associated with intima-media thickening on univariable [odds ratio = 1.445 (1.106-1.889), p = 0.007] and multivariable [odds ratio = 1.643 (1.166-2.314), p = 0.005] logistic regression analysis when adjusted for multiple cardiovascular risk factors and biomarkers. Furthermore, receiver operating characteristic analysis demonstrated that anxA5 predicted intima-media thickening with low-moderate diagnostic efficiency [area under the curve = 0.700 (0.592-0.808)]. In contrast, there was no association between anxA5 levels and coronary plaque composition as assessed by optical coherence tomography including the presence of lipid, calcified, fibrous plaque or the minimal thickness of the fibrous cap overlying the necrotic lipid core ( p = ns).

CONCLUSION

Circulating anxA5 levels are associated with carotid intima-media thickness but not coronary plaque composition in high-risk patients with diabetes mellitus.

Time-dependent proteomic and genomic alterations in Toll-like receptor-4-activated human chondrocytes: increased expression of lamin A/C and annexins

Activation of Toll-like receptor-4 (TLR-4) in articular chondrocytes increases the catabolic compartment and leads to matrix degradation during the development of osteoarthritis. In this study, we determined the proteomic and genomic alterations in human chondrocytes during lipopolysaccharide (LPS)-induced inflammation to elucidate the underlying mechanisms and consequences of TLR-4 activation. Human chondrocytes were cultured with LPS for 12, 24, and 36 h to induce TLR-4 activation. The TLR-4-induced inflammatory response was confirmed by real-time PCR analysis of increased interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) expression levels. In TLR-4-activated chondrocytes, proteomic changes were determined by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-mass spectroscopy analysis, and genomic changes were determined by microarray and gene ontology analyses. Proteomics analysis identified 26 proteins with significantly altered expression levels; these proteins were related to the cytoskeleton and oxidative stress responses. Gene ontology analysis indicated that LPS treatment altered specific functional pathways including ‘chemotaxis’, ‘hematopoietic organ development’, ‘positive regulation of cell proliferation’, and ‘regulation of cytokine biosynthetic process’. Nine of the 26 identified proteins displayed the same increased expression patterns in both proteomics and genomics analyses. Western blot analysis confirmed the LPS-induced increases in expression levels of lamin A/C and annexins 4/5/6. In conclusion, this study identified the time-dependent genomic, proteomic, and functional pathway alterations that occur in chondrocytes during LPS-induced TLR-4 activation. These results provide valuable new insights into the underlying mechanisms that control the development and progression of osteoarthritis.

Annexin A5 regulates Leydig cell testosterone production via ERK1/2 pathway

This study was to investigate the effect of annexin A5 on testosterone secretion from primary rat Leydig cells and the underlying mechanisms. Isolated rat Leydig cells were treated with annexin A5. Testosterone production was detected by chemiluminescence assay. The protein and mRNA of Steroidogenic acute regulatory (StAR), P450scc, 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), and 17α-hydroxylase were examined by Western blotting and semi-quantitative RT-PCR, respectively. Annexin A5 significantly stimulated testosterone secretion from rat Leydig cells in dose- and time-dependent manners and increased mRNA and protein expression of StAR, P450scc, 3β-HSD, and 17β-HSD but not 17α-hydroxylase. Annexin A5 knockdown by siRNA significantly decreased the level of testosterone and protein expression of P450scc, 3β-HSD, and 17β-HSD. The significant activation of ERK1/2 signaling was observed at 5, 10, and 30 min after annexin A5 treatment. After the pretreatment of Leydig cells with ERK inhibitor PD98059 (50 μmol l⁻¹) for 20 min, the effects of annexin A5 on promoting testosterone secretion and increasing the expression of P450scc, 3β-HSD, and 17β-HSD were completely abrogated (P < 0.05). Thus, ERK1/2 signaling is involved in the roles of annexin A5 in mediating testosterone production and the expression of P450scc, 3β-HSD, and 17β-HSD in Leydig cells.

Expression Profiling of Genes Related to Endothelial Cells Biology in Patients with Type 2 Diabetes and Patients with Prediabetes

Endothelial dysfunction appears to be an early sign indicating vascular damage and predicts the progression of atherosclerosis and cardiovascular disorders. Extensive clinical and experimental evidence suggests that endothelial dysfunction occurs in Type 2 Diabetes Mellitus (T2DM) and prediabetes patients. This study was carried out with an aim to appraise the expression levels in the peripheral blood of 84 genes related to endothelial cells biology in patients with diagnosed T2DM or prediabetes, trying to identify new genes whose expression might be changed under these pathological conditions. The study covered a total of 45 participants. The participants were divided into three groups: group 1, patients with T2DM; group 2, patients with prediabetes; group 3, control group. The gene expression analysis was performed using the Endothelial Cell Biology RT² Profiler PCR Array. In the case of T2DM, 59 genes were found to be upregulated, and four genes were observed to be downregulated. In prediabetes patients, increased expression was observed for 49 genes, with two downregulated genes observed. Our results indicate that diabetic and prediabetic conditions change the expression levels of genes related to endothelial cells biology and, consequently, may increase the risk for occurrence of endothelial dysfunction.

Vein graft failure: from pathophysiology to clinical outcomes

Occlusive arterial disease is a leading cause of morbidity and mortality worldwide. Aside from balloon angioplasty, bypass graft surgery is the most commonly performed revascularization technique for occlusive arterial disease. Coronary artery bypass graft surgery is performed in patients with left main coronary artery disease and three-vessel coronary disease, whereas peripheral artery bypass graft surgery is used to treat patients with late-stage peripheral artery occlusive disease. The great saphenous veins are commonly used conduits for surgical revascularization; however, they are associated with a high failure rate. Therefore, preservation of vein graft patency is essential for long-term surgical success. With the exception of 'no-touch' techniques and lipid-lowering and antiplatelet (aspirin) therapy, no intervention has hitherto unequivocally proven to be clinically effective in preventing vein graft failure. In this Review, we describe both preclinical and clinical studies evaluating the pathophysiology underlying vein graft failure, and the latest therapeutic options to improve patency for both coronary and peripheral grafts.

Lipid-Targeting Peptide Probes for Extracellular Vesicles

Extracellular vesicles released from cells are under intense investigation for their roles in cell-cell communication and cancer progression. However, individual vesicles have been difficult to probe as their small size renders them invisible by conventional light microscopy. However, as a consequence of their small size these vesicles possess highly curved lipid membranes that offer an unconventional target for curvature-sensing probes. In this article, we present a strategy for using peptide-based biosensors to detect highly curved membranes and the negatively charged membrane lipid phosphatidylserine, we delineate several assays used to validate curvature- and lipid-targeting mechanisms, and we explore potential applications in probing extracellular vesicles released from sources such as apoptotic cells, cancer cells, or activated platelets. J. Cell. Physiol. 231: 2327-2332, 2016. © 2016 Wiley Periodicals, Inc.

Circulating annexin A5 predicts mortality in patients with heart failure

BACKGROUND

Natriuretic peptides are currently used to predict mortality in patients with heart failure (HF). However, novel independent biomarkers are needed to improve risk stratification in these patients. We hypothesized that annexin A5 (anxA5) would be highly expressed by organs which are generally affected by HF and that circulating anxA5 levels would predict mortality in HF patients.

METHODS

We prospectively determined the diagnostic value of anxA5, N-terminal pro-B-type natriuretic peptide (NT-proBNP), C-reactive protein (CRP) and estimated glomerular filtration rate (eGFR) to predict mortality in 180 HF patients during a median follow-up of 3.6 years. Studies were conducted with anxA5(-/-) mice to investigate the underlying mechanisms.

RESULTS

AnxA5 levels were significantly elevated in HF patients compared to healthy control subjects. Cox regression analysis demonstrated that anxA5, NT-proBNP and eGFR all predict mortality independently. AnxA5 significantly improved the diagnostic efficiency of NT-proBNP alone (improvement of c-statistic from 0.662 to 0.705, P < 0.001) and also combined with eGFR and CRP (improvement of c-statistic from 0.675 to 0.738, P < 0.001) to predict mortality in the Cox regression model. Receiver operating characteristic curve analysis showed that anxA5 predicted 3-year survival (area under curve 0.708) with an optimal cut-off value of 2.24 ng mL(-1) . Using anxA5(-/-) mice, we demonstrated that anxA5 is highly expressed in organs that are often affected by HF including lung, kidney, liver and spleen. Lysis of these organs in vitro resulted in a marked and significant increase in anxA5 concentrations.

CONCLUSION

AnxA5 improves the diagnostic efficiency of conventional biomarkers to predict mortality in HF patients. Whereas natriuretic peptides originate from the myocardium, high circulating anxA5 levels in patients with HF are likely to reflect peripheral organ damage secondary to HF.

Increased alveolar soluble annexin V promotes lung inflammation and fibrosis

The causes underlying the self-perpetuating nature of idiopathic pulmonary fibrosis (IPF), a progressive and usually lethal disease, remain unknown. We hypothesised that alveolar soluble annexin V contributes to lung fibrosis, based on the observation that human IPF bronchoalveolar lavage fluid (BALF) containing high annexin V levels promoted fibroblast involvement in alveolar epithelial wound healing that was reduced when annexin V was depleted from the BALF. Conditioned medium from annexin V-treated alveolar epithelial type 2 cells (AEC2), but not annexin V per se, induced proliferation of human fibroblasts and contained pro-fibrotic, IPF-associated proteins, as well as pro-inflammatory cytokines that were found to correlate tightly (r>0.95) with annexin V levels in human BALF. ErbB2 receptor tyrosine kinase in AECs was activated by annexin V, and blockade reduced the fibrotic potential of annexin V-treated AEC-conditioned medium. In vivo, aerosol delivery of annexin V to mouse lung induced inflammation, fibrosis and increased hydroxyproline, with activation of Wnt, transforming growth factor-β, mitogen-activated protein kinase and nuclear factor-κB signalling pathways, as seen in IPF. Chronically increased alveolar annexin V levels, as reflected in increased IPF BALF levels, may contribute to the progression of IPF by inducing the release of pro-fibrotic mediators.

Endosomolytic Nano-Polyplex Platform Technology for Cytosolic Peptide Delivery To Inhibit Pathological Vasoconstriction

A platform technology has been developed and tested for delivery of intracellular-acting peptides through electrostatically complexed nanoparticles, or nano-polyplexes, formulated from an anionic endosomolytic polymer and cationic therapeutic peptides. This delivery platform has been initially tested and optimized for delivery of two unique vasoactive peptides, a phosphomimetic of heat shock protein 20 and an inhibitor of MAPKAP kinase II, to prevent pathological vasoconstriction (i.e., vasospasm) in human vascular tissue. These peptides inhibit vasoconstriction and promote vasorelaxation by modulating actin dynamics in vascular smooth muscle cells. Formulating these peptides into nano-polyplexes significantly enhances peptide uptake and retention, facilitates cytosolic delivery through a pH-dependent endosomal escape mechanism, and enhances peptide bioactivity in vitro as measured by inhibition of F-actin stress fiber formation. In comparison to treatment with the free peptides, which were endowed with cell-penetrating sequences, the nano-polyplexes significantly increased vasorelaxation, inhibited vasoconstriction, and decreased F-actin formation in the human saphenous vein ex vivo. These results suggest that these formulations have significant potential for treatment of conditions such as cerebral vasospasm following subarachnoid hemorrhage. Furthermore, because many therapeutic peptides include cationic cell-penetrating segments, this simple and modular platform technology may have broad applicability as a cost-effective approach for enhancing the efficacy of cytosolically active peptides.

Expression of regulatory proteins in choroid plexus changes in early stages of Alzheimer disease

Recent studies indicate that the choroid plexus has important physiologic and pathologic roles in Alzheimer disease (AD). To obtain additional insight on choroid plexus function, we performed a proteomic analysis of choroid plexus samples from patients with AD stages I to II (n = 16), III to IV (n = 16), and V to VI (n = 11) and 7 age-matched control subjects. We used 2-dimensional differential gel electrophoresis coupled with mass spectrometry to generate a complete picture of changes in choroid plexus protein expression occurring in AD patients. We identified 6 proteins: 14-3-3 β/α, 14-3-3 ε, moesin, proteasome activator complex subunit 1, annexin V, and aldehyde dehydrogenase, which were significantly regulated in AD patient samples (p < 0.05, >1.5-fold variation in expression vs control samples). These proteins are implicated in major physiologic functions including mitochondrial dysfunction and apoptosis regulation. These findings contribute additional significance to the emerging importance of molecular and functional changes of choroid plexus function in the pathophysiology of AD.

Annexin A5 promotes macrophage activation and contributes to pulmonary fibrosis induced by silica particles

OBJECTIVE

To investigate the contributions and underlying molecular mechanisms of annexin A5 toward silica-induced pulmonary fibrosis.

METHODS

Male C57BL/6 mice were randomly divided into three groups and instilled intratracheally with silica, saline, or air. Mice were euthanized at 3, 7, 14, or 28 days following treatment. Annexin A5 levels in serum and lung tissues were detected by enzyme-linked immunosorbant assay (ELISA) assays or Western blots. The association of annexin A5 levels with silica-induced lung fibrosis was further investigated in the macrophage cell line, RAW264.7. Following exposure of these cells to silica at a concentration of 200 μg/ml for 6 or 12 h, the expression levels of transforming growth factor β1 (TGF-β1), interleukin 1α (IL-1α), Fas ligand (FasL), and their downstream targets were evaluated by Western blots. Furthermore, annexin A5 and FasL were knocked down by small interfering ribonucleic acid (siRNA) and TGF-β1 secretion into the cell culture medium was measured by ELISA assays or Western blots.

RESULTS

Mice treated with silica demonstrated lung fibrosis at 28 days following exposure, whereas, in controls, only mild and transient inflammation was evident at day 3 and day 7 postinstillation and was not present at day 14. Furthermore, silica-exposed mice exhibited significantly (p < 0.05) elevated levels of annexin A5 in serum and lung tissues, relative to control groups. Consistent with these findings, silica exposure of RAW264.7 cells for 6 or 12 h, led to an annexin A5-dependent increase in the expression levels of TGF-β1, IL-1α, FasL, and their downstream target molecules. These silica-induced changes were reversed by siRNA-mediated knockdown of annexin A5, but downregulation of FasL led to increased annexin A5 expression and reduced levels of TGF-β1, IL-1α, and FasL downstream target molecules.

CONCLUSIONS

These findings define a role of annexin A5 in promoting macrophage activation via Fas/FasL pathways in silica-induced lung fibrosis.

Platelets in inflammation and atherogenesis

Platelets contribute to processes beyond thrombus formation and may play a so far underestimated role as an immune cell in various circumstances. This review outlines immune functions of platelets in host defense, but also how they may contribute to mechanisms of infectious diseases. A particular emphasis is placed on the interaction of platelets with other immune cells. Furthermore, this article outlines the features of atherosclerosis as an inflammatory vascular disease highlighting the role of platelet crosstalk with cellular and soluble factors involved in atheroprogression. Understanding, how platelets influence these processes of vascular remodeling will shed light on their role for tissue homeostasis beyond intravascular thrombosis. Finally, translational implications of platelet-mediated inflammation in atherosclerosis are discussed.

Annexin A1 counteracts chemokine-induced arterial myeloid cell recruitment

RATIONALE

Chemokine-controlled arterial leukocyte recruitment is a crucial process in atherosclerosis. Formyl peptide receptor 2 (FPR2) is a chemoattractant receptor that recognizes proinflammatory and proresolving ligands. The contribution of FPR2 and its proresolving ligand annexin A1 to atherosclerotic lesion formation is largely undefined.

OBJECTIVE

Because of the ambivalence of FPR2 ligands, we here investigate the role of FPR2 and its resolving ligand annexin A1 in atherogenesis.

METHODS AND RESULTS

Deletion of FPR2 or its ligand annexin A1 enhances atherosclerotic lesion formation, arterial myeloid cell adhesion, and recruitment. Mechanistically, we identify annexin A1 as an endogenous inhibitor of integrin activation evoked by the chemokines CCL5, CCL2, and CXCL1. Specifically, the annexin A1 fragment Ac2-26 counteracts conformational activation and clustering of integrins on myeloid cells evoked by CCL5, CCL2, and CXCL1 through inhibiting activation of the small GTPase Rap1. In vivo administration of Ac2-26 largely diminishes arterial recruitment of myeloid cells in a FPR2-dependent fashion. This effect is also observed in the presence of selective antagonists to CCR5, CCR2, or CXCR2, whereas Ac2-26 was without effect when all 3 chemokine receptors were antagonized simultaneously. Finally, repeated treatment with Ac2-26 reduces atherosclerotic lesion sizes and lesional macrophage accumulation.

CONCLUSIONS

Instructing the annexin A1-FPR2 axis harbors a novel approach to target arterial leukocyte recruitment. With the ability of Ac2-26 to counteract integrin activation exerted by various chemokines, delivery of Ac2-26 may be superior in inhibition of arterial leukocyte recruitment when compared with blocking individual chemokine receptors.

Annexin A5 haplotypes in familial hypercholesterolemia: lack of association with carotid intima-media thickness and cardiovascular disease risk

OBJECTIVE

Annexin A5 (ANXA5) has been suggested to possess antiatherogenic properties. We investigated whether ANXA5 genetic variations and plasma ANXA5 levels were associated with carotid atherosclerosis and contributed to cardiovascular disease (CVD) risk in patients with familial hypercholesterolemia (FH).

METHODS

We sequenced the promoter region and exon 2 of ANXA5 in 284 FH patients from the ASAP (Atorvastatin versus Simvastatin on Atherosclerosis Progression) trial. Common haplotypes (H) were constructed based on seven single nucleotide polymorphisms (SNPs). We studied whether plasma ANXA5 levels or ANXA5 haplotypes were associated with the extent of atherosclerosis (evaluated by carotid intima-media thickness (IMT). The association between ANXA5 haplotypes and the risk for CVD events was investigated in 1730 FH patients from the GIRaFH (Genetic Identification of Risk factors in Familial Hypercholesterolemia) study.

RESULTS

In ASAP, individuals carrying the ANXA5 haplotype H2 exhibited lower plasma ANXA5 levels, whereas H4 carriers had increased levels of circulating ANXA5 compared to non-carriers. Plasma ANXA5 levels were not associated with carotid IMT. None of the four ANXA5 haplotypes correlated with the age-related IMT progression (ASAP study) or contributed to CVD risk (GIRaFH cohort).

CONCLUSIONS

Both ANXA5 haplotypes and plasma ANXA5 levels were not associated with carotid IMT progression or CVD risk in FH patients.

Induction of dendritic cell-mediated T-cell activation by modified but not native low-density lipoprotein in humans and inhibition by annexin a5: involvement of heat shock proteins

OBJECTIVE

Atherosclerosis is an inflammatory disease, where activated immunocompetent cells, including dendritic cells (DCs) and T cells are abundant in plaques. Low-density lipoprotein modified either by oxidation (oxLDL) or by human group X-secreted phospholipase A2 (LDLx) and heat shock proteins (HSP), especially HSP60 and 90, have been implicated in atherosclerosis. We previously reported that Annexin A5 inhibits inflammatory effects of phospholipids, decreases vascular inflammation and improves vascular function in apolipoprotein E(-/-) mice. Here, we focus on the LDLx effects on human DCs and T cells.

APPROACH AND RESULTS

Human DCs were differentiated from peripheral blood monocytes, stimulated by oxLDL or LDLx. Naive autologous T cells were cocultured with pretreated DCs. oxLDL and LDLx, in contrast to LDL, induced DC-activation and T-cell proliferation. T cells exposed to LDLx-treated DCs produced interferon-γ, interleukin (IL)-17 but not IL-4 and IL-10. Annexin A5 abrogated LDLx effects on DCs and T cells and increased production of transforming growth factor-β and IL-10. Furthermore, IL-10 producing T cells suppressed primary T-cell activation via soluble IL-10, transforming growth factor-β, and cell-cell contact. Lentiviral-mediated shRNA knock-down HSP60 and 90 in DCs attenuated the effect of LDLx on DCs and subsequent T-cell proliferation. Experiments on DC and T cells derived from carotid atherosclerotic plaques gave similar results.

CONCLUSIONS

Our data show that modified forms of LDL such as LDLx but not native LDL activate human T cells through DCs. HSP60 and 90 contribute to such T-cell activation. Annexin A5 promotes induction of regulatory T cells and is potentially interesting as a therapeutic agent.

AnxA5 reduces plaque inflammation of advanced atherosclerotic lesions in apoE(-/-) mice

Annexin A5 (AnxA5) exerts anti-inflammatory, anticoagulant and anti-apoptotic effects through binding cell surface expressed phosphatidylserine. The actions of AnxA5 on atherosclerosis are incompletely understood. We investigated effects of exogenous AnxA5 on plaque morphology and phenotype of advanced atherosclerotic lesions in apoE^−/− mice. Advanced atherosclerotic lesions were induced in 12 weeks old Western type diet fed apoE^−/− mice using a collar placement around the carotid artery. After 5 weeks mice were injected either with AnxA5 (n = 8) or vehicle for another 4 weeks. AnxA5 reduced plaque macrophage content both in the intima (59% reduction, P < 0.05) and media (73% reduction, P < 0.01) of advanced atherosclerotic lesions of the carotid artery. These findings corroborated with advanced lesions of the aortic arch, where a 67% reduction in plaque macrophage content was observed with AnxA5 compared to controls (P < 0.01). AnxA5 did not change lesion extension, plaque apoptosis, collagen content, smooth muscle cell content or acellular plaque composition after 4 weeks of treatment as determined by immunohistochemistry in advanced carotid lesions. In vitro, AnxA5 exhibited anti-inflammatory effects in macrophages and a flow chamber based assay demonstrated that AnxA5 significantly inhibited capture, rolling, adhesion as well as transmigration of peripheral blood mononuclear cells on a TNF-α-activated endothelial cell layer. In conclusion, short-term treatment with AnxA5 reduces plaque inflammation of advanced lesions in apoE^−/− mice likely through interfering with recruitment and activation of monocytes to the inflamed lesion site. Suppressing chronic inflammation by targeting exposed phosphatidylserine may become a viable strategy to treat patients suffering from advanced atherosclerosis.