Plaque Disruption Research Articles

Mechanisms of Coronary Ischemia in Women.

Obstructive coronary artery disease is a major cause of ischemia in both men and women; however, women are more likely to present with ischemia in the setting of no obstructive coronary arteries (INOCA) and myocardial infarction with no obstructive coronary arteries (MINOCA), conditions that are associated with adverse cardiovascular prognosis despite absence of coronary stenosis. In this review, we focus on mechanisms of coronary ischemia that should be considered in the differential diagnosis when routine anatomic clinical investigation leads to the finding of non-obstructive coronary artery disease on coronary angiography in the setting of acute myocardial infarction. There are multiple mechanisms that contribute to MINOCA, including atherosclerotic plaque disruption, coronary artery spasm, coronary microvascular dysfunction (CMD), coronary embolism and/or thrombosis, and spontaneous coronary artery dissection. Non-coronary causes such as myocarditis or supply-demand mismatch should also be considered on the differential when there is an unexplained troponin elevation. Use of advanced imaging and diagnostic techniques to determine the underlying etiology of MINOCA is feasible and helpful, as this has the potential to guide management and secondary prevention. Failure to identify the underlying cause(s) may result in inappropriate treatment and inaccurate counseling to patients. MINOCA predominates in young women and is associated with a guarded prognosis. The diagnosis of MINOCA should prompt further investigation to determine the underlying cause of troponin elevation. Patients with INOCA and MINOCA are heterogeneous, and response to treatments can be variable. Large randomized controlled trials to determine longer-term optimal medical therapy for management of these conditions are under investigation.

Non-Invasive Modalities in the Assessment of Vulnerable Coronary Atherosclerotic Plaques.

Coronary atherosclerosis is a complex, multistep process that may lead to critical complications upon progression, revolving around plaque disruption through either rupture or erosion. Several high-risk features are associated with plaque vulnerability and may add incremental prognostic information. Although invasive imaging modalities such as optical coherence tomography or intravascular ultrasound are considered to be the gold standard in the assessment of vulnerable coronary atherosclerotic plaques (VCAPs), contemporary evidence suggests a potential role for non-invasive methods in this context. Biomarkers associated with deleterious pathophysiologic pathways, including inflammation and extracellular matrix degradation, have been correlated with VCAP characteristics and adverse prognosis. However, coronary computed tomography (CT) angiography has been the most extensively investigated technique, significantly correlating with invasive method-derived VCAP features. The estimation of perivascular fat attenuation as well as radiomic-based approaches represent additional concepts that may add incremental information. Cardiac magnetic resonance imaging (MRI) has also been evaluated in clinical studies, with promising results through the various image sequences that have been tested. As far as nuclear cardiology is concerned, the implementation of positron emission tomography in the VCAP assessment currently faces several limitations with the myocardial uptake of the radiotracer in cases of fluorodeoxyglucose use, as well as with motion correction. Moreover, the search for the ideal radiotracer and the most adequate combination (CT or MRI) is still ongoing. With a look to the future, the possible combination of imaging and circulating inflammatory and extracellular matrix degradation biomarkers in diagnostic and prognostic algorithms may represent the essential next step for the assessment of high-risk individuals.

Mechanisms of Myocardial Ischemia in Cancer Patients: A State-of-the-Art Review of Obstructive Versus Non-Obstructive Causes.

In patients with cancer, myocardial infarction (MI) has distinct features and mechanisms compared to the non-oncology population. Triggers of myocardial ischemia specific to the oncology population have been increasingly identified. Coronary plaque disruption, coronary vasospasm, coronary microvascular dysfunction, spontaneous coronary artery dissection, and coronary oxygen supply-demand mismatch are all causes of MI that have been shown to have specific triggers related to either the treatments or complications of cancer. MI can occur in the presence or absence of atherosclerotic coronary artery disease (CAD). MI with nonobstructive CAD (MINOCA) is a heterogeneous syndrome that has distinct pathophysiology and different epidemiology from MI with significant CAD (MI-CAD). Recognition and differentiation of MI-CAD and MINOCA is essential in the oncology population, due to unique etiology and impact on diagnosis, management, and overall outcomes. There are currently no reports in the literature concerning MINOCA as a unified syndrome in oncology patients. The purpose of this review is to analyze the literature for studies related to known triggers of myocardial ischemia in cancer patients, with a focus on MINOCA. We propose that certain cancer treatments can induce MINOCA-like states, and further research is warranted to investigate mechanisms that may be unique to certain cancer states and types of treatment.

Atherothrombosis-on-Chip: A Site-Specific Microfluidic Model for Thrombus Formation and Drug Discovery.

Atherothrombosis, an atherosclerotic plaque disruption condition with superimposed thrombosis, is the underlying cause of cardiovascular episodes. Herein, a unique design is presented to develop a microfluidic site-specific atherothrombosis-on-chip model, providing a universal platform for studying the crosstalk between blood cells and plaque components. The device consists of two interconnected microchannels, namely main and supporting channels: the former mimics the vessel geometry with different stenosis, and the latter introduces plaque components to the circulation simultaneously. The unique design allows the site-specific introduction of plaque components in stenosed channels ranging from 0% to above 50%, resulting in thrombosis, which has not been achieved previously. The device successfully explains the correlation between vessel geometry and thrombus formation phenomenon as well as the influence of shear rate on platelet aggregation, confirming the reliability and the effectiveness of the design. The device exhibits significant sensitivity to aspirin. In therapeutic doses (50 × 10-6 and 100× 10-6 m), aspirin delays and prevents platelet adhesion, thereby reducing the thrombus area in a dose-dependent manner. Finally, the device is effectively employed in testing the targeted binding of the RGD (arginyl-glycyl-aspartic acid) labeled polymeric nanoparticles on the thrombus, extending the use of the device to examine targeted drug carriers.

Unifying theory of carotid plaque disruption based on structural phenotypes and forces expressed at the lumen/wall interface

ObjectivesTo integrate morphological, haemodynamic and mechanical analysis of carotid atheroma driving plaque disruption.Materials and methodsFirst, we analysed the phenotypes of carotid endarterectomy specimens in a photographic dataset A, and matched...

Inpatient myocardial perfusion imaging characteristics of patients admitted with suspected type 2 myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Background ESC defines a type 1 myocardial infarction (T1MI) as "MI caused by atherosclerotic coronary artery disease and usually precipitated by atherosclerotic plaque disruption" and type 2 myocardial infarction (T2MI) as "ischaemic myocardial injury in the context of a mismatch between oxygen supply and demand". In practice it can be difficult to differentiate between MI types and the role of myocardial perfusion imaging (MPI) in making this distinction remains unclear. Purpose To establish whether suspected T2MI has different characteristics on MPI compared to suspected T1MI. Methods All inpatient MPI scans at our institution between 01/03/2018 and 28/02/2020 were retrospectively reviewed. Patients were excluded if they had a previous diagnosis of coronary artery disease, an invasive coronary angiogram prior to MPI, or a maximal troponin T < 14ng/l. Diagnoses were categorised based on review of scan request information. Echocardiography images were reviewed if within 30 days of MPI. Results 58 patients were included: 28 with suspected type 2 MI and 30 with suspected type 1 MI (mean age 70 vs. 75). There was no statistically significant difference in maximal troponin T between groups (T2MI 394.0 ng/l, T1MI 415.6 ng/l; p=0.90). 50% T2MI patients and 53% T1MI patients had a territorial defect on MPI (fully reversible defect 25% vs. 17%, partially reversible defect 7% vs. 33%, irreversible defect 14% vs. 3% for T2MI vs T1MI respectively). 25% T2MI patients had an area >10% LV myocardium volume showing reversibility, compared with 33% T1MI (p=0.49). Both groups had similar proportions of left ventricular (LV) impairment (both had 65% of patients with normal LV ejection fraction) and prevalence of regional wall motion abnormalities ((RWMA) 39% for T2MI, 35% for T1MI, p=0.76) on echocardiography. Conclusions A clinically significant proportion of the suspected T2MI group had territorial ischaemia. Additionally, both patient groups demonstrated similar proportion of patients with reversible ischaemia and of LV systolic dysfunction. Therefore differentiation between T2MI and T1MI can be challenging both clinically and with MPI. Prospective studies are required to establish the optimal methods for making the distinction between types of MI.

Abstract 346: Mri Guided Experimental Study To Determine The Mechanistic Performance Of Vessel Prep V. Poba In Infrapopliteal Lesions

Objective: To present initial results of an ongoing ex-vivo experimental study to compare vessel preparation with intravascular lithotripsy (IVL) or orbital atherectomy (OA) versus plain old balloon angioplasty (POBA) in tibial arteries. Method: We will study amputated limbs that have concentric calcification, in three arms, 1. POBA, 2. IVL, and 3. OA. Amputated limbs are first scanned on 7T MRI using UTE (Ultra-short echo time) and T2 weighted sequences to characterize target lesions with concentric calcium at high resolution. The diameter of balloon is sized based on diameter of the vessel proximal and distal to target lesion and confirmed with intravascular ultrasound (IVUS). A through-and-through wire is placed and angiography and IVUS are performed. POBA, IVL or OA is performed. In lesions with vessel prep, angioplasty is performed. All angioplasties are performed at minimum pressure required for the balloon to reach profile diameter. Finally, the ex-vivo harvested specimens are imaged in 9.4T MRI for 3-D plaque analysis prior to histologic sectioning and staining. Results: We have 7 experiments, 3 BKA and 4 AKA. Balloon angioplasty without vessel prep was performed in 3/7, OA in 2/7 and IVL in 2/7. Lesions angioplastied without vessel prep required higher than burst pressure to reach profile. Lesions treated with OA and IVL required pressures between nominal and burst to reach profile. POBA samples demonstrated plaque disruption and dissections with more luminal gain compared with lesions that underwent vessel prep prior to angioplasty. Conclusion: This study elucidates the mechanism of vessel prep and how it assists POBA in protecting the vessel wall. Vessel prep did not “debulk” or improve luminal gain substantially but required lower inflation pressures and had less uncontrolled dissections and disruptions of the vessel wall. Initial results demonstrate a compelling indication for vessel preparation in select tibial lesions with 360-degree concentric calcium.

Gingival Curettage for the Management of Chronic Periodontitis: A Case Report

Background: The current therapy for periodontitis entails periodontal debridement, which involves the removal or disruption of bacterial plaque, its byproducts and retained calculus deposits from the coronal surfaces, root surfaces and the tissue walls of the periodontal pocket. Gingival curettage was designed to promote new connective tissue attachment to root surfaces by removing the pocket lining and junctional epithelium with a curette.
 Objective: This case report discusses the gingival curettage for periodontitis treatment on upper right posterior of a 25-year-old female patient with a chief complaint of occasional bleeding while brushing the teeth.
 Case Report: Intraoral examination showed bleeding on probing and 4-mm periodontal pocket on the upper right posterior. Periapical radiographic examination of the upper right posterior displayed alveolar crest reduction.
 Conclusion: The accomplishment of the treatment was proven by gingival curettage after the second visit.
 Keywords: chronic periodontitis, curettage, periodontal regeneration

Myocardial Infarction With Non-obstructive Coronary Arteries: An Updated Overview of Pathophysiology, Diagnosis, and Management.

Myocardial infarction with non-obstructive coronary arteries (MINOCA) refers to acute myocardial infarction with normal or near-normal coronary arteries. The MINOCA is a heterogeneous group of conditions, and possible etiologies are coronary artery spasm, spontaneous coronary artery dissection, coronary thromboembolism, coronary plaque disruption, coronary microvascular dysfunction, supply and demand mismatch. It is more common in young adults, with women having a higher chance of getting MINOCA than men. Considering MINOCA as a clinically dynamic working diagnostic that needs further investigation rather than a “true” diagnosis is proposed. Optical coherence tomography (OCT), intravenous ultrasound (IVUS), cardiac MRI may be required to stratify the underlying mechanism. Due to the lack of evidence-based literature and prospective randomized controlled studies, therapeutic management is limited. Consequently, the strategy is patient-specific. The prognosis of MINOCA patients remains unclear and depends upon the underlying etiology. This article aims to review the literature about various aspects of MINOCA, including pathophysiology, diagnosis, prognosis, and treatment.

Transcarotid artery revascularization (TCAR) stenting or angioplasty for intracranial carotid artery stenosis: Case series and novel application.

Carotid artery stenting is associated with a higher rate of stroke compared to carotid endarterectomy (CEA). This is likely due to procedural emboli resulting from plaque disruption. The transcarotid artery revascularization (TCAR) method aims to reduce the stroke rate by flow-reversal. TCAR, which has yet to be utilized for intracranial atherosclerotic disease (ICAD), may be particularly valuable given the lack of surgical treatment options for intracranial arterial stenosis. Presented here are five cases of angioplasty or stenting that demonstrate the feasibility of TCAR for intracranial Internal Carotid Artery (ICA) stenosis treatment. Five cases were reviewed retrospectively and summarized using PROCESS and CARE guidelines. All patients who underwent intervention between the petrous and ophthalmic segment of the ICA had no new neurologic deficit nor detected embolic stroke. One patient experienced an asymptomatic 5 mm hemorrhage on postoperative routine Computed Tomography (CT) head imaging. This highlights a new method for treating intracranial ICA stenosis with a potentially reduced stroke risk. Given the historically higher stroke rates for cervical ICA stenting compared to carotid artery endarterectomy, this method may improve the previously higher stroke rates in endovascular carotid artery treatment, compared to CEA. Although this series is small, it illustrates a novel use for a rising technique that should be further evaluated in a larger study to validate its efficacy as a new treatment modality for surgically inaccessible intracranial disease.

Immune Mechanisms of Plaque Instability

Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.

Optical coherence tomography in the diagnosis of myocardial infarction with non-obstructive coronary arteries.

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a working diagnosis and requires identification of the underlying causes to optimize treatment, improve prognosis, and prevent the recurrence of myocardial infarction. According to the literature, the prognosis of patients diagnosed with MINOCA is comparable to the group of patients with myocardial infarction (MI) and significant stenosis of the coronary arteries. Intracoronary imaging is a crucial diagnostic tool used in identifying epicardial causes of MINOCA that are not visible in coronary angiography. Optical coherence tomography (OCT) provides the highest spatial resolution, simultaneously allowing detailed visualization of plaque pathology in individuals with MINOCA and identifying the cause of MI in up to 80% of patients. Common causes of a MINOCA may include plaque disruption, spontaneous coronary artery dissection (SCAD), coronary artery spasm, and coronary thromboembolism. The optimization of pharmacological treatment in this group of patients, especially dual antiplatelet therapy and statins, improves the prognosis. Data on the indications for invasive treatment of patients with MINOCA based on OCT findings are insufficient. There is a strong need for research comparing treatment strategies, especially in high-risk lesions visualized in OCT. The main aim of this review is to demonstrate the usefulness of OCT in determining the mechanism of MINOCA.

Role of Multimodality Imaging in the Assessment of Myocardial Infarction With Nonobstructive Coronary Arteries: Beyond Conventional Coronary Angiography.

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a heterogeneous clinical entity, encompassing multiple different causes, and a cause of substantial morbidity and mortality. Current guidelines suggest a multimodality imaging approach in establishing the underlying cause for MINOCA, which is considered a working diagnosis. Recent studies have suggested that an initial workup consisting of cardiac magnetic resonance and invasive coronary imaging can yield the diagnosis in most patients. Cardiac magnetic resonance is particularly helpful in excluding nonischemic causes that can mimic MINOCA including myocarditis and Takotsubo cardiomyopathy, as well as for long‐term prognostication. Additionally, intracoronary imaging with intravascular ultrasound or optical coherence tomography may be warranted to evaluate plaque composition, or evaluate for plaque disruption or spontaneous coronary dissection. The role of noninvasive imaging modalities such as coronary computed tomography angiography is currently being investigated in the diagnostic approach and follow‐up of MINOCA and may be appropriate in lieu of invasive coronary angiography in select patients. In recent years, many strides have been made in the workup of MINOCA; however, significant knowledge gaps remain in the field, particularly in terms of treatment strategies. In this review, we summarize recent society guideline recommendations and consensus statements on the initial evaluation of MINOCA, review contemporary multimodality imaging approaches, and discuss treatment strategies including an ongoing clinical trial.

Imaging High-Risk Atherothrombosis Using a Novel Fibrin-Binding Positron Emission Tomography Probe.

High-risk atherosclerosis is an underlying cause of cardiovascular events, yet identifying the specific patient population at immediate risk is still challenging. Here, we used a rabbit model of atherosclerotic plaque rupture and human carotid endarterectomy specimens to describe the potential of molecular fibrin imaging as a tool to identify thrombotic plaques. Atherosclerotic plaques in rabbits were induced using a high-cholesterol diet and aortic balloon injury (N=13). Pharmacological triggering was used in a group of rabbits (n=9) to induce plaque disruption. Animals were grouped into thrombotic and nonthrombotic plaque groups based on gross pathology (gold standard). All animals were injected with a novel fibrin-specific probe 68Ga-CM246 followed by positron emission tomography (PET)/magnetic resonance imaging 90 minutes later. 68Ga-CM246 was quantified on the PET images using tissue-to-background (back muscle) ratios and standardized uptake value. Both tissue-to-background (back muscle) ratios and standardized uptake value were significantly higher in the thrombotic versus nonthrombotic group (P<0.05). Ex vivo PET and autoradiography of the abdominal aorta correlated positively with in vivo PET measurements. Plaque disruption identified by 68Ga-CM246 PET agreed with gross pathology assessment (85%). In ex vivo surgical specimens obtained from patients undergoing elective carotid endarterectomy (N=12), 68Ga-CM246 showed significantly higher binding to carotid plaques compared to a D-cysteine nonbinding control probe. We demonstrated that molecular fibrin PET imaging using 68Ga-CM246 could be a useful tool to diagnose experimental and clinical atherothrombosis. Based on our initial results using human carotid plaque specimens, in vivo molecular imaging studies are warranted to test 68Ga-CM246 PET as a tool to stratify risk in atherosclerotic patients.

NLRP3 Inflammasome Activation Controls Vascular Smooth Muscle Cells Phenotypic Switch in Atherosclerosis.

(1) Background: Monocytes and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome orchestrate lipid-driven amplification of vascular inflammation promoting the disruption of the fibrous cap. The components of the NLRP3 inflammasome are expressed in macrophages and foam cells within human carotid atherosclerotic plaques and VSMCs in hypertension. Whether monocytes and NLRP3 inflammasome activation are direct triggers of VSMC phenotypic switch and plaque disruption need to be investigated. (2) Methods: The direct effect of oxLDL-activated monocytes in VSMCs co-cultured system was demonstrated via flow cytometry, qPCR, ELISA, caspase 1, and pyroptosis assay. Aortic roots of VSMCs lineage tracing mice fed normal or high cholesterol diet and human atherosclerotic plaques were used for immunofluorescence quantification of NLRP3 inflammasome activation/VSMCs phenotypic switch. (3) Results: OxLDL-activated monocytes reduced α-SMA, SM22α, Oct-4, and upregulation of KLF-4 and macrophage markers MAC2, F4/80 and CD68 expression as well as caspase 1 activation, IL-1β secretion, and pyroptosis in VSMCs. Increased caspase 1 and IL-1β in phenotypically modified VSMCs was detected in the aortic roots of VSMCs lineage tracing mice fed high cholesterol diet and in human atherosclerotic plaques from carotid artery disease patients who experienced a stroke. (4) Conclusions: Taken together, these results provide evidence that monocyte promote VSMC phenotypic switch through VSMC NLRP3 inflammasome activation with a likely detrimental role in atherosclerotic plaque stability in human atherosclerosis.

Abstract 11768: Role of Endothelial Shear Stress and Endothelial Shear Stress Gradient in Plaques Associated With Acute Erosion vs. Stable Control Plaques and Relationship Between Plaque Slope and Localization of Plaque Erosion

Introduction: The role of endothelial shear stress (ESS) in the development of coronary plaque erosion is unknown. High ESS gradient (ESSG) has been hypothesized to promote plaque erosion, but no studies have included matched control stable plaques with the same minimal and reference lumen area (MLA, RLA, respectively). No studies examined the location of plaque erosion (proximal vs distal to MLA of the culprit plaque) related to the max magnitude of upslope vs downslope of the lumen obstruction. Aims: (1) to compare ESSG between plaques with erosion and similar control plaques that remained stable; (2) among erosion plaques, to study the effect of max slope steepness (Δ lumen area/frame) up- and down-stream from the culprit plaque MLA on thrombus location. Methods: We studied 46 patients from TOTAL and COMPLETE trials who underwent angiography and OCT imaging: 46 arteries: 27 LAD, 6 LCX, 13 RCA. Plaques were divided into Plaque Erosion (n=24) with OCT features of erosion before PCI (17 definite, 7 probable erosion) and matched coronary plaques from separate control patients (n=22) without plaque disruption. Orthogonal angiographic views were used to generate a 3-D arterial reconstruction, and angio centerline was combined with OCT centerline. Local ESS distribution was assessed by computational fluid dynamics and reported in consecutive 3-mm segments. Among the plaque erosions, we calculated the up- and down-slope (Δ lumen area/frame) of lumen obstruction for each culprit plaque. Results: See Table Conclusion: In plaques with similarly severe obstruction, plaque erosion is associated with higher max ESS and max ESSG vs plaques that remain stable. Proximal plaque erosion/thrombus is associated with steeper plaque upslope vs downslope, and distal plaque erosion/thrombus is associated with steeper plaque downslope vs upslope. Absolute ESSG is higher in downslope vs upslope erosions. These features may help prognosticate individual plaques at risk for future erosion.

Characterization of Atherosclerotic Plaque Coating for Thrombosis Microfluidics Assays

IntroductionStudying arterial thrombus formation by in vitro flow assays is a widely used approach. Incorporating human atherosclerotic plaque material as a thrombogenic surface in these assays represents a method to model the pathophysiological environment of thrombus formation upon plaque disruption. Up until now, achieving a homogeneous coating of plaque material and subsequent reproducible platelet adhesion has been challenging. Here, we characterized a novel method for coating of plaque material on glass coverslips for use in thrombosis microfluidic assays.MethodsA homogenate of human atherosclerotic plaques was coated on glass coverslips by conventional manual droplet coating or by spin coating. Prior to coating, a subset of coverslips was plasma treated. Water contact angle measurements were performed as an indicator for the hydrophilicity of the coverslips. Homogeneity of plaque coatings was determined using profilometric analysis and scanning electron microscopy. Thrombogenicity of the plaque material was assessed in real time by microscopic imaging while perfusing whole blood at a shear rate of 1500 s−1 over the plaque material.ResultsPlasma treatment of glass coverslips, prior to spin coating with plaque material, increased the hydrophilicity of the coverslip compared to no plasma treatment. The most homogeneous plaque coating and highest platelet adhesion was obtained upon plasma treatment followed by spin coating of the plaque material. Manual plaque coating on non-plasma treated coverslips yielded lowest coating homogeneity and platelet adhesion and activation.ConclusionSpin coating of atherosclerotic plaque material on plasma treated coverslips leads to a more homogenous coating and improved platelet adhesion to the plaque when compared to conventional droplet coating on non-plasma treated coverslips. These properties are beneficial in ensuring the quality and reproducibility of flow experiments.

Proton Stimulation Targeting Plaque Magnetite Reduces Amyloid-β Plaque and Iron Redox Toxicity and Improves Memory in an Alzheimer's Disease Mouse Model.

The coexistence of magnetite within protein aggregates in the brain is a typical pathologic feature of Alzheimer's disease (AD), and the formation of amyloid-β (Aβ) plaques induces critical impairment of cognitive function. This study aimed to investigate the therapeutic effect of proton stimulation (PS) targeting plaque magnetite in the transgenic AD mouse brain. A proton transmission beam was applied to the whole mouse brain at a single entrance dose of 2 or 4 Gy to test the effect of disruption of magnetite-containing Aβ plaques by electron emission from magnetite. The reduction in Aβ plaque burden and the cognitive function of the PS-treated mouse group were assayed by histochemical analysis and memory tests, respectively. Aβ-magnetite and Aβ fibrils were treated with PS to investigate the breakdown of the amyloid protein matrix. Single PS induced a 48-87%reduction in both the amyloid plaque burden and ferrous-containing magnetite level in the early-onset AD mouse brain while saving normal tissue. The overall Aβ plaque burden (68-82%) and (94-97%) hippocampal magnetite levels were reduced in late onset AD mice that showed improvements in cognitive function after PS compared with untreated AD mice (p < 0.001). Analysis of amyloid fibrils after exposure to a single 2 or 4 Gy proton transmission beam demonstrated that the protein matrix was broken down only in magnetite-associated Aβ fibrils. Single PS targeting plaque magnetite effectively decreases the amyloid plaque burden and the ferrous-containing magnetite level, and this effect is useful for memory recovery.

In Vivo Human Single-Chain Fragment Variable Phage Display-Assisted Identification of Galectin-3 as a New Biomarker of Atherosclerosis.

BackgroundAtherosclerosis is a complex pathology in which dysfunctional endothelium, activated leucocytes, macrophages, and lipid‐laden foam cells are implicated, and in which plaque disruption is driven by many putative actors. This study aimed to identify accurate targetable biomarkers using new in vivo approaches to propose tools for improved diagnosis and treatment.Methods and ResultsHuman scFv (single‐chain fragment variable) selected by in vivo phage display in a rabbit model of atherosclerosis was reformatted as scFv fused to the scFv‐Fc (single‐chain fragment variable fused to the crystallizable fragment of immunoglobulin G format) antibodies. Their reactivity was tested using flow cytometry and immunoassays, and aorta sections from animal models and human carotid and coronary artery specimens. A pool of atherosclerotic proteins from human endarterectomies was co‐immunoprecipitated with the selected scFv‐Fc followed by mass spectrometry for target identification. Near‐infrared fluorescence imaging was performed in Apoe −/− mice after injection of an Alexa Fluor 647–labeled scFv‐Fc‐2c antibody produced in a baculovirus system with 2 additional cysteine residues (ie, 2c) for future coupling to nano‐objects for theranostic applications. One scFv‐Fc clone (P3) displayed the highest cross‐reactivity against atherosclerotic lesion sections (rabbit, mouse, and human) and was chosen for translational development. Mass spectrometry identified galectin‐3, a β‐galactoside‐binding lectin, as the leader target. ELISA and immunofluorescence assays with a commercial anti‐galectin‐3 antibody confirmed this specificity. P3 scFv‐Fc‐2c specifically targeted atherosclerotic plaques in the Apoe −/− mouse model.ConclusionsThese results provide evidence that the P3 antibody holds great promise for molecular imaging of atherosclerosis and other inflammatory pathologies involving macrophages. Recently, galectin‐3 was proposed as a high‐value biomarker for the assessment of coronary and carotid atherosclerosis.

Inflammation during the life cycle of the atherosclerotic plaque.

Inflammation orchestrates each stage of the life cycle of atherosclerotic plaques. Indeed, inflammatory mediators likely link many traditional and emerging risk factors with atherogenesis. Atheroma initiation involves endothelial activation with recruitment of leucocytes to the arterial intima, where they interact with lipoproteins or their derivatives that have accumulated in this layer. The prolonged and usually clinically silent progression of atherosclerosis involves periods of smouldering inflammation, punctuated by episodes of acute activation that may arise from inflammatory mediators released from sites of extravascular injury or infection or from subclinical disruptions of the plaque. Smooth muscle cells and infiltrating leucocytes can proliferate but also undergo various forms of cell death that typically lead to formation of a lipid-rich 'necrotic' core within the evolving intimal lesion. Extracellular matrix synthesized by smooth muscle cells can form a fibrous cap that overlies the lesion's core. Thus, during progression of atheroma, cells not only procreate but perish. Inflammatory mediators participate in both processes. The ultimate clinical complication of atherosclerotic plaques involves disruption that provokes thrombosis, either by fracture of the plaque's fibrous cap or superficial erosion. The consequent clots can cause acute ischaemic syndromes if they embarrass perfusion. Incorporation of the thrombi can promote plaque healing and progressive intimal thickening that can aggravate stenosis and further limit downstream blood flow. Inflammatory mediators regulate many aspects of both plaque disruption and healing process. Thus, inflammatory processes contribute to all phases of the life cycle of atherosclerotic plaques, and represent ripe targets for mitigating the disease.