Hypertensive Pressure Mechanosensing Alone Triggers Lipid Droplet Accumulation and Transdifferentiation of Vascular Smooth Muscle Cells to Foam Cells

Arterial Vascular smooth muscle cells (VSMCs) play a central role in the onset and progression of atherosclerosis. Upon exposure to pathological stimuli, they can take on alternative phenotypes that, among others, have been described as macrophage like, or foam cells. VSMC foam cells make up >50% of all arterial foam cells and have been suggested to retain an even higher proportion of the cell stored lipid droplets, further leading to apoptosis, secondary necrosis, and an inflammatory response. However, the mechanism of VSMC foam cell formation is still unclear. Here, it is identified that mechanical stimulation through hypertensive pressure alone is sufficient for the phenotypic switch. Hyperspectral stimulated Raman scattering imaging demonstrates rapid lipid droplet formation and changes to lipid metabolism and changes are confirmed in ABCA1, KLF4, LDLR, and CD68 expression, cell proliferation, and migration. Further, a mechanosignaling route is identified involving Piezo1, phospholipid, and arachidonic acid signaling, as well as epigenetic regulation, whereby CUT&Tag epigenomic analysis confirms changes in the cells (lipid) metabolism and atherosclerotic pathways. Overall, the results show for the first time that VSMC foam cell formation can be triggered by mechanical stimulation alone, suggesting modulation of mechanosignaling can be harnessed as potential therapeutic strategy.

Investigating novel roles for nesprin-1 and the LINC complex in Dilated Cardiomyopathy

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): British Heart Foundation

Cardiomyopathies are an important cause of heart failure and sudden cardiac death. Recent studies have demonstrated the importance of the "passive" mechanical components of cardiomyocytes (CMs) as new causes for dilated cardiomyopathy (DCM). Nesprin-1/-2 are highly expressed in skeletal and cardiac muscle and together with SUN (Sad1p/UNC84)-domain containing proteins form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex at the nuclear envelope (NE), which, in association with lamin A/C and emerin, mechanically couples the nucleus to the cytoskeleton. We have recently identified novel nesprin-1 mutants in  DCM patients, which cause LINC complex disruption, leading to defects in nuclear organisation and myogenesis in vitro. We aim to investigate mechanisms through which these mutations lead to DCM. Therefore, we have generated a nesprin-1 mutant R8253Q knock-in (KI) mouse line (equivalent to human SYNE1 R8272Q) as the first clinically relevant animal model. 2. R8272Q is in close proximity to the binding regions to microtubule (MT) associated proteins kinesin light chain-1/2 and Akap6 at the nuclear envelope, which is potentially in involved in MT organization. Preliminary mouse echocardiography data showed significantly reduced thickness of left ventricle (LV) posterior wall in diastole, and reduced % ejection fraction in the KIs at 15 weeks after birth, suggesting LV dysfunction and a tendency of DCM. Immunofluorescence (IF) of isolated adult cardiomyocytes (ACM) from KI mice showed perinuclear MT localization was significantly reduced, KLC-1/2 and AKAP6 were mislocalized from the NE and altered nuclear positioning. Therefore, we propose to investigate novel roles of nesprin-1 and the LINC complex in cardiomyocyte mechanotransduction using this KI model to explore roles of  nesprin-1 in microtubule organization, nuclear positioning, and CM homeostasis, which will yield insights into signalling leading to DCM and heart failure as well as inform strategies for translational approaches.

Abstract 373: Senescence Drives Changes In Vesicle Secretion And Extracellular Matrix Organisation To Enhance Vascular Amyloidosis

Background: Vascular amyloidosis, caused when peptide monomers aggregate into insoluble amyloid, is a prevalent age-associated pathology. Aortic medial amyloid (AMA) is the most common human amyloid and is composed of medin, a 50-amino acid fragment of milk fat globule EGF-factor 8 (MFGE8). Emerging evidence has implicated extracellular vesicles (EVs) as mediators of pathological amyloid metabolism and accumulation in the extracellular matrix (ECM). MFGE8 has been identified as EV cargo in several cell types, including vascular smooth muscle cells (VSMCs). To determine the mechanisms of AMA formation with age, we explored the impact of VSMC senescence, EV secretion and ECM remodelling on medin accumulation.

Methods: Primary human VSMCs were used for in vitro experiments, including EV isolation and synthesis of decellularised ECM for Western blotting, immunofluorescence and mass spectrometry analysis.

Results: Medin was detected in EVs secreted from VSMCs. Small, round medin aggregates colocalised with EV markers in the ECM and medin was shown on the surface of EVs deposited in the ECM. Decreasing VSMC EV secretion with an inhibitor attenuated aggregation and deposition of medin in the ECM. Medin accumulation in the aortic wall of human subjects was strongly correlated with age. VSMC senescence increased EV secretion, increased EV medin loading and triggered extracellular deposition of medin in fibrillar form. Proteomic analysis showed VSMC senescence induced changes in EV cargo and ECM composition. These changes led to enhanced EV-ECM binding in the senescent ECM and accelerated aggregation of medin into amyloid fibrils. Abundance of the proteoglycan, HSPG2, was increased in the senescent ECM and colocalised with EVs and medin. Knock-down of HSPG2 decreased medin fibril formation in the senescent ECM.

Conclusions: Medin is secreted into the ECM by VSMC-derived EVs, which enhance its aggregation. Senescence induces changes in EV secretion and cargo and ECM composition. Together, these changes trigger accumulation of fibrillar medin, contributing to the age-associated development of AMA.

Pressure and stiffness sensing together regulate vascular smooth muscle cell phenotype switching

Vascular smooth muscle cells (VSMCs) play a central role in the progression of atherosclerosis, where they switch from a contractile to a synthetic phenotype. Because of their role as risk factors for atherosclerosis, we sought here to systematically study the impact of matrix stiffness and (hemodynamic) pressure on VSMCs. Thereby, we find that pressure and stiffness individually affect the VSMC phenotype. However, only the combination of hypertensive pressure and matrix compliance, and as such mechanical stimuli that are prevalent during atherosclerosis, leads to a full phenotypic switch including the formation of matrix-degrading podosomes. We further analyze the molecular mechanism in stiffness and pressure sensing and identify a regulation through different but overlapping pathways culminating in the regulation of the actin cytoskeleton through cofilin. Together, our data show how different pathological mechanical signals combined but through distinct pathways accelerate a phenotypic switch that will ultimately contribute to atherosclerotic disease progression.

Linked chromosome 16q13 chemokines, macrophage-derived chemokine, fractalkine, and thymus- and activation-regulated chemokine, are expressed in human atherosclerotic lesions

Chemokines are important mediators of macrophage and T-cell recruitment in a number of inflammatory pathologies, and chemokines expressed in atherosclerotic lesions may play an important role in mononuclear cell recruitment and macrophage differentiation. We have analyzed the expression of the linked chromosome 16q13 genes that encode macrophage-derived chemokine (MDC/CCL22), thymus- and activation-regulated chemokine (TARC/CCL17), and the CX(3)C chemokine fractalkine (CX(3)CL1) in primary macrophages and human atherosclerotic lesions by reverse transcription-polymerase chain reaction and immunohistochemistry. We show that macrophage expression of the chemokines MDC, fractalkine, and TARC is upregulated by treatment with the Th2-type cytokines interleukin-4 and interleukin-13. High levels of MDC, TARC, and fractalkine mRNA expression are seen in some, but not all, human arteries with advanced atherosclerotic lesions. Immunohistochemistry shows that MDC, fractalkine, and TARC are expressed by a subset of macrophages within regions of plaques that contain plaque microvessels. We conclude that MDC, fractalkine, and TARC, which are chromosome 16q13 chemokines, could play a role in mononuclear cell recruitment into atherosclerotic lesions and influence the subsequent inflammatory response. Macrophage-expressed chemokines upregulated by interleukin-4 may be useful surrogate markers for the presence of Th2-type immune responses in human atherosclerotic lesions.

Payer-based case management: perspectives on managing brain-injured patient

As the payer environment is carved into many segments, each with its own accountability relative to its financial liability, family members, providers, and even other case managers often find it difficult to comprehend the perspectives of the various parties represented. Indeed, one brain injury case I recently evaluated had four payer case managers: one from the patient's health plan, one from a disease management program for his premorbid diabetes, and two from Medicaid-sponsored programs for the disabled. For payer-based case managers, the ubiquitous case manager role confusion compounds product unfamiliarity.

Use of cDNA representational difference analysis to identify disease-specific genes in human atherosclerotic plaques

Changes in gene expression underlie many biological phenomena, including cellular differentiation and activation, embryonic development, and pathological processes. In recent years, much attention has been focused on the identification of genes that are differentially expressed between normal and disease states: the isolation of disease-specific genes is not only essential for our understanding of the molecular basis of pathological conditions, but may potentially highlight novel therapeutic targets.

The effect of context and metamemory judgements on automatic processes in memory

These experiments examine two aspects of the automatic influences on memory as measured by target responding in the exclusion condition within the process dissociation framework. In Experiment 1, we examine the extent to which congruency between study and test contexts affects automatic processes in memory. In Experiment 2, we investigate qualitative differences in consciously controlled and automatic processing as indexed by metamemory judgements. In both experiments, a process-dissociation procedure was used to separate automatic and consciously controlled uses of memory in a stem completion task. In the study phase of Experiment 1, subjects read a passage from one of two directed perspectives. The subsequent stem completion task, which subjects performed while mindful of the study perspective, contained (a) old words congruent with the directed perspective, (b) old words congruent with a different (non-directed) perspective, and (c) words that had not been presented. Estimates of automatic influences for words congruent with the directed perspective were found to be greater than estimates for words incongruent with the directed perspective. These results provide evidence for the automatic or unconscious influences of meaning on task performance, which is uncontaminated by the influence of consciously controlled recollection which may occur in indirect memory tests. In Experiment 2, judgements of learning made prior to retrieval under inclusion and exclusion instructions were found to be different for consciously controlled and automatic processes, suggesting that memory as measured by the opposition (exclusion) procedure is involuntary and unconscious, with prospective monitoring of performance not sensitive to eventual performance.

G protein subunit levels in fibroblasts from familial Alzheimer's disease patients: lower levels of high molecular weight Gs alpha isoform in patients with decreased beta-adrenergic receptor stimulated cAMP formation

Abnormalities in G protein linked signal transduction pathways have been detected in fibroblasts from individuals with familial and sporadic Alzheimer's disease. The present study used Gs alpha, Gi alpha, Gq alpha and Go alpha G protein subunit antisera, immunoblotting and densitometry to quantify levels of these proteins in control fibroblasts and in fibroblasts from individuals with familial Alzheimer's disease (FAD). The FAD fibroblasts were from individuals with the APPK670N,M671L mutation, different presenilin 1 (PS1) mutations and one fibroblast cell line from an individual with FAD of unknown genetic aetiology. Results revealed a significant reduction in the large Gs alpha subunit in fibroblasts with the PS1 mutations and in the fibroblast cell line of unknown genetic aetiology, when compared to control levels. This decrease was not apparent in the APPK670N,M671L FAD fibroblasts. Immunoreactivity for Go alpha was not detected in any of the fibroblast cell lines. No differences were observed in Gi alpha or Gq alpha levels when comparing any of the control and Alzheimer's disease fibroblast groups. WE conclude that with the exception of decreased levels of the large Gs alpha subunit, gross alterations in the levels of the Gi alpha, Gq alpha and Go alpha are not associated with the G protein-coupled signal transduction disturbances described previously for some of these FAD fibroblasts.

Molecular cloning of cDNA encoding the 110 kDa and 21 kDa regulatory subunits of smooth muscle protein phosphatase 1M

The structures of the M110 and M21 regulatory subunits of protein phosphatase-1M, the major enzyme which dephosphorylates myosin in smooth muscle, have been deduced from cloned cDNAs. The N-terminus of the M110 subunit from rat aorta contains seven ankyrin repeats, while the C-terminus of the M21 subunit from chicken gizzard contains a leucine zipper motif. The M110 subunit is expressed in two different forms which differ in their C-terminal sequences. One of these is highly homologous to the whole of the M21 subunit.

Psychiatric nursing education in Nebraska: 1989-1990

The academic and clinical content of psychiatric nursing curricula in the registered nurse basic educational programs in Nebraska for academic year 1989-1990 was explored by the Nebraska Sub-group of the Nursing Curriculum and Training Task Force of the National Alliance for the Mentally Ill. The review includes literature regarding the history, development, and future trends of psychiatric nursing; factors affecting nursing student attitudes toward psychiatric patients; basic content included in psychiatric and psychosocial nursing curricula; and concepts essential in working with the seriously, persistently mentally ill. Contrary to current trends in the United States, all Nebraska schools of nursing have a generic psychiatric nursing course taught by clinical specialists in psychiatric-mental health nursing. Hands-on clinical time spent with patients with psychiatric diagnoses as well as those with psychosocial needs varies from 84 to 200 hr per semester. Not all students are exposed to patients with severe and persistent mental illness. Fewer than 5% of Nebraska graduates choose psychiatric nursing as their area of practice. The authors express grave concern for the future of psychiatric nursing education. Implications for curriculum revision and replication studies are suggested.