LOX-1 deletion and macrophage trafficking in atherosclerosis.

BACKGROUND: Atherosclerosis is associated with macrophage accumulation. LOX-1 has been shown to induce macrophage attachment, and its deletion (LOX-1 knockout, KO) reduces atherosclerosis in LDLr KO mice fed a high cholesterol diet. We examined differences in macrophage trafficking in age-matched wild type, LOX-1 KO, LDLr KO, and LDLr/LOX-1 double KO mice. METHODS: Sections of aortas of mice fed high cholesterol diet were collected at weeks 0, 4, 8, 12 and 19 and analyzed by immunohistochemistry and flow cytometry. RESULTS: In the LDLr KO mice aorta, CD68 positivity (macrophage accumulation) increased over time up to 12 weeks, and then the accumulation fell modestly but significantly. The periaortal fat and adventitia showed more CD68 positivity than the media and intima. This pattern was also evident in the non-atherosclerotic areas. Importantly, LOX-1 KO and LDLr-LOX-1 double KO mice showed diminished CD68 positivity in comparison to wild type and LDLR KO mice, respectively. Further, macrophages from LOX-1 KO mice revealed a marked reduction in migration (vs. macrophages from wild type mice) in in vitro migration assay. CONCLUSIONS: LOX-1 deletion translates into reduction in macrophage trafficking in the aorta of LDLr KO mice. Most of the macrophage trafficking appears in the subadventitial regions.

Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices.

The success of left ventricular assist device (LVAD) therapy is hampered by complications such as thrombosis and bleeding. Understanding blood flow interactions between the heart and the LVAD might help optimize treatment and decrease complication rates. We hypothesized that LVADs modify shear stresses and blood transit in the left ventricle (LV) by changing flow patterns and that these changes can be characterized using 2D echo color Doppler velocimetry (echo-CDV). We used echo-CDV and custom postprocessing methods to map blood flow inside the LV in patients with ongoing LVAD support (Heartmate II, N = 7). We compared it to healthy controls (N = 20) and patients with dilated cardiomyopathy (DCM, N = 20). We also analyzed intraventricular flow changes during LVAD ramp tests (baseline ± 400 rpm). LVAD support reversed the increase in blood stasis associated with DCM, but it did not reduce intraventricular shear exposure. Within the narrow range studied, the ventricular flow was mostly insensitive to changes in pump speed. Patients with significant aortic insufficiency showed abnormalities in blood stasis and shear indices. Overall, this study suggests that noninvasive flow imaging could potentially be used in combination with standard clinical methods for adjusting LVAD settings to optimize flow transport and minimize stasis on an individual basis.

Mineralocorticoid Receptor Antagonists in the Management of Heart Failure and Resistant Hypertension: A Review.

IMPORTANCE: Heart failure (HF), with or without reduced ejection fraction, and multidrug-resistant hypertension (RHT) are major worldwide health problems of ever-increasing proportions. The mineralocorticoid receptor antagonists (MRAs) spironolactone and eplerenone have proved valuable additions to the overall management of these disorders in patients without significant renal dysfunction. OBSERVATIONS: Neurohormonal activation, including aldosteronism, in HF and RHT, has provided the pathophysiologic basis for the inclusion of MRA in the overall management of these disorders and the respective survival benefit and control of blood pressure. Furthermore, MRAs attenuate the appearance of secondary hyperparathyroidism that accompanies excretory Ca2+ losses induced by aldosteronism in which elevated parathyroid hormone levels raise the risk of adverse cardiovascular events and atraumatic bone fracture. Serial surveillance of serum electrolytes and creatinine levels is mandated to avoid serious hyperkalemia (potassium concentration >5.5 mEq/L) and its attendant risks in patients receiving MRAs. CONCLUSIONS AND RELEVANCE: Mineralocorticoid receptor antagonists are a valuable addition to the practice of medicine. Their judicious use in patients with HF or RHT can improve treatment of these patients.

Next-generation airbags and the possibility of negative outcomes due to thoracic injury.

Airbags have been shown to decrease morbidity and mortality associated with motor vehicle accidents when used in conjunction with seat belts. Airbag deployment alone however, has recently been implicated as a cause of significant thoracic injuries to unrestrained drivers. Resulting injuries include major cardiovascular and pulmonary complications. Airbags provide safety to occupants of cars and reduce mortality by 25%-30%. When not used in accordance with international standards, however, they can cause serious injury. We searched online databases from 1970 to January 2013 and included 17 retrospective studies, 12 systematic review articles, 18 case reports, 5 prospective studies, 1 lab study, 3 cohort studies, and 1 meta-analysis. Outcomes included clinical/functional response, left ventricular remodelling, hospitalizations, and mortality. Physicians must maintain a high index of suspicion for injury when evaluating drivers who were not wearing seat belts when airbags deployed, regardless of the speed of the collision, because increased risk of thoracic injury with airbags has been described in the literature. Our review indicates that even new technology, specifically the side air bag, has been associated with a risk of thoracic injury. Considering that regulations are a driving force for airbag technology, further research and scrutiny by medical teams is needed to consider the effects of airbag technology advancements on morbidity and mortality rates of car accidents, to help in guiding further improvement, and to help lawmakers in implementing rules that protect the safety of occupants.

Decorin in atherosclerosis.

Atherosclerotic cardiovascular disease is a major cause of morbidity and mortality in the Western world. Despite tremendous strides in understandings its pathogenesis, it still remains a challenge because of gaps in our understanding of its initiation, progression and complications leading to the clinical syndromes of angina, acute coronary syndrome, cerebrovascular disease and peripheral vascular disease. Recent studies have provided impetus on the shift from models of atherosclerosis based on cellular interactions to models where the important role of extracellular matrix is recognized. Proteoglycans, especially those belonging to the small leucine-rich proteoglycan family of which decorin is a representative example, have come under close scrutiny for their role in atherogenesis. There is evidence from in vitro and in vivo animal models as well as humans to suggest an important role of decorin in attenuating progression of atherosclerosis. Decorin distribution in different blood vessels has been shown to inversely correlate with the tendency to develop atherosclerosis. Decorin seems to interact closely with different cellular components of the plaque milieu, thereby suggesting its role in influencing atherogenesis at different steps. Here we review the current understanding of the role of decorin in the pathogenesis of atherosclerosis.

Mice lacking histone deacetylase 6 have hyperacetylated tubulin but are viable and develop normally.

Posttranslational modifications play important roles in regulating protein structure and function. Histone deacetylase 6 (HDAC6) is a mostly cytoplasmic class II HDAC, which has a unique structure with two catalytic domains and a domain binding ubiquitin with high affinity. This enzyme was recently identified as a multisubstrate protein deacetylase that can act on acetylated histone tails, alpha-tubulin and Hsp90. To investigate the in vivo functions of HDAC6 and the relevance of tubulin acetylation/deacetylation, we targeted the HDAC6 gene by homologous recombination in embryonic stem cells and generated knockout mice. HDAC6-deficient mice are viable and fertile and show hyperacetylated tubulin in most tissues. The highest level of expression of HDAC6 is seen in the testis, yet development and function of this organ are normal in the absence of HDAC6. Likewise, lymphoid development is normal, but the immune response is moderately affected. Furthermore, the lack of HDAC6 results in a small increase in cancellous bone mineral density, indicating that this deacetylase plays a minor role in bone biology. HDAC6-deficient mouse embryonic fibroblasts show apparently normal microtubule organization and stability and also show increased Hsp90 acetylation correlating with impaired Hsp90 function. Collectively, these data demonstrate that mice survive well without HDAC6 and that tubulin hyperacetylation is not detrimental to normal mammalian development.

Epithelial and mesenchymal hamartomatous changes in a mature port-wine stain: Morphologic evidence for a multiple germ layer field defect.

The port-wine stain (PWS) is a congenital cutaneous venulocapillary malformation of unknown pathogenesis. Many patients with facial PWS develop thickening with cobblestoning and nodularity during adult life. The histologic correlates of this maturational change are poorly documented and its mechanisms remain unclear. In this case study we present new histologic observations that may elucidate this phenomenon. An extensive PWS on the face of a 75-year-old man exhibited gross thickening with cobblestoning and nodularity. Histologic examination revealed not only the expected vascular abnormalities, but also a number of widely distributed epithelial, neural, and mesenchymal hamartomatous changes. Epithelial changes included epidermal nevus, sebaceous trichofolliculoma, and basaloid follicular hamartoma. Changes of connective tissue nevus, smooth-muscle hamartoma, neural hamartoma, and subcuticular hamartoma were also noted. The complex hamartomatous changes observed in the PWS of this patient involved multiple germ lines and were distributed in a widespread pattern. These changes not only offer an explanation for the skin thickening and nodularity of this patient, but also suggest a genetically determined, multilineage developmental field defect in the pathogenesis of this lesion. Further studies of other patients are necessary to understand the full implications of these findings in the late stage of PWS.

Somatic mutation of vascular endothelial growth factor receptors in juvenile hemangioma.

Juvenile hemangiomas are the most common tumors of infancy, occurring in as many as 10% of all births. These benign vascular lesions enlarge rapidly during the first year of life by hyperplasia of endothelial cells and attendant pericytes and then spontaneously involute over a period of years, leaving loose fibrofatty tissue. Several hypotheses have been put forth concerning hemangiogenesis, including the possibility that the tumor is the result of somatic mutation in one or more components of critical vascular growth-regulatory pathways. To test this hypothesis, we obtained 15 proliferative-phase hemangiomas after surgical resection and dissected them to enrich for the lesional (endothelial and pericytic) components of each specimen. To determine whether hemangiomas represent a clonal expansion from a single progenitor cell, we assayed X-inactivation patterns for each lesion by using the polymorphic X-linked human androgen receptor gene. Twelve of 14 informative hemangiomas showed a significant degree of allelic loss after methylation-based and transcription-based polymerase chain reaction clonality assays, suggesting a nonrandom X-inactivation pattern and, thus, a monoclonal origin. We then sequenced genes encoding the receptors of the vascular endothelial growth factors (VEGFs) as candidates for potential somatic mutation. Mutations were found in two of the 15 hemangioma specimens: a missense mutation (P1147S) in the kinase domain of the VEGFR2 (FLK1/KDR) gene in one specimen and a missense mutation (P954S) in the kinase insert of the VEGFR3 (FLT4) gene in another specimen. In each case, the mutation was detected in tumor tissue but not in adjacent normal tissue. These results suggest that one potential mechanism involved in hemangioma formation is the alteration of the VEGF signaling pathway in endothelial and/or pericytic cells.