Augmented atrial apoptosis, angiotensin II expression, and related signalling pathway activation have been shown in clinical atrial fibrillation (AF), but their significance is poorly understood. This study evaluated temporal relationships between changes in atrial histopathology, selected signalling mediators, and AF promotion, as well as effects of angiotensin-converting enzyme (ACE) inhibition, in a canine model of congestive heart failure (CHF). Dogs were subjected to ventricular tachypacing (VTP) for varying periods up to 5 weeks. Apoptosis was assessed by terminal dUTP nick-end labelling (TUNEL) and DNA fragmentation. Protein expression was determined by Western blot, angiotensin II concentration by ELISA (tissue) and radioimmunoassay (plasma), and caspase-3 activity by enzymatic assay. Histopathological analyses were used to quantify fibrosis, inflammation, and cell death. Significant apoptosis developed 24 h after VTP onset and persisted for 1 week, returning to baseline thereafter. Apoptosis was preceded by increases in tissue (but not plasma) angiotensin II concentration; enhanced expression of phosphorylated mitogen-activated protein (MAP) kinases p38, JNK, and ERK; and augmented ratios of the proapoptotic protein Bax to the antiapoptotic protein Bcl-2. Increased cell death, leukocyte infiltration, and caspase-3 activity occurred at the time of peak apoptosis. Apoptosis was followed by interstitial fibrosis, which peaked at 5 weeks. ACE inhibition (enalapril) prevented increases in tissue angiotensin II concentration, phosphorylated ERK expression, Bax/Bcl-2 ratio, and cellular apoptosis, but did not affect total cell death, leukocyte infiltration, JNK or p38 activation, and reduced but did not eliminate tissue fibrosis. AF-promoting atrial structural remodeling in experimental CHF involves angiotensin II-dependent and angiotensin II-independent pathways. Significant apoptosis occurs, but prevention of apoptosis by ACE inhibition only partially prevents atrial structural remodeling.

Aging is a modern concept: human life expectancy has more than doubled in less than 150 yr in Western countries. Longer life span, however, reveals age-related diseases, including cerebrovascular diseases. The vascular system is a prime target of aging: the “wear and tear” of large elastic arteries exposed to a lifelong pulsatile pressure causes arterial stiffening by fragmentation of elastin fibers and replacement by stiffer collagen. This arterial stiffening increases in return the amplitude of the pulse pressure (PP), its wave penetrating deeper into the microcirculation of low-resistance, high-flow organs such as the brain. Several studies have associated peripheral arterial stiffness responsible for the sustained increase in PP, with brain microvascular diseases such as cerebral small vessel disease, cortical gray matter thinning, white matter atrophy, and cognitive dysfunction in older individuals and prematurely in hypertensive and diabetic patients. The rarefaction of white matter is also associated with middle cerebral artery pulsatility that is strongly dependent on PP and artery stiffness. PP and brain damage are likely associated, but the sequence of mechanistic events has not been established. Elevated PP promotes endothelial dysfunction that may slowly develop in parallel with the accumulation of proinflammatory senescent cells and oxidative stress, generating cerebrovascular damage and remodeling, as well as brain structural changes. Here, we review data suggesting that age-related increased peripheral artery stiffness may promote the penetration of a high PP to cerebral microvessels, likely causing functional, structural, metabolic, and hemodynamic alterations that could ultimately promote neuronal dysfunction and cognitive decline.

A chronic and gradual increase in pulse pressure (PP) is associated with cognitive decline and dementia in older individuals, but the mechanisms remain ill-defined. We hypothesized that a chronic elevation of PP would cause brain microvascular endothelial mechanical stress, damage the neurovascular unit, and ultimately induce cognitive impairment in mice, potentially contributing to the progression of vascular dementia and Alzheimer disease. To test our hypothesis, male control wild-type mice and Alzheimer disease model APP/PS1 (amyloid precursor protein/presenilin 1) mice were exposed to a transverse aortic constriction for 6 weeks, creating a PP overload in the right carotid (ipsilateral). We show that the transverse aortic constriction procedure associated with high PP induces a cascade of vascular damages in the ipsilateral parenchymal microcirculation: in wild-type mice, it impairs endothelial dilatory and blood brain barrier functions and causes microbleeds, a reduction in microvascular density, microvascular cell death by apoptosis, leading to severe hypoperfusion and parenchymal cell senescence. These damages were associated with brain inflammation and a significant reduction in learning and spatial memories. In APP/PS1 mice, that endogenously display severe cerebral vascular dysfunctions, microbleeds, parenchymal inflammation and cognitive dysfunction, transverse aortic constriction–induced high PP further aggravates cerebrovascular damage, Aβ (beta-amyloid) accumulation, and prevents learning. Our study, therefore, demonstrates that brain microvessels are vulnerable to a high PP and mechanical stress associated with transverse aortic constriction, promoting severe vascular dysfunction, disruption of the neurovascular unit, and cognitive decline. Hence, chronic elevated amplitude of the PP could contribute to the development and progression of vascular dementia including Alzheimer disease.

Eye drops of aganirsen, an antisense oligonucleotide preventing insulin receptor substrate-1 expression, inhibited corneal neovascularization in a previous dose-finding phase II study. We aimed to confirm these results in a phase III study and investigated a potential clinical benefit on visual acuity (VA), quality of life (QoL), and need for transplantation. Multicenter, double-masked, randomized, placebo-controlled phase III study. Analysis of 69 patients with keratitis-related progressive corneal neovascularization randomized to aganirsen (34 patients) or placebo (35 patients). Patients applied aganirsen eye drops (86 μg/day/eye) or placebo twice daily for 90 days and were followed up to day 180. The primary end point was VA. Secondary end points included area of pathologic corneal neovascularization, need for transplantation, risk of graft rejection, and QoL. Although no significant differences in VA scores between groups were observed, aganirsen significantly reduced the relative corneal neovascularization area after 90 days by 26.20% (P = 0.014). This improvement persisted after 180 days (26.67%, P = 0.012). Aganirsen tended to lower the transplantation need in the intent-to-treat (ITT) population at day 180 (P = 0.087). In patients with viral keratitis and central neovascularization, a significant reduction in transplantation need was achieved (P = 0.048). No significant differences between groups were observed in the risk of graft rejection. However, aganirsen tended to decrease this risk in patients with traumatic/viral keratitis (P = 0.162) at day 90. The QoL analyses revealed a significant improvement with aganirsen in composite and near activity subscores (P = 0.039 and 0.026, respectively) at day 90 in the per protocol population. Ocular and treatment-related treatment-emergent adverse events (TEAEs) were reported in a lower percentage with aganirsen compared with placebo. Only 3 serious TEAEs (2 with aganirsen and 1 with placebo) were considered treatment-related. This first phase III study on a topical inhibitor of corneal angiogenesis showed that aganirsen eye drops significantly inhibited corneal neovascularization in patients with keratitis. The need for transplantation was significantly reduced in patients with viral keratitis and central neovascularization. Topical application of aganirsen was safe and well tolerated.

Werner syndrome (WS) is a premature aging disorder caused by mutations in a RecQ‐like DNA helicase. Mice lacking the helicase domain of the WRN homologue exhibit many phenotypic features of WS, including a prooxidant status and a shorter mean life span compared to wild‐type animals. Here, we show that Wrn mutant mice also develop premature liver sinusoidal endothelial defenestration along with inflammation and metabolic syndrome. Vitamin C supplementation rescued the shorter mean life span of Wrn mutant mice and reversed several age‐related abnormalities in adipose tissues and liver endothelial defenestration, genomic integrity, and inflammatory status. At the molecular level, phosphorylation of age‐related stress markers like Akt kinase‐specific substrates and the transcription factor NF‐κB, as well as protein kinase Cδ and Hif‐1α transcription factor levels, which are increased in the liver of Wrn mutants, were normalized by vitamin C. Vitamin C also increased the transcriptional regulator of lipid metabolism PPARα. Finally, microarray and gene set enrichment analyses on liver tissues revealed that vitamin C decreased genes normally up‐regulated in human WS fibroblasts and cancers, and it increased genes involved in tissue injury response and adipocyte dedifferentiation in obese mice. Vitamin C did not have such effect on wild‐type mice. These results indicate that vitamin C supplementation could be beneficial for patients with WS.—Massip, L., Garand, C., Paquet, E. R., Cogger, V. C., O'Reilly, J. N., Tworek, L., Hatherell, A., Taylor, C. G., Thorin, E., Zahradka, P., Le Couteur, D. G., Lebel, M. Vitamin C restores healthy aging in a mouse model for Werner syndrome. FASEB J . 24, 158–172 (2010). www.fasebj.org