Calcium homeostasis and nerve growth factor secretion from vascular and bladder smooth muscle cells

Bladder and vascular smooth muscle cells cultured from four rat strains (WKY, SHR, WKHA, WKHT) differing in rates of nerve growth factor (NGF) production were used to determine whether a relationship exists between intracellular calcium and NGF secretion. Basal cytosolic calcium was related to basal NGF secretion rates in bladder and vascular smooth muscle cells from all four strains with the exception of WKHT bladder muscle cells. Thrombin is a calcium-mobilizing agent and increases NGF production from vascular but not bladder smooth muscle cells. Strain differences were found in the magnitude of the calcium peak induced by thrombin in vascular smooth muscle cells, but these differences did not correlate with NGF secretion. Thrombin caused a calcium response in bladder smooth muscle cells without influencing NGF production. Quenching the calcium transient with a calcium chelator had no effect on thrombin-inducted NGF secretion rates in vascular smooth muscle cells. Thus, basal intracellular calcium may establish a set point for NGF secretion from smooth muscle. In addition, transient elevations in cytosolic calcium were unrelated to the induction of NGF output.     

The onset of left ventricular diastolic dysfunction in SHR rats is not related to hypertrophy or hypertension

Left ventricular (LV) diastolic dysfunction, particularly relaxation abnormalities, are known to be associated with the development of LV hypertrophy (LVH). Preliminary human and animal studies suggested that early LV diastolic dysfunction may be revealed independently of LVH. However, whether LV diastolic dysfunction is compromised before the onset of hypertension and LVH remains unknown. We therefore evaluated LV diastolic function in spontaneously hypertensive rats (SHR) at different ages and tested whether LV diastolic dysfunction is associated with abnormal intracellular calcium homeostasis. LV systolic and diastolic functions were evaluated by invasive and echocardiographic methods in 3-week-old (without hypertension) and 5-week-old (with hypertension) SHR and Wistar-Kyoto control rats. Basal intracytoplasmic calcium and sarcoplasmic reticulum (SR) Ca(2+) contents were measured in cardiomyocytes using fura-2 AM. Sarco(endo)plasmic Ca(2+)-ATPase isoform 2a (SERCA 2a) and phospholamban (PLB) expressions were quantified by Western blot and quantitative RT-PCR techniques. LV relaxation dysfunction was observed in 3-week-old SHR rats before onset of hypertension and LVH. An increase in basal intracytoplasmic Ca(2+) and a decrease in SR Ca(2+) release were demonstrated in SHR. Decreased expression of SERCA 2a and Ser16 PLB (p16-PLB) protein levels was also observed in SHR rats, whereas mRNA expression was not decreased. For the first time, we have shown that LV myocardial dysfunction precedes hypertension in 3-week-old SHR rats. This LV myocardial dysfunction was associated with high diastolic [Ca(2+)](i) possibly due to decreased SERCA 2a and p16-PLB protein levels. Diastolic dysfunction may be a potential predictive marker of arterial hypertension in genetic hypertension syndromes.     

Comparison of Ca<Superscript>2+</Superscript> Currents of Chromaffin Cells from Normotensive Wistar Kyoto and Spontaneously Hypertensive Rats

Spontaneously hypertensive rats (SHR) are widely used as model to investigate the pathophysiological mechanisms of essential hypertension. Catecholamine plasma levels are elevated in SHR, suggesting alterations of the sympathoadrenal axis. The residual hypertension in sympathectomized SHR is reduced after demedullation, suggesting a dysfunction of the adrenal medulla. Intact adrenal glands exposed to acetylcholine or high K⁺ release more catecholamine in SHR than in normotensive Wistar Kyoto (WKY) rats, and adrenal chromaffin cells (CCs) from SHR secrete more catecholamines than CCs from WKY rats. Since Ca²⁺ entry through voltage-gated Ca²⁺ channels (VGCC) triggers exocytosis, alterations in the functional properties of these channels might underlie the enhanced catecholamine release in SHR. This study compares the electrophysiological properties of VGCC from CCs in acute adrenal slices from WKY rats and SHR at an early stage of hypertension. No significant differences were found in the macroscopic Ca²⁺ currents (current density, I–V curve, voltage dependence of activation and inactivation, kinetics) between CCs of SHR and WKY rats, suggesting that Ca²⁺ entry through VGCC is not significantly different between these strains, at least at early stages of hypertension. Ca²⁺ buffering, sequestration and extrusion mechanisms, as well as Ca²⁺ release from intracellular stores, must now be evaluated to determine if alterations in their function can explain the enhanced catecholamine secretion reported in CCs from SHR.     

Effects of growth rate and cell density on nerve growth factor secretion in cultures of vascular and bladder smooth muscle cells from hypertensive and hyperactive rats

Elevated target-derived smooth muscle nerve growth factor (NGF) and resultant neurogenic plasticity are associated with both hypertension and hyperactive voiding in spontaneously hypertensive rats (SHRs: hypertensive, behaviorally hyperactive). In culture, vascular (VSMCs) and bladder (BSMCs) smooth muscle cells derived from SHRs secrete higher levels of NGF, proliferate more rapidly, and achieve higher density at confluence than do control Wistar-Kyoto (WKY) cells. To elucidate growth-related contributions to the elevated tissue NGF observed in SHRs, we examined vascular VSMC and BSMC NGF secretion in two inbred cell lines (WKHTs, hypertensive; WKHAs, hyperactive) derived from SHRs and WKYs to assess the phenotypic association of altered NGF metabolism with either hypertension or behavioral hyperactivity. Cell density, rather than growth rates, was the most important factor with respect to NGF secretion. VSMC density varied such that WKHT=SHR>WKY= WKHA, higher VSMC density being associated with higher NGF output. However, in BSMC cultures, NGF output was the lowest in high density cell lines, with WKHT>SHR>WKY>WKHA. SHR BSMCs had the second highest cell density and NGF secretion level. Elevated packing density, presumably because of a lack of contact inhibition, co-segregated with the hypertensive phenotype in both VSMCs and BSMCs. Thus, dysfunctional smooth muscle growth characteristics may contribute to the augmented vascular and bladder NGF content associated with high blood pressure and hyperactive voiding in SHRs.     

Cardiac mitochondrial function and tissue remodelling are improved by a non-antihypertensive dose of enalapril in spontaneously hypertensive rats

Renal and cardiac benefits of renin-angiotensin system inhibition exceed blood pressure (BP) reduction and seem to involve mitochondrial function. It has been shown that RAS inhibition prevented mitochondrial dysfunction in spontaneously hypertensive rats (SHR) kidneys. Here, it is investigated whether a non-antihypertensive enalapril dose protects cardiac tissue and mitochondria function. Three-month-old SHR received water containing enalapril (10 mg/kg/day, SHR+Enal) or no additions (SHR-C) for 5 months. Wistar-Kyoto rats (WKY) were normotensive controls. At month 5, BP was similar in SHR+Enal and SHR-C. In SHR+Enal and WKY, heart weight and myocardial fibrosis were lower than in SHR-C. Matrix metalloprotease-2 activity was lower in SHR+Enal with respect to SHR-C and WKY. In SHR+Enal and WKY, NADH/cytochrome c oxidoreductase activity, eNOS protein and activity and mtNOS activity were higher and Mn-SOD activity was lower than in SHR-C. In summary, enalapril at a non-antihypertensive dose prevented cardiac hypertrophy and modifies parameters of cardiac mitochondrial dysfunction in SHR.     

Early postnatal changes in sarcoplasmic reticulum calcium transport function in spontaneously hypertensive rats

This comparative study investigates the relationship between sarcoplasmic reticulum (SR) calcium(Ca²⁺)-ATPase transport activity and phospholamban (PLB) phosphorylation in whole cardiac homogenates of spo`ntaneously hypertensive rats (SHR) and their parent, normotensive Wistar Kyoto (WKY) strain during early postnatal development at days 1, 3, 6, 12 and at day 40 to ascertain any difference in SR Ca²⁺ handling before the onset of hypertension. At day 1, the rate of homogenate oxalate-supported Ca²⁺ uptake was significantly higher in SHR than in WKY (0.25 ± 0.02 vs 0.12 ± 0.01 nmoles Ca²⁺/mg wet ventricular weight/min, respectively; p < 0.001). This interstrain difference disappeared with further developmental increase in SR Ca²⁺ transport. Western Blot analysis and a semiquantitative ELISA did not reveal any difference in the amount of immunoreactive PLB (per mg of total tissue protein) between strains at any of the ages studied. In addition, levels of phosphorylated PLB formed in vitro in the presence of radiolabelled ATP and catalytic (C) subunit of protein kinase A did not differ between SHR and WKY at days 1, 3, 6 and 12. At day 40, C subunit-catalyzed formation of ³²P-PLB was reduced by 66% (p < 0.001) in SHR when compared to age-matched WKY In the early postnatal period between day 1 and 12 SR Ca²⁺-transport values were linearly related to the respective ³²P-PLB levels of both SHR and WKY rats. The results indicate that cardiac SR of SHR can sequester Ca²⁺ at a much higher rate immediately after birth compared to WKY rats. The disappearance of this interstrain difference with further development suggests that some endogenous neuroendocrine or nutritional factor(s) from the hypertensive mother may exert an influence upon the developing heart in utero resulting in a transiently advanced maturation of the SR Ca²⁺ transport function in SHR pups at the time of birth.     

Segmental and Regional Differences in Neuronal Expression of the Leech Hox Genes Lox1 and Lox2 During Embryogenesis

Using double immunofluorescence experiments, we described the expression of the leech Hox genes, Lox1 and Lox2 by central neurons that stained for either serotonin or the leech-specific neuronal marker, Laz1-1. The goal is to determine whether the segmental boundaries of Lox1 and Lox2 expression in identified neurons coincide with segmental and regional differences in the differentiation of these cells. A number of neurons described here have been previously identified. The anteromedial serotonergic neurons are restricted to rostral ganglion 1 (R1) to midbody ganglion 3 (M3), but only express Lox1 in M2 and M3. The posteromedial serotonergic neurons which are situated in all segments as bilateral pairs early in development, but later become unpaired starting at M3, expressed Lox1 only in M2 and M3, and Lox2 in M8 to M21, in all paired and unpaired stages. The Retzius neurons, which stain for serotonin, express Lox2 in M7 to M21 where they exhibit different morphologies from their segmental homologs of the sex ganglia in M5 and M6. The Laz1-1 immunoreactive (Laz1-1⁺) heart accessory-like neurons express Lox1 in M4 and Lox2 in M7 to M17, but not in their segmental homologs of the heart accessory (HA) neurons located exclusively in M5 and M6. Also, Laz1-1⁺ neurons, which we named Lz3 expressed Lox1 in M4 to M8 where they are unpaired, but express Lox2 in M9 to M16 where they are bilaterally paired. Other Laz1-1 cells show more restricted and isolated Lox1 and Lox2 expression patterns. These results suggest a role of Lox1 and/or Lox2 in defining the anteroposterior boundaries of segmentally iterated neurons.     

Increased calcium release from sarcoplasmic reticulum stimulated by inositol trisphosphate in spontaneously hypertensive rat heart cells

It is known that inositol (1, 4, 5)-trisphosphate (IP₃) stimulates Ca²⁺ release from sarcoplasmic reticulum (SR) in several tissues, but in cardiac myocytes this phenomenon has not been confirmed. The purpose of the present study was to confirm the effect of (1, 4, 5)-IP₃ on Ca²⁺ release from SR in cardiac myocytes. The effect of IP₃ on Ca²⁺ release from SR in hypertrophic cardiac cells was also determined.We examined the effects of IP₃ on Ca²⁺ release from cardiac myocyte SR by the bigital-image method in a single cell. We also determined the effect of IP₃ on calcium release from isolated SR. SR was prepared from spontaneous hypertensive rat hearts and Wistar kyoto rat hearts. The SR was prelabeled with⁴⁵Ca²+, and then incubated with the indicated concentrations of IP³ for 1 min at 37°C. In cardiac myocytes treated with saponin, Ca²⁺ release stimulated by 10 M (1, 4, 5)-IP₃ was detected by fura-2. In⁴⁵Ca²⁺ prelabeled SR, the maximal Ca²⁺ release was achieved at 10 M IP₃ incubated for 1 min. The release of Ca²⁺ was higher in Sr of SHR than in the SR of WKY. IP₃ stimulates Ca²⁺ release from cardiac SR, and this release is greater in SHR than in WKY. However, it is uncertain whether this phenomenon plays a role in cardiac hypertrophy.     

Kallikrein gene delivery attenuates cardiac remodeling and promotes neovascularization in spontaneously hypertensive rats

Hypertension that results in left ventricular (LV) hypertrophy and/or fibrosis can lead to cardiac dysfunction. Spontaneously hypertensive rats (SHR) develop high blood pressure and LV hypertrophy at an early age and are a popular model of human essential hypertension. To investigate the role of the tissue kallikrein-kinin system in cardiac remodeling, an adenovirus containing the human tissue kallikrein gene was injected intravenously into adult SHR and normotensive Wistar-Kyoto (WKY) rats. The blood pressure of WKY rats remained unchanged throughout the experiment. Alternatively, kallikrein gene transfer reduced blood pressure in SHR for the first 2 wk, but had no effect from 3 to 5 wk. Five weeks after kallikrein gene delivery, SHR showed significant reductions in LV-to-heart weight ratio, LV long axis, and cardiomyocyte size; however, these parameters were unaffected in WKY rats. Interestingly, cardiac collagen density was decreased in both SHR and WKY rats receiving the kallikrein gene. Kallikrein gene transfer also increased cardiac capillary density in SHR, but not in WKY rats. The morphological changes after kallikrein gene transfer were associated with decreases in JNK activation as well as transforming growth factor (TGF)-beta 1 and plasminogen activator inhibitor-1 levels in the heart. In addition, kallikrein gene delivery elevated LV nitric oxide and cGMP levels in both rat strains. These results indicate that kallikrein-kinin attenuates cardiac hypertrophy and fibrosis and enhances capillary growth in SHR through the suppression of JNK, TGF-beta 1, and plasminogen activator inhibitor-1 via the nitric oxide-cGMP pathway.     

Effects of the iron chelator deferiprone and the T-type calcium channel blocker efonidipine on cardiac function and Ca2+ regulation in iron-overloaded thalassemic mice

Although disturbance of cardiac Ca²⁺ regulation is involved in the pathophysiology of iron-overload cardiomyopathy, the obvious mechanisms involved in the dysregulation of iron-induced cardiac Ca²⁺ are unclear. Moreover, the roles of the iron chelator deferiprone and the T-type calcium channel blocker efonidipine on cardiac intracellular Ca²⁺ transients and Ca²⁺ regulatory proteins in thalassemic mice are still unknown. We tested the hypothesis that treatment with either deferiprone or efonidipine attenuated cardiac Ca²⁺ dysregulation and led to improved left ventricular (LV) function in iron-overloaded thalassemic mice. Wild-type (WT) mice and β-thalassemic (HT) mice were fed with either a normal diet (ND) or a high iron-diet (FE) for 90 days. Then, the FE-fed mice were treated with either deferiprone (75 mg/kg/day) or efonidipine (4 mg/kg/day) for 30 days. ND-fed HT mice had an increase in T-type calcium channels (TTCC) and an increased level of sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), compared with ND-fed WT mice. Chronic iron feeding led to an increase in TTCC and expression of SERCA proteins in FE-fed WT mice. Moreover, chronic iron overload led to increased plasma non-transferrin bound iron (NTBI) and cardiac iron deposition, impaired cardiac intracellular Ca²⁺ transients including decreased intracellular Ca²⁺ transient amplitude, rising rate and decay rate, as well as impaired LV function as indicated by a decreased %LV ejection fraction (%LVEF) in both WT and HT mice. Our findings showed that treatment with either deferiprone (DFP) or efonidipine (EFO) showed similar benefits in reducing plasma NTBI and cardiac iron deposition, and improving %LVEF from 84.3 (WT) to 89.3 (DFP) and 89.2 (EFO) treatment; and from 84.2 (HT) to 88.8 (DFP) and 89.5 (EFO) treatment, however there was no improvement in the regulation of cardiac Ca²⁺ in iron-overloaded thalassemic mice. These findings provide the understanding of the effects of these drugs on the iron-overloaded heart in thalassemic mice and suggest that an alternative intervention that could improve calcium regulation under this condition is needed to improve the therapeutic outcome. Moreover, whether the benefits of the TTCC blocker is via its inhibition of the TTCC alone or together with its ability to chelate iron are still unclear and need further investigation.     

Effect of oxidative stress on telomere maintenance in aortic smooth muscle cells

Reactive oxygen species (ROS) and telomere dysfunction are both associated with aging and the development of age-related diseases. Although there is evidence for a direct relationship between ROS and telomere dysfunction as well as an independent association of oxidative stress and telomere attrition with age-related disorders, there has not been sufficient exploration of how the interaction between oxidative stress and telomere function may contribute to the pathophysiology of cardiovascular diseases (CVD). To better understand the complex relationships between oxidative stress, telomerase biology and pathophysiology, we examined the telomere biology of aortic smooth muscle cells (ASMCs) isolated from mutant mouse models of oxidative stress. We discovered that telomere lengths were significantly shorter in ASMCs isolated from superoxide dismutase 2 heterozygous (Sod2^+/?) mice, which exhibit increased arterial stiffness with aging, and the observed telomere attrition occurred over time. Furthermore, the telomere erosion occurred even though telomerase activity increased. In contrast, telomeres remained stable in wild-type and superoxide dismutase 1 heterozygous (Sod1^+/?) mice, which do not exhibit CVD phenotypes. The data indicate that mitochondrial oxidative stress, in particular elevated superoxide levels and decreased hydrogen peroxide levels, induces telomere erosion in the ASMCs of the Sod2^+/? mice. This reduction in telomere length occurs despite an increase in telomerase activity and correlates with the onset of disease phenotype. Our results suggest that the oxidative stress caused by imbalance in mitochondrial ROS, from deficient SOD2 activity as a model for mitochondrial dysfunction results in telomere dysfunction, which may contribute to pathogenesis of CVD.     

Synthetic Phosphopeptides Enable Quantitation of the Content and Function of the Four Phosphorylation States of Phospholamban in Cardiac Muscle

We have studied the differential effects of phospholamban (PLB) phosphorylation states on the activity of the sarcoplasmic reticulum Ca-ATPase (SERCA). It has been shown that unphosphorylated PLB (U-PLB) inhibits SERCA and that phosphorylation of PLB at Ser-16 or Thr-17 relieves this inhibition in cardiac sarcoplasmic reticulum. However, the levels of the four phosphorylation states of PLB (U-PLB, P16-PLB, P17-PLB, and doubly phosphorylated 2P-PLB) have not been measured quantitatively in cardiac tissue, and their functional effects on SERCA have not been determined directly. We have solved both problems through the chemical synthesis of all four PLB species. We first used the synthetic PLB as standards for a quantitative immunoblot assay, to determine the concentrations of all four PLB phosphorylation states in pig cardiac tissue, with and without left ventricular hypertrophy (LVH) induced by aortic banding. In both LVH and sham hearts, all phosphorylation states were significantly populated, but LVH hearts showed a significant decrease in U-PLB, with a corresponding increase in the ratio of total phosphorylated PLB to U-PLB. To determine directly the functional effects of each PLB species, we co-reconstituted each of the synthetic peptides in phospholipid membranes with SERCA and measured calcium-dependent ATPase activity. SERCA inhibition was maximally relieved by P16-PLB (the most highly populated PLB state in cardiac tissue homogenates), followed by 2P-PLB, then P17-PLB. These results show that each PLB phosphorylation state uniquely alters Ca²⁺ homeostasis, with important implications for cardiac health, disease, and therapy.     

Angiotensin converting enzyme inhibitors,left ventricular hypertrophy and fibrosis

From pharmacological investigations and clinical studies, it is known that angiotensin converting enzyme (ACE) inhibitors exhibit additional local actions, which are not related to hemodynamic changes and which cannot be explained only by interference with the renin angiotensin system (RAS) by means of an inhibition of angiotensin II (ANG II) formation. Since ACE is identical to kininase II, which inactivates the nonapeptide bradykinin (BK) and related kinins, potentiation of kinins might be responsible for these additional effects of ACE inhibitors.

1. In rats made hypertensive by aortic banding, the effect of ramipril in left ventricular hypertrophy (LVH) was investigated. Ramipril in the antihypertensive dose of 1 mg/kg/day for 6 weeks prevented the increase in blood pressure and the development of LVH. The low dose of ramipril (10 μg/kg/day for 6 weeks) had no effect on the increase in blood pressure or on plasma ACE activity but also prevented LVH after aortic banding. The antihypertrophic effect of the higher and lower doses of ramipril, as well as the antihypertensive action of the higher dose of ramipril, was abolished by coadmistration of the kinin receptor antagonist icatibant. In the regression study the antihypertrophic actions of ramipril were not blocked by the kinin receptor antagonist. Chronic administration of BK had similar beneficial effects in a prevention study which were abolished by icatibant and N^G-nitro-L-arginine (L-NNA). In a one year study the high and low dose of ramipril prevented LVH and fibrosis. Ramipril had an early direct effect in hypertensive rats on the mRNA expression for myocardial collagen I and III, unrelated to its blood pressure lowering effect.
2. In spontaneously hypertensive rats (SHR) the preventive effects of chronic treatment with ramipril on myocardial LVH was investigated. SHR were treated in utero and, subsequently, up to 20 weeks of age with a high dose (1 mg/kg/day) or with a low dose (10 μg/kg/day) of ramipril. Animals on a high dose remained normotensive, whereas those on a low dose developed hypertension in parallel to vehicle-treated controls. Left ventricular mass was reduced only in high-dose-treated, but not in low-dose treated animals but both groups revealed an increase in myocardial capillary length density. In SHR stroke prone animals cardiac function and metabolism was improved by ramipril and abolished by coadministration of icatibant. In contrast to the prevention studies, in a regression study ramipril reduced cardiac hypertrophy also by low dose treatment.
3. In rats chronic nitric oxide (NO) inhibition by N^G-nitro-L-arginine-methyl ester (L-NAME) treatment induced hypertension and LVH. Ramipril protected against blood pressure increase and partially against myocardial hypertrophy.

These experimental findings in different models of LVH characterise ACE inhibitors as remarkable antihypertrophic and antifibrotic substances.     

Ischemia induces aggravation of baseline repolarization abnormalities in left ventricular hypertrophy: a deleterious interaction.

Epidemiological studies show that left ventricular hypertrophy (LVH) and hypertension (HT) in coronary artery disease increases the risk for cardiovascular events including sudden cardiac death (SCD). According to experimental studies, myocardial hypertrophy is associated both with altered electrophysiological properties (including prolonged repolarization) and increased vulnerability to ischemia. However, human data to support a repolarization-related mechanism for the increased SCD risk has not been provided. We therefore studied 187 patients undergoing three-dimensional vectorcardiographic monitoring during coronary angioplasty. Eight parameters reflecting different aspects of ventricular repolarization were used: 1) the ST segment (ST-VM and STC-VM), 2) the T vector (QRS-T angle, Televation, and Tazimuth), and 3) the T vector loop (Tavplan, Teigenv, and Tarea). Data collection was performed at rest and at the time of maximum ischemia during coronary occlusion. The patients were divided into three groups: 33 patients with ECG signs of LVH (18 with HT), 54 with HT but without LVH signs, and 100 patients with neither. Coronary artery disease patients with LVH not only had the most abnormal baseline repolarization (as expected) but also a significantly more pronounced repolarization response during coronary occlusion, whereas HT patients had mean parameter values between LVH patients and those without neither HT nor LVH signs. Because there is a relation between increased SCD risk and repolarization disturbances in various clinical settings, the results of the present study are in agreement with animal data and epidemiological observations, although other factors than disturbed repolarization might be of importance.     

Lysyl oxidase-like 2 represses Notch1 expression in the skin to promote squamous cell carcinoma progression

Lysyl oxidase-like 2 (LOXL2) is involved in a wide range of physiological and pathological processes, including fibrosis and tumor progression, implicating intracellular and extracellular functions. To explore the specific in vivo role of LOXL2 in physiological and tumor contexts, we generated conditional gain- and loss-of-function mouse models. Germ-line deletion of Loxl2 promotes lethality in half of newborn mice mainly associated to congenital heart defects, while Loxl2 overexpression triggers male sterility due to epididymal dysfunction caused by epithelial disorganization, fibrosis and acute inflammation. Remarkably, when challenged to chemical skin carcinogenesis, Loxl2-overexpressing mice increased tumor burden and malignant progression, while Loxl2-deficient mice exhibit the opposite phenotypes. Loxl2 levels in premalignant tumors negatively correlate with expression of epidermal differentiation markers and components of the Notch1 pathway. We show that LOXL2 is a direct repressor of NOTCH1. Additionally, we identify an exclusive expression pattern between LOXL2 and members of the canonical NOTCH1 pathway in human HNSCC. Our data identify for the first time novel LOXL2 roles in tissue homeostasis and support it as a target for SCC therapy.     

Early experimental hypertension preserves the myocardial microvasculature but aggravates cardiac injury distal to chronic coronary artery obstruction

Coronary artery disease is a leading cause of death. Hypertension (HT) increases the incidence of cardiac events, but its effect on cardiac adaptation to coexisting coronary artery stenosis (CAS) is unclear. We hypothesized that concurrent HT modulates microvascular function in chronic CAS and aggravates microvascular remodeling and myocardial injury. Four groups of pigs (n=6 each) were studied: normal, CAS, HT, and CAS+HT. CAS and HT were induced by placing local irritant coils in the left circumflex coronary artery and renal artery, respectively. Six weeks later multidetector computerized tomography (CT) was used to assess systolic and diastolic function, microvascular permeability, myocardial perfusion, and responses to adenosine in the "area at risk." Microvascular architecture, inflammation, and fibrosis were then explored in cardiac tissue. Basal myocardial perfusion was similarly decreased in CAS and CAS+HT, but its response to adenosine was significantly more attenuated in CAS. Microvascular permeability in CAS+HT was greater than in CAS and was accompanied by amplified myocardial inflammation, fibrosis, and microvascular remodeling, as well as cardiac systolic and diastolic dysfunction. On the other hand, compared with normal, micro-CT-derived microvascular (20-200 μm) transmural density decreased in CAS but not in HT or CAS+HT. We conclude that the coexistence of early renovascular HT exacerbated myocardial fibrosis and vascular remodeling distal to CAS. These changes were not mediated by loss of myocardial microvessels, which were relatively preserved, but possibly by exacerbated myocardial inflammation and fibrosis. HT modulates cardiac adaptive responses to CAS and bears cardiac functional consequences.