[Cost-effectiveness of pneumococcal vaccination among patients with chronic heart failure]

Aim      To analyze the cost-effectiveness of pneumococcal vaccination in 40- and 65-year-old patients with chronic heart failure (CHF).Material and methods  Analysis was performed by Markov modeling from the perspective of the healthcare system. The evaluation was based on Russian epidemiological data taking into account results of international studies. The analyzed schedule of vaccination included one dose of 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent polysaccharide vaccine (PPSV23) after one year and vaccination with only one dose of PCV13. The time horizon of the study was 5 years. Costs and life expectancy were discounted at 3.5% per year.Results The cost-effectiveness of vaccination for both 65-year-old and 40-year-old CHF patients is very high: the incremental cost of one additional QALY (Quality-Adjusted Life Year) for PCV13+PPSV23 vaccination is 113.24 thousand rubles, while vaccination with PCV13 entails a reduction in costs by 556.50 rubles per one vaccinated patient. For vaccination of 40-year-old CHF patients with PCV13+PPSV23, the incremental costs per 1 QALY will be 519.72 thousand rubles, while for vaccination with PCV13 it will be 99.33 thousand rubles.Conclusion      Pneumococcal vaccination of CHF patients reduces the associated morbidity and mortality and is highly cost effective.

Role of PDE10A in vascular smooth muscle cell hyperplasia and pathological vascular remodelling

AIMS

Intimal hyperplasia is a common feature of vascular remodelling disorders. Accumulation of synthetic smooth muscle cell (SMC)-like cells is the main underlying cause. Current therapeutic approaches including drug-eluting stents are not perfect due to the toxicity on endothelial cells and novel therapeutic strategies are needed. Our preliminary screening for dysregulated cyclic nucleotide phosphodiesterases (PDEs) in growing SMCs revealed the alteration of PDE10A expression. Herein, we investigated the function of PDE10A in SMC proliferation and intimal hyperplasia both in vitro and in vivo.

METHODS AND RESULTS

RT-qPCR, immunoblot, and in situ proximity ligation assay were performed to determine PDE10A expression in synthetic SMCs and injured vessels. We found that PDE10A mRNA and/or protein levels are up-regulated in cultured SMCs upon growth stimulation, as well as in intimal cells in injured mouse femoral arteries. To determine the cellular functions of PDE10A, we focused on its role in SMC proliferation. The anti-mitogenic effects of PDE10A on SMCs were evaluated via cell counting, BrdU incorporation, and flow cytometry. We found that PDE10A deficiency or inhibition arrested the SMC cell cycle at G1-phase with a reduction of cyclin D1. The anti-mitotic effect of PDE10A inhibition was dependent on cGMP-dependent protein kinase Iα (PKGIα), involving C-natriuretic peptide (CNP) and particulate guanylate cyclase natriuretic peptide receptor 2 (NPR2). In addition, the effects of genetic depletion and pharmacological inhibition of PDE10A on neointimal formation were examined in a mouse model of femoral artery wire injury. Both PDE10A knockout and inhibition decreased injury-induced intimal thickening in femoral arteries by at least 50%. Moreover, PDE10A inhibition decreased ex vivo remodelling of cultured human saphenous vein segments.

CONCLUSIONS

Our findings indicate that PDE10A contributes to SMC proliferation and intimal hyperplasia at least partially via antagonizing CNP/NPR2/cGMP/PKG1α signalling and suggest that PDE10A may be a novel drug target for treating vascular occlusive disease.

Natriuretic Peptide Receptor 2 Locus Contributes to Carotid Remodeling

Background Carotid artery intima/media thickness (IMT) is a hallmark trait associated with future cardiovascular events. The goal of this study was to map new genes that regulate carotid IMT by genome-wide association. Methods and Results We induced IMT by ligation procedure of the left carotid artery in 30 inbred mouse strains. Histologic reconstruction revealed significant variation in left carotid artery intima, media, adventitia, external elastic lamina volumes, intima-to-media ratio, and (intima+media)/external elastic lamina percent ratio in inbred mice. The carotid remodeling trait was regulated by distinct genomic signatures with a dozen common single-nucleotide polymorphisms associated with left carotid artery intima volume, intima-to-media ratio, and (intima+media)/external elastic lamina percent ratio. Among genetic loci on mouse chromosomes 1, 4, and 12, there was natriuretic peptide receptor 2 (Npr2), a strong candidate gene. We observed that only male, not female, mice heterozygous for a targeted Npr2 deletion (Npr2^+/-) exhibited defective carotid artery remodeling compared with Npr2 wild-type (Npr2^+/+) littermates. Fibrosis in carotid IMT was significantly increased in Npr2^+/- males compared with Npr2^+/- females or Npr2^+/+ mice. We also detected decreased Npr2 expression in human atherosclerotic plaques, similar to that seen in studies in Npr2^+/- mice. Conclusions We found that components of carotid IMT were regulated by distinct genetic factors. We also showed a critical role for Npr2 in genetic regulation of vascular fibrosis associated with defective carotid remodeling.

The Protective Role of Natriuretic Peptide Receptor 2 against High Salt Injury in the Renal Papilla

Mutations in natriuretic peptide receptor 2 (Npr2) gene cause a rare form of short-limbed dwarfism, but its physiological effects have not been well studied. Human and mouse genetic data suggest that Npr2 in the kidney plays a role in salt homeostasis. Herein, we described anatomic changes within renal papilla of Npr2 knockout (Npr2-/-) mice. Dramatic reduction was found in diuresis, and albuminuria was evident after administration of 1% NaCl in drinking water in Npr2-/- and heterozygous (Npr2+/-) mice compared with their wild-type (Npr2+/+) littermates. There was indication of renal epithelial damage accompanied by high numbers of red blood cells and inflammatory cells (macrophage surface glycoproteins binding to galectin-3) and an increase of renal epithelial damage marker (T-cell Ig and mucin domain 1) in Npr2-/- mice. Addition of 1% NaCl tended to increase apoptotic cells (cleaved caspase 3) in the renal papilla of Npr2-/- mice. In vitro, genetic silencing of the Npr2 abolished protective effects of C-type natriuretic peptide, a ligand for Npr2, against death of M-1 kidney epithelial cells exposed to 360 mmol/L NaCl. Finally, significantly lower levels of expression of the NPR2 protein were detected in renal samples of hypertensive compared with normotensive human subjects. Taken together, these findings suggest that Npr2 is essential to protect renal epithelial cells from high concentrations of salt and prevent kidney injury.

Innate Immune Cells Are Regulated by Axl in Hypertensive Kidney

The balance between adaptive and innate immunity in kidney damage in salt-dependent hypertension is unclear. We investigated early renal dysfunction and the influence of Axl, a receptor tyrosine kinase, on innate immune response in hypertensive kidney in mice with lymphocyte deficiency (Rag1^-/-). The data suggest that increased presence of CD11b⁺ myeloid cells in the medulla might explain intensified salt and water retention as well as initial hypertensive response in Rag1^-/- mice. Global deletion of Axl on Rag1^-/- background reversed kidney dysfunction and accumulation of myeloid cells in the kidney medulla. Chimeric mice that lack Axl in innate immune cells (in the absence of lymphocytes) significantly improved kidney function and abolished early hypertensive response. The bioinformatics analyses of Axl-related gene-gene interaction networks established tissue-specific variation in regulatory pathways. It was confirmed that complement C3 is important for Axl-mediated interactions between myeloid and vascular cells in hypertensive kidney. In summary, innate immunity is crucial for renal dysfunction in early hypertension, and is highly influenced by the presence of Axl.

Strain-selective efficacy of sacubitril/valsartan on carotid fibrosis in response to injury in two inbred mouse strains

BACKGROUND AND PURPOSE

Sacubitril/valsartan (Sac/val) is more effective than valsartan in lowering BP and mortality in patients with heart failure. Here, we proposed that Sac/val treatment would be more effective in preventing pathological vascular remodelling in 129X1/SvJ (129X1), than in C57BL/6J (B6) inbred mice.

EXPERIMENTAL APPROACH

Sac/val (60 mg·kg^-1 ·day^-1 ) and valsartan (27 mg·kg^-1 ·day^-1 ) were given as prophylactic or therapeutic treatments, to 129X1 or B6 mice with carotid artery ligation for 14 days. Blood flow was measured by ultrasound. Ex vivo, carotid tissue was analysed with histological and morphometric techniques, together with RNA sequencing and gene ontology.

KEY RESULTS

Sac/val was more effective than valsartan in lowering BP in 129X1 compared with B6 mice. Liver expression of CYP2C9 and plasma cGMP levels were similar across treatments. A reduction in carotid thickening after prophylactic treatment with valsartan or Sac/val also resulted in significant arterial shrinkage in B6 mice. In 129X1 mice, Sac/val and prophylactic treatment with valsartan had no effect on carotid thickening but preserved carotid size. BP lowering significantly correlated with a decline in carotid stiffness (R²  = .37, P = .0096) in 129X1 but not in B6 mice. The gene expression signature associated with hyalurononglucosaminidase activity was down-regulated in injured arteries after both regimens of Sac/val only in 129X1 mice. Administration of Sac/val but not valsartan significantly reduced deposition of hyaluronic acid and carotid fibrosis in 129X1 mice.

CONCLUSION AND IMPLICATIONS

These results underscore the importance of the genetic background in the efficacy of the Sac/val on vascular fibrosis.

Aged marrow macrophages expand platelet-biased hematopoietic stem cells via Interleukin1B

The bone marrow microenvironment (BMME) contributes to the regulation of hematopoietic stem cell (HSC) function, though its role in age-associated lineage skewing is poorly understood. Here we show that dysfunction of aged marrow macrophages (Mφs) directs HSC platelet-bias. Mφs from the marrow of aged mice and humans exhibited an activated phenotype, with increased expression of inflammatory signals. Aged marrow Mφs also displayed decreased phagocytic function. Senescent neutrophils, typically cleared by marrow Mφs, were markedly increased in aged mice, consistent with functional defects in Mφ phagocytosis and efferocytosis. In aged mice, Interleukin 1B (IL1B) was elevated in the bone marrow and caspase 1 activity, which can process pro-IL1B, was increased in marrow Mφs and neutrophils. Mechanistically, IL1B signaling was necessary and sufficient to induce a platelet bias in HSCs. In young mice, depletion of phagocytic cell populations or loss of the efferocytic receptor Axl expanded platelet-biased HSCs. Our data support a model wherein increased inflammatory signals and decreased phagocytic function of aged marrow Mφs induce the acquisition of platelet bias in aged HSCs. This work highlights the instructive role of Mφs and IL1B in the age-associated lineage-skewing of HSCs, and reveals the therapeutic potential of their manipulation as antigeronic targets.

Role of Axl in T-Lymphocyte Survival in Salt-Dependent Hypertension

OBJECTIVE

Survival of immune and nonimmune cells relies on Axl, a receptor tyrosine kinase, which is implicated in hypertension. Activated T lymphocytes are involved in regulation of high blood pressure. The goal of the study was to investigate the role of Axl in T-lymphocyte functions and its contribution to salt-dependent hypertension.

APPROACH AND RESULTS

We report increased apoptosis in peripheral blood from Axl(-/-) mice because of lower numbers of white blood cells mostly lymphocytes. In vitro studies showed modest reduction in interferon gamma production in Axl(-/-) type 1 T helper cells. Axl did not affect basic proliferation capacity or production of interleukin 4 in Axl(-/-) type 2 T helper cells. However, competitive repopulation of Axl(-/-) bone marrow or adoptive transfer of Axl(-/-) CD4(+) T cells to Rag1(-/-) mice showed robust effect of Axl on T lymphocyte expansion in vivo. Adoptive transfer of Axl(-/-) CD4(+) T cells was protective in a later phase of deoxycorticosterone-acetate and salt hypertension. Reduced numbers of CD4(+) T cells in circulation and in perivascular adventitia decreased vascular remodeling and increased vascular apoptosis in the late phase of hypertension.

CONCLUSIONS

These findings suggest that Axl is critical for survival of T lymphocytes, especially during vascular remodeling in hypertension.

Abstract 073: Expression of Axl in Innate Immune Cells Contributes to Kidney Dysfunction and Onset of Hypertension

Introduction: We previously reported that expression of the receptor tyrosine kinase Axl in hematopoietic cells is critical for kidney dysfunction in early hypertension. Here we investigated the role of Axl expression in innate immune cells in deoxycorticosterone acetate (DOCA)-salt induced hypertension.

Methods and Results: RAG1-/- mice lack adaptive immune cells and displayed the same (~25 mmHg) increase in systolic blood pressure (BP) as C57BL/6J mice after 1 week of DOCA-salt. While in metabolic cages RAG1-/- drank more (14.3±0.9 mL) than C57BL/6J mice (10.6±2.5 mL) per day after 1 week of DOCA-salt. Ultrasound imaging confirmed that RAG1-/- had ~20 % larger kidneys vs. C57BL/6J mice after DOCA-salt. RAG1-/- kidneys accumulated 2 times more fluid (2.8±0.1 %) compared to C57BL/6J mice (1.4±0.5 %) after DOCA-salt. Flow cytometry on kidneys from RAG1-/- confirmed absence of T and B lymphocytes, while DOCA-salt increased presence of macrophages (1.1±0.3 x10 9 ) compared to C57BL/6J mice (0.6±0.1 x10 9 ). We successfully generated Axl/RAG1 double knockout mice and subjected the littermates to 1 week of DOCA-salt. Increases in systolic BP were the same in Axl/RAG1+/+ and Axl/RAG1-/- littermate mice. No differences were found in kidney volumes between the Axl/RAG1 genotypes as well. However, 24 hrs excretion volumes increased in Axl/RAG1-/- (50±6 %) compared to Axl/RAG1+/+ (31±6 %) littermates. Finally, renal artery blood flow velocity (611±52 mm/s) and resistive index (0.62±0.03) were reduced in Axl/RAG1+/+ but not in Axl/RAG1-/- mice (665±45 mm/s and 0.68±0.01, respectively) when compared to their controls.

Conclusions: Our findings suggest that mice lacking lymphocytes compensate by increasing kidney macrophages that contribute to initial increase in BP. Depletion of Axl in innate immune cells partially reverses kidney dysfunction by improving renal artery function in early hypertension.

Abstract 005: Axl Controls Survival of the CD4+ T Lymphocytes in Salt-dependent Hypertension

Introduction: Axl, a receptor tyrosine kinase, is required for vascular and immune cell survival. We sought to investigate the effects of Axl on T lymphocyte survival during deoxycorticosterone acetate (DOCA)-salt hypertension in mice.

Methods and Results: We found significant reduction in systolic blood pressure (BP) after 5-6 weeks of DOCA-salt in RAG1-/- mice after adoptive transfer of CD4+ T cells from Axl knockout (Axl-/- →RAG1-/-) compared to transferred CD4+ T cells from wild type (Axl+/+ →RAG1-/-) mice. Media area of the mesenteric artery was significantly lower in Axl-/- →RAG1-/- (4.2±0.7x10 3 m 2 ) vs. Axl+/+ →RAG1-/- (6.0±0.9x10 3 m 2 ) or Axl+/+ (6.8±0.6x10 3 m 2 ) mice. There was significant decrease in interferon gamma production by the T cells from Axl-/- (396±23 ng/mL) compared to Axl+/+ (512±42 ng/mL) after T h 1-priming. The number of carboxyfluorescein succinimidyl ester-positive cells in 6 th division was dramatically declined in Axl-/- (~0.3%) vs. Axl+/+ (~1.8%) in culture. Accordingly, we found lower number of lymphocytes in blood from Axl-/- (4.5±0.7x10 9 ) compared to Axl+/+ (7.8±0.7x10 9 ) mice. Blood leukocyte apoptosis was 2.5-fold higher in Axl-/- mice. We next investigated repopulation capacities of the hematopoietic cells from Axl-/- vs. Axl+/+ mice. There was significant decrease in Axl-/- CD3+ T cells (21±3 %) than Axl+/+ (49±3 %) in spleen after 8 weeks of competitive repopulation of bone marrow-derived cells. However, we found even greater reduction of Axl-/- T lymphocytes (15±1 %) vs. Axl+/+ T lymphocytes (52±6 %) in peripheral blood after 8 weeks of competitive repopulation. Finally, percentage of apoptotic cells was the greatest in the media (20±7 %) and adventitia (13±5 %) from Axl-/- →RAG1-/- mice compared to vascular apoptosis (6-14 % in media; and 6-9 % in adventitia) in other groups after 6 weeks of DOCA-salt.

Conclusions: Our data suggest that Axl-dependent survival of the T lymphocytes is crucial for the late increase in BP in DOCA-salt hypertension.

Axl modulates immune activation of smooth muscle cells in vein graft remodeling

The pathophysiological mechanisms of the immune activation of smooth muscle cells are not well understood. Increased expression of Axl, a receptor tyrosine kinase, was recently found in arteries from patients after coronary bypass grafts. In the present study, we hypothesized that Axl-dependent immune activation of smooth muscle cells regulates vein graft remodeling. We observed a twofold decrease in intimal thickening after vascular and systemic depletion of Axl in vein grafts. Local depletion of Axl had the greatest effect on immune activation, whereas systemic deletion of Axl reduced intima due to an increase in apoptosis in vein grafts. Primary smooth muscle cells isolated from Axl knockout mice had reduced proinflammatory responses by prevention of the STAT1 pathway. The absence of Axl increased suppressor of cytokine signaling (SOCS)1 expression in smooth muscle cells, a major inhibitory protein for STAT1. Ultrasound imaging suggested that vascular depletion of Axl reduced vein graft stiffness. Axl expression determined the STAT1-SOCS1 balance in vein graft intima and progression of the remodeling. The results of this investigation demonstrate that Axl promotes STAT1 signaling via inhibition of SOCS1 in activated smooth muscle cells in vein graft remodeling.

[Latencies of Repeated Responses to Single Pulse Stimulation of the Schaffer Collaterals Registered in Hippocampal Field CA1 in Rats During Sleep]

It is assumed that hippocampal neurons which were activated via the neocortex by new stimulus during the wakefulness and after that maintain its transient memory trace must be reactivated during the sleep to consolidate corresponding permanent memory trace in the neocortex. So we investigated the possibility of reverberation of excitation in the neuronal circuits connecting the hippocampus and entorhinal cortex. In sleeping rats within proximal part of the field CA1 of dorsal hippocampus we recorded double and triple responses to single pulse stimulation of Schaffer collaterals with previously potentiated synapses. Analysis of latent periods of repeated responses permitted to assume that the wave of excitation that was initiated in the field CA1 and returned from the entorhinal cortex to the locus of registration in the CA1 directly via perforant path fibers or throw the field CA2, can evoke repeated discharge of neurons in the CA1 but not the same that were activated initially by stimulation of Schaffer collaterals. So the neuronal circuits connecting the hippocampus and entorhinal cortex don't maintain reactivation of "learned" neurons in following periods of sleep.

Autonomic dysfunction determines stress-induced cardiovascular and immune complications in mice

BACKGROUND

Clinical studies suggest that acute inflammation in patients with elevated heart rate (HR) increases morbidity and mortality. The SJL/J (SJL) inbred mouse strain is a unique genetic model that has higher HR and systemic and vascular inflammation compared with C3HeB/FeJ (C3HeB) mice. The goal of this study was to investigate the role of stress on cardiac and vascular complications between 2 strains.

METHODS AND RESULTS

Radiotelemetry was used for continuous recordings of HR and blood pressure in mice. Hemodynamic differences between mouse strains were very small without stress; however, tail-cuff training generated mild stress and significantly increased HR (≈2-fold) in SJL compared with C3HeB mice. Circulating proinflammatory monocytes (CD11b(+)Ly6C(H) (i)) significantly increased in SJL mice but not in C3HeB mice after stress. Presence of Ly6C(+) cells in injured carotids was elevated only in SJL mice after stress; however, a transfer of bone marrow cells from SJL/C3HeB to C3HeB/SJL chimeras had no effect on HR or vascular inflammation following stress. Arterial inflammation (VCAM-1(+)) was greater in SJL inbred mice or SJL recipient chimeras, even without stress or injury. HR variability was reduced in SJL mice compared with C3HeB mice.

CONCLUSIONS

We found that impaired parasympathetic activity is central for stress-induced elevation of HR and systemic and vascular inflammation; however, immune cells from stress-susceptible mice had no effect on HR or vascular inflammation in stress-protected mice.

Thalidomide ameliorates portal hypertension via nitric oxide synthase independent reduced systolic blood pressure

AIM: Portal hypertension is a common complication of liver cirrhosis and significantly increases mortality and morbidity. Previous reports have suggested that the compound thalidomide attenuates portal hypertension (PHT). However, the mechanism for this action is not fully elucidated. One hypothesis is that thalidomide destabilizes tumor necrosis factor α (TNFα) mRNA and therefore diminishes TNFα induction of nitric oxide synthase (NOS) and the production of nitric oxide (NO). To examine this hypothesis, we utilized the murine partial portal vein ligation (PVL) PHT model in combination with endothelial or inducible NOS isoform gene knockout mice.

METHODS: Wild type, inducible nitric oxide synthase (iNOS)^-/- and endothelial nitric oxide synthase (eNOS)^-/- mice received either PVL or sham surgery and were given either thalidomide or vehicle. Serum nitrate (total nitrate, NOx) was measured daily for 7 d as a surrogate of NO synthesis. Serum TNFα level was quantified by enzyme-linked immunosorbent assay. TNFα mRNA was quantified in liver and aorta tissue by reverse transcription-polymerase chain reaction. PHT was determined by recording splenic pulp pressure (SPP) and abdominal aortic flow after 0-7 d. Response to thalidomide was determined by measurement of SPP and mean arterial pressure (MAP).

RESULTS: SPP, abdominal aortic flow (Qao) and plasma NOx were increased in wild type and iNOS^-/- PVL mice when compared to sham operated control mice. In contrast, SPP, Qao and plasma NOx were not increased in eNOS^-/- PVL mice when compared to sham controls. Serum TNFα level in both sham and PVL mice was below the detection limit of the commercial ELISA used. Therefore, the effect of thalidomide on serum TNFα levels was undetermined in wild type, eNOS^-/- or iNOS^-/- mice. Thalidomide acutely increased plasma NOx in wild type and eNOS^-/- mice but not iNOS^-/- mice. Moreover, thalidomide temporarily (0-90 min) decreased mean arterial pressure, SPP and Qao in wild type, eNOS^-/- and iNOS^-/- PVL mice, after which time levels returned to the respective baseline.

CONCLUSION: Thalidomide does not reduce portal pressure in the murine PVL model by modulation of NO biosynthesis. Rather, thalidomide reduces PHT by decreasing MAP by an undetermined mechanism.

Abstract 001: Axl Expression by CD4+ T Lymphocytes Promotes Salt-Dependent Hypertension

Introduction: Our laboratory has shown that Axl, a receptor tyrosine kinase, is important in both vascular and immune functions during deoxycorticosterone acetate (DOCA)-salt hypertension. We hypothesized that Axl activity specifically in T lymphocytes could explain the dependence of hypertension on Axl.

Methods and Results: We did adoptive transfers of either Axl+/+ or Axl-/- CD4+ T cells to RAG1-/- mice that lack mature T cells. Once CD4+ T cell repopulations were confirmed, we induced DOCA-salt hypertension for 6 weeks. Systolic blood pressure (BP, mmHg) increased by 20±5 in Axl+/+RAG-/- mice after DOCA-salt, but Axl-/- RAG-/- mice had increases in BP by only 6+3 after 6 weeks of DOCA-salt. We isolated naïve CD4+ T cells from both Axl+/+ and Axl-/- littermates and primed them under either Th1 or Th2 polarizing conditions in culture. Production of interferon gamma (IFN-γ ng/mL) was significantly decreased (-23%, p<0.05) in Axl-/- (396±23) compared to Axl+/+ (512±42) under Th1-priming. However, Axl had no effect on interleukin 4 (IL-4, ng/mL) production under Th2 polarizing conditions. Intracellular staining of the Th1/Th2 cells with IFN-γ and IL-4 antibodies by flow cytometry confirmed expression of cytokines in culture media. Complete blood counts showed that Axl-/- mice had significantly lower white blood cells due to decreased numbers of lymphocytes (4.5±0.7x10 9 ) compared to Axl+/+ mice (7.8±0.7x10 9 ). We found a higher population of AnnexinV (marker of early apoptosis)-positive peripheral leukocytes in Axl-/- mice (10±1%) compared to Axl+/+ (4±1%) by flow cytometry; while the percentages of dead cells (~10%) were similar between Axl+/+ and Axl-/- mice.

Conclusions: Altogether we show that expression of Axl by T cells drives salt-induced hypertension. The mechanism of Axl-dependent effects on T cells occurs via T-cell-dependent expression of the pro-inflammatory cytokine IFN-γ. In addition, Axl plays a role in inhibiting lymphocyte apoptosis in the circulation. Future work will focus on how Axl expression in T cells affects T cell-dependent vascular remodeling during hypertension.

Abstract 566: A Genetic Locus on Mouse Chromosome 11 controls Endothelial Dysfunction

Introduction: Carotid intima formation is a significant risk factor for cardiovascular disease. C3H/FeJ (C3H/F) and SJL/J (SJL) inbred mouse strains differ in susceptibility to immune and vascular traits. Using a congenic approach we demonstrated that the Intima modifier 2 ( Im 2) locus on chromosome 11 regulates leukocyte infiltration. We sought to determine whether inflammation was due to changes in circulating immune cells or activation of vascular wall cells in genetically pure Im 2 (C3H/F.SJL.11.1) mice.

Methods and Results: Complete blood counts showed no differences in circulating cells between C3H/F and C3H/F.SJL.11.1 compared to SJL mice. Aortic vascular cell adhesion molecule-1 (VCAM-1) total protein levels were dramatically increased in SJL and C3H/F.SJL.11.1 compared to C3H/F mice. Immunostaining of aortic endothelial cells (EC) showed a significant increase in VCAM-1 expression area (um 2 ) in SJL (0.18±0.02) and C3H/F.SJL.11.1 (0.19±0.02) compared to C3H/F (0.09±0.02) under steady flow conditions. In regions of disturbed flow we observed a significant decrease in EC area, measured by membrane staining, in SJL (500±50) and C3H/F.SJL.11.1 (500±30) versus C3H/F (800±50). Vascular permeability measured by the Miles assay (Evans’ blue dye ug per mg of aorta) was significantly higher in SJL (0.043±0.006) compared to C3H/F (0.010±0.005). In C3H/F.SJL.11.1 congenic mice vascular permeability varied from 0.006 to 0.665 but the average trended toward SJL values.

Conclusions: Our results indicate that Im 2 regulation of leukocyte infiltration is mediated by EC inflammation and permeability. Comparative analysis of gene polymorphisms in human regions syntenic with the mouse Im 2 locus provides new insights into candidate genes that regulate vascular wall inflammation.

Intima modifier locus 2 controls endothelial cell activation and vascular permeability

Carotid intima formation is a significant risk factor for cardiovascular disease. C3H/FeJ (C3H/F) and SJL/J (SJL) inbred mouse strains differ in susceptibility to immune and vascular traits. Using a congenic approach we demonstrated that the Intima modifier 2 (Im2) locus on chromosome 11 regulates leukocyte infiltration. We sought to determine whether inflammation was due to changes in circulating immune cells or activation of vascular wall cells in genetically pure Im2 (C3H/F.SJL.11.1) mice. Complete blood counts showed no differences in circulating monocytes between C3H/F and C3H/F.SJL.11.1 compared with SJL mice. Aortic vascular cell adhesion molecule-1 (VCAM-1) total protein levels were dramatically increased in SJL and C3H/F.SJL.11.1 compared with C3H/F mice. Immunostaining of aortic endothelial cells (EC) showed a significant increase in VCAM-1 expression in SJL and C3H/F.SJL.11.1 compared with C3H/F under steady flow conditions. Immunostaining of EC membranes revealed a significant decrease in EC size in SJL and C3H/F.SJL.11.1 vs. C3H/F in regions of disturbed flow. Vascular permeability was significantly higher in C3H/F.SJL.11.1 compared with C3H/F. Our results indicate that Im2 regulation of leukocyte infiltration is mediated by EC inflammation and permeability. RNA sequencing and pathway analyses comparing genes in the Im2 locus to C3H/F provide insight into candidate genes that regulate vascular wall inflammation and permeability highlighting important genetic mechanisms that control vascular intima in response to injury.

Abstract 146: Expression of Axl, a Receptor Tyrosine Kinase, Regulates Vein Graft Remodeling

Introduction: We recently found that expression of Axl, a receptor tyrosine kinase, in non-bone marrow derived cells is important for carotid thickening in response to low flood flow. We hypothesize that Axl plays a role in smooth muscle cell functions during vein graft remodeling.

Methods and Results: A segment of inferior vena cava was harvested from male Axl wild type (Axl+/+) or knockout (Axl-/-) mice and anastomosed to a carotid artery in female Axl+/+ mice under isoflurane anesthesia. Ultrasound Vevo2100 system was used to evaluate successful engraftment of the veins. Initial assessments of the blood flow through the graft were done at 1week after the surgery. A 3-dimensional high-resolution imaging was performed in mice after 3weeks after surgery. We found similar mean blood flow velocity ~110mm/s in the vein grafts between Axl+/+ >Axl+/+ and Axl-/- >Axl+/+ mice. There were no differences in the length of the graft between the groups in reconstruction of 3D-Mode imaging. However, graft volumes had a tendency (p~0.1) to be lower in Axl-/- >Axl+/+ vs. Axl+/+ >Axl+/+ mice (5.3±0.2 vs. 5.8±0.4mm 3 ). We also observed ~20% reduction of graft wall thickness in Axl-/- >Axl+/+ mice. Finally, pulsatility and resistive indexes of vein grafts were ~10% lower in Axl-/- >Axl+/+ mice.

Conclusions: This is the first study to demonstrate contribution of Axl to vein graft remodeling. Although, to confirm ultrasound differences between experimental groups vein graft wall changes are being evaluated by histology.

[Method for correction of perspective distortions during videotracking of the animal in Morris watermaze]

Analysis of correlations between the neuronal activity and animal behavior requires recordings of neuronal activity combined with video tracking. Recordings of neuronal activity in animals performing spatial task in Morris water maze requires angular position of recording camera to avoid "dead zones". If optical axe forms the angle with the water surface, perspective distortions occur. This leads to false results in analysis of trajectories. The paper suggests the method for correction of perspective distortions.

Role of Axl in early kidney inflammation and progression of salt-dependent hypertension

The Gas6/Axl pathway regulates many cell functions and is implicated in hypertension. In this study, we aimed to investigate the role of Axl in immune cells on initiation and progression of salt-dependent hypertension. Deoxycorticosterone acetate (75 mg/60 days release)-salt hypertension was induced for 1 week or 6 weeks in Axl chimeras generated by bone marrow transplant to restrict Axl deficiency to hematopoietic or nonhematopoietic compartments. Depletion of Axl in hematopoietic cells (Axl(-/-) →Axl(+/+)) reduced (133 ± 2 mm Hg) increase in systolic blood pressure compared with other Axl chimeras (≈150 mm Hg) 1 week after deoxycorticosterone acetate-salt. Urine protein and renal oxidative stress were lowest in Axl(-/-) →Axl(+/+) at 1 week after deoxycorticosterone acetate-salt. Compensatory increase in Gas6 in kidneys of recipient Axl(-/-) may affect kidney function and blood pressure in early phase of hypertension. Flow cytometry on kidneys from Axl(-/-) →Axl(+/+) showed increase in total leukocytes, B, and dendritic cells and decrease in macrophages compared with Axl(+/+) →Axl(+/+). These immune changes were associated with decrease in proinflammatory gene expression, in particular interferon γ. Systolic blood pressure returned to baseline in Axl(-/-) →Axl(+/+) and Axl(-/-) →Axl(-/-) but remained increased in Axl(+/+) →Axl(+/+) and Axl(+/+) →Axl(-/-) chimeras after 6 weeks of deoxycorticosterone acetate-salt. Vascular apoptosis was increased in the global Axl(-/-) chimeras in the late phase of hypertension. In summary, we found that expression of Axl in hematopoietic cells is critical for kidney pathology in early phase of salt-dependent hypertension. However, Axl in both hematopoietic and nonhematopoietic lineages contributes to the late phase of hypertension.

Platelet factor 4 mediates vascular smooth muscle cell injury responses

Activated platelets release many inflammatory molecules with important roles in accelerating vascular inflammation. Much is known about platelet and platelet-derived mediator interactions with endothelial cells and leukocytes, but few studies have examined the effects of platelets on components of the vascular wall. Vascular smooth muscle cells (VSMCs) undergo phenotypic changes in response to injury including the production of inflammatory molecules, cell proliferation, cell migration, and a decline in the expression of differentiation markers. In this study, we demonstrate that the platelet-derived chemokine platelet factor 4 (PF4/CXCL4) stimulates VSMC injury responses both in vitro and in vivo in a mouse carotid ligation model. PF4 drives a VSMC inflammatory phenotype including a decline in differentiation markers, increased cytokine production, and cell proliferation. We also demonstrate that PF4 effects are mediated, in part, through increased expression of the transcription factor Krüppel-like factor 4. Our data indicate an important mechanistic role for platelets and PF4 in VSMC injury responses both in vitro and in vivo.

Abstract 317: A Congenic Mouse Model for Carotid Intima-Media Thickening Demonstrates that Leukocyte Infiltration is a Genetically Regulated Trait

We demonstrated that inflammation and intima-media thickening (IMT) are increased in carotids exposed to low blood flow in the SJL/J (SJL) mouse strain compared to other strains. We identified three novel quantitative trait loci (QTLs) on chromosomes (chr) 2, 11, and 18 that control IMT in a genetic cross between C3HeB/FeJ (C3H/F) and SJL mice. Using a genetic backcross of C3H/FxSJL we measured inflammation in carotid IMT as a quantitative trait. Immunostaining for CD45+ (a pan-specific leukocyte marker) was performed on carotids from C3H/F, SJL, F1 and N2 progeny to measure leukocyte infiltration. A QTL for CD45+ cell infiltration was identified on chr11 (17cM, LOD=2.3). Interval mapping showed that the CD45+ locus accounted for 8% of the variation in the C3H/FxSJL backcross. Importantly, the CD45+ locus co-localized with our previously reported intima modifier 2 (Im2) locus. We created two Im2 congenic mice (C3H/F.SJL.11.1 and C3H/F.SJL.11.2) to define the contribution of chr11 to IMT. The C3H/F.SJL.11.1 congenic mouse showed elevated CD45+ staining in the vascular wall in response to low flow. Thus, the CD45+ trait partially explains the intima trait. This reveals a potential mechanistic relationship between leukocyte infiltration and IMT in response to decreased blood flow.

Abstract 183: Differences in Genetic Regulation of Carotid Stenosis and Thickening in Mice

Introduction

Most clinical and experimental studies are focused on the artery wall using a carotid intima-media thickening (IMT) phenotype. In physiological remodeling increases in IMT are coupled with increased arterial dimensions that preserve arterial blood flow. In contrast, pathological remodeling results in arterial stenosis. The goal of this study was to investigate genetic mechanisms of the carotid stenosis in inbred mice.

Methods and Results

We ligated external and internal branches of the left carotid artery, leaving the occipital artery patent to induce carotid IMT in mice. We evaluated flow-induced carotid remodeling in 9-12 week old males of 30 inbred mouse strains (n=270). Relative reductions in the left carotid blood flow were very similar among the mouse strains (Mean+SD= -86+7%) after two weeks after ligation. All animals were perfusion fixed with formalin and carotid arteries were stained with hematoxylin and eosin. There was less than 2-fold variation in carotid traits in controls. However, ligation resulted in a greater variation of carotid IMT (~6-fold) compared to carotid stenosis (~3-fold). The highest carotid IMT values were in SEA/GnJ, while the lowest IMT was in C3H/HeJ mice. Carotid stenosis was >60% in SEA/GnJ and SJL/J strains. There was significant correlation (R 2 =0.40) between carotid stenosis and IMT across 30 strains. We performed genome-wide association by using Efficient Mixed Model Association method for carotid traits in 30 inbred mice. Comparable numbers of genetic loci were associated with carotid IMT and stenosis after ligation. However, none of these loci overlap between the carotid stenosis and carotid IMT.

Conclusions

We found that major genetic modifiers for carotid stenosis are different from those that control carotid IMT. Our data also suggest that identification of mechanisms that determine carotid stenosis is difficult through studies on the carotid IMT.

Identification of a genetic locus on chromosome 11 that regulates leukocyte infiltration in mouse carotid artery

OBJECTIVE

We demonstrated that inflammatory cells and intima-media thickening are increased in carotids exposed to low-blood flow in the SJL/J (SJL) strain compared with other mouse strains. We hypothesized that the extent of inflammation associated with intima-media thickening is a genetically regulated trait.

APPROACH AND RESULTS

We performed a whole genome approach to measure leukocyte infiltration in the carotid intima as a quantitative trait in a genetic cross between C3HeB/FeJ (C3H/F) and SJL mice. Immunostaining for CD45(+) (a pan-specific leukocyte marker) was performed on carotids from C3H/F, SJL, F1, and N2 progeny to measure leukocyte infiltration. We identified a nearly significant quantitative trait locus for CD45(+) on chromosome (chr) 11 (17 cM, LOD=2.3; significance was considered at threshold P=0.05). Interval mapping showed that the CD45(+) locus on chr 11 accounted for 8% of the variation in the logarithm of odds backcross. Importantly, the CD45(+) locus colocalized with the intima-modifier 2 (Im2) locus, which controls 17% of intima variation. We created 2 Im2 congenic lines of mice (C3H/F.SJL.11.1 and C3H/F.SJL.11.2) to better understand the regulation of intima-media thickening by the chr 11 locus. The C3H/F.SJL.11.1 congenic mouse showed ≈30% of the SJL trait, confirming that CD45(+) cell infiltration contributed to the intima trait.

CONCLUSIONS

We discovered a novel locus on chr 11 that controls leukocyte infiltration in the carotid. Importantly, this locus overlaps with our previously published Im2 locus on chr 11. Our study reveals a potential mechanistic relationship between leukocyte infiltration and intima-media thickening in response to decreased blood flow.

G-protein-coupled receptor kinase interacting protein-1 mediates intima formation by regulating vascular smooth muscle proliferation, apoptosis, and migration

OBJECTIVE

The G-protein-coupled receptor kinase interacting protein-1 (GIT1) is a scaffold protein that is important for phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling induced by angiotensin II and epidermal growth factor. Because GIT1 regulates signaling by several vascular smooth muscle cell (VSMC) growth factors, we hypothesized that intima formation would be inhibited by GIT1 depletion.

APPROACH AND RESULTS

Complete carotid ligation was performed on GIT1 wild-type and knockout (KO) mice. We compared changes between GIT1 wild-type and KO mice in carotid vascular remodeling, VSMC proliferation, and apoptosis in vivo and in vitro. Our data demonstrated that GIT1 deficiency significantly decreased intima formation after carotid ligation as a result of both reduced VSMC proliferation and enhanced apoptosis. To confirm the effects of GIT1 in vitro, we performed proliferation and apoptosis assays in VSMC. In mouse aortic smooth muscle cells (MASM), we found that the growth rate and [3H]-thymidine incorporation of the GIT1 KO MASM were significantly decreased compared with the wild-type MASM. Cyclin D1, which is a key cell cycle regulator, was significantly decreased in GIT1 KO cells. Serum deprivation of GIT1 KO MASM increased apoptosis 3-fold compared with wild-type MASM. Treatment of rat aortic smooth muscle cells with GIT1 small interfering RNA impaired cell migration. Both phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling were required for GIT1-dependent VSMC proliferation and migration, whereas only phospholipase Cγ was involved in GIT1-mediated VSMC apoptosis.

CONCLUSIONS

GIT1 is a novel mediator of vascular remodeling by regulating VSMC proliferation, migration, and apoptosis through phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling pathways.

Ribosomal protein L17, RpL17, is an inhibitor of vascular smooth muscle growth and carotid intima formation

BACKGROUND

Carotid intima-media thickening is associated with increased cardiovascular risk in humans. We discovered that intima formation and cell proliferation in response to carotid injury is greater in SJL/J (SJL) in comparison with C3HeB/FeJ (C3H/F) mice. The purpose of this study was to identify candidate genes contributing to intima formation.

METHODS AND RESULTS

We performed microarray and bioinformatic analyses of carotid arteries from C3H/F and SJL mice. Kyoto Encyclopedia of Genes and Genomes analysis showed that the ribosome pathway was significantly up-regulated in C3H/F in comparison with SJL mice. Expression of a ribosomal protein, RpL17, was >40-fold higher in C3H/F carotids in comparison with SJL. Aortic vascular smooth muscle cells from C3H/F grew slower in comparison to SJL. To determine the role of RpL17 in vascular smooth muscle cell growth regulation, we analyzed the relationship between RpL17 expression and cell cycle progression. Cultured vascular smooth muscle cells from mice, rats, and humans showed that RpL17 expression inversely correlated with growth as shown by decreased cells in S phase and increased cells in G(0)/G(1). To prove that RpL17 acted as a growth inhibitor in vivo, we used pluronic gel delivery of RpL17 small interfering RNA to C3H/F carotid arteries. This resulted in an 8-fold increase in the number of proliferating cells. Furthermore, following partial carotid ligation in SJL mice, RpL17 expression in the intima and media decreased, but the number of proliferating cells increased.

CONCLUSIONS

RpL17 acts as a vascular smooth muscle cell growth inhibitor (akin to a tumor suppressor) and represents a potential therapeutic target to limit carotid intima-media thickening.

Abstract 359: Hemodynamic Differences in Normal and Stress Conditions between SJL/J and C3HeB/FeJ Inbred Mouse Strains

Introduction: SJL/J (SJL) mice have elevated (80beats/min) heart rate (HR) compared to C3HeB/FeJ (C3HeB) mouse strain then measured by tail-cuff plethysmography. SJL and C3HeB are differed in behavioral phenotypes. The goal of this study was to investigate hemodynamic responses to normal and stress conditions between SJL and C3HeB inbred mouse strains.

Methods and Results: Radio telemetry was used for continuous recordings of HR and systolic blood pressure (SBP) in C3HeB (n=5-10) and SJL (n=4-10) mice. We found that both strains showed normal circadian rhythms with little differences in HR and SBP. However, a locomotor activity (LA) of SJL was lower compared to C3HeB (7.8±0.4 vs. 10.0±0.1counts) during the lights off period. A correlation between LA and HR was reduced in SJL (R 2 =0.27) compared to C3HeB (R 2 =0.67) during the lights off period. After a mild stress (transfer to a cage) SJL had a slight HR elevation (70 beats/min) compared to C3HeB in first 5min. LA and SBP were similar between inbred strains after a novel cage test. The HR changes were significantly higher (2.5-fold, p<0.05) in SJL vs. C3HeB during first 5min (30min of restraining period) on the first day of tail-cuff training. Five days of tail-cuff procedures resulted in 2-fold elevation of HR in SJL compared to C3HeB for 30min restraining period. Interestingly, changes in SBP were similar between mouse strains on first day, while SBP showed a trend to be 2-fold higher in SJL vs. C3HeB for 30min on day five. Autonomic control of HR was determined by pharmacological blockages in mice. Atropine (1mg/kg, i.p.) caused significantly greater increases in HR in SJL (160+8beats/min, p<0.05) compared to C3HeB (62+11beats/min). Administration of propranolol (4mg/kg, i.p.) resulted in similar HR reductions between these strains.

Conclusions: We found that SJL mice are susceptible to elevation of hemodynamic parameters after chronic stress. An increase in sympathetic nervous system activity may explain HR differences between SJL and C3HeB inbred strains. This study was supported in part by funds from Russian Program "Scientific and scientific-pedagogical personnel of innovative Russia" for 2009-2013 GK№14.740.11.0923 and HL105623 (VAK)

Abstract 175: The Role of Axl in Accumulation of Immune Cells in Kidney and the Onset of Hypertension

Introduction: Gas6/Axl pathway contributes to elevation of blood pressure. Immune cells are implicated in initiation and maintenance of hypertension. In this study we aimed to investigate the role of Axl in immune cells on kidney injury and initiation of hypertension.

Methods and Results: Deoxycorticosterone-acetate (DOCA; 75mg, 60days release) and salt hypertension was induced for 1wk or 6wks in four groups of Axl chimeras (n=4-5) that were generated by bone marrow (BM) transplant. Multi parameter flow cytometry was used to quantify five major immune cell subsets in digested kidneys from Axl chimeras. Systolic blood pressure (SBP) increased by 30mmHg in Axl+/+ →Axl+/+, Axl-/- →Axl-/- and Axl+/+ →Axl-/- mice after 1wk of DOCA-salt. However, chimeras that lack Axl in the BM cells (Axl-/- →Axl+/+) showed reduction in early increase in SBP (16+2mmHg). We observed a significant decrease in urine protein levels in Axl-/- →Axl+/+ (0.3+0.1μg/μl) compared to other Axl chimeras (∼0.7μg/μl) after 1wk of DOCA-salt. Kidney glomeruli areas were reduced in Axl-/- →Axl+/+ (4,143+229μm 2 ) compared to other Axl chimeras (∼6,000μm 2 ) after 6wks of DOCA-salt. Kidneys from Axl-/- →Axl-/- showed an increase in total leukocytes (8 vs. 4%), B cells (29 vs. 12%) and decrease in monocytes/macrophages (16 vs. 22%) and dendritic cells (5 vs. 10%) compared to Axl+/+ →Axl+/+. Moreover, Axl-/- →Axl+/+ showed further increase in leukocytes (17%), B (39%) and dendritic (13%) cells in kidneys compared to other Axl chimeras. In addition a small percentage of wild type T cells was increased in the kidneys from Axl-/- →Axl+/+ chimeras.

Conclusions: These findings suggest that Axl expression in BM-derived cells is critical for kidney injury in DOCA-salt hypertension. Axl-dependent pathways regulate immune cell populations in the kidneys during initiation of hypertension. This study was supported by HL105623 grant (VAK)

Hybrid mouse diversity panel: a panel of inbred mouse strains suitable for analysis of complex genetic traits

We have developed an association-based approach using classical inbred strains of mice in which we correct for population structure, which is very extensive in mice, using an efficient mixed-model algorithm. Our approach includes inbred parental strains as well as recombinant inbred strains in order to capture loci with effect sizes typical of complex traits in mice (in the range of 5% of total trait variance). Over the last few years, we have typed the hybrid mouse diversity panel (HMDP) strains for a variety of clinical traits as well as intermediate phenotypes and have shown that the HMDP has sufficient power to map genes for highly complex traits with resolution that is in most cases less than a megabase. In this essay, we review our experience with the HMDP, describe various ongoing projects, and discuss how the HMDP may fit into the larger picture of common diseases and different approaches.

Immune modulation of vascular resident cells by Axl orchestrates carotid intima-media thickening

Cellular mechanisms of carotid intima-media thickening (IMT) are largely unknown. The receptor tyrosine kinase Axl is essential for function of both bone marrow (BM) and non-BM cells. We studied the mechanisms by which Axl expression in BM-derived cells (compared with non-BM-derived cells) mediates carotid IMT. Partial ligation of the left carotid artery resulted in a similar carotid blood flow reduction in Axl chimeras. Neither irradiation nor bone marrow transplantation had any effect on the 40% difference in carotid IMT between Axl genotypes. Axl-dependent survival is very important for intimal leukocytes; however, Axl expression in BM cells contributes to <30% of carotid IMT. Axl in non-BM cells has a greater effect on carotid remodeling. Expression of Axl in non-BM cells is crucial for the up-regulation of several key proinflammatory signals (eg, IL-1) in the carotid. We found that Axl is involved in immune activation of cultured smooth muscle cells and in immune heterogeneity of medial cells (measured by major histocompatibility complex class II) after carotid injury. Finally, a lack of Axl in non-BM cells increased collagen Iα expression, which may play a critical role in carotid remodeling. Our data suggest that Axl contributes to carotid remodeling not only by inhibition of apoptosis but also via regulation of immune heterogeneity of vascular cells, cytokine/chemokine expression, and extracellular matrix remodeling.

Genetic locus on mouse chromosome 7 controls elevated heart rate

Elevated heart rate (HR) is a risk factor for cardiovascular diseases. The goal of the study was to map HR trait in mice using quantitative trait locus (QTL) analysis followed by genome-wide association (GWA) analysis. The first approach provides mapping power and the second increases genome resolution. QTL analyses were performed in a C3HeB×SJL backcross. HR and systolic blood pressure (SBP) were measured by the tail-cuff plethysmography. HR was ∼80 beats/min higher in SJL compared with C3HeB. There was a wide distribution of the HR (536-763 beats/min) in N2 mice. We discovered a highly significant QTL (logarithm of odds = 6.7, P < 0.001) on chromosome 7 (41 cM) for HR in the C3HeB×SJL backcross. In the Hybrid Mouse Diversity Panel (58 strains, n = 5-6/strain) we found that HR (beats/min) ranged from 546 ± 12 in C58/J to 717 ± 7 in MA/MyJ mice. SBP (mmHg) ranged from 99 ± 6 in strain I/LnJ to 151 ± 4 in strain BXA4/PgnJ. GWA analyses were done using the HMDP, which revealed a locus (64.2-65.1 Mb) on chromosome 7 that colocalized with the QTL for elevated HR found in the C3HeB×SJL backcross. The peak association was observed for 17 SNPs that are localized within three GABA(A) receptor genes. In summary, we used a combined genetic approach to fine map a novel elevated HR locus on mouse chromosome 7.

[The excitation wave returning to the hippocampus through the entorhinal cortex can reactivate the populations of "trained" CA1 neurons during deep sleep]

It is suggested that the information about a new stimulus from the neocortex is transferred to the hippocampus and forms there a transient trace in the form of a distributed pattern of modified synapses. During sleep, the neuronal populations which store this trace are reactivated and return to the neocortex the information necessary for consolidation of the permanent memory trace. A possible mechanism of the reactivation of the "learned" hippocampal neurons during memory consolidation is the reverberation of excitation in the neuronal circuits connecting the hippocampus and the entorhinal cortex. In rats, we recorded responses in hippocampal field CA1 to stimulation of the Schaffer collaterals with potentiated synapses during wakefulness and sleep. We showed that in the periods of deep sleep, after the discharge of CA1 neurons, the wave of excitation passes through the entorhinal cortex and via the perforant path fibers enters the hippocampus and the dentate gyrus, causing in the latter the discharge of neurons. The repeated discharge of the CA1 neurons develops as the result of interaction of the early wave which is returned directly via the perforant path fibers and the late wave which is returned via the Schaffer collaterals, but not through the dentate gyrus and hippocampal field CA3 (trisynaptic pathway), but, probably, through the field CA2.

Pharmacological inhibition of Axl affects smooth muscle cell functions under oxidative stress

We previously demonstrated that reactive oxygen species (ROS) activate Axl, a receptor tyrosine kinase, resulting in increased survival of rat aortic smooth muscle cells (RASMs). Our experiments in Axl knockout mice showed significant reduction in vascular pathologies. We hypothesize that selective pharmacological inhibitors of Axl could prove beneficial in treating vascular diseases associated with oxidative stress. We investigated a role for two novel compounds specific for Axl (R428 and R572) on ligand independent activation of Axl mediated cell survival and migration. Stimulation of RASMs with H(2)O(2) for 5 min significantly increased Akt phosphorylation (p-Akt). Inhibition at 50% (IC(50)) of p-Akt was calculated at lower concentrations in R428 (100 nM) and R572 (10 nM) compared to Fc-Axl (2 microg/mL). Flow cytometry staining with Annexin V showed a 2-fold increase in apoptosis with R428 and R572 compared to Fc-Axl after H(2)O(2), which was validated by concomitant increases in cleaved caspase-3. Pretreatment with R428 and R572 decreased cell migration by approximately 50% in response to 20% serum (similar to that after Fc-Axl). R428 and R572 decreased intracellular production of ROS in comparison to Fc-Axl. In conclusion, R428 and R572 are more potent inhibitors of ligand independent mediated Axl signaling compared to Fc-Axl in RASMs under oxidative stress.

Gas6-Axl pathway: the role of redox-dependent association of Axl with nonmuscle myosin IIB

In vascular smooth muscle cells, Axl is a key receptor tyrosine kinase, because it is upregulated in injury, increases migration and neointima formation, and is activated by reactive oxygen species. Reaction of glutathione with cysteine residues (termed "glutathiolation") is an important posttranslational redox modification that may alter protein activity and protein-protein interactions. To investigate the mechanisms by which reactive oxygen species increase Axl-dependent vascular smooth muscle cell function we assayed for glutathiolated proteins that associated with Axl in a redox-dependent manner. We identified glutathiolated nonmuscle myosin heavy chain (MHC)-IIB as a novel Axl interacting protein. This interaction was specific in that other myosins did not interact with Axl. The endogenous ligand for Axl, Gas6, increased production of reactive oxygen species in vascular smooth muscle cells and also increased the association of Axl with MHC-IIB. Antioxidants ebselen and N-acetylcysteine decreased the association of Axl with MHC-IIB in response to both Gas6 and reactive oxygen species. Blocking the Axl-MHC-IIB interaction with the specific myosin II inhibitor blebbistatin decreased phosphorylation of Axl and activation of extracellular signal-regulated kinase 1/2 and Akt. Association of MHC-IIB with Axl was increased in balloon-injured rat carotid vessels. Finally, expression of MHC-IIB was upregulated in the neointima of the carotid artery after balloon injury similar to upregulation of Axl protein expression, as shown in our previous studies. These results demonstrate a novel interaction between Axl and MHC-IIB in response to reactive oxygen species. This interaction provides a direct link between Axl and molecular motors crucial for directed cell migration, which may mediate increased migration in vascular dysfunction.

[Study of extracellular concentration of dopamine and its metabolites in mice striatum by a microdialysis technique at intraperitoneal administration of MPTP]

In this paper a structure of a microdialytic cannula inserted into brain areas just before a microdialysis is described. The cannula used allowed to find out a correspondence of behavioral and biochemical changes in C57BL/6 mice at various time intervals after a single dose administration (20 mg/kg) of the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, without any additional pharmacological actions enhancing an extracellular striatal dopamine concentration. Immediately after 1-methyl-4-phenyl-1.2,3.6-tetrahydropyridine administration an essential disturbance of mice behavior and a significant reduction of the extracellular concentration of dopamine and homovanillic acid were observed in striatum. A week after the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration neither behavior nor the extracellular dopamine and homovanillic acid striatal concentration substantially differed from those of controls. 30 days after the neurotoxin administration there was again an essential disturbance of behavior and the large reduction of dopamine and its metabolite concentration in striatum. There was suggested that a reduction of the dopamine concentration immediately after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injection connected with abnormalities of dopamine synthesis and metabolism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine whereas a reduction of the extracellular striatal dopamine concentration 30 days after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration related to damage of the nigrastriatal dopaminergic system.

Fibronectin is an important regulator of flow-induced vascular remodeling

OBJECTIVE

Fibronectin is an important regulator of cell migration, differentiation, growth, and survival. Our data show that fibronectin also plays an important role in regulating extracellular matrix (ECM) remodeling. Fibronectin circulates in the plasma and is also deposited into the ECM by a cell dependent process. To determine whether fibronectin affects vascular remodeling in vivo, we asked whether the fibronectin polymerization inhibitor, pUR4, inhibits intima-media thickening, and prevents excess ECM deposition in arteries using a mouse model of vascular remodeling.

METHODS AND RESULTS

To induce vascular remodeling, partial ligation of the left external and internal carotid arteries was performed in mice. pUR4 and the control peptide were applied periadventitially in pluronic gel immediately after surgery. Animals were euthanized 7 or 14 days after surgery. Morphometric analysis demonstrated that the pUR4 fibronectin inhibitor reduced carotid intima (63%), media (27%), and adventitial thickening (40%) compared to the control peptide (III-11C). Treatment with pUR4 also resulted in a dramatic decrease in leukocyte infiltration into the vessel wall (80%), decreased ICAM-1 and VCAM-1 levels, inhibited cell proliferation (60% to 70%), and reduced fibronectin and collagen I accumulation in the vessel wall. In addition, the fibronectin inhibitor prevented SMC phenotypic modulation, as evidenced by the maintenance of smooth muscle (SM) alpha-actin and SM myosin heavy chain levels in medial cells.

CONCLUSIONS

These data are the first to demonstrate that fibronectin plays an important role in regulating the vascular remodeling response. Collectively, these data suggest a therapeutic benefit of periadventitial pUR4 in reducing pathological vascular remodeling.

[Return of excitatory waves from the field CA1 to the hippocampal formation is facilitated after Schaffer collateral tetanization and during sleep]

In agreement with existing notion, in a waking animal, novel information during learning transfers from the neocortex to the hippocampus where creates a transient trace in the form of a distributed pattern of modified synapses. During sleep, due to reactivation of neuronal populations initially activated by novel stimulus, this information flows back to the neocortex thus facilitating permanent memory trace consolidation. Information transfer between the neocortex and hippocampal formation is realized, in general, via the entorhinal cortex whose intrinsic connections basically permit "messages" from the exit of the hippocampal formation to return to its entrances. In waking and sleeping rats, we demonstrated a possibility of the return of the excitatory waves to hippocampal field CA1 and dentate gyrus via perforant path fibers that initially enter the CA1 via potentiated Schaffer collateral synapses. During sleep the returned excitatory waves were of maximal amplitude and with a high probability elicited a discharge of dentate neurons. Thus, a novel stimulus that potentiates synaptic connections during waking in the hippocampus and probably in the entorhinal cortex creates conditions for reactivation of corresponding neuronal populations in the hippocampus during sleep by excitatory waves returning via the entorhinal cortex.

Bcr kinase activation by angiotensin II inhibits peroxisome-proliferator-activated receptor gamma transcriptional activity in vascular smooth muscle cells

Bcr is a serine/threonine kinase activated by platelet-derived growth factor that is highly expressed in the neointima after vascular injury. Here, we demonstrate that Bcr is an important mediator of angiotensin (Ang) II and platelet-derived growth factor-mediated inflammatory responses in vascular smooth muscle cells (VSMCs). Among transcription factors that might regulate Ang II-mediated inflammatory responses we found that ligand-mediated peroxisome proliferator-activated receptor (PPAR)gamma transcriptional activity was significantly decreased by Ang II. Ang II increased Bcr expression and kinase activity. Overexpression of Bcr significantly inhibited PPARgamma activity. In contrast, knockdown of Bcr using Bcr small interfering RNA and a dominant-negative form of Bcr (DN-Bcr) reversed Ang II-mediated inhibition of PPARgamma activity significantly, suggesting the critical role of Bcr in Ang II-mediated inhibition of PPARgamma activity. Point-mutation and in vitro kinase analyses showed that PPARgamma was phosphorylated by Bcr at serine 82. Overexpression of wild-type Bcr kinase did not inhibit ligand-mediated PPARgamma1 S82A mutant transcriptional activity, indicating that Bcr regulates PPARgamma activity via S82 phosphorylation. DN-Bcr and Bcr small interfering RNA inhibited Ang II-mediated nuclear factor kappaB activation in VSMCs. DN-PPARgamma reversed DN-Bcr-mediated inhibition of nuclear factor kappaB activation, suggesting that PPARgamma is downstream from Bcr. Intimal proliferation in low-flow carotid arteries was decreased in Bcr knockout mice compared with wild-type mice, suggesting the critical role of Bcr kinase in VSMC proliferation in vivo, at least in part, via regulating PPARgamma/nuclear factor kappaB transcriptional activity.

Genetic modifier loci linked to intima formation induced by low flow in the mouse carotid

OBJECTIVE

Previously we found dramatic strain-dependent differences in a low flow model of vascular remodeling. Specifically, intima formation in the left common carotid artery was approximately 30-fold greater in SJL compared to C3HeB/Fe (C3H/F) mice. We hypothesized that a few genes control intima formation in response to low flow. A C3H/F and SJL backcross resulted in broad range of N2 intima phenotypes.

METHODS AND RESULTS

Using genome-wide scan we identified two highly significant quantitative trait loci (QTLs) for intima, Im1 (intima modifier 1 locus) on chromosome 2 (Chr2; 77.6 cM, LOD=6.4), and Im2 on Chr11 (17 cM, LOD=5.3). One significant QTL Im3 was found on Chr18 (6 cM, LOD=3.0), and two suggestive QTLs (LOD=1.5 and 1.8) were identified on Chr7 and Chr17, respectively. Interestingly, the intima/media ratio trait mapped to the same QTLs as the intima trait. Haplotype mapping predicted 40 candidate genes. Six of these genes contained SNPs that differed between C3H/F and SJL.

CONCLUSIONS

We have successfully mapped 3 QTLs (Im1, Im2, and Im3) that are associated with carotid intima formation in response to low blood flow. These results may be important in identifying genes that influence carotid intima-media thickening and predict cardiovascular disease in humans.

[A miniature multichannel preamplifier for recording electrophysiological activity in freely moving animals]

A design of a miniature lightweight multichannel preamplifier for recording electrophysiological activity in freely moving small animals is presented. The advantages of this construction include the possibility to obtain differential multichannel recording of neuronal activity, EEG and evoked potentials, relatively simple fabrication and exploitation. If necessary, the preamplifier may be easily disassembled for repair. Fine and flexible cable and "soft" hanger do not disturb free movement of an animal. The lightweight construction may be used for recording neuronal activity even in mice performing spatial task in Morris water maze.

Genetic determinants of vascular remodelling

Vascular remodelling is an important physiological mechanism that occurs as a result of changes in hemodynamics, and is a pathological process that plays a major role in the clinical manifestations of cardiovascular diseases. Using a mouse model, it was recently established that vascular remodelling is partially based on ligation of the carotid. In this model, low flow was associated with intima media thickening (IMT). IMT is a major manifestation of atherosclerosis of the carotid artery, and it is an important predictor of cardiovascular events. Carotid IMT has a strong genetic component. It was hypothesized that there would be genetically determined differences in outward remodelling and IMT induced by carotid flow alterations. Vascular remodelling among five inbred strains of mice were compared. Despite similar changes in flow in the left carotid among the strains, dramatic differences in remodelling of the partially ligated left carotid relative to control were observed. IMT correlated significantly with heart rate, outward remodelling and changes in plasminogen activator expression, cell proliferation and apoptosis. There were significant strain-dependent differences in the remodelling index (measured as the ratio of vessel area to IMT), which suggest fundamental alterations in sensing or transducing hemodynamic signals among strains. This model should be useful to identify and characterize the role of genes that mediate vascular remodelling.

Impaired vasorelaxation in inbred mice is associated with alterations in both nitric oxide and super oxide pathways

Recently, we showed that genetic factors determine flow-dependent vascular remodeling. Among five inbred mouse strains, the SJL strain developed the largest intima in response to low flow. Because SJL mice have a spontaneous mutation in superoxide dismutase 2 (SOD-2) we tested the hypothesis that strain-specific variations in vascular function are due to alterations in redox and nitric oxide (NO) pathways. Vasorelaxation to acetylcholine was significantly impaired in aortic rings from SJL compared to C3H or FVB mice (up to 40%). Relaxation to the endothelium-independent vasodilator sodium nitroprusside (SNP) in SJL mice was also significantly impaired at low concentrations, with decreases in sensitivity and maximal relaxation to SNP compared to C3H and FVB mice. Western blot analyses showed significantly decreased expression (approximately 40%) of eNOS, PKG and SOD-2 proteins in SJL vasculature compared to C3H. Intact aortas from SJL showed significantly increased nitrotyrosine and decreased SOD-2 expression compared to C3H by immunohistochemistry. Basal levels of superoxide in aortas from SJL were not significantly different than C3H as measured by dihydroethidine. In summary, relatively small alterations in redox (SOD-2) and NO pathways (eNOS and PKG) may contribute to significantly impaired vasorelaxation in SJL mice.

Vascular remodeling: hemodynamic and biochemical mechanisms underlying Glagov's phenomenon

An important concept for vascular remodeling, termed Glagov's phenomenon, is that arteries remodel to maintain constant flow despite increases in atherosclerotic lesion mass. Although Glagov's phenomenon was originally described only for the case of arterial remodeling in response to growth of atherosclerotic plaques, experimental and clinical observations indicate that blood flow properties influence remodeling after angioplasty, hypertension, and flow diversion as well as atherosclerotic plaque progression. This review attempts to define Glagov's observation in terms of the physical parameters of blood in conduit arteries that must determine the remodeling response. Next we review experiments that have begun to identify specific molecules that influence vascular remodeling and therefore may serve as mediators for the phenomena. More comprehensive analyses of the specific molecular pathways in the vessels that determine constant flow may provide new therapeutic approaches to regulate vascular remodeling.

[Conditions required for appearance of a double response to a single-shock stimulation of Schaffer collaterals in hippocampal field CA1 in freely moving rats]

Schaffer collateral stimulation with a single current impulse can evoke a double response in hippocampal field CA1 of freely moving rats. The late response appears as a population excitatory postsynaptic potential with a preceding short-term potential (frequently biphasic) only after the early population spike and is time-locked to it. The wave shape and polarity of the late response, its latency with respect to the peak of the early population spike suggest that the excitation wave produced in the CA1 field by the stimulation of Schaffer collaterals passes across the entorhinal cortex and returns to the CA1 directly via the perforant path fibers. In waking rat, the medium-intensity stimulation of Schaffer collaterals (able to evoke in the CA1 an early population spike of sufficiently high amplitude) usually does not result in the appearance of the late response. However, similar stimulation becomes efficient after the tetanization of Schaffer collaterals, under conditions of the long-term potentiation of the early population spike. Moreover, the late response occurrence is facilitated in a rat falling asleep after the development in the CA1 of high-amplitude low-frequency EEG oscillations typical for the slow-wave sleep and in a sleeping rat independently of the EEG pattern.

Angiotensin II type 2 receptor expression after vascular injury: differing effects of angiotensin-converting enzyme inhibition and angiotensin receptor blockade

It has been suggested that the effects of angiotensin II type 1 receptor (AT1R) blockers are in part because of angiotensin II type 2 receptor (AT2R) signaling. Interactions between the AT2R and kinins modulate cardiovascular function. Because AT2R expression increases after vascular injury, we hypothesized that the effects on vascular remodeling of the AT1R blocker valsartan and the ACE inhibitor benazepril require AT2R signaling through the bradykinin 1 and 2 receptors (B1R and B2R). To test this hypothesis, Brown Norway rats were assigned to 8 treatments (n=16): valsartan, valsartan+PD123319 (AT2R inhibitor), valsartan+des-arg9-[Leu8]-bradykinin (B1R inhibitor), valsartan+HOE140 (B2R inhibitor), benazepril, benazepril+HOE140, amlodipine, and vehicle. After 1 week of treatment, carotid balloon injury was performed. Two weeks later, carotids were harvested for morphometry and analysis of receptor expression by immunohistochemistry and Western blotting. Valsartan and benazepril significantly reduced the intima:media ratio compared with vehicle. Blockade of AT2R, B1R, or B2R in the presence of valsartan prevented the reduction seen with valsartan alone. B2R blockade inhibited the effect of benazepril. Injury increased AT1R, AT2R, B1R, and B2R expression. Treatment with valsartan but not benazepril significantly increased intima AT2R expression 2-fold compared with vehicle, which was not reversed by inhibition of AT2R, B1R, and B2R. Functionally, valsartan increased intimal cGMP levels compared with vehicle, and this increase was inhibited by blocking the AT2R, B1R, and B2R. Results suggest that AT2R expression and increased cGMP represent a molecular mechanism that differentiates AT1R blockers, such as valsartan, from angiotensin-converting enzyme inhibitors like benazepril.