Cell-Specific Effects of GATA (GATA Zinc Finger Transcription Factor Family)-6 in Vascular Smooth Muscle and Endothelial Cells on Vascular Injury Neointimal Formation.

Objective- Transcription factor GATA (GATA zinc finger transcription factor family)-6 is highly expressed in vessels and rapidly downregulated in balloon-injured carotid arteries and viral delivery of GATA-6 to the vessels limited the neointimal formation, however, little is known about its cell-specific regulation of in vivo vascular smooth muscle cell (VSMC) phenotypic state contributing to neointimal formation. This study aims to determine the role of vascular cell-specific GATA-6 in ligation- or injury-induced neointimal hyperplasia in vivo. Approach and Results- Endothelial cell and VSMC-specific GATA-6 deletion mice are generated, and the results indicate that endothelial cell-specific GATA-6 deletion mice exhibit significant decrease of VSMC proliferation and attenuation of neointimal formation after artery ligation and injury compared with the wild-type littermate control mice. PDGF (platelet-derived growth factor)-B is identified as a direct target gene, and endothelial cell-GATA-6-PDGF-B pathway regulates VSMC proliferation and migration in a paracrine manner which controls the neointimal formation. In contrast, VSMC-specific GATA-6 deletion promotes injury-induced VSMC transformation from contractile to proliferative synthetic phenotype leading to increased neointimal formation. CCN (cysteine-rich 61/connective tissue growth factor/nephroblastoma overexpressed family)-5 is identified as a novel target gene, and VSMC-specific CCN-5 overexpression in mice reverses the VSMC-GATA-6 deletion-mediated increased cell proliferation and migration and finally attenuates the neointimal formation. Conclusions- This study gives us a direct in vivo evidence of GATA-6 cell lineage-specific regulation of PDGF-B and CCN-5 on VSMC phenotypic state, proliferation and migration contributing to neointimal formation, which advances our understanding of in vivo neointimal hyperplasia, meanwhile also provides opportunities for future therapeutic interventions.

Dysfunctional endothelial-derived microparticles promote inflammatory macrophage formation via NF-кB and IL-1ß signal pathways.

BACKGROUND: Circulating endothelial-derived microparticles (EMPs) are reported to be increased in acute coronary syndrome (ACS). However, it remains unclear whether EMPs from dysfunctional endothelium participate in the initiation and progression of ACS and what the underlying mechanisms might be. METHODS: Plasma EMPs were measured in 22 patients with ACS and 20 control patients without coronary artery diseases. EMPs from dysfunctional human umbilical vein endothelial cells (HUVECs) stressed by serum-starvation or hypoxia were compared to the EMPs from healthy HUVECs. Confocal and fluorescent microscopy was used to visualize the incorporation of EMPs into monocytes and the translocation of NF-кB. Monocyte adhesion, cell proliferation, and phagocytosis were detected by PKH26 red fluorescent labelling, Ki67 immunostaining, and Sudan IV staining for uptake of oxidized low-density lipoprotein, respectively. RESULTS: Plasma EMPs was significantly increased in ACS patients compared to controls. EMPs were incorporated into monocytes and EMPs from stressed HUVECs produced more pro-inflammatory cytokines compared to vehicle control, which was depended on NF-кB and IL-1ß signal pathways. EMPs from dysfunctional endothelium promoted monocyte adherence via NF-кB and IL-1ß-mediated MCP-1 and CCR-5 signals, as well as proliferation via the NF-кB and IL-1ß-mediated Cyclin D1 signals. Finally, EMPs from dysfunctional endothelium showed greater promotion of macrophage phagocytosis forming foam cells to produce more pro-inflammatory cytokines. CONCLUSION: MPs might be involved in the inflammatory process in patients with ACS via NF-κB and IL-1ß-dependent signals. Targeting EMP-mediated inflammatory responses may be a promising therapeutic strategy to limit the progression of disease in ACS.

Hyperhomocysteinemia Increases Risk of Metabolic Syndrome and Cardiovascular Death in an Elderly Chinese Community Population of a 7-Year Follow-Up Study.

BACKGROUND: Hyperhomocysteinemia (HHcy) and abdominal obesity are risk factors for metabolic syndrome (MetS) and death from cardiovascular disease (CVD). Recent studies have shown a correlation between HHcy and abdominal obesity, suggesting that they may have a combined effect on the risk of MetS and CVD mortality. However, this suspicion remains to be confirmed, particularly in the elderly population. We explored their combined effects on the risk of MetS and CVD mortality among the community population aged 65 and above in China. METHODS AND RESULTS: This prospective study enrolled 3,675 Chinese community residents aged 65 and above in May 2013 with 7-year follow-up of all-cause and CVD mortality. HHcy was defined as the blood homocysteine (Hcy) level >15 µmol/L and abdominal obesity as waist circumference (WC) ≥90 cm for men and ≥80 cm for women (HWC). All participants were grouped into four categories by WC and the blood level of Hcy: NWC (normal WC) /HHcy(-), NWC/HHcy(+), HWC/HHcy(-), and HWC/HHcy(+). The relationship of combined HHcy and abdominal obesity with MetS and metabolic profile was evaluated by logistic regression analysis and the association of combined HHcy and abdominal obesity with CVD and all-cause mortality evaluated by Cox regression analysis. The prevalence of HHcy, abdominal obesity and MetS in elderly Chinese community residents was 40.1, 59.3, and 41.4%, respectively. Using group without HHcy and abdominal obesity [NWC/HHcy(-)] as reference, the participants of other three groups had significantly higher risk of MetS and its component abnormalities, with HWC/HHcy(+) group having the highest risk (OR = 13.52; 95% CI = 8.61-14.55). After a median of 6.94 (±1.48) years follow-up, 454 deaths occurred with 135 CVD deaths. Compared with NWC/HHcy(-) group, the risk of 7-year follow-up CVD mortality (HR = 1.75; 95% CI = 1.02-3.03) and all-cause mortality (HR = 1.23; 95% CI = 1.04-2.18) of HWC/HHcy(+) group increased considerably after adjustment for major MetS and CVD risk factors. CONCLUSIONS: There is high prevalence of HHcy, abdominal obesity, and MetS in the elderly Chinese community population. HHcy increases risk of MetS, CVD, and all-cause mortality, especially in the populations with abdominal obesity.

Endothelial Klf2-Foxp1-TGFß signal mediates the inhibitory effects of simvastatin on maladaptive cardiac remodeling.

Aims: Pathological cardiac fibrosis and hypertrophy are common features of left ventricular remodeling that often progress to heart failure (HF). Endothelial cells (ECs) are the most abundant non-myocyte cells in adult mouse heart. Simvastatin, a strong inducer of Krüppel-like Factor 2 (Klf2) in ECs, ameliorates pressure overload induced maladaptive cardiac remodeling and dysfunction. This study aims to explore the detailed molecular mechanisms of the anti-remodeling effects of simvastatin. Methods and Results: RGD-magnetic-nanoparticles were used to endothelial specific delivery of siRNA and we found absence of simvastatin's protective effect on pressure overload induced maladaptive cardiac remodeling and dysfunction after in vivo inhibition of EC-Klf2. Mechanism studies showed that EC-Klf2 inhibition reversed the simvastatin-mediated reduction of fibroblast proliferation and myofibroblast formation, as well as cardiomyocyte size and cardiac hypertrophic genes, which suggested that EC-Klf2 might mediate the anti-fibrotic and anti-hypertrophy effects of simvastatin. Similar effects were observed after Klf2 inhibition in cultured ECs. Moreover, Klf2 regulated its direct target gene TGFß1 in ECs and mediated the protective effects of simvastatin, and inhibition of EC-Klf2 increased the expression of EC-TGFß1 leading to simvastatin losing its protective effects. Also, EC-Klf2 was found to regulate EC-Foxp1 and loss of EC-Foxp1 attenuated the protective effects of simvastatin similar to EC-Klf2 inhibition. Conclusions: We conclude that cardiac microvasculature ECs are important in the modulation of pressure overload induced maladaptive cardiac remodeling and dysfunction, and the endothelial Klf2-TGFß1 or Klf2-Foxp1-TGFß1 pathway mediates the preventive effects of simvastatin. This study demonstrates a novel mechanism of the non-cholesterol lowering effects of simvastatin for HF prevention.