LTBP2 knockdown by siRNA reverses myocardial oxidative stress injury, fibrosis and remodelling during dilated cardiomyopathy.

AIM: Dilated cardiomyopathy (DCM) is characterised by left ventricular dilation and associated with systolic dysfunction. Recent evidence has reported the high expression of latent transforming growth factor beta binding protein 2 (LTBP2) in heart diseases, which may play a role in regulating multiple biological functions of myocardial cells. Thus, this study set out to investigate the molecular mechanism and effects of LTBP2 in myocardial oxidative stress injury, fibrosis and remodelling in a rat model of DCM, with the involvement of NF-κB signalling pathway. METHODS: The rat model of DCM was treated with si-LTBP2 and/or activator of NF-κB signalling pathway to examine the haemodynamic indexes, cardiac functions, oxidative stress injury, fibrosis and remodelling. Moreover, in vitro experiments were conducted to verify the regulatory role of LTBP2 and NF-κB signalling pathway in DCM. RESULTS: LTBP2 was up-regulated in DCM rats. After LTBP2 was knocked down, haemodynamic indexes, HW/BW ratio, collagen volume fraction (CVF) level, positive expression of LTBP2, levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), tumour necrosis factor beta 1 (TGF-ß1) and brain natriuretic peptide (BNP) were all decreased. Meanwhile, levels of LTBP2, Col-I, Col-III, p65 and p52 were also reduced, while HW, BW and levels of SOD and TAOC were increased. In contrast, activation of NF-κB signalling pathway reversed effects of LTBP2 gene silencing. These findings were confirmed by in vivo experiments. CONCLUSIONS: LTBP2 silencing can attenuate myocardial oxidative stress injury, myocardial fibrosis and myocardial remodelling in DCM rats by down-regulating the NF-κB signalling pathway.

Atorvastatin suppresses vascular hypersensitivity and remodeling induced by transient adventitial administration of lipopolysaccharide in rats.

BACKGROUND: The phenotypic transition of vascular smooth muscle cells (VSMCs) from a contractile to a proliferative state markedly affects the pathophysiology of cardiovascular diseases. The adventitial inflammation can promote neointimal formation and vascular remodeling. We used direct administration of lipopolysaccharide (LPS) into the periphery of the carotid artery to investigate the influence of transient adventitial inflammation on vascular remodeling and its potential mechanism. METHODS: Male 15-week-old Wistar rats were randomly assigned to four groups with six rats in each group. The rats of groups I and II were administered distilled water, and group III and IV were treated with fasudil and atorvastatin respectively. All treatments were given daily for 11 days. On day 8, the adventitia in group I was injected with 5 µL sterile saline, and the group II-IV were injected with 5 µL sterilized LPS. The carotid blood flow and femoral blood pressure were measured in vivo, and the thickness of vascular intima and middle layer was measured in vitro. Serum interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) were determined using enzyme-linked immunosorbent assay (ELISA) assay. And the Rho-associated coiled-coil-containing protein kinase 2 (ROCK2), myosin phosphatase target subunit 1 (MYPT1), myosin light chain (MLC), myocardin, SM-α actin or glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected by western blot. The comparisons were made by one-way analysis of variance with Bonferroni's post hoc test. A value of P<0.05 was considered to represent a statistically significant difference. RESULTS: Transient adventitial inflammation induced by LPS caused no obvious change in basal blood flow, but did lead to vascular hypersensitivity to serotonin. Morphological examinations revealed that the medial layer was the only domain affected, and showed VSMC proliferation and rearrangement. LPS increased serum IL-6 and TNFα contents, ROCK2 expression and activity, and caused changes in the expression levels of some stereotypical VSMC genes. Similar to the Rho-kinase inhibitor fasudil, atorvastatin completely restored the morphological alterations, even increased blood flow. CONCLUSIONS: Our study confirms the beneficial effect of atorvastatin on the vascular system in terms of morphology and function.

Inflammation inhibitory effects of sirolimus and paclitaxel-eluting stents on interleukin-1ß-induced coronary artery in-stent restenosis in pigs.

BACKGROUND: Coronary artery in-stent restenosis (ISR) and late stent thrombosis remain as important complications of stenting. The inflammation reactions to sirolimus and paclitaxel-eluting stents were investigated in a swine stenosis model induced by interleukin (IL)-1ß. METHODS: Mini pigs (n = 12; 2-3 months old and weighing 25-30 kg) were subjected to thoracotomy. Segments (10 mm) of the mid left anterior descending coronary artery and left circumflex coronary artery were exposed and aseptically wrapped with a cotton mesh soaked with IL-1ß (5 µg). After 2 weeks, the animals were anesthetized and quantitative coronary arteriography (QCA) was performed. The stenosis sites were randomized into three groups for stent insertion: a sirolimus-eluting stent (SES) group (Firebird(TM), n = 7), a paclitaxel-eluting stent (PES) group (TAXUS(TM), n = 9), and a bare-metal stent (BMS) group (YINYITM, Dalian Yinyi Biomaterials Development Co., Ltd, China, n = 8). The three different stents were randomly implanted into stenosis segments. Expression of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), P-selectin and vascular cell adhesion molecule-1 (VCAM-1) was determined by reverse transcription-coupled polymerase chain reaction (RT-PCR). RESULTS: QCA showed severe stenosis in IL-1ß treated segments. The SES and PES groups showed lower 1-month angiographic late lumen loss (LLL) within the stent and the lesion compared with BMS (P < 0.05) by follow-up QCA. The SES showed lower LLL than that of PES in reducing 1-month inflammation lesions in pigs by follow-up QCA ((0.15 ± 0.06) mm vs. (0.33 ± 0.01) mm, P < 0.0001). The neointimal hyperplasia areas in SES and PES showed lower than those of BMS (SES (11.6 ± 1.7) mm(2), PES (27.2 ± 1.6) mm(2) vs. BMS (76.2 ± 1.3) mm(2), P < 0.0001). The mRNA expression of MCP-1 by RT-PCR in SES and PES showed lower than that of BMS at 30 days after stenting (SES 0.20 ± 0.03, PES 0.48 ± 0.49 vs. BMS 0.58 ± 0.07, P < 0.05). Levels of VCAM-1 in SES were significantly lower than those of PES and BMS (SES 0.35 ± 0.08 vs. PES 0.65 ± 0.13, BMS 0.70 ± 0.06, P < 0.05). Histochemical immunostaining of vessel walls showed lower inflammatory chemokine MCP-1 expression in the SES and PES groups compared with BMS. CONCLUSION: SESs were superior in reducing 1-month angiographic LLL in inflammation lesions in pigs, strongly suggesting that SESs can suppress inflammatory reactions in ISR at multiple points.

[Pitavastatin enhances angiogenesis and perfusion in a murine mode of limb ischemia].

OBJECTIVE: We investigated the effects of pitavastatin on angiogenesis and perfusion in C3H/He mice with unilateral hind limb ischemia. METHODS: C3H/He mice treated with saline (n = 15) or pitavastatin (1 mg.kg(-1).d(-1), n = 15) per gavage for 1 week underwent unilateral hind limb ischemia surgery and were treated for another 5 weeks. Hind-limb blood flow was measured by Laser Doppler perfusion imager (LDPI, ischemic/nonischemic limb, %) at baseline, immediately after ischemia and weekly thereafter for 5 weeks. Endpoints included local vessel counts by immunofluorescence, phospho-Akt positive cell counts by immunoenzyme histochemical technique, vascular endothelial growth factors (VEGFs) expression in ischemic limbs by Western blot and serum nitric oxide metabolite (NOx) by chrome dioxide Griess method. RESULTS: Lower extremity perfusion was significantly improved in pitavastatin treated mice vs. controls as measured by LDPI% at 1 week post ischemia and thereafter (P < 0.05). Pitavastatin treatment was associated with significantly increased capillary count [(47 +/- 11) vs. (26 +/- 14)/per high-power field (x 200), P < 0.05] and greater percentage of phospho-Akt positive cells [(6 +/- 1) vs. (2 +/- 0)/per high-power field (x 200), P < 0.05] in ischemic limbs. Serum NOx [(77.3 +/- 21.8) vs. (52.1 +/- 11.2) mol/L, P < 0.05) and VEGF protein expression in ischemic limbs were also significantly increased in pitavastatin group than those in control group. CONCLUSIONS: Pitavastatin enhances angiogenesis and perfusion in CsH/He mice with limb ischemia.

[The pro-angiogenesis effect of Pitavastatin in the Klotho gene-knockout mice].

AIM: To discuss the effect of Pitavastatin on angiogenesis in vivo and its mechanism in Klotho heterozygous deficient mice. METHODS: The heterozygous deficient Klotho mice (kl +/-) and wild mice (kl +/+) from the same litter were used to establish the animal model of hind-limb ischemia and grouped into control and Pitavastatin group, respectively. Hind-limb blood flow was evaluated using Laser Doppler perfusion imager (LDPI) before treatment and after operation of hind-limbs. The capillaries in muscle of limbs were counted by means of CD-31 labeled immuno-fluorescence. The phosphorylation of Akt (Protein kinase B) in cells was measured by direct immunohistochemical technique. The expression of vascular endothelial growth factors (VEGFs) in muscle of limbs was assessed using Western blotting. RESULTS: After treatment of Pitavastatin, the blood flow in ischemic limbs of the Kl +/- and wild mice improved obviously, the ratio of blood flow area in ischemic limb to that in non-ischemic limb increased and the density of capillaries increased in ischemic limbs of the Kl +/- and wild mice. Pitavastatin enhanced the phosphorylation of Akt and the expression of VEGF in ischemic limbs of the Kl +/- and wild mice. CONCLUSION: Pitavastatin has the pro-angiogenesis effect in vivo and the VEGF-p-Akt-NO pathway may be involved in the mechanism of the effect of Pitavastatin.