Epidermal growth factor receptor tyrosine kinase (EGFRtk) and endoplasmic reticulum (ER) stress are important factors in cardiovascular complications. Understanding whether enhanced EGFRtk activity and ER stress induction are involved in cardiac damage, and microvascular dysfunction in type 1 diabetes mellitus is an important question that has remained unanswered. Cardiac fibrosis and microvascular function were determined in C57BL/6J mice injected with streptozotocin only or in combination with EGFRtk inhibitor (AG1478), ER stress inhibitor (Tudca), or insulin for 2 weeks. In diabetic mice, we observed an increase in EGFRtk phosphorylation and ER stress marker expression (CHOP, ATF4, ATF6, and phosphorylated-eIF2α) in heart and mesenteric resistance arteries, which were reduced with AG1478, Tudca, and insulin. Cardiac fibrosis, enhanced collagen type I, and plasminogen activator inhibitor 1 were decreased with AG1478, Tudca, and insulin treatments. The impaired endothelium-dependent relaxation and -independent relaxation responses were also restored after treatments. The inhibition of NO synthesis reduced endothelium-dependent relaxation in control and treated streptozotocin mice, whereas the inhibition of NADPH oxidase improved endothelium-dependent relaxation only in streptozotocin mice. Moreover, in mesenteric resistance arteries, the mRNA levels of Nox2 and Nox4 and the NADPH oxidase activity were augmented in streptozotocin mice and reduced with treatments. This study unveiled novel roles for enhanced EGFRtk phosphorylation and its downstream ER stress in cardiac fibrosis and microvascular endothelial dysfunction in type 1 diabetes mellitus.

Coronary artery disease in patients with hypertension is increasing worldwide and leads to severe cardiovascular complications. The cellular and molecular mechanisms that underlie this pathologic condition are not well understood. Experimental and clinical research indicates that immune cells and inflammation play a central role in the pathogenesis of cardiovascular diseases. Recently, it has been reported that CD4(+)CD25(+) regulatory T cells (Tregs) regulate heart fibrosis in hypertension. In this study, we determined the role of Tregs in coronary arteriolar endothelial dysfunction in angiotensin II-dependent hypertensive mice. Mice infused with angiotensin II had significantly increased blood pressure, as determined using telemetry, and apoptotic Treg numbers, as measured using flow cytometry. The mice displayed inflammation, assessed by macrophage activation/infiltration into coronary arterioles and the heart, and increased local tumor necrosis factor-α release, which participates in reduced coronary arteriolar endothelial-dependent relaxation in response to acetylcholine using an arteriograph. Hypertensive mice injected with Tregs isolated from control mice had significantly reduced macrophage activation and infiltration, reduced tumor necrosis factor-α release, and improved coronary arteriolar endothelium-dependent relaxation. Our novel data indicate that Tregs are important in the development of coronary arteriolar endothelial dysfunction in hypertension. These results suggest a new direction in the investigation of vascular disease in hypertension and could lead to a therapeutic strategy that involves immune system modulation using Tregs.

Type 2 diabetes (T2D) is associated with vascular dysfunction. We hypothesized that increased nuclear factor-κB (NF-κB) signaling contributes to vascular dysfunction in T2D. We treated type 2 diabetic (db−/db−) and control (db−/db+) mice with two NF-κB inhibitors (6 mg/kg dehydroxymethylepoxyquinomicin twice a week and 500 μg/kg/day IKK-NBD peptide) for 4 weeks. Pressure-induced myogenic tone was significantly potentiated, while endothelium-dependent relaxation (EDR) was impaired in small coronary arterioles and mesenteric resistance artery from diabetic mice compared with controls. Interestingly, diabetic mice treated with NF-κB inhibitors had significantly reduced myogenic tone potentiation and improved EDR. Importantly, vascular function was also rescued in db−/db−p50NF-κB−/− and db−/db−PARP-1−/− double knockout mice compared with db−/db− mice. Additionally, the acute in vitro downregulation of NF-κB–p65 using p65NF-κB short hairpin RNA lentivirus in arteries from db−/db− mice also improved vascular function. The NF-κB inhibition did not affect blood glucose level or body weight. The RNA levels for Sp-1 and eNOS phosphorylation were decreased, while p65NF-κB phosphorylation, cleaved poly(ADP-ribose) polymerase (PARP)-1, and cyclooxygenase (COX)-2 expression were increased in arteries from diabetic mice, which were restored after NF-κB inhibition and in db−/db−p50NF-κB−/− and db−/db−PARP-1−/− mice. In the current study, we provided evidence that enhanced NF-κB activity impairs vascular function by PARP-1–, Sp-1–, and COX-2–dependent mechanisms in male type 2 diabetic mice. Therefore, NF-κB could be a potential target to overcome diabetes-induced vascular dysfunction.

Serum leptin/BMI levels were increased and significantly associated with IL-6 levels and disease activity in men with AS, suggesting a possible role for leptin in the inflammatory reactions of AS.

Endoplasmic reticulum (ER) stress and inflammation are important mechanisms that underlie many of the serious consequences of type II diabetes. However, the role of ER stress and inflammation in impaired ischaemia-induced neovascularization in type II diabetes is unknown. We studied ischaemia-induced neovascularization in the hind-limb of 4-week-old db−/db− mice and their controls treated with or without the ER stress inhibitor (tauroursodeoxycholic acid, TUDCA, 150 mg/kg per day) and interleukin-1 receptor antagonist (anakinra, 0.5 μg/mouse per day) for 4 weeks. Blood pressure was similar in all groups of mice. Blood glucose, insulin levels, and body weight were reduced in db−/db− mice treated with TUDCA. Increased cholesterol and reduced adiponectin in db−/db− mice were restored by TUDCA and anakinra treatment. ER stress and inflammation in the ischaemic hind-limb in db−/db− mice were attenuated by TUDCA and anakinra treatment. Ischaemia-induced neovascularization and blood flow recovery were significantly reduced in db−/db− mice compared to control. Interestingly, neovascularization and blood flow recovery were restored in db−/db− mice treated with TUDCA or anakinra compared to non-treated db−/db− mice. TUDCA and anakinra enhanced eNOS-cGMP, VEGFR2, and reduced ERK1/2 MAP-kinase signalling, while endothelial progenitor cell number was similar in all groups of mice. Our findings demonstrate that the inhibition of ER stress and inflammation prevents impaired ischaemia-induced neovascularization in type II diabetic mice. Thus, ER stress and inflammation could be potential targets for a novel therapeutic approach to prevent impaired ischaemia-induced vascular pathology in type II diabetes.

Type 2 diabetes (T2D) is associated with microvascular dysfunction. We hypothesized that increased Poly - (ADP-ribose) polymerase-1 (PARP-1) activity contributes to microvascular dysfunction in T2D. T2D (db-/db-) and non-diabetic control (db-/db+) mice were treated with two different PARP-1 inhibitors (INO-1001, 5 mg/Kg/day and ABT-888, 15 mg/Kg/day) for two weeks. Isolated coronary arterioles (CA) were mounted in an arteriograph. Pressure-induced myogenic tone (MT) was significantly potentiated, while endothelium-dependent relaxation (EDR) was significantly attenuated in diabetic mice compared to control. These results were associated with decreased endothelial nitric oxide synthase (eNOS) phosphorylation, cyclic guanosine 3’ 5’-monophosphate (cGMP) level and increased PARP-1 activity in CA from diabetic mice compared to control. Interestingly, PARP-1 inhibitors significantly reduced the potentiation of MT, improved EDR, restored eNOS phosphorylation, cGMP and attenuated cleaved PARP-1. These results were supported by in vitro studies indicating that down-regulation of PARP-1 in mesenteric resistance arteries (MRA) using PARP-1 shRNA lenti-viral particles significantly improved EDR in MRA from diabetic mice compared to control. The inhibition of nitric oxide synthesis by N G-nitro-L-arginine methyl ester (L-NAME) significantly reduced the EDR in CA and MRA from control and diabetic mice treated with PARP-1 inhibitors and PARP-1 shRNA lenti-viral particles. In addition, we demonstrated that enhanced cleaved PARP-1, its binding to DNA and DNA damage were reduced after PARP-1 inhibition in cultured endothelial cells stimulated with high glucose. We provide evidence that T2D impairs microvascular function by an enhanced PARP-1 activity-dependent mechanism. Therefore, PARP-1 could be a potential target for overcoming diabetic microvascular complications.

Computer-assisted navigation gives a more consistent alignment correction and reduces outliers during implant positioning.

Our results suggest that constriction of coronary arteries in response to the bioactive lipid S1P or SPC occurs by distinct signalling pathways. Activation of the RhoA/RhoA-associated kinase pathway and subsequent phosphorylation of MYPT1 play a key role in SPC-induced coronary contraction, whereas elevation of [Ca2+]i is crucial for S1P-induced coronary constriction.