Sitagliptin reduces plaque macrophage content and stabilises arteriosclerotic lesions in Apoe −/− mice

Aims/hypothesis  

Inhibitors of dipeptidyl peptidase-IV (DPP-IV), such as sitagliptin, increase glucagon-like peptide-1 (GLP-1) concentrations and are current treatment options for patients with type 2 diabetes mellitus. As patients with diabetes exhibit a high risk of developing severe atherosclerosis, we investigated the effect of sitagliptin on atherogenesis in Apoe ^−/− mice.     

Adenoviral transfer of HIF-1α enhances vascular responses to critical limb ischemia in diabetic mice

Diabetes is a major risk factor for ischemic disease. Treatment options for diabetic patients with peripheral arterial disease when revascularization is not possible are limited, resulting in a high incidence of limb amputation. We evaluated the therapeutic potential of AdCA5, an adenovirus encoding a constitutively active form of HIF-1α, in a diabetic model of critical limb ischemia. Diabetic db/db and nondiabetic db/+ mice were subjected to unilateral femoral artery ligation. Limb perfusion, tissue viability, and motor function were more severely impaired in db/db mice. Intramuscular injection of AdCA5 into the ischemic limb of db/db mice increased the recovery of limb perfusion and function, reduced tissue necrosis, rescued the diabetes-associated impairment of circulating angiogenic cells, enhanced endothelial nitric oxide synthase activation, and increased vessel density and luminal area in the ischemic limb.     

Moderate GSK-3β inhibition improves neovascular architecture,reduces vascular leakage,and reduces retinal hypoxia in a model of ischemic retinopathy

In ischemic retinopathies, unrelieved hypoxia induces the formation of architecturally abnormal, leaky blood vessels that damage retina and ultimately can cause blindness. Because these newly formed blood vessels are functionally defective, they fail to alleviate underlying hypoxia, resulting in more pathological neovascularization and more damage to retina. With an established model of ischemic retinopathy, we investigated inhibition of glycogen synthase kinase-3β (GSK-3β) as a means for improving the architecture and functionality of pathological blood vessels in retina. In vitro, hypoxia increased GSK-3β activity in retinal endothelial cells, reduced β-catenin, and correspondingly impaired integrity of cell/cell junctions. Conversely, GSK-3β inhibitors restored β-catenin, improved cell/cell junctions, and enhanced the formation of capillary cords in three-dimensional collagen matrix. In vivo, GSK-3β inhibitors, at appropriately moderate doses, strongly reduced abnormal vascular tufts, reduced abnormal vascular leakage, and improved vascular coverage and perfusion during the proliferative phase of ischemia-driven retinal neovascularization. Most importantly, these improvements in neovasculature were accompanied by marked reduction in retinal hypoxia, relative to controls. Thus, GSK-3β inhibitors offer a promising strategy for alleviating retinal hypoxia by correcting key vascular defects typically associated with ischemia-driven neovascularization.     

PPARδ reduces abdominal aortic aneurysm formation in angiotensin II-infused apolipoprotein E-deficient mice by regulating extracellular matrix homeostasis and inflammatory responses

Background

Abdominal aortic aneurysm (AAA) is an inflammatory disorder characterized by a localized degradation of connective tissue and apoptosis of vascular smooth muscle cells. This study examined whether the ligand-activated peroxisome proliferator-activated receptor (PPAR) δ can directly antagonize angiotensin II (Ang II)-induced AAA formation in apoE-deficient mice.

Methods and results

Six-month-old male apoE-deficient mice were infused with Ang II and/or GW501516 (1.44 and 3.3 mg/kg/day, respectively) via osmotic mini-pumps. At day 28, aortic size was measured and tissues were collected for analyses. Co-infusion of GW501516, an activator of PPARδ, attenuated both the incidence and the severity of Ang II-induced AAA in apoE-deficient mice. Ligand-activated PPARδ also reduced infiltration of macrophages, resulting in significant decreases in chemotactic proteins such as monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and inducible nitric oxide synthase. The anti-inflammatory effect of GW501516 was associated with the suppression of apoptotic cell death, along with the inhibition of medial smooth muscle cell loss and focal elastin destruction, which leads to a medial dissection and aortic rupture. These ameliorative effects of GW501516 on Ang II-induced aneurysm were correlated with increased expression of extracellular matrix (ECM) proteins, such as types I and III collagen, fibronectin, and elastin, along with the up-regulation of transforming growth factor-β1. In addition, ligand-activated PPARδ also increased the expression of tissue inhibitor of metalloproteinase (TIMP)-2 and TIMP-3, while it strongly suppressed that of matrix metalloproteinase-2.

Conclusions

PPARδ attenuates Ang II-induced AAA formation by regulating ECM homeostasis and inflammatory responses, suggesting a novel strategy for the treatment of AAA.     

Reduction of experimental diabetic vascular leakage and pericyte apoptosis in mice by delivery of αA-crystallin with a recombinant adenovirus

Aims/hypothesis  

The study aimed to evaluate the efficacy of recombinant adenovirus expressing αA-crystallin (Ad-αAc-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes.     

Pharmacological or genetic depletion of senescent astrocytes prevents whole brain irradiation–induced impairment of neurovascular coupling responses protecting cognitive function in mice

GeroScience - Whole brain irradiation (WBI, also known as whole brain radiation therapy or WBRT) is a mainstream therapy for patients with identifiable brain metastases and as a prophylaxis for...     

Pharmacological and genetic modifications of somatic cholesterol do not substantially alter the course of CNS disease in Niemann–Pick C mice

Niemann–Pick type C (NPC) is a neurodegenerative disorder with somatically altered cholesterol metabolism. The NPC1 gene has recently been cloned and shown to have sequences shared with known sterol-sensing proteins. We have used a mouse model with a disrupted Npc1 gene to study two cholesterol-lowering drugs (nifedipine and probucol) and the effects of introducing a null mutation in the low-density lipoprotein receptor (LDLR). Although these treatments significantly ameliorated liver cholesterol storage, little effect on the onset of neurological symptoms was found.     

TGF-β in inflammatory bowel disease: a key regulator of immune cells,epithelium, and the intestinal microbiota

Inflammatory bowel disease (IBD) is defined as chronic intestinal inflammation, and includes ulcerative colitis and Crohn’s disease. Multiple factors are involved in the pathogenesis of IBD, and the condition is characterized by aberrant mucosal immune reactions to intestinal microbes in genetically susceptible hosts. Transforming growth factor-β (TGF-β) is an immune-suppressive cytokine produced by many cell types and activated by integrins. Active TGF-β binds to its receptor and regulates mucosal immune reactions through the TGF-β signaling pathway. Dysregulated TGF-β signaling is observed in the intestines of IBD patients. TGF-β signal impairment in specific cell types, such as T-cells and dendritic cells, results in spontaneous colitis in mouse models. In addition, specific intestinal microbes contribute to immune homeostasis by modulating TGF-β production. In this review, we describe the role of TGF-β in intestinal immunity, focusing on immune cells, epithelium, and intestinal microbes. In addition, we present potential therapeutic strategies for IBD that target TGF-β.

     

Thrombomodulin domain 1 ameliorates diabetic nephropathy in mice via anti-NF-κB/NLRP3 inflammasome-mediated inflammation, enhancement of NRF2 antioxidant activity and inhibition of apoptosis

Aims/hypothesis

Chronic inflammatory processes have been increasingly shown to be involved in the pathogenesis of diabetes and diabetic nephropathy. Recently, we demonstrated that a lectin-like domain of thrombomodulin (THBD), which is known as THBD domain 1 (THBDD1) and which acts independently of protein C activation, neutralised an inflammatory response in a mouse model of sepsis. Here, therapeutic effects of gene therapy with adeno-associated virus (AAV)-carried THBDD1 (AAV-THBDD1) were tested in a mouse model of type 2 diabetic nephropathy.

Methods

To assess the therapeutic potential of THBDD1 and the mechanisms involved, we delivered AAV-THBDD1 (10¹¹ genome copies) into db/db mice and tested the effects of recombinant THBDD1 on conditionally immortalised podocytes.

Results

A single dose of AAV-THBDD1 improved albuminuria, renal interstitial inflammation and glomerular sclerosis, as well as renal function in db/db mice. These effects were closely associated with: (1) inhibited activation of the nuclear factor κB (NF-κB) pathway and the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome; (2) promotion of nuclear factor (erythroid-derived 2)-like 2 (NRF2) nuclear translocation; and (3) suppression of mitochondria-derived apoptosis in the kidney of treated mice.

Conclusions/interpretation

AAV-THBDD1 gene therapy resulted in improvements in a model of diabetic nephropathy by suppressing the NF-κB–NLRP3 inflammasome-mediated inflammatory process, enhancing the NRF2 antioxidant pathway and inhibiting apoptosis in the kidney.     

Relationships among protein tyrosine phosphatase 1B,angiotensin II,and insulin-mediated aortic responses in type 2 diabetic Goto–Kakizaki rats

Objective

We investigated the relationships among protein tyrosine phosphatase 1B (PTP1B), angiotensin II (Ang II), and insulin signaling in the presence of endothelial dysfunction in type 2 diabetic Goto–Kakizaki (GK) rat aortas.

Methods and results

Aortas isolated from GK or control Wistar rats were examined in the presence or absence of Ang II with or without a selective antagonist of the Ang II type 1 (AT₁) receptor or a PTP1B inhibitor to evaluate vascular functional and molecular mechanisms, such as insulin-induced relaxation, nitric oxide (NO) production, phosphorylation of insulin receptor substrate (IRS)-1, endothelial NO synthase (eNOS), and phosphorylation, and the subcellular localization of PTP1B. GK aortas exhibited reductions of: 1) insulin-induced relaxation, 2) NO production, 3) Ser¹¹⁷⁷-p-eNOS, and 4) Tyr⁶¹²-p-IRS-1. Pre-incubation with a PTP1B inhibitor normalized these reductions. In Wistar aortas, the four above-mentioned parameters were reduced by Ang II, but were completely inhibited by co-treatment with the PTP1B inhibitor. The membrane expression of PTP1B was greater in GK than in Wistar aortas, and it was increased by Ang II in Wistar rats. The membrane PTP1B expression in the presence of insulin + Ang II was reduced by the PTP1B inhibitor or AT₁-receptor antagonist.

Conclusions

These results suggest that the membrane PTP1B suppressed insulin-mediated aortic relaxation, and this was due to the Ang II-AT₁-receptor signaling pathway. The inhibition of PTP1B warrants further investigation as a potential therapeutic target for endothelial dysfunction in type 2 diabetes.     

Rates of infiltration by macrophages and dendritic cells and expression of interleukin-18 and interleukin-12 in the chronic inflammatory lesions of Sjögren's syndrome: correlation with certain features of immune hyperactivity and factors associated with high risk of lymphoma development

OBJECTIVE: To evaluate the expression profile of infiltrating macrophages and dendritic cells (DCs) as well as of interleukin-18 (IL-18) and IL-12 in the minor salivary gland (MSG) lesions of patients with Sj?gren's syndrome (SS), and to assess the relationship of these factors with disease parameters. METHODS: Macrophages, DCs, T cells, B cells, proIL-18, mature IL-18, and IL-12 were detected by single- and double-labeling immunohistochemistry in MSG specimens from 21 patients with primary SS (13 of 21 tested for IL-12), 7 patients with secondary SS, and 9 disease control patients. Expression profiles were assessed for correlations with various disease parameters, including adverse predictors of lymphoma development. RESULTS: MSGs from patients with SS (but not from disease controls) manifested increased infiltration by macrophages and DCs, strong expression of IL-18 by macrophages (particularly in B cell-rich areas and in germinal center-like structures in primary SS), and expression of IL-12 by mononuclear cell infiltrates. In primary SS, high infiltration by macrophages correlated with SG enlargement (P = 0.01). The DC infiltration rate correlated positively with the macrophage infiltration rate (P = 0.04), occurrence of SG enlargement (P = 0.03), and presence of C4 hypocomplementemia (P = 0.05), and inversely with serum C4 complement levels (P = 0.001). The rate of infiltration by IL-18-expressing cells correlated positively with biopsy focus scores (P < 0.001), larger infiltrates of macrophages (P = 0.01), DCs (P = 0.01), and B cells (P = 0.02), and SG enlargement (P = 0.02), and negatively with serum C4 complement levels (P = 0.02). The rate of infiltration by IL-12-expressing cells correlated inversely with that by IL-18-expressing cells (P = 0.001), biopsy focus scores (P = 0.003), and SG enlargement (P = 0.01), and positively with serum C4 complement levels (P = 0.05). CONCLUSION: In patients with primary SS, infiltration of the SG by macrophages and DCs and expression of IL-18 and IL-12 appear to play active roles in the expansion and organization of infiltrative injuries and have a correlation with certain predictors of lymphoma development.     

Effects of OX40–OX40 ligand interaction on the levels of ROS and Cyclophilin A in C57BL/6J mice atherogenesis

Background

An increasing amount of evidence shows that the OX40–OX40L interaction serves an important function in atherosclerosis. However, the mechanism of the OX40 signaling pathway remains unclear. This study investigates the effect of OX40–OX40L interaction on the levels of intracellular reactive oxygen species (ROS) and the secretion of Cyclophilin A (CyPA) in C57BL/6J mice atherogenesis.

Methods

The atherosclerotic plaque model was established by placing a rapid perivascular carotid collar on C57BL/6J mice fed with a western-type diet. In vivo, the expressions of CyPA in mouse plaque and lymphocytes were detected by immunohistochemical and Western blot analyses, respectively. In vitro, the expression of CyPA protein in cultured lymphocytes of C57BL/6J mice was assessed by using Western blot analysis. The level of ROS was detected through flow cytometry.

Results

CyPA expression was significantly increased in the atherosclerotic lesions and lymphocytes from C57BL/6J mice. The ROS levels in OX40⁺-lymphocytes were increased in vitro and in vivo. After stimulating the OX40–OX40L interaction, the ROS and CyPA levels in lymphocytes were obviously increased in vitro, whereas anti-OX40L mAb significantly down-regulated the anti-OX40 mAb-induced ROS generation and inhibited CyPA secretion in lymphocytes.

Conclusion

The OX40–OX40L interaction up-regulates intracellular levels of ROS in C57BL/6J mice and increases CyPA secretion in lymphocytes. Increased CyPA secretion may serve an important function in atherosclerotic plaque formation.     

Inhibitor of G protein-coupled receptor kinase 2 normalizes vascular endothelial function in type 2 diabetic mice by improving β-arrestin 2 translocation and ameliorating Akt/eNOS signal dysfunction

In type 2 diabetes, although Akt/endothelial NO synthase (eNOS) activation is known to be negatively regulated by G protein-coupled receptor kinase 2 (GRK2), it is unclear whether the GRK2 inhibitor would have therapeutic effects. Here we examined the hypotensive effect of the GRK2 inhibitor and its efficacy agonist both vascular (aortic) endothelial dysfunction (focusing especially on the Akt/eNOS pathway) and glucose intolerance in two type 2 diabetic models (ob/ob mice and nicotinamide+streptozotocin-induced diabetic mice). Mice were treated with a single injection of the GRK2 inhibitor or vehicle, and the therapeutic effects were compared by examining vascular function and by Western blotting. The GRK2 inhibitor lowered blood pressure in both diabetic models but not in their age-matched controls. The GRK2 inhibitor significantly improved clonidine-induced relaxation only in diabetic (ob/ob and DM) mice, with accompanying attenuations of GRK2 activity and translocation to the plasma membrane. These protective effects of the GRK2 inhibitor may be attributable to the augmented Akt/eNOS pathway activation (as evidenced by increases in Akt phosphorylation at Ser(473) and at Thr(308), and eNOS phosphorylation at Ser(1177)) and to the prevention of the GRK2 translocation and promotion of β-arrestin 2 translocation to the membrane under clonidine stimulation. Moreover, the GRK2 inhibitor significantly improved the glucose intolerance seen in the ob/ob mice. Our work provides the first evidence that in diabetes, the GRK2 inhibitor ameliorates vascular endothelial dysfunction via the Akt/eNOS pathway by inhibiting GRK2 activity and enhancing β-arrestin 2 translocation under clonidine stimulation, thereby contributing to a blood pressure-lowering effect. We propose that the GRK2 inhibitor may be a promising therapeutic agent for cardiovascular complications in type 2 diabetes.     

The reduction of apnea–hypopnea duration ameliorates endothelial dysfunction,vascular inflammation,and systemic hypertension in a rat model of obstructive sleep apnea

Sleep and Breathing - We aimed to investigate the effect of obstructive sleep apnea (OSA) and apnea–hypopnea duration on endothelial, ventricular function, blood pressure, and inflammation in...     

Prospective, open-label, uncontrolled pilot study to study safety and efficacy of sildenafil in systemic sclerosis–related pulmonary artery hypertension and cutaneous vascular complications

Pulmonary artery hypertension (PAH) remains the leading cause of morbidity and mortality in systemic sclerosis, while Raynaud’s phenomenon and digital ulcers significantly add to the morbidity in systemic sclerosis (SSc). This study was undertaken to evaluate the role of sildenafil in PAH, Raynaud’s phenomenon, and digital ulcers in systemic sclerosis patients. A prospective, open-label, uncontrolled pilot study was done at a tertiary care centre in India to study the safety and efficacy of oral sildenafil in PAH, Raynaud’s phenomenon, digital infarcts, and ulcers in SSc. Seventeen patients fulfilling ACR classification criteria for scleroderma and having PAH were recruited. Six-minute walk test, WHO class of dyspnoea, severity of Raynaud’s phenomenon, and 2D ECHO were performed in all the study subjects at baseline and at 3 months post-treatment. All patients were treated with oral sildenafil 25 mg three times a day for a period of 3 months. The pre- and post-treatment values of mean pulmonary artery pressure (PAP), 6-min walk test, WHO class of dyspnoea, and severity of Raynaud’s phenomenon were compared to look for any significant change. Sixteen patients who completed 3-month follow-up had shown statistically significant improvement in 6-min walk test, WHO class of dyspnoea, severity of Raynaud’s phenomenon, and mPAP. Also, there was no occurrence of new digital infarcts or ulcers, and existing ulcers showed signs of healing. Sildenafil is highly efficacious cheaper and safe alternative to other available therapies for SSc-associated PAH, Raynaud’s phenomenon, and digital infarcts/ulcers.