Impaired Interleukin-15 Signaling via BMPR2 Loss Drives Natural Killer Cell Deficiency and Pulmonary Hypertension.

BACKGROUND: Natural killer (NK) cell impairment is a feature of pulmonary arterial hypertension (PAH) and contributes to vascular remodeling in animal models of disease. Although mutations in BMPR2, the gene encoding the BMP (bone morphogenetic protein) type-II receptor, are strongly associated with PAH, the contribution of BMPR2 loss to NK cell impairment remains unknown. We explored the impairment of IL (interleukin)-15 signaling, a central mediator of NK cell homeostasis, as both a downstream target of BMPR2 loss and a contributor to the pathogenesis of PAH. METHODS: The expression, trafficking, and secretion of IL-15 and IL-15Rα (interleukin 15 α-type receptor) were assessed in human pulmonary artery endothelial cells, with or without BMPR2 silencing. NK cell development and IL-15/IL-15Rα levels were quantified in mice bearing a heterozygous knock-in of the R899X-BMPR2 mutation (bmpr2+/R899X). NK-deficient Il15-/- rats were exposed to the Sugen/hypoxia and monocrotaline models of PAH to assess the impact of impaired IL-15 signaling on disease severity. RESULTS: BMPR2 loss reduced IL-15Rα surface presentation and secretion in human pulmonary artery endothelial cells via impaired trafficking through the trans-Golgi network. bmpr2+/R899X mice exhibited a decrease in NK cells, which was not attributable to impaired hematopoietic development but was instead associated with reduced IL-15/IL-15Rα levels in these animals. Il15-/- rats of both sexes exhibited enhanced disease severity in the Sugen/hypoxia model, with only male Il15-/- rats developing more severe PAH in response to monocrotaline. CONCLUSIONS: This work identifies the loss of IL-15 signaling as a novel BMPR2-dependent contributor to NK cell impairment and pulmonary vascular disease.

Evolving Concepts in Endothelial Pathobiology of Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a deadly disease, characterized by increased vascular resistance, pulmonary arteriolar loss, and occlusive arterial remodeling, leading to eventual right heart failure. Evidence increasingly points to the pulmonary endothelium as a central actor in PAH. Endothelial cell apoptosis can result directly in distal lung arteriolar pruning and indirectly in the formation of complex and occlusive arterial lesions, reflecting an imbalance between endothelial injury and repair in the development and progression of PAH. Many of the mutations implicated in PAH are in genes, which are predominantly, or solely, expressed in endothelial cells, and the endothelium is a major target for therapeutic interventions to restore BMP signaling. We explore how arterial pruning can promote the emergence of occlusive arterial remodeling mediated by ongoing endothelial injury secondary to hemodynamic perturbation and pathological increases in luminal shear stress. The emerging role of endothelial cell senescence is discussed in the transition from reversible to irreversible arterial remodeling in advanced PAH, and we review the sometimes conflicting evidence that female sex hormones can both protect or promote vascular changes in disease. Finally, we explore the contribution of the endothelium to metabolic changes and the altered inflammatory and immune state in the PAH lung, focusing on the role of excessive TGFß signaling. Given the complexity of the endothelial pathobiology of PAH, we anticipate that emerging technologies that allow the study of molecular events at a single cell level will provide answers to many of the questions raised in this review.

Efficacy and tolerance of 200 mg micronised fenofibrate administered over a 6-month period in hyperlipidaemic patients: an open Belgian multicenter study.

The authors report the results of a large open multicenter study using 200 mg micronised fenofibrate once a day. Among 1545 selected patients who underwent a 3-month period with nutritional advice, 1334 were included in a 6-month drug study. Inclusion criteria were total serum cholesterol equal to or above 250 mg/dl and/or serum triglycerides equal to or above 200 mg/dl. At 6 months, average changes from inclusion levels were -20.5, -26.1. -7.5 and +15.2% for total cholesterol, LDL-cholesterol > or = 160 mg/dl on inclusion, plasma fibrinogen and HDL-cholesterol, respectively. Median decrease of serum triglycerides was 46.5%. Trial discontinuation for clinical and biological adverse events were 5 and 1%, respectively. In conclusion, micronised fenofibrate at a daily dose of 200 mg had significant lipid-modifying properties but also exhibited a beneficial effect on other related risk factors such as fibrinogen reduction. The safety profile was very satisfactory providing an excellent benefit/risk ratio.

Prevention of deep vein thrombosis after hip replacement: randomised comparison between unfractionated heparin and low molecular weight heparin.

OBJECTIVE: To evaluate the efficacy and safety of two subcutaneous prophylactic regimens for postoperative deep vein thrombosis after total hip replacement. DESIGN: Prospective open randomised multicentre trial. SETTING: 28 European departments of orthopaedic surgery. INTERVENTION: All patients had bilateral phlebography 10 days after surgery. 31 patients receiving low molecular weight heparin and 29 receiving unfractionated heparin were excluded from the efficacy analysis for various reasons. PATIENTS: 349 patients undergoing total hip replacement between September 1988 and May 1989. 174 patients received subcutaneously a low molecular weight heparin (Fraxiparine) with anti-factor Xa activity of 41 IU/kg/day for three days, then 62 IU/kg/day from day 4 to day 10. 175 patients received subcutaneous unfractionated heparin at intervals of eight hours; doses were adjusted to maintain the activated thromboplastin time at two to five seconds above control values. MAIN OUTCOME MEASURE: Total incidence of deep vein thrombosis and incidence of proximal deep vein thrombosis on bilateral phlebography. RESULTS: The total incidence of deep vein thrombosis was 16% in patients receiving unfractionated heparin and 12.6% in patients receiving low molecular weight heparin (p = 0.45), and the incidence of thrombosis of the proximal veins was 13.1% and 2.9% respectively (p less than 0.001). Four patients receiving unfractionated heparin and one receiving low molecular weight heparin developed pulmonary embolism. The incidence of bleeding complications was low and comparable in the two groups. CONCLUSION: Low molecular weight heparin is at least as effective as unfractionated heparin in preventing deep vein thrombosis and is more effective at preventing thrombosis of the proximal veins in patients undergoing hip replacement. Low molecular weight heparin is not more likely to cause bleeding complications and is simpler to give than unfractionated heparin.

[Indications and results of combined urokinase-lys plasminogen in acute ischemic pathology of the legs]. / Indications et résultats de l'association urokinase-lys plasminogène dans la pathologie ischémique aiguë des membres inférieurs.

Low dose urokinase-lys plasminogen was used to treat 10 patients with acute ischemia of lower limbs. Preliminary results are reported and indications defined, the combination producing effective relief and being very well tolerated biologically and clinically. All patients presented clear signs of ischemia provoking a short term risk for the limb. Direct femoral puncture arteriography of the ischemic limb was an essential pretreatment investigation. A thin catheter left in contact with the thrombus allowed localized fibrinolysis to be performed. Follow up arteriography examinations assessed clinicopathologic results, while biologic surveillance of principal coagulation parameters showed a lack of significant alterations during treatment. Ischemic signs were totally relieved in 7 cases, with arterial repermeabilization allowing recuperation of one (3 cases) or both (2 cases) distal pulses. Persistence of a popliteal thrombus in one case required a fogarty after a direct approach and the limb was saved. Two patients had to be amputated because of delayed treatment. These encouraging results suggest that this procedure of local thrombolysis be reserved for popliteal or infra-popliteal occlusions accompanied by sensory-motor signs and of recent (less than 72 hours) onset. Follow up for 8 months is insufficient but has shown the absence of deterioration, but this is obviously a function of the natural course of the underlying atheromatous disease.

Effects of a single bolus of urokinase in patients with life-threatening pulmonary emboli: a descriptive trial.

To evaluate hemodynamic, angiographic, and biological effects of a single bolus of urokinase, an open descriptive trial was conducted in a homogeneous group of 14 patients with acute life-threatening pulmonary emboli and without prior cardiopulmonary disease. For every patient the efficacy of the treatment was evaluated by comparing control and posttherapeutic values after the bolus injection of 15,000 IU/kg body weight urokinase (urinary source) administered in 10 min in the right atrium, followed by continuous intravenous full-dose heparin therapy. In two patients clinical status, hemodynamics, vascular obstruction, and biological (fibrinogen and plasminogen levels) parameters remained unchanged. One of these two patients died, making the mortality rate for the whole group 7%. Twelve of 14 patients showed rapid clinical improvement. Evaluation at 12 hr demonstrated significant decreases in pulmonary vascular obstruction (Miller index, 34%), total pulmonary vascular resistances (37%), and fibrinogen and plasminogen levels (41% and 40%, respectively), without any significant change in cardiac index. The hemodynamic sequential measurements performed (1,3, 6, and 12 hr) in seven of the 12 improved patients showed that the greatest percentage of the total hemodynamic improvement occurred within the first 3 hr after bolus administration of urokinase. No severe hemorrhagic complications were observed. Because of its rapid efficacy and its low cost, the bolus technique appeared particularly useful in the treatment of patients with acute life-threatening pulmonary emboli.

[Local low-dose thrombolytic treatment with sequential urokinase-plasminogen in deep central venous thrombosis]. / Traitement thrombolytique local à faibles doses par des séquences urokinase-plasminogène des thromboses veineuses profondes centrales.

Four patients with recent central deep vein thrombosis (pelvis-superior mediastinum) were treated by local low dose infusions of urokinase (500 to 1000 IU/kg/h for 6 to 9 hours) followed by plasminogen (20 to 30 microkatals/h for 2 to 3 hours) associated with simultaneous anticoagulation with heparin. The treatment was continued for 83 to 160 hours until control phlebography showed dissolution of the thrombus. There were no haemorrhagic complications despite the presence of a number of risk factors which contraindicated treatment by a systemic route. Fibrinogen and FDP levels did not alter significantly. This therapeutic approach is worth considering and should be integrated among the therapeutic options available for cases of central deep vein thrombosis.