[Show abstract][Hide abstract] ABSTRACT: Inflammatory cytokine interleukin (IL)-6 is elevated in the serum and lungs of patients with pulmonary artery hypertension (PAH). Several animal models of PAH cite the potential role of inflammatory mediators. We investigated role of IL-6 in the pathogenesis of pulmonary vascular disease. Indices of pulmonary vascular remodeling were measured in lung-specific IL-6-overexpressing transgenic mice (Tg(+)) and compared to wild-type (Tg(-)) controls in both normoxic and chronic hypoxic conditions. The Tg(+) mice exhibited elevated right ventricular systolic pressures and right ventricular hypertrophy with corresponding pulmonary vasculopathic changes, all of which were exacerbated by chronic hypoxia. IL-6 overexpression increased muscularization of the proximal arterial tree, and hypoxia enhanced this effect. It also reproduced the muscularization and proliferative arteriopathy seen in the distal arteriolar vessels of PAH patients. The latter was characterized by the formation of occlusive neointimal angioproliferative lesions that worsened with hypoxia and were composed of endothelial cells and T-lymphocytes. IL-6-induced arteriopathic changes were accompanied by activation of proangiogenic factor, vascular endothelial growth factor, the proproliferative kinase extracellular signal-regulated kinase, proproliferative transcription factors c-MYC and MAX, and the antiapoptotic proteins survivin and Bcl-2 and downregulation of the growth inhibitor transforming growth factor-beta and proapoptotic kinases JNK and p38. These findings suggest that IL-6 promotes the development and progression of pulmonary vascular remodeling and PAH through proproliferative antiapoptotic mechanisms.
Full-text · Article · Jan 2009 · Circulation Research
[Show abstract][Hide abstract] ABSTRACT: Pulmonary arterial hypertension (PAH) is a progressive and often fatal disease. Currently available pharmacotherapies are
often suboptimal when used singly, due to either a poor clinical response or a complication from the therapy. As a consequence,
transitioning patients from one therapy to another or adding a therapy is a frequently encountered clinical conundrum. This
chapter examines the rationale and limited data surrounding transitioning patients from one pharmacotherapy to another and
combining individual therapies to produce an improvement in clinical outcomes. Much of the research discussed deals with animal
models used to test combination therapies, as there are few clinical trials in human subjects, but this is rapidly changing,
as a number of controlled trials are currently either in the planning stages or in progress. Transitions clearly have a role
in enhancing the convenience and safety of pulmonary hypertension therapy for some patients. Combination therapy looks promising
and may well represent the future of PAH pharmacotherapy.
[Show abstract][Hide abstract] ABSTRACT: Endothelin receptor antagonism has emerged as an important therapeutic approach in pulmonary arterial hypertension (PAH). Bench to bedside scientific research has shown that endothelin-1 (ET-1) is overexpressed in several forms of pulmonary vascular disease and may play an important pathogenetic role in the development and progression of PAH. Oral endothelin receptor antagonists (ERAs) improved exercise capacity, functional status, pulmonary hemodynamics, and delayed the time to clinical worsening in several randomized placebo-controlled trials. Two ERAs are currently approved by the US Food and Drug Administration: bosentan, a dual ERA for patients with class III and IV PAH, and ambrisentan, a selective ERA for patients with class II and III PAH. Sitaxsentan, another selective ERA, has been approved in Europe, Canada, and Australia. The objective of this review is to evaluate the available evidence describing the pharmacology, efficacy, safety, and tolerability, and patient-focused perspectives regarding the different types of endothelin receptor antagonists. Ongoing and forthcoming randomized trials are also highlighted including the approach of combining this class of drugs with other drugs that target different cellular pathways believed to be etiologically important in PAH.
Full-text · Article · Feb 2008 · Vascular Health and Risk Management
[Show abstract][Hide abstract] ABSTRACT: We assessed the efficacy of bosentan in transitioning from prostacyclin infusions in patients with pulmonary arterial hypertension (PAH).
Twenty-two PAH patients were recruited from five PAH centers if they had been clinically stable while receiving therapy with IV epoprostenol or subcutaneous treprostinil for at least 3 months. Patients were observed in an open-label prospective trial while bosentan was added to therapy, and then epoprostenol or treprostinil were tapered after 2 months.
Ten of the 22 patients were transitioned off prostacyclin infusion therapy after a mean (+/- SEM) duration of 6.1 +/- 1.2 months. Of those patients, seven patients have continued not receiving prostacyclin infusion therapy for a mean duration of 17.7 +/- 5.3 months, with no significant changes in pulmonary artery (PA) pressure estimated by echocardiography, World Health Organization (WHO)/New York Heart Association (NYHA) functional class, 6-min walk distance (6MWD), or Borg dyspnea score. The conditions of three patients deteriorated, necessitating the resumption of prostacyclin therapy, and two patients subsequently died. Twelve patients failed to transition or even lower the prostacylin infusion rate and had worsening of their WHO/NYHA functional class and estimated systolic PA pressures, and had a trend toward deterioration in their mean 6MWD (294 +/- 41 to 198 +/- 34 m, respectively; p = 0.2). Of these, two patients subsequently died. The baseline characteristics of those who transitioned successfully vs those who transitioned unsuccessfully were a lower prostacyclin infusion rate, and less severe elevations in the mean and estimated systolic PA pressures.
Transitioning from therapy with prostacyclin to bosentan is possible in some PAH patients, mainly in those receiving lower prostacyclin doses and having less pulmonary hypertension at baseline. Careful patient selection and close interim monitoring is needed because the conditions of patients can deteriorate, and they may not respond to the resumption of therapy with prostacyclin.
[Show abstract][Hide abstract] ABSTRACT: Phosphodiesterase-5 (PDE5) inhibitors and other agents that modulate intracellular cGMP are now emerging as promising, safe, and easy to administer therapies for pulmonary hypertension, with relatively few side effects. Recent studies have shown that PDE5 inhibitors are potent acute pulmonary vasodilators in experimental models that partially reverse established pulmonary arterial hypertension and blunt chronic pulmonary hypertension. In addition, studies on animals reveal that PDE5 inhibitors work in concert with nitric oxide and/or natriuretic peptide levels by enhancing intracellular cGMP and cGMP-mediated vasodilator effects. Further, the combination of PDE5 inhibitors and agents that increase cGMP or cAMP also yields additive beneficial effects on pulmonary hemodynamics in patients with pulmonary arterial hypertension.
Full-text · Article · Jul 2005 · Current Opinion in Pharmacology