Citations

Background— Smoothelins are actin-binding proteins that are abundantly expressed in healthy visceral (smoothelin-A) and vascular (smoothelin-B) smooth muscle. Their expression is strongly associated with the contractile phenotype of smooth muscle cells. Analysis of mice lacking both smoothelins ( Smtn-A/B −/− mice) previously revealed a critical role for smoothelin-A in intestinal smooth muscle contraction. Here, we report on the generation and cardiovascular phenotype of mice lacking only smoothelin-B ( Smtn-B −/− ). Methods and Results— Myograph studies revealed that the contractile capacity of the saphenous and femoral arteries was strongly reduced in Smtn-B −/− mice, regardless of the contractile agonist used to trigger contraction. Arteries from Smtn-A/B −/− compound mutant mice exhibited a similar contractile deficit. Smtn-B −/− arteries had a normal architecture and expressed normal levels of other smooth muscle cell–specific genes, including smooth muscle myosin heavy chain, α-smooth muscle actin, and smooth muscle-calponin. Decreased contractility of Smtn-B −/− arteries was paradoxically accompanied by increased mean arterial pressure (20 mm Hg) and concomitant cardiac hypertrophy despite normal parasympathetic and sympathetic tone in Smtn-B −/− mice. Magnetic resonance imaging experiments revealed that cardiac function was not changed, whereas distension of the proximal aorta during the cardiac cycle was increased in Smtn-B −/− mice. However, isobaric pulse wave velocity and pulse pressure measurements indicated normal aortic distensibility. Conclusions— Collectively, our results identify smoothelins as key determinants of arterial smooth muscle contractility and cardiovascular performance. Studies on mutations in the Smtn gene or alterations in smoothelin levels in connection to hypertension in humans are warranted.

Abstract Rationale An efficacious medical therapy for idiopathic pulmonary fibrosis (IPF) remains elusive. Objectives To explore the efficacy and safety of etanercept in the treatment of IPF. Methods This was a randomized, prospective, double-blind, placebo-controlled, multicenter exploratory trial in subjects with clinically progressive IPF. Primary endpoints included changes in the percentage of predicted FVC and lung diffusing capacity for carbon monoxide corrected for hemoglobin (DlCOHb) and change in the alveolar to arterial oxygen pressure difference P(a–a)O2 at rest from baseline over 48 weeks. Measurements and Main Results Eighty-eight subjects received subcutaneous etanercept (25 mg) or placebo twice weekly as their sole treatment for IPF. No differences in baseline demographics and disease status were detected between treatment groups; the mean time from first diagnosis was 13.6 months and mean FVC was 63.9% of predicted. At 48 weeks, no significant differences in efficacy endpoints were observed between the groups. A nonsignificant reduction in disease progression was seen in several physiologic, functional, and quality-of-life endpoints among subjects receiving etanercept. There was no difference in adverse events between treatment groups. Conclusions In this exploratory study in patients with clinically progressive IPF, etanercept was well tolerated. Although there were no differences in the predefined endpoints, a decreased rate of disease progression was observed on several measures. Further evaluation of TNF antagonists in the treatment of IPF may be warranted. Clinical trial registered with www.clinicaltrials.gov (NCT 00063869).