Radiofrequency therapy improves exercise capacity of mice with emphysema.

Emphysema is a common phenotype of chronic obstructive pulmonary disease (COPD). Although resection of emphysematous tissue can improve lung mechanics, it is invasive and fraught with adverse effects. Meanwhile, radiofrequency (RF) treatment is an extracorporeal method that leads to tissue destruction and remodeling, resulting in "volume reduction" and overall improvement in lung compliance of emphysematous lungs. Whether these changes lead to improved exercise tolerance is unknown. Here, we investigated the effectiveness of RF treatment to improve the exercise capacity of mice with emphysema. Fifty-two mice (7 weeks of age) were used in this experiment. A bilateral emphysema model was created by intratracheally instilling porcine pancreatic elastase (PPE) (1.5U/100 g body weight). RF treatment (0.5 W/ g body weight) was administered extracorporeally 14 days later and mice were sacrificed after another 21 days. The exercise capacity of mice was measured using a treadmill. Treadmill runs were performed just before PPE instillation (baseline), before RF treatment and before sacrifice. Following sacrifice, lung compliance and mean linear intercept (Lm) were measured and fibrosis was assessed using a modified Ashcroft score. There were 3 experimental groups: controls (instilled with saline, n = 12), emphysema (instilled with porcine pancreatic elastase, PPE, n = 11) and emphysema + treatment (instilled with PPE and given RF, n = 9). At endpoint, the maximum velocity of the emphysema + treatment group was significantly higher than that of the emphysema group, indicating improved exercise tolerance (86.29% of baseline vs 61.69% of baseline, p = 0.01). Histological analysis revealed a significant reduction in emphysema as denoted by Lm between the two groups (median 29.60 µm vs 35.68 µm, p = 0.03). The emphysema + treatment group also demonstrated a higher prevalence of lung fibrosis (≧Grade 3) compared with the emphysema group (11.7% vs 5.4%, p < 0.01). No severe adverse events from RF were observed. RF treatment improved the exercise capacity of mice with emphysema. These data highlight the therapeutic potential of RF treatment in improving the functional status of patients with COPD.

BMI is associated with FEV1 decline in chronic obstructive pulmonary disease: a meta-analysis of clinical trials.

BACKGROUND: There is considerable heterogeneity in the rate of lung function decline in chronic obstructive pulmonary disease (COPD), the determinants of which are largely unknown. Observational studies in COPD indicate that low body mass index (BMI) is associated with worse outcomes, and overweight/obesity has a protective effect - the so-called "obesity paradox". We aimed to determine the relationship between BMI and the rate of FEV1 decline in data from published clinical trials in COPD. METHODS: We performed a systematic review of the literature, and identified 5 randomized controlled trials reporting the association between BMI and FEV1 decline. Four of these were included in the meta-analyses. We analyzed BMI in 4 categories: BMI-I (< 18.5 or <  20 kg/m2), BMI-II (18.5 or 20 to < 25 kg/m2), BMI-III (25 to < 29 or < 30 kg/m2) and BMI-IV (≥29 or ≥ 30 kg/m2). We then performed a meta-regression of all the estimates against the BMI category. RESULTS: The estimated rate of FEV1 decline decreased with increasing BMI. Meta-regression of the estimates showed that BMI was significantly associated with the rate of FEV1 decline (linear trend p = 1.21 × 10- 5). CONCLUSIONS: These novel findings support the obesity paradox in COPD: compared to normal BMI, low BMI is a risk factor for accelerated lung function decline, whilst high BMI has a protective effect. The relationship may be due to common but as-of-yet unknown causative factors; further investigation into which may reveal novel endotypes or targets for therapeutic intervention.

Smooth Muscle Cells Contribute the Majority of Foam Cells in ApoE (Apolipoprotein E)-Deficient Mouse Atherosclerosis.

Objective- Smooth muscle cells (SMCs) are the most abundant cells in human atherosclerotic lesions and are suggested to contribute at least 50% of atheroma foam cells. In mice, SMCs contribute fewer total lesional cells. The purpose of this study was to determine the contribution of SMCs to total foam cells in apolipoprotein E-deficient (ApoE-/-) mice, and the utility of these mice to model human SMC foam cell biology and interventions. Approach and Results- Using flow cytometry, foam cells in the aortic arch of ApoE-/- mice were characterized based on the expression of leukocyte-specific markers. Nonleukocyte foam cells increased from 37% of total foam cells in 27-week-old to 75% in 57-week-old male ApoE-/- mice fed a chow diet and were ≈70% in male and female ApoE-/- mice following 6 weeks of Western diet feeding. A similar contribution to total foam cells by SMCs was found using SMC-lineage tracing ApoE-/- mice fed the Western diet for 6 or 12 weeks. Nonleukocyte foam cells contributed a similar percentage of total atheroma cholesterol and exhibited lower expression of the cholesterol exporter ABCA1 (ATP-binding cassette transporter A1) when compared with leukocyte-derived foam cells. Conclusions- Consistent with previous studies of human atheromas, we present evidence that SMCs contribute the majority of atheroma foam cells in ApoE-/- mice fed a Western diet and a chow diet for longer periods. Reduced expression of ABCA1, also seen in human intimal SMCs, suggests a common mechanism for formation of SMC foam cells across species, and represents a novel target to enhance atherosclerosis regression.

Surfactant protein-D deficiency suppresses systemic inflammation and reduces atherosclerosis in ApoE knockout mice.

AIMS: Although surfactant protein-D (SP-D) is a pneumoprotein that is predominantly synthesized by type II epithelial cells in the lung, individuals with increased circulating levels of SP-D are at an elevated risk of mortality from ischemic heart disease. Whether SP-D contributes directly to atherosclerosis is unknown. We determined the effects of SP-D gene deletion in a mouse model of atherosclerosis. METHODS AND RESULTS: SP-D knockout (KO) mice were crossed with hyperlipidemic and atherosclerosis-prone apolipoprotein E (ApoE) KO mice to generate SP-D/ApoE double knockout (DKO) mice. Mice were placed on a high-fat diet for 12 weeks beginning at 8 weeks of age. Compared with ApoE KO mice, SP-D/ApoE DKO mice had significantly less atherosclerosis with reduced macrophage accumulation, decreased local macrophage proliferation, and increased smooth muscle cell coverage in plaques. Interestingly, SP-D deficiency worsened hypercholesterolemia and induced obesity and insulin resistance but suppressed plasma interleukin-6 (IL-6) levels. SP-D deficiency also reduced blood monocytes and neutrophils counts in ApoE KO mice. CONCLUSION: SP-D deficiency reduces atherosclerosis in part by decreasing the accumulation and proliferation of macrophages and by reducing IL-6 levels systemically. SP-D is a promising therapeutic target for cachectic COPD patients with elevated circulating SP-D levels who are at increased risk of cardiovascular morbidity and mortality.

Lung exposure to lipopolysaccharide causes atherosclerotic plaque destabilisation.

Epidemiological studies have implicated lung inflammation as a risk factor for acute cardiovascular events, but the underlying mechanisms linking lung injury with cardiovascular events are largely unknown.Our objective was to develop a novel murine model of acute atheromatous plaque rupture related to lung inflammation and to investigate the role of neutrophils in this process.Lipopolysaccharide (LPS; 3 mg·kg(-1)) or saline (control) was instilled directly into the lungs of male apolipoprotein E-null C57BL/6J mice following 8 weeks of a Western-type diet. 24 h later, atheromas in the right brachiocephalic trunk were assessed for stability ex vivo using high-resolution optical projection tomography and histology. 68% of LPS-exposed mice developed vulnerable plaques, characterised by intraplaque haemorrhage and thrombus, versus 12% of saline-exposed mice (p=0.0004). Plaque instability was detectable as early as 8 h post-intratracheal LPS instillation, but not with intraperitoneal instillation. Depletion of circulating neutrophils attenuated plaque rupture.We have established a novel plaque rupture model related to lung injury induced by intratracheal exposure to LPS. In this model, neutrophils play an important role in both lung inflammation and plaque rupture. This model could be useful for screening therapeutic targets to prevent acute vascular events related to lung inflammation.

Unifying thoracic biomarkers: surfactant protein-D and beyond.

Chronic obstructive pulmonary disease (COPD) is a progressive disorder that affects 300 million people worldwide and is responsible for 3 million deaths annually. Currently, there are no accepted biomarkers of COPD, which has impaired drug development and management of patients with COPD. Pneumoproteins, which are proteins synthesized predominantly in the lungs, are promising blood biomarkers because they have high specificity for lung disease. The most promising is surfactant protein-D, which is synthesized largely in Type 2 pneumocytes, and its blood concentrations have been associated with COPD and with certain clinical end points such as mortality. In this paper, we discuss surfactant protein-D and other pneumoproteins as promising biomarkers of COPD.

Endotoxin-induced cardiovascular dysfunction in mice: effect of simvastatin.

Lung infections are associated with acute lung injury (ALI), systemic inflammation, and vascular events. Clinical studies suggest that statins improve health outcomes of patients with pneumonia and ALI. The mechanisms by which this occurs are unknown. The aim of this study was to determine whether statins attenuate systemic inflammation and cardiovascular dysfunction related to ALI in mice. Simvastatin (SS; 20 mg/kg) or vehicle solution was instilled intraperitoneally into mice 24 h before and again just prior to intratracheal LPS instillation (1 µg/g). These mice were then anesthetized with 2.0% isoflurane and underwent a short surgical procedure to instill LPS. Four hours later, IL-6 levels in bronchoalveolar lavage fluid and in arterial and venous serum were measured. Cardiac function was evaluated using 2-D echocardiography, and endothelial function was determined using wire myography on aortic sections. LPS induced a significant increase in serum IL-6 levels. SS reduced venous (P = 0.040) but not arterial concentrations of IL-6 (P = 0.112). SS improved the maximal vasodilatory response of the aorta to ACh (P = 0.004) but not to sodium nitroprusside (P = 1.000). SS also improved cardiac output (P = 0.023). Vasodilatory response to ACh was impaired when aorta from untreated mice was incubated with ex vivo IL-6 (P = 0.004), whereas in the aorta from mice pretreated with SS, the vasodilatory response did not change with IL-6 incubation (P = 0.387). SS significantly improved LPS-induced cardiovascular dysfunction possibly by reducing systemic expression of IL-6 and its downstream signaling pathways. These findings may explain how statins improve health outcomes in patients with ALI.

Acute lung injury induces cardiovascular dysfunction: effects of IL-6 and budesonide/formoterol.

Acute lung injury (ALI) is associated with systemic inflammation and cardiovascular dysfunction. IL-6 is a biomarker of this systemic response and a predictor of cardiovascular events, but its possible causal role is uncertain. Inhaled corticosteroids and long-acting ß2 agonists (ICS/LABA) down-regulate the systemic expression of IL-6, but whether they can ameliorate the cardiovascular dysfunction related to ALI is uncertain. We sought to determine whether IL-6 contributes to the cardiovascular dysfunction related to ALI, and whether budesonide/formoterol ameliorates this process. Wild-type mice were pretreated for 3 hours with intratracheal budesonide, formoterol, or both, before LPS was sprayed into their tracheas. IL-6-deficient mice were similarly exposed to LPS. Four hours later, bronchoalveolar lavage fluid (BALF) and serum were collected, and endothelial and cardiac functions were measured, using wire myography of the aortic tissue and echocardiography, respectively. LPS significantly impaired vasodilatory responses to acetylcholine (P < 0.001) and cardiac output (P = 0.002) in wild-type but not IL-6-deficient mice. Intratracheal instillations of exogenous IL-6 into IL-6-deficient mice restored these impairments (vasodilatory responses to acetylcholine, P = 0.005; cardiac output, P = 0.025). Pretreatment with the combination of budesonide and formoterol, but not either alone, ameliorated the vasodilatory responses to acetylcholine (P = 0.018) and cardiac output (P < 0.001). These drugs also attenuated the rise in the systemic expression of IL-6 (P < 0.05) related to LPS. IL-6 contributes to the cardiovascular dysfunction related to LPS, and pretreatment with budesonide/formoterol reduces the systemic expression of IL-6 and improves cardiovascular dysfunction. ICS/LABA may reduce acute cardiovascular events related to ALI.