Reuben Howden

Nrf2 and Cardiovascular Defense

The cardiovascular system is susceptible to a group of diseases that are responsible for a larger proportion of morbidity and mortality than any other disease. Many cardiovascular diseases are associated with a failure of defenses against oxidative stress-induced cellular damage and/or death, leading to organ dysfunction. The pleiotropic transcription factor, nuclear factor-erythroid (NF-E) 2-related factor 2 (Nrf2), regulates the expression of antioxidant enzymes and proteins through the antioxidant response element. Nrf2 is an important component in antioxidant defenses in cardiovascular diseases such as atherosclerosis, hypertension, and heart failure. Nrf2 is also involved in protection against oxidant stress during the processes of ischemia-reperfusion injury and aging. However, evidence suggests that Nrf2 activity does not always lead to a positive outcome and may accelerate the pathogenesis of some cardiovascular diseases (e.g., atherosclerosis). The precise conditions under which Nrf2 acts to attenuate or stimulate cardiovascular disease processes are unclear. Further studies on the cellular environments related to cardiovascular diseases that influence Nrf2 pathways are required before Nrf2 can be considered a therapeutic target for the treatment of cardiovascular diseases.

Protective role of interleukin-10 in ozone-induced pulmonary inflammation.

Background The mechanisms underlying ozone (O3)-induced pulmonary inflammation remain unclear. Interleukin-10 (IL-10) is an anti-inflammatory cytokine that is known to inhibit inflammatory mediators. Objectives We investigated the molecular mechanisms underlying interleuken-10 (IL-10)–mediated attenuation of O3-induced pulmonary inflammation in mice. Methods Il10-deficient (Il10−/−) and wild-type (Il10+/+) mice were exposed to 0.3 ppm O3 or filtered air for 24, 48, or 72 hr. Immediately after exposure, differential cell counts and total protein (a marker of lung permeability) were assessed from bronchoalveolar lavage fluid (BALF). mRNA and protein levels of cellular mediators were determined from lung homogenates. We also used global mRNA expression analyses of lung tissue with Ingenuity Pathway Analysis to identify patterns of gene expression through which IL-10 modifies O3-induced inflammation. Results Mean numbers of BALF polymorphonuclear leukocytes (PMNs) were significantly greater in Il10−/− mice than in Il10+/+ mice after exposure to O3 at all time points tested. O3-enhanced nuclear NF-κB translocation was elevated in the lungs of Il10−/− compared with Il10+/+ mice. Gene expression analyses revealed several IL-10–dependent and O3-dependent mediators, including macrophage inflammatory protein 2, cathepsin E, and serum amyloid A3. Conclusions Results indicate that IL-10 protects against O3-induced pulmonary neutrophilic inflammation and cell proliferation. Moreover, gene expression analyses identified three response pathways and several genetic targets through which IL-10 may modulate the innate and adaptive immune response. These novel mechanisms of protection against the pathogenesis of O3-induced pulmonary inflammation may also provide potential therapeutic targets to protect susceptible individuals.

Influence of acute and chronic streptozotocin-induced diabetes on the rat tendon extracellular matrix and mechanical properties

Diabetes is a major risk factor for tendinopathy, and tendon abnormalities are common in diabetic patients. The purpose of the present study was to evaluate the effect of streptozotocin (60 mg/kg)-induced diabetes and insulin therapy on tendon mechanical and cellular properties. Sprague-Dawley rats (n = 40) were divided into the following four groups: nondiabetic (control), 1 wk of diabetes (acute), 10 wk of diabetes (chronic), and 10 wk of diabetes with insulin treatment (insulin). After 10 wk, Achilles tendon and tail fascicle mechanical properties were similar between groups (P > 0.05). Cell density in the Achilles tendon was greater in the chronic group compared with the control and acute groups (control group: 7.8 ± 0.5 cells/100 μm(2), acute group: 8.3 ± 0.4 cells/100 μm(2), chronic group: 10.9 ± 0.9 cells/100 μm(2), and insulin group: 9.2 ± 0.8 cells/100 μm(2), P < 0.05). The density of proliferating cells in the Achilles tendon was greater in the chronic group compared with all other groups (control group: 0.025 ± 0.009 cells/100 μm(2), acute group: 0.019 ± 0.005 cells/100 μm(2), chronic group: 0.067 ± 0.015, and insulin group: 0.004 ± 0.004 cells/100 μm(2), P < 0.05). Patellar tendon collagen content was ∼32% greater in the chronic and acute groups compared with the control or insulin groups (control group: 681 ± 63 μg collagen/mg dry wt, acute group: 938 ± 21 μg collagen/mg dry wt, chronic: 951 ± 52 μg collagen/mg dry wt, and insulin group: 596 ± 84 μg collagen/mg dry wt, P < 0.05). In contrast, patellar tendon hydroxylysyl pyridinoline cross linking and collagen fibril organization were unchanged by diabetes or insulin (P > 0.05). Our findings suggest that 10 wk of streptozotocin-induced diabetes does not alter rat tendon mechanical properties even with an increase in collagen content. Future studies could attempt to further address the mechanisms contributing to the increase in tendon problems noted in diabetic patients, especially since our data suggest that hyperglycemia per se does not alter tendon mechanical properties.

Factors influencing isometric exercise training-induced reductions in resting blood pressure.

Hypertension is a major health concern, and current recommendations for blood pressure management (lifestyle modifications and pharmacological intervention) have not been universally successful. For two decades, isometric exercise training (IET) has become established as effective at reducing in resting BP (RBP) in a short period (4–10 weeks). The most common IET modes have comprised isometric handgrip (IHG) or isometric bilateral leg (IBL) training and 4 × 2‐min contractions at ∼20–50% maximal voluntary contraction with 1–5‐min rest between. Although this type of exercise training could have important implications, for hypertensive patients and in preventing hypertension development, little is known about the mechanisms responsible for IET‐induced RBP reductions. This uncertainty derives from a lack of understanding concerning the most effective IET programs for specific populations. Possible influential factors and mechanisms include age, sex, pre‐existing disease and medication, and IET‐induced adaptations in the exercising muscle and nervous system, which are discussed in this review. Designing effective IET programs may involve manipulation of exercise intensity, frequency, duration and mode, as well as consideration of yet discovered mechanisms for RBP reductions. We call for additional research designed to understand more about the mechanisms involved in IET‐induced RBP reductions for maximum effectiveness.

Intensity-dependent reductions in resting blood pressure following short-term isometric exercise training

Abstract To reduce resting blood pressure, a minimum isometric exercise training (IET) intensity has been suggested, but this is not known for short-term IET programmes. We therefore compared the effects of moderate- and low-intensity IET programmes on resting blood pressure. Forty normotensive participants (22.3 ± 3.4 years; 69.5 ± 15.5 kg; 170.2 ± 8.7 cm) were randomly assigned to groups of differing training intensities [20%EMGpeak (~23%MVC, maximum voluntary contraction, or 30%EMGpeak (~34%MVC)] or control group; 3 weeks of IET at 30%EMGpeak resulted in significant reductions in resting mean arterial pressure (e.g. −3.9 ± 1.0 mmHg, P < 0.001), whereas 20%EMGpeak did not (−2.3 ± 2.9 mmHg; P > 0.05). Moreover, after pooling all female versus male participants, IET induced a 6.9-mmHg reduction in systolic blood pressure in female participants, but only a 1.5-mmHg reduction in systolic blood pressure in male participants, although the difference was not significant. An IET intensity between 20%EMGpeak and 30%EMGpeak is sufficient to elicit significant resting blood pressure reductions in a short-term training period (3 weeks). In addition, sexual dimorphism may exist in the magnitude of reductions, but further work is required to confirm this possibility, which could be important in understanding the mechanisms responsible.

Healthcare Cost and Utilization before and after Diagnosis of Pseudomonas aeruginosa among Patients with Non-Cystic Fibrosis Bronchiectasis in the U.S.

Non-cystic fibrosis bronchiectasis (NCFBE) is a rare, chronic lung disease characterized by bronchial inflammation and permanent airway dilation. Chronic infections with P. aeruginosa have been linked to higher morbidity and mortality. To understand the impact of P. aeruginosa in NCFBE on health care costs and burden, we assessed healthcare costs and utilization before and after P. aeruginosa diagnosis. Using data from 2007 to 2013 PharMetrics Plus administrative claims, we included patients with ≥2 claims for bronchiectasis and >1 claim for P. aeruginosa; then excluded those with a claim for cystic fibrosis. Patients were indexed at first claim for P. aeruginosa and were required to have >12 months before and after the index P. aeruginosa. The mean differences in utilization and costs were assessed using paired Student’s t-tests for statistical significance. Mean total healthcare costs per patient were

The Influence of Nrf2 on Cardiac Responses to Environmental Stressors

36,213 pre-P. aeruginosa diagnosis versus

Genetic and Environmental Influences on Gas Exchange

67,764 post-P. aeruginosa, an increase of 87% (p < 0.0001). Inpatient costs represented the largest proportion of total healthcare costs post-P. aeruginosa (54%) with an increase of four hospitalizations per patient (p < 0.0001). NCFBE patients with evidence of P. aeruginosa incur substantially greater healthcare costs and utilization after P. aeruginosa diagnosis. Future research should explore methods of earlier identification of NCFBE patients with P. aeruginosa, as this may lead to fewer severe exacerbations, thereby resulting in a reduction in hospitalizations and healthcare costs.

Healthcare utilization and costs associated with COPD among SEER-Medicare beneficiaries with NSCLC

Nrf2 protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role of Nrf2 on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption of Nrf2 would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures. Nrf2−/− and Nrf2+/+ mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P < 0.001) and HF HRV (P < 0.001) in Nrf2−/− mice compared to Nrf2+/+ mice. Nrf2−/− mice tolerated hyperoxia significantly less than Nrf2+/+ mice (~22 hrs; P < 0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater in Nrf2−/− compared to Nrf2+/+ mice (P < 0.01). Results demonstrate that Nrf2 deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

Cost-effectiveness of angiotensin-converting enzyme inhibitors versus angiotensin II receptor blockers as first-line treatment in autosomal dominant polycystic kidney disease

Gas exchange is a critical process required for sufficient tissue perfusion. The environment, genetics, or a combination of the two can affect this process. Various strategies have evolved to overcome the specific gas exchange challenges in different environments and it is clear that some genes are pivotal to the development of gas exchanging organs (e.g. Bmp4). Lower partial pressure of oxygen (hypoxia), reducing the partial pressure gradient, makes gas exchange more challenging and therefore the height to which gas exchangers can travel above sea level is limited. However, some human populations (e.g. Tibetans) and other animals (e.g. Bar-headed goose) have adapted well to profoundly hypoxic conditions, suggesting genetic factors are important. Gas exchange can also be affected by air pollution, including particulate matter and ozone among others, and exposure can lead to cardiopulmonary responses depending on individual susceptibility or preexisting disease, both of which have genetic and environmental components. Diseases that affect gas exchange include, but are not limited to, pulmonary hypertension, chronic obstructive pulmonary disease (COPD), and bronchopulmonary dysplasia. Moreover, different species successfully exchange gases in their specific environment, for example animals that fly or burrow. Under these conditions, common genetic mechanisms, and their interaction with environment, help to maintain, or are detrimental to, gas exchange.