Augmentation of arginase 1 expression by exposure to air pollution exacerbates the airways hyperresponsiveness in murine models of asthma

Abstract Background Arginase overexpression contributes to airways hyperresponsiveness (AHR) in asthma. Arginase expression is further augmented in cigarette smoking asthmatics, suggesting that it may be upregulated by environmental pollution. Thus, we hypothesize that arginase contributes to the exacerbation of respiratory symptoms following exposure to air pollution, and that pharmacologic inhibition of arginase would abrogate the pollution-induced AHR. Methods To investigate the role of arginase in the air pollution-induced exacerbation of airways responsiveness, we employed two murine models of allergic airways inflammation. Mice were sensitized to ovalbumin (OVA) and challenged with nebulized PBS (OVA/PBS) or OVA (OVA/OVA) for three consecutive days (sub-acute model) or 12 weeks (chronic model), which exhibit inflammatory cell influx and remodeling/AHR, respectively. Twenty-four hours after the final challenge, mice were exposed to concentrated ambient fine particles plus ozone (CAP+O3), or HEPA-filtered air (FA), for 4 hours. After the CAP+O3 exposures, mice underwent tracheal cannulation and were treated with an aerosolized arginase inhibitor (S-boronoethyl-L-cysteine; BEC) or vehicle, immediately before determination of respiratory function and methacholine-responsiveness using the flexiVent®. Lungs were then collected for comparison of arginase activity, protein expression, and immunohistochemical localization. Results Compared to FA, arginase activity was significantly augmented in the lungs of CAP+O3-exposed OVA/OVA mice in both the sub-acute and chronic models. Western blotting and immunohistochemical staining revealed that the increased activity was due to arginase 1 expression in the area surrounding the airways in both models. Arginase inhibition significantly reduced the CAP+O3-induced increase in AHR in both models. Conclusions This study demonstrates that arginase is upregulated following environmental exposures in murine models of asthma, and contributes to the pollution-induced exacerbation of airways responsiveness. Thus arginase may be a therapeutic target to protect susceptible populations against the adverse health effects of air pollution, such as fine particles and ozone, which are two of the major contributors to smog

Miniature Schnauzers under primary veterinary care in the UK in 2013: demography, mortality and disorders

Individual dog breeds are often reported as predisposed to specific breed-related disorders but reliable epidemiological data on disease prevalence are sparse. The Miniature Schnauzer in the UK is a popular small breed dog that is often considered as relatively healthy and long-lived, but is this really true? This study aimed to use data from the VetCompass™ Programme at the Royal Veterinary College to characterise the demography, mortality and common disorders of the general population of Miniature Schnauzers under veterinary care in the UK

Misregulation of the arginase pathway in tissues of spontaneously hypertensive rats.

International audienceThere is a growing evidence that arginase has a role in the pathophysiology of cardiovascular diseases including hypertension. We recently reported arginase upregulation in aortas from hypertensive spontaneously hypertensive rats (SHRs). The aim of this study was to determine whether arginase abnormalities occur in other tissues of SHR, including the target organs of hypertension. Experiments were conducted on 5-, 10-, 19- and 26-week-old SHRs and Wistar-Kyoto (WKY) rats. Arginase activity and expression were evaluated in heart, kidney, liver, lung and brain tissue extracts. To investigate the role of blood pressure by itself in arginase abnormalities, arginase activity was determined in 10-week-old SHRs previously treated with hydralazine (20 mg kg(-1) per day, for 5 weeks). Compared with WKY rats, cardiac arginase activity was higher in hypertensive SHRs aged 10 weeks (+46%, P<0.05), 19 weeks (+29%, P<0.05) and 26 weeks (+23%, NS). Similar results were found in lungs in which arginase activity was increased in SHRs aged 10 weeks (+39%, P<0.05), 19 weeks (+49%, P<0.05) and 26 weeks (+36%, P<0.05) compared with WKY rats. The changes in arginase activity in these tissues were not associated with changes in enzyme expression. The prevention of hypertension by hydralazine blunted the increase in arginase activity in the hearts but not in the lungs. No change in arginase activity/expression was found in the kidney, liver or brain. In conclusion, this study shows that increased arginase activity is not restricted to large vessels in SHRs and suggests that cardiac arginase activity is hemodynamic sensitive