BH4 Increases nNOS Activity and Preserves Left Ventricular Function in Diabetes.

RATIONALE: In diabetic patients, heart failure with predominant left ventricular (LV) diastolic dysfunction is a common complication for which there is no effective treatment. Oxidation of the NOS (nitric oxide synthase) cofactor tetrahydrobiopterin (BH4) and dysfunctional NOS activity have been implicated in the pathogenesis of the diabetic vascular and cardiomyopathic phenotype. OBJECTIVE: Using mice models and human myocardial samples, we evaluated whether and by which mechanism increasing myocardial BH4 availability prevented or reversed LV dysfunction induced by diabetes. METHODS AND RESULTS: In contrast to the vascular endothelium, BH4 levels, superoxide production, and NOS activity (by liquid chromatography) did not differ in the LV myocardium of diabetic mice or in atrial tissue from diabetic patients. Nevertheless, the impairment in both cardiomyocyte relaxation and [Ca2+]i (intracellular calcium) decay and in vivo LV function (echocardiography and tissue Doppler) that developed in wild-type mice 12 weeks post-diabetes induction (streptozotocin, 42-45 mg/kg) was prevented in mGCH1-Tg (mice with elevated myocardial BH4 content secondary to trangenic overexpression of GTP-cyclohydrolase 1) and reversed in wild-type mice receiving oral BH4 supplementation from the 12th to the 18th week after diabetes induction. The protective effect of BH4 was abolished by CRISPR/Cas9-mediated knockout of nNOS (the neuronal NOS isoform) in mGCH1-Tg. In HEK (human embryonic kidney) cells, S-nitrosoglutathione led to a PKG (protein kinase G)-dependent increase in plasmalemmal density of the insulin-independent glucose transporter GLUT-1 (glucose transporter-1). In cardiomyocytes, mGCH1 overexpression induced a NO/sGC (soluble guanylate cyclase)/PKG-dependent increase in glucose uptake via GLUT-1, which was instrumental in preserving mitochondrial creatine kinase activity, oxygen consumption rate, LV energetics (by 31phosphorous magnetic resonance spectroscopy), and myocardial function. CONCLUSIONS: We uncovered a novel mechanism whereby myocardial BH4 prevents and reverses LV diastolic and systolic dysfunction associated with diabetes via an nNOS-mediated increase in insulin-independent myocardial glucose uptake and utilization. These findings highlight the potential of GCH1/BH4-based therapeutics in human diabetic cardiomyopathy. Graphic Abstract: A graphic abstract is available for this article.

Healthcare Service Usage and Costs for Elderly Patients with Obstructive Lung Disease.

Background: The worldwide prevalence of obstructive lung disease (OLD) is increasing, especially among people >65 years old, and nearly three in four adults with OLD have two or more comorbid conditions. This study describes the impact of such comorbidities on the healthcare service usage and related costs in a country with universal health coverage, basing on a large cohort of elderly patients with OLD and employing real-world data. Methods: We carried out a retrospective cohort study on a large population of elderly (age >64 years) patients with OLD served by a Local Health Unit in northern Italy. Their comorbidities were assessed using the clinical diagnoses assigned by the Adjusted Clinical Group (ACG) system to individual patients by combining different information flows. Correlations between number of comorbidities and total annual healthcare service usage and costs were examined with Spearman's test. Regression models were applied to analyze the associations between the above-mentioned variables, adjusting for age and sex. Results: All types of healthcare service usage (access to emergency care; number of outpatient visits; number of hospital admissions) and pharmacy costs increased significantly with the number of comorbidities. Average total annual costs increased steadily with the number of comorbidities, ranging from € 1158.84 with no comorbidities up to € 9666.60 with 6 comorbidities or more. Poisson regression analyses showed an independent association between the number of comorbidities and the use of every type of healthcare service. Conclusion: These results based on real-world data provide evidence that the burden of care for OLD patients related to their comorbidities is independent of and in addition to the burden related to OLD alone and is strongly dependent on the number of comorbidities, suggesting a holistic approach to multimorbid patients with OLD is the most sound public health strategy.