Impaired angiogenesis and peripheral muscle microcirculation loss contribute to exercise intolerance in pulmonary arterial hypertension.

RATIONALE: Pulmonary arterial hypertension (PAH) is characterized by significant exercise intolerance, which is multifactorial and involves skeletal muscle alterations. There is growing evidence that microRNAs (miRs) are involved in PAH pathogenesis. OBJECTIVES: We hypothesized that miR-126, an endothelial-specific, proangiogenic miR, is down-regulated in the peripheral muscles of patients with PAH, which would account for skeletal muscle microcirculation loss and exercise intolerance. MEASUREMENTS AND MAIN RESULTS: Patients with PAH displayed decreases in exercise capacity ([Formula: see text]o2max) and microcirculation loss on quadriceps muscle biopsy (in CD31(+) immunofluorescence experiments) compared to control subjects. Exercise capacity correlated with muscle capillarity (r = 0.84, P < 0.01). At the cellular level, vascular endothelial growth factor (VEGF) and VEGF receptor 2 expression were similar in both groups. Conversely, PAH was associated with a 60% decrease in miR-126 expression in a quantitative reverse transcriptase polymerase chain reaction experiment (P < 0.01), resulting in up-regulation of its targeted protein, Sprouty-related, EVH1 domain-containing protein 1 (SPRED-1), and a marked decrease in the downstream effectors of the VEGF pathway, p-Raf/Raf and p-ERK/ERK, as determined by immunoblot analysis. Using freshly isolated CD31(+) cells from human quadriceps biopsies, we found that the down-regulation of miR-126 in PAH triggered the activation of SPRED-1, impairing the angiogenic response (Matrigel assay). These abnormalities were reversed by treating the PAH cells with miR-126 mimic, whereas inhibition of miR-126 (antagomir) in healthy CD31(+) cells fully mimicked the PAH phenotype. Finally, miR-126 down-regulation in skeletal muscle of healthy rats decreased muscle capillarity in immunofluorescence assays (P < 0.05) and exercise tolerance in treadmill tests (P < 0.05), whereas miR-126 up-regulation increased them in monocrotaline PAH rats. CONCLUSIONS: We demonstrate for the first time that exercise intolerance in PAH is associated with skeletal muscle microcirculation loss and impaired angiogenesis secondary to miR-126 down-regulation.

Preserved function and reduced angiogenesis potential of the quadriceps in patients with mild COPD.

BACKGROUND: Little is known about limb muscle abnormalities in mild COPD. Inactivity and systemic inflammation could play a role in the development of limb muscle dysfunction in COPD. The objective of the present study was to characterize quadriceps function, enzymatic activities and morphometry, levels of plasma inflammatory markers and physical activity levels in daily life (PAdl) in patients with mild COPD (GOLD 1). METHODS: Mid-thigh muscle cross-sectional area (MTCSA), quadriceps strength, endurance, fiber-type distribution, capillarity, pro-angiogenesis factors (VEGF-A, angiopoietin I and II) and muscle oxidative capacity were assessed in 37 patients with mild COPD and 19 controls. Systemic inflammatory markers (CRP, IL-6, TNF-α, Fibrinogen, SP-D) and PAdl were assessed. RESULTS: MTCSA, quadriceps strength and endurance were not different between COPD and controls. Capillarity and muscle oxidative capacity were all preserved in mild COPD. Reduced pro-angiogenesis factor mRNA expression was seen in COPD. The level of moderately active intensity (>3 METs) was significantly lower in mild COPD and, in multiple regression analyses, the level of physical activity was a determinant of muscle oxidative capacity and capillarization. No between-group differences were found regarding muscle oxidative stress while circulating IL-6 levels were elevated in mild COPD. CONCLUSIONS: The quadriceps muscle function was preserved in mild COPD although a reduced potential for angiogenesis was found. The reduced level of daily activities and evidence of systemic inflammation in these individuals suggest that these factors precede the development of overt limb muscle dysfunction in COPD.

Stability of Opened Durvalumab (IMFINZI) Vials. The Beginning of the End of Costly Product Wastage?

Durvalumab is a monoclonal antibody approved for the treatment of lung, urothelial and biliary tract cancers. Durvalumab is supplied in vials as a solution containing no preservatives. Monographs recommend single use of durvalumab vials, and that any leftovers be discarded within 24 h. Thus, significant portions of unused product from opened vials are wasted on a daily basis, generating considerable financial losses. The objective of the present study was to assess the physicochemical and microbiological stability of durvalumab vials kept at 4 °C or room temperature, at 7 and 14 days after opening. Following pH and osmolality measurements, turbidity and submicronic aggregation of durvalumab solution were evaluated by spectrophotometry and dynamic light scattering, respectively. Moreover, steric exclusion high performance liquid chromatography (SE-HPLC), ion exchange HPLC (IEX-HPLC) and peptide mapping HPLC were used to respectively assess aggregation/fragmentation, charge distribution and primary structure of durvalumab. Microbiological stability of durvalumab was evaluated by incubation of vial leftovers on blood agar. All experiments showed physicochemical and microbiological stability of durvalumab vial leftovers for at least 14 days when aseptically handled and kept at either 4 °C or at room temperature. These results suggest the possible extension of utilization of durvalumab vial leftovers well beyond 24 h.