Intravenous sildenafil citrate and post-cardiac surgery acute kidney injury: a double-blind, randomised, placebo-controlled trial.

BACKGROUND: This study assessed whether i.v. sildenafil citrate prevented acute kidney injury in at-risk patients undergoing cardiac surgery with cardiopulmonary bypass. METHODS: In a double-blind RCT, adults at increased risk of acute kidney injury undergoing cardiac surgery in a single UK tertiary centre were randomised to receive sildenafil citrate 12.5 mg kg-1 i.v. over 150 min or dextrose 5% at the commencement of surgery. The primary outcome was serum creatinine measured at six post-randomisation time points. The primary analysis used a linear mixed-effects model adjusted for the stratification variables, baseline estimated glomerular filtration rate, and surgical procedure. Secondary outcomes considered clinical events and potential disease mechanisms. Effect estimates were expressed as mean differences (MDs) or odds ratios with 95% confidence intervals. RESULTS: The analysis population comprised eligible randomised patients that underwent valve surgery or combined coronary artery bypass graft and valve surgery, with cardiopulmonary bypass, between May 2015 and June 2018. There were 60 subjects in the sildenafil group and 69 in the placebo control group. The difference between groups in creatinine concentration was not statistically significant (MD: 0.88 µmol L-1 [-5.82, 7.59]). There was a statistically significant increase in multiple organ dysfunction scores in the sildenafil group (MD: 0.54 [0.02, 1.07]; P=0.044). Secondary outcomes, and biomarkers of kidney injury, endothelial function, and inflammatory cell activation, were not significantly different between the groups. CONCLUSIONS: These results do not support the use of i.v. sildenafil citrate for kidney protection in adult cardiac surgery. CLINICAL TRIAL REGISTRATION: ISRCTN18386427.

Biomarkers of Inflammation and Lung Recovery in Extracorporeal Membrane Oxygenation Patients With Persistent Pulmonary Hypertension of the Newborn: A Feasibility Study.

OBJECTIVES: Extracorporeal membrane oxygenation is a treatment for Persistent Pulmonary Hypertension of the Newborn with high mortality. HYPOTHESIS: the extracorporeal membrane oxygenation circuit results in inflammatory responses that mitigate against successful weaning. DESIGN: Single-center prospective observational feasibility study. SETTING: PICU. PATIENTS: Twenty-four neonates requiring extracorporeal membrane oxygenation support for Persistent Pulmonary Hypertension of the Newborn. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The reference outcome was death or more than 7 days of extracorporeal membrane oxygenation support. Other outcomes included serial measures of plasma-free hemoglobin and markers of its metabolism, leucocyte, platelet and endothelial activation, and biomarkers of inflammation. Of 24 participants recruited between February 2016 and June 2017, 10 died or required prolonged extracorporeal membrane oxygenation support. These patients were sicker at baseline with higher levels of plasma-free hemoglobin within 12 hours of cannulation (geometric mean ratio, 1.92; 95% CIs, 1.00-3.67; p = 0.050) but not thereafter, versus those requiring less than 7 days extracorporeal membrane oxygenation. Serum haptoglobin concentrations were significantly elevated in both groups. Patients who died or required prolonged extracorporeal membrane oxygenation support demonstrated elevated levels of platelet-leucocyte aggregation, but decreased concentrations of mediators of the inflammatory response: interleukin-8, C-reactive protein, and tumor necrosis factor α. CONCLUSIONS: Clinical status at baseline and not levels of plasma-free hemoglobin or the systemic inflammatory response may determine the requirement for prolonged extracorporeal membrane oxygenation support in neonates.

Effect of sildenafil (Revatio) on postcardiac surgery acute kidney injury: a randomised, placebo-controlled clinical trial: the REVAKI-2 trial protocol.

Introduction: Acute kidney injury (AKI) is a common and severe complication of cardiac surgery. The administration of pharmacological renoprotective agents during the perioperative period could prevent or reduce the severity of AKI and improve clinical outcomes. Experimental studies suggest that sildenafil may have therapeutic potential for the prevention of AKI. This trial will test the hypothesis that postoperative AKI will be reduced in cardiac surgery patients if they receive sildenafil compared with placebo. Methods and analysis: Adult cardiac surgery patients 18 years of age or above undergoing cardiac surgery with cardiopulmonary bypass and cardioplegic arrest at a single tertiary cardiac centre in the UK will be randomised in a 1:1 ratio to receive either sildenafil or placebo. The primary outcome is serum creatinine concentration measured at preoperation and daily for up to 7 days postoperatively. Secondary outcomes will include measures of inflammation, organ injury, volumes of blood transfused and resource use. Allocation concealment, internet-based randomisation stratified by operation type, and blinding of outcome assessors will reduce the risk of bias. A sample size of 112 patients will have a 90% power to detect a mean difference of 10 µmol/L for serum creatinine values between treatment and placebo control groups with an alpha value of 0.05. Ethics and dissemination: The trial protocol was approved by a UK ethics committee (reference 15/YH/0489). The trial findings will be disseminated in scientific journals and meetings. Trial registration number: ISRCTN18386427.

An Observational Cohort Feasibility Study to Identify Microvesicle and Micro-RNA Biomarkers of Acute Kidney Injury Following Pediatric Cardiac Surgery.

OBJECTIVES: Micro-RNA, small noncoding RNA fragments involved in gene regulation, and microvesicles, membrane-bound particles less than 1 µm known to regulate cellular processes including responses to injury, may serve as disease-specific biomarkers of acute kidney injury. We evaluated the feasibility of measuring these signals as well as other known acute kidney injury biomarkers in a mixed pediatric cardiac surgery population. DESIGN: Single center prospective cohort feasibility study. SETTING: PICU. PATIENTS: Twenty-four children (≤ 17 yr) undergoing cardiac surgery with cardiopulmonary bypass without preexisting inflammatory state, acute kidney injury, or extracorporeal life support. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Acute kidney injury was defined according to modified Kidney Diseases Improving Global Outcomes criteria. Blood and urine samples were collected preoperatively and at 6-12 and 24 hours. Microvesicles derivation was assessed using flow cytometry and NanoSight analysis. Micro-RNAs were isolated from plasma and analyzed by microarray and quantitative real-time polymerase chain reaction. Data completeness for the primary outcomes was 100%. Patients with acute kidney injury (n = 14/24) were younger, underwent longer cardiopulmonary bypass, and required greater inotrope support. Acute kidney injury subjects had different fractional content of platelets and endothelial-derived microvesicles before surgery. Platelets and endothelial microvesicles levels were higher in acute kidney injury patients. A number of micro-RNA species were differentially expressed in acute kidney injury patients. Pathway analysis of candidate target genes in the kidney suggested that the most often affected pathways were phosphatase and tensin homolog and signal transducer and activator of transcription 3 signaling. CONCLUSIONS: Microvesicles and micro-RNAs expression patterns in pediatric cardiac surgery patients can be measured in children and potentially serve as tools for stratification of patients at risk of acute kidney injury.

A Comparison of Red Cell Rejuvenation versus Mechanical Washing for the Prevention of Transfusion-associated Organ Injury in Swine.

BACKGROUND: We evaluated the effects of two interventions that modify the red cell storage lesion on kidney and lung injury in experimental models of transfusion. METHODS: White-landrace pigs (n = 32) were allocated to receive sham transfusion (crystalloid), 14-day stored allogeneic red cells, 14-day red cells washed using the red cells washing/salvage system (CATS; Fresenius, Germany), or 14-day red cells rejuvenated using the inosine solution (Rejuvesol solution; Zimmer Biomet, USA) and washed using the CATS device. Functional, biochemical, and histologic markers of organ injury were assessed for up to 24 h posttransfusion. RESULTS: Transfusion of 14 day red cells resulted in lung injury (lung injury score vs. sham, mean difference -0.3 (95% CI, -0.6 to -0.1; P = 0.02), pulmonary endothelial dysfunction, and tissue leukocyte sequestration. Mechanical washing reduced red cell-derived microvesicles but increased cell-free hemoglobin in 14-day red cell units. Transfusion of washed red cells reduced leukocyte sequestration but did not reduce the lung injury score (mean difference -0.2; 95% CI, -0.5 to 0.1; P = 0.19) relative to 14-day cells. Transfusion of washed red cells also increased endothelial activation and kidney injury. Rejuvenation restored adenosine triphosphate to that of fresh red cells and reduced microvesicle concentrations without increasing cell-free hemoglobin release. Transfusion of rejuvenated red cells reduced plasma cell-free hemoglobin, leukocyte sequestration, and endothelial dysfunction in recipients and reduced lung and kidney injury relative to 14-day or washed 14-day cells. CONCLUSIONS: Reversal of the red cell storage lesion by rejuvenation reduces transfusion-associated organ injury in swine.

A Phase I study to determine the pharmacokinetic profile, safety and tolerability of sildenafil (Revatio® ) in cardiac surgery: the REVAKI-1 study.

AIMS: Acute kidney injury (AKI) is a common and severe complication of cardiac surgery. There is no effective prevention or treatment. Sildenafil citrate (Revatio® , Pfizer Inc.), a phosphodiesterase type 5 inhibitor, prevents post cardiac surgery AKI in pre-clinical studies, however its use is contraindicated in patients with symptomatic cardiovascular disease. The aim of this study is to assess the safety and pharmacokinetics of intravenous sildenafil in cardiac surgery patients. METHODS: We conducted an open label, dose escalation study with six patients per dose level. The six doses were 2.5 mg, 5 mg or 10 mg as a bolus, either alone or followed by an additional 2 h infusion of 2.5 mg sildenafil. RESULTS: Thirty-six patients entered the trial, of which 33 completed it. The mean age was 69.9 years. One patient died during surgery, two others were removed from the trial before dosing (all at dose level 5 mg + 2.5 mg). The pharmacokinetic profile of sildenafil was similar to previously published studies. For a dose of 10 mg administered as a bolus followed by 2.5 mg administered over 2 h the results were AUC∞ 537 ng h ml-1 , Cmax 189.4 ng ml-1 and t1/2 10.5 h. The drug was well tolerated with no serious adverse events related to drug administration. Higher sildenafil doses stabilized post-surgery nitric oxide bioavailability. CONCLUSIONS: Pharmacokinetics of sildenafil during cardiopulmonary bypass were comparable to those of other patient groups. The drug was well tolerated at therapeutic plasma levels. These results support the further evaluation of sildenafil for the prevention of AKI in cardiac surgery.

Effects of sex hormones on bronchial reactivity during the menstrual cycle.

BACKGROUND: Many asthmatic women complain of symptom exacerbations in particular periods, i.e. during pregnancy and menstrual cycles (perimenstrual asthma: PMA)". The goal of this study was to study the effect of the luteal and follicular phases of the menstrual cycle on bronchial reactivity (BR) in a group of asthmatic women. METHODS: For this purpose, 36 pre-menopausal women were enrolled and underwent testing for resting pulmonary function, measurement of the diffusing capacity of the lung for carbon monoxide (DLCO), and airway responsiveness to methacholine in the follicular and luteal phases of their menstrual cycles. We also measured plasma hormone levels and levels of cyclic adenosine monophosphate (cAMP; a mediator of bronchial smooth muscle contraction) and testosterone in induced sputum samples. RESULTS: Our study showed that about 30% of the asthmatic women had decreased PC20FEV1.0 in the follicular phase of menstrual cycle with a significant correlation between PC20FEV1.0 and serum testosterone levels. Moreover, marked increases in sputum testosterone levels (mean=2.6-fold increase) together with significant increases in sputum cAMP concentrations (mean=3.6-fold increases) were observed during the luteal phase of asthmatic patients, suggesting that testosterone contributes to the pathophysiology of PMA. We excluded the possibility that testosterone directly inhibits phosphodiesterase (PDE) activity as incubating PDE with testosterone in vitro did not reduce PDE catalytic activity. CONCLUSIONS: In conclusion, our data show that PC20FEV1.0 was decreased in the follicular phase of the menstrual cycle in about 30% of women and was associated with lower cAMP levels in sputum samples, which may contribute to bronchoconstriction. Our results also suggest a link between PMA and testosterone levels. However, whether these findings are of clinical significance in terms of the management of asthma or asthma worsening during the menstrual cycle needs further investigation.

Skeletal muscle oxidative metabolism in an animal model of pulmonary emphysema: formoterol and skeletal muscle dysfunction.

Skeletal muscle dysfunction is a significant contributor to exercise limitation in pulmonary emphysema. This study investigated skeletal muscle oxidative metabolism before and after aerosol exposure to a long-acting ß-agonist (LABA), such as formoterol, in the pallid mouse (B6.Cg-Pldnpa/J), which has a deficiency in serum α(1)-antitrypsin (α(1)-PI) and develops spontaneous pulmonary emphysema. C57 BL/6J and its congener pallid mice of 8-12 and 16 months of age were treated with vehicle or formoterol aerosol challenge for 120 seconds. Morphological and morphometric studies and evaluations of mitochondrial adenosine diphosphate-stimulated respiration and of cytochrome oxidase activity on skeletal muscle were performed. Moreover, the mtDNA content in skeletal muscle and the mediators linked to muscle mitochondrial function and biogenesis, as well as TNF-α and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), were also evaluated. The lungs of pallid mice at 12 and 16 months of age showed patchy areas of airspace enlargements, with the destruction of alveolar septa. No significant differences were observed in basal values of mitochondrial skeletal muscle oxidative processes between C57 BL/6J and pallid mice. Exposure to LABA significantly improved mitochondrial skeletal muscle oxidative processes in emphysematous mice, where the mtDNA content was significantly higher with respect to 8-month-old pallid mice. This effect was compared with a significant increase of PGC-1α in skeletal muscles of 16-month-old pallid mice, with no significant changes in TNF-α concentrations. In conclusion, in emphysematous mice that showed an increased mtDNA content, exposure to inhaled LABA can improve mitochondrial skeletal muscle oxidative processes. PGC-1α may serve as a possible mediator of this effect.

Mesenchymal stem cell therapy for the treatment of chronic obstructive pulmonary disease.

Recent studies have revealed that adult stem cells such as bone marrow-derived cells contribute to lung tissue regeneration and protection, and thus administration of exogenous stem/progenitor cells may be a potent next-generation therapy for COPD. Pathogenesis of COPD is characterized by an upregulation of inflammatory processes leading to irreversible events such as apoptosis of epithelial cells, proteolysis of the terminal air-space and lung extracellular matrix components. The available pharmacological treatments are essentially symptomatic, therefore, there is a need to develop more effective therapeutic strategies. It has been previously demonstrated that transplanted MSC home to the lung in response to lung injury and adopt phenotypes of alveolar epithelial cells, endothelial cells, fibroblasts and bronchial epithelial cells. However, engraftment and differentiation are now felt to be rare occurrences and other mechanisms might be involved and play a more important role. Importantly, MSCs protect lung tissue through suppression of proinflammatory cytokines, and through triggering production of reparative growth factors. Accordingly, it is not clear if and how these cells will be able to repair, to slow or to prevent the disease. This article reviews recent advances in regenerative medicine in COPD and highlights that their potential application although promising and very attractive, are still a far away opinion.

Exercise capacity and cytochrome oxidase activity in muscle mitochondria of COPD patients.

Skeletal muscle dysfunction (SMD) often occurs in patients with COPD, affecting their quality of life and mitochondrion is one of the cellular organelles involved in the pathogenesis of SMD in COPD. The aim of this study was to investigate exercise capacity and mitochondria skeletal muscle oxidative processes using a pilot study, with 20 COPD patients and 10 healthy subjects, prior to and following LABA treatment. The two groups were similar for BODE (2-7) and GOLD stages (2-3), and no one was cachectic or more symptomatic. The patients were randomized according to a distribution list. The Cycle Ergometry test with tau evaluation was used to determine exercise capacity, while a skeletal muscle biopsy for cytochrome oxidase (CytOX) activity evaluation was used to determine mitochondria skeletal muscle oxidative processes. In six of the COPD treated patients the individual values of tau and CytOX activity showed inversely parallel changes with a significant relationship between the tau values and the CytOX activity. No significant differences in tau values were observed in healthy subjects. In conclusion, LABA treatment may improve skeletal muscle oxidative processes, enhancing the CytOX activity and, at least in some COPD patients, such effects could be strictly linked to the kinetic exchanges occurring at skeletal muscle level, implying an important link between the regulation of oxygen uptake, energy production and the exercise capacity of these patients. Nevertheless, further studies are required and a better understanding of the mechanism(s) underlying LABA effects might allow us to identify or unmask new therapeutic target(s) in such patients.

Stem cell therapy: the great promise in lung disease.

Lung injuries are leading causes of morbidity and mortality worldwide. Pulmonary diseases such as asthma or chronic obstructive pulmonary disease characterized by loss of lung elasticity, small airway tethers, and luminal obstruction with inflammatory mucoid secretions, or idiopathic pulmonary fibrosis characterized by excessive matrix deposition and destruction of the normal lung architecture, have essentially symptomatic treatments and their management is costly to the health care system.Regeneration of tissue by stem cells from endogenous, exogenous, and even genetically modified cells is a promising novel therapy. The use of adult stem cells to help with lung regeneration and repair could be a newer technology in clinical and regenerative medicine. In fact, different studies have shown that bone marrow progenitor cells contribute to repair and remodeling of lung in animal models of progressive pulmonary hypertension.Therefore, lung stem cell biology may provide novel approaches to therapy and could represent a great promise for the future of molecular medicine. In fact, several diseases can be slowed or even blocked by stem cell transplantation.