Maternal nano-titanium dioxide inhalation exposure alters placental cyclooxygenase and oxidant balance in a sexually dimorphic manner

The placenta plays a critical role in nutrient-waste exchange between the maternal and fetal circulation, and thus impacts fetal growth and development. We have previously shown that nano-titanium dioxide (nano-TiO2) inhalation exposure during gestation decreased fetal female pup and placenta mass [1], which persists in the following generation [2]. In utero exposed females, once mated, their offspring's placentas had increased capacity for H2O2 production. Generation of oxidants such as hydrogen peroxide (H2O2), have been shown to impact cyclooxygenase activity, specifically metabolites such as prostacyclin (PGI2) or thromboxane (TXA2). Therefore, we hypothesized that maternal nano-TiO2 inhalation exposure during gestation results in alterations in placental production of prostacyclin and thromboxane mediated by enhanced H2O2 production in a sexually dimorphic manner. Pregnant Sprague-Dawley rats were exposed to nano-TiO2 aerosols or filtered air (sham--control) from gestational day (GD) 10-19. Dams were euthanized on GD 20, and fetal serum and placental tissue were collected based on fetal sex. Fetal placental zones (junctional zone (JZ) and labyrinth zone (LZ)) were assessed for xanthine oxidoreductase (XOR) activity, H2O2, and catalase activity, as well as 6-keto-PGF1α and TXB2 levels. Nano-TiO2 exposed fetal female LZ demonstrated significantly greater XOR activity compared to exposed males. Exposed fetal female LZ also demonstrated significantly diminished catalase activity compared to sham-control females. Exposed fetal female LZ had significantly increased abundance of 6-keto-PGF1α compared to sham-control females and increased TXB2 compared to exposed males. In the aggregate these data indicate that maternal nano-TiO2 inhalation exposure has a greater impact on redox homeostasis and PGI2/TXA2 balance in the fetal female LZ. Future studies need to address if treatment with an XO inhibitor during gestation can prevent diminished fetal female growth during maternal nano-TiO2 inhalation exposure.

Dietary inflammation index association with serum levels of nitric oxide, prostacyclin, and thromboxane B2 among prinzmetal angina patients and healthy persons

BACKGROUND AND AIM

This study aimed to assess the association between dietary inflammation index with serum Nitric oxide, Prostacyclin, and Thromboxane B2 among Prinzmetal angina patients and healthy persons.

METHODS AND RESULTS

This case-control study was conducted among 120 Prinzmetal angina patients and 120 healthy persons referred to the Ardabil Imam Khomeini Hospital between 2021 and 2022. Blood samples were gained from all study participants for measurement of serum Nitric oxide, Prostacyclin, and Thromboxane B2. The serum Nitric oxide in patients who had higher DII was less than in patients with less dietary inflammation index (β = -0.75 p = 0.02). The serum Prostacyclin level in patients with greater dietary inflammation index was 0.68 ng/ml less than in patients with less dietary inflammation index (β = -0.68 p = 0.04). The level of serum Thromboxane B2 had a positive association with dietary inflammation index (β = 0.81 p = 0.04).

CONCLUSION

In Prinzmetal angina patients, more dietary inflammation index can increase the serum Thromboxane B2 and decrease the serum Nitric oxide and Prostacyclin. More clinical trial study is needed to confirm these results.

Tributyltin-induced oxidative stress causes developmental damage in the cardiovascular system of zebrafish (Danio rerio)

Tributyltin (TBT) can be used as an antifouling agent with anticorrosive, antiseptic and antifungal properties and is widely used in wood preservation and ship painting. However, it has recently been found that TBT can be harmful to aquatic organisms. In this study, to gain insight into the effects of TBT with respect to the development of the cardiovascular system in zebrafish embryos, zebrafish embryos were exposed to different concentrations of TBT solutions (0.2 μg/L, 1 μg/L, and 2 μg/L) at 2 h post-fertilization (hpf) TBT exposure resulted in decreased hatchability and heart rate, deformed features such as pericardial edema, yolk sac edema, and spinal curvature in zebrafish embryos, and impaired heart development. Expression of cardiac development-related genes (vmhc, myh6, nkx2.5, tbx5a, gata4, tbx2b, nppa) is dysregulated. Transgenic zebrafish Tg (fli1: EGFP) were used to explore the effects of TBT exposure on vascular development. It was found that TBT exposure could lead to impaired development of intersegmental vessels (ISVs), common cardinal vein (CCV), subintestinal vessels (SIVs) and cerebrovascular. The expression of vascular endothelial growth factor (VEGF) signaling pathway-related genes (flt1, flt4, kdr, vegfa) was downregulated. Biochemical indices showed that ROS and MDA levels were significantly elevated and that SOD and CAT activities were significantly reduced. The expression of key genes for prostacyclin synthesis (pla2, ptgs2a, ptgs2b, ptgis, ptgs1) is abnormal. Therefore, it is possible that oxidative stress induced by TBT exposure leads to the blockage of arachidonic acid (AA) production in zebrafish embryos, which affects prostacyclin synthesis and consequently the normal development of the heart and blood vessels in zebrafish embryos.

Targeted Therapies for Neonatal Pulmonary Hypertension: Beyond Nitric Oxide

Pulmonary hypertension in the neonatal population can be acute or chronic and carries significant risk for morbidity and mortality. It can be idiopathic but more often is associated with comorbid pulmonary and heart disease. There are several pharmacotherapeutics aimed at pulmonary vasodilation. This review highlights the most common agents as well as those on the horizon for the treatment of pulmonary hypertension in the neonate.

Dietary fatty acids and flight-training influence the expression of the eicosanoid hormone prostacyclin in songbirds

Diet shifts can alter tissue fatty acid composition in birds, which is subsequently related to metabolic patterns. Eicosanoids, short-lived fatty acid-derived hormones, have been proposed to mediate these relationships but neither baseline concentrations nor the responses to diet and exercise have been measured in songbirds. We quantified a stable derivative of the vasodilatory eicosanoid prostacyclin in the plasma of male European Starlings (Sturnus vulgaris, N = 25) fed semisynthetic diets with either high (PUFA) or low (MUFA) amounts of n6 fatty acid precursors to prostacyclin. Plasma samples were taken from each bird before, immediately after, and two days following a 15-day flight-training regimen that a subset of birds (N = 17) underwent. We found elevated prostacyclin levels in flight-trained birds fed the PUFA diet compared to those fed the MUFA diet and a positive relationship between prostacyclin and body condition, indexed by fat score. Prostacyclin concentrations also significantly decreased at the final time point. These results are consistent with the proposed influences of precursor availability (i.e., dietary fatty acids) and regulatory feedback associated with exercise (i.e., fuel supply and inflammation), and suggest that prostacyclin may be an important mediator of dietary influence on songbird physiology.

Oral Treprostinil is Associated with Improved Survival in FREEDOM-EV and its Open-Label Extension

INTRODUCTION

In the event-driven FREEDOM-EV trial, oral treprostinil delayed clinical worsening in patients with pulmonary arterial hypertension (PAH). Open-label extension studies offer additional data about tolerability, efficacy, and survival, especially for those initially assigned placebo. The aim of the current study was to determine if oral treprostinil changed survival when considering the parent and extension study, if treprostinil provides functional benefits for participants initially assigned to placebo, and if the benefits observed for those treated with treprostinil were durable.

METHODS

Both active and placebo participants from FREEDOM-EV could enroll in the FREEDOM-EV open-label extension (OLE) study after experiencing an investigator-assessed clinical worsening event or after parent study closure. All participants in the OLE were offered open-label oral treprostinil. Previously assigned placebo participants titrated to maximally tolerated doses; previously assigned treprostinil participants continued dose titration. We repeated assessments including functional class and 6-min walk distance (6MWD) at 12-week intervals and measured N-terminal pro-brain natriuretic peptide (NT-proBNP) at week 48. Survival was estimated by Kaplan-Meier analysis, and we estimated hazard ratio (HR) using Cox proportional hazards.

RESULTS

Of 690 FREEDOM-EV participants, 470 enrolled in the OLE; vital status was available for 89% of initial Freedom-EV participants. When considering the combined parent and open-label data, initial assignment to oral treprostinil reduced mortality (HR 0.64, 95% confidence interval 0.46-0.91, p = 0.013); absolute risk reduction was 9%. Participants randomized to placebo who initiated oral treprostinil after clinical worsening and tolerated treatment through week 48 demonstrated favorable shifts in functional class (p < 0.0001), 6MWD improvements of + 84 m (p < 0.0001), and a reduction in NT-proBNP of - 778 pg/mL (p = 0.02), compared to OLE baseline. Modest trends toward benefit were measured for those initially assigned placebo who did not have clinical worsening, and 132/144 (92%) of treprostinil assigned participants without clinical worsening remained on drug at week 48 in the OLE study. Adverse events were consistent with FREEDOM-EV.

CONCLUSION

Initial treprostinil assignment improved survival in the entire data set; those who began treprostinil after a clinical worsening in the placebo arm and tolerated drug to week 48 enjoyed substantial functional gains.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT01560637.

Frostbite treatment: a systematic review with meta-analyses

INTRODUCTION

Our objective was to perform a systematic review of the outcomes of various frostbite treatments to determine which treatments are effective. We also planned to perform meta-analyses of the outcomes of individual treatments for which suitable data were available.

MAIN BODY

We performed a systematic review and meta-analyses in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We searched PubMed, Cochrane Trials, and EMBase to identify primary references from January 1, 1900, to June 18, 2022. After eliminating duplicates, we screened abstracts to identify eligible studies containing information on treatment and outcomes of Grade 2 to 4 frostbite. We performed meta-analyses of groups of articles that provided sufficient data. We registered our review in the prospective registry of systematic reviews PROSPERO (Nr. 293,693). We identified 4,835 potentially relevant studies. We excluded 4,610 studies after abstract screening. We evaluated the full text of the remaining 225 studies, excluding 154. Ultimately, we included 71 articles with 978 cases of frostbite originating from 1 randomized controlled trial, 20 cohort studies and 51 case reports. We found wide variations in classifications of treatments and outcomes. The two meta-analyses we performed both found that patients treated with thrombolytics within 24 h had better outcomes than patients treated with other modalities. The one randomized controlled trial found that the prostacyclin analog iloprost was beneficial in severe frostbite if administered within 48 h.

CONCLUSIONS

Iloprost and thrombolysis may be beneficial for treating frostbite. The effectiveness of other commonly used treatments has not been validated. More prospective data from clinical trials or an international registry may help to inform optimal treatment.

Tyvaso DPI: Drug-device characteristics and patient clinical considerations

Tyvaso DPI is a drug-device combination therapy comprised of a small, portable, reusable, breath-powered, dry powder inhaler (DPI) for the delivery of treprostinil. It is approved for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. Tyvaso DPI utilizes single-use prefilled cartridges to ensure proper dosing. Unlike nebulizer devices, administration of Tyvaso DPI is passive and does not require coordination with the device. The low-flow rate design results in targeted delivery to the peripheral lungs due to minimal drug loss from impaction in the oropharynx. The inert fumaryl diketopiperazine (FDKP) excipient forms microparticles that carry treprostinil into the airways, with a high fraction of the particles in the respirable range. In a clinical study in patients with pulmonary arterial hypertension, Tyvaso DPI had similar exposure and pharmacokinetics, low incidence of adverse events, and high patient satisfaction compared with nebulized treprostinil solution. Tyvaso DPI may be considered as a first prostacyclin agent or for those that do not tolerate other prostacyclin formulations, patients with pulmonary comorbidities, patients with mixed Group 1 and Group 3 pulmonary hypertension, or those that prefer an active lifestyle and need a portable, non-invasive treatment. Tyvaso DPI is a patient-preferred, maintenance-free, safe delivery option that may improve patient compliance and adherence.

Parenteral treprostinil induction for rapid attainment of therapeutic doses of oral treprostinil

RATIONALE

Oral treprostinil slows disease progression and improves exercise capacity in pulmonary arterial hypertension; however, titration can be prolonged. Published data suggests prostacyclin-naïve patients achieve total daily oral treprostinil doses of about 6 mg by Week 16, while those on prior parenteral treprostinil reach higher doses at the same timepoint.

OBJECTIVES

EXPEDITE (NCT03497689), a single-arm, multicenter study, assessed the efficacy of rapid parenteral treprostinil induction to quickly reach higher doses of oral treprostinil for the treatment of pulmonary arterial hypertension.

METHODS

Parenteral treprostinil was titrated for 2-8 weeks, followed by cross-titration of oral treprostinil. The primary endpoint was percentage of patients reaching ≥12 mg daily of oral treprostinil at Week 16. Secondary endpoints included clinical changes from baseline to Week 16.

RESULTS

Twenty-nine prostacyclin-naïve patients were included in efficacy analyses. At Week 16, the mean daily oral treprostinil dose was 16.4 mg; 79% of patients met the primary endpoint. From baseline to Week 16, median REVEAL Lite 2 score improved (decreased) from 6 to 3.5 (p = 0.0006). Statistically significant improvements were also seen in World Health Organization Functional Class, N-terminal-pro brain natriuretic peptide levels, 6-minute walk distance, right atrial area, Borg Dyspnea Score, and emPHasis-10 score. Favorable trends were seen in risk stratification, echocardiography parameters, disease symptoms, and treatment satisfaction.

CONCLUSION

Short-course parenteral treprostinil induction resulted in oral treprostinil doses over twice those reported in de novo initiations and may be a useful approach to quickly achieve the therapeutic benefits of oral treprostinil.

Long-Term Safety, Outcome, and Clinical Effects of Subcutaneous and Intravenous Treprostinil Treatment in Patients with Severe Chronic Pulmonary Arterial Hypertension

BACKGROUND

Current guidelines recommend treatment with parenteral prostacyclin analogs in patients with severe pulmonary arterial hypertension (PAH), who have insufficient response to treatment. Real-life data are sought to help physicians in treatment decisions and clinical care of patients.

OBJECTIVE

This study analyzed safety, clinical effects, and long-term outcomes of subcutaneous (sc) and/or intravenous (iv) treprostinil via different pump systems in consecutive patients with PAH.

METHODS

Thirty-seven patients with severe progressive PAH despite dual combination therapy (20 female, mean age: 52.3 ± 15 years, mean pulmonary vascular resistance: 12.1 ± 5.1 WU) were initiated with add-on treprostinil sc and were routinely clinically assessed. Changes in clinical parameters, adverse events, and outcome were analyzed retrospectively.

RESULTS

In 24 of 37 patients, treprostinil administration was continued iv via implantation of LENUS Pro® pump after 3 ± 1.3 months, 6 patients continued with sc therapy, and 7 discontinued treatment. After 3, 6, 9, and 12 months of treprostinil treatment, patients showed a significant improvement in mean 6-min walk distance and tricuspid annular plane systolic excursion compared to baseline. In 8 of the 24 patients, iv pumps required surgical revision. During a mean follow-up of 2.82 ± 1.95 years, 12 patients died, four received lung transplantation. Transplant-free survival after 1, 2, and 3 years was 85.7%, 69.2%, and 65.3%, respectively.

CONCLUSION

sc treprostinil as add-on to double combination treatment significantly improved exercise capacity and right heart function. In most patients, treprostinil could be continued via more tolerable iv administration approach (LENUS Pro® pump), showing reasonable overall survival with respect to the severity of PAH.

Prostacyclin mimetics inhibit DRP1-mediated pro-proliferative mitochondrial fragmentation in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiopulmonary disorder, involving the remodelling of the small pulmonary arteries. Underlying this remodelling is the hyper-proliferation of pulmonary arterial smooth muscle cells within the medial layers of these arteries and their encroachment on the lumen. Previous studies have demonstrated an association between excessive mitochondrial fragmentation, a consequence of increased expression and post-translational activation of the mitochondrial fission protein dynamin-related protein 1 (DRP1), and pathological proliferation in PASMCs derived from PAH patients. However, the impact of prostacyclin mimetics, widely used in the treatment of PAH, on this pathological mitochondrial fragmentation remains unexplored. We hypothesise that these agents, which are known to attenuate the proliferative phenotype of PAH PASMCs, do so in part by inhibiting mitochondrial fragmentation. In this study, we confirmed the previously reported increase in DRP1-mediated mitochondrial hyper-fragmentation in PAH PASMCs. We then showed that the prostacyclin mimetic treprostinil signals via either the Gs-coupled IP or EP2 receptor to inhibit mitochondrial fragmentation and the associated hyper-proliferation in a manner analogous to the DRP1 inhibitor Mdivi-1. We also showed that treprostinil recruits either the IP or EP2 receptor to activate PKA and induce the phosphorylation of DRP1 at the inhibitory residue S637 and inhibit that at the stimulatory residue S616, both of which are suggestive of reduced DRP1 fission activity. Like treprostinil, MRE-269, an IP receptor agonist, and butaprost, an EP2 receptor agonist, attenuated DRP1-mediated mitochondrial fragmentation through PKA. We conclude that prostacyclin mimetics produce their anti-proliferative effects on PAH PASMCs in part by inhibiting DRP1-mediated mitochondrial fragmentation.

The use of selexipag, a prostacyclin receptor analog, for treatment of severe pulmonary artery hypertension during pregnancy, a case report

Pregnancy in patients with pulmonary artery hypertension (PAH) is associated with high mortality and morbidity. Despite the risks, more patients with PAH are becoming pregnant. Case reports and case series have described the use of IV epoprostenol in these patients with some success. However, there are no published reports regarding the use of oral prostacyclins and prostacyclin receptor agonists in pregnancy. We describe the use of selexipag, an oral prostacyclin receptor agonist, for treating severe PAH during pregnancy in a patient who refused IV prostacyclin therapy. She remained stable throughout pregnancy and delivered a healthy baby girl; however, she died 13 days after her delivery by cesarean section due to developing worsening heart failure. While there is data and support for IV prostacyclins in pregnancy, patients may opt for oral formulations, like in our case. Registry data on the use of oral prostacyclins and prostacyclin receptor agonists in pregnancy may help improve patient outcomes.

Laser Speckle Contrast Imaging-based diagnosis of severe mesenteric traction syndrome: Hemodynamics and prostacyclin - A prospective cohort study

BRIEF ABSTRACT

Today, the diagnosis and grading of mesenteric traction syndrome relies on a subjective assessment of facial flushing. However, this method has several limitations. In this study, Laser Speckle Contrast Imaging and a predefined cut-off value are assessed and validated for the objective identification of severe mesenteric traction syndrome.

BACKGROUND

Severe mesenteric traction syndrome (MTS) is associated with increased postoperative morbidity. The diagnosis is based on an assessment of the developed facial flushing. Today this is performed subjectively, as no objective method exists. One possible objective method is Laser Speckle Contrast Imaging (LSCI), which has been used to show significantly higher facial skin blood flow in patients developing severe MTS. Using these data, a cut-off value has been identified. This study aimed to validate our predefined LSCI cut-off value for identifying severe MTS.

METHODS

A prospective cohort study was performed on patients planned for open esophagectomy or pancreatic surgery from March 2021 to April 2022. All patients underwent continuous measurement of forehead skin blood flow using LSCI during the first hour of surgery. Using the predefined cut-off value, the severity of MTS was graded. In addition, blood samples for prostacyclin (PGI₂) analysis and hemodynamics were collected at predefined time points to validate the cut-off value.

MAIN RESULTS

Sixty patients were included in the study. Using our predefined LSCI cut-off value, 21 (35 %) patients were identified as developing severe MTS. These patients were found to have higher concentrations of 6-Keto-PGF_aα (p = 0.002), lower SVR (p < 0.001), lower MAP (p = 0.004), and higher CO (p < 0.001) 15 min into surgery, as compared with patients not developing severe MTS.

CONCLUSION

This study validated our LSCI cut-off value for the objective identification of severe MTS patients as this group developed increased concentrations of PGI₂ and more pronounced hemodynamic alterations compared with patients not developing severe MTS.

Adherence to the Mediterranean Diet Association with Serum Levels of Nitric Oxide, Prostacyclin, and Thromboxane B2 among Prinzmetal Angina Patients and Healthy Persons

This study aimed to assess the association between adherence to the Mediterranean diet with serum Nitric oxide, Prostacyclin, and Thromboxane B₂ among Prinzmetal angina patients and healthy persons. This case-control study was conducted among 100 Prinzmetal angina patients and 100 healthy persons referred to the Ardabil Imam Khomeini hospital between 2021 and 2022. Blood samples were obtained from all study participants for measurement of serum Nitric oxide, Prostacyclin, and Thromboxane B₂. To calculate adherence to the Mediterranean diet, the ten-item screener was used. The serum Nitric oxide in patients who adhered more to the Mediterranean diet was higher than patients with less adherence (coeff. = 0.41 p = 0.04). The serum Prostacyclin level in patients with greater adherence to the Mediterranean diet was 0.34 units higher than patients with less adherence (coeff. = 0.34 p = 0.02). The level of serum Thromboxane B₂ had a negative association with adherence to the Mediterranean diet (coeff. = -0.48 p = 0.04). The amount of consumption of olive oil, fruits, vegetables, and legumes in healthy people was more than Prinzmetal angina patients. In Prinzmetal angina patients, more adherence to the Mediterranean diet can decrease the serum Thromboxane B₂ and increase the serum Nitric oxide and Prostacyclin.

Mesenteric traction syndrome - Incidence, impact, and treatment: A systematic scoping review of the literature

BACKGROUND

Mesenteric traction syndrome (MTS) is commonly seen during major abdominal surgery and is characterised by facial flushing, hypotension, and tachycardia 15 min into surgery. MTS also impacts the postoperative course, as severe MTS has been associated with increased postoperative morbidity. However, despite MTS being common and severe MTS causing increased postoperative morbidity, the gaps in the literature are not clearly defined. We aimed to examine the diagnostic criteria, incidence, intraoperative and postoperative impact, and potential preventative measures of MTS while highlighting potential gaps in the literature.

METHODS

We followed the Prisma guidelines and performed a systematic literature search. We included only human studies examining MTS. All hits were screened for title and abstract, followed by a full-text review by at least two authors for determining eligibility for inclusion. Data were extracted and risk of bias was assessed by two independent reviewers.

RESULTS

A total of 37 studies, comprising 1102 patients were included in the review. The combined incidence of MTS during open abdominal surgery was found to be 76%, with 35% developing severe MTS. It was found that the development of MTS was associated with marked haemodynamic changes. It was also found that several different subjective diagnostic criteria exist and that severe MTS was associated with increased postoperative morbidity. Furthermore, several preventative measures for protecting against MTS have been examined, but only on the incidence of MTS and not on the postoperative course.

CONCLUSION

MTS occurs in 76% of patients undergoing major abdominal surgery and is associated with deleterious haemodynamic effects, which are more pronounced in patients developing severe MTS. Severe MTS is also associated with a worse postoperative outcome. However, gaps are still present in the current literature on MTS.

Prevention and treatment of atherothrombosis: Potential impact of nanotechnology

Complications with atherosclerosis can often lead to fatal clot formation and blood vessel occlusion - also known as atherothrombosis. A key component to the development of atherosclerosis and atherothrombosis is the endothelium and its ability to regulate the balance between prothrombotic and antithrombotic activities. Endothelial surface glycocalyx has a critical role in maintenance of vascular integrity. The endothelial glycocalyx, nitric oxide, prostacyclins, heparan sulfate, thrombomodulin, and tissue factor pathway inhibitor all prevent thrombosis, while P-selectin, among many other factors, favors thrombosis. However, endothelial dysfunction gives rise to the acceleration of thrombotic development and eventually the requirement of antithrombotic therapy. Most FDA-approved anticoagulant and antiplatelet therapies today carry a side effect profile of major bleed. Within the past five years, several preclinical studies using different endothelial targets and nanotechnology as a drug delivery method have emerged to target the endothelium and to enhance current antithrombosis without increasing bleed risk. While clinical studies are required, this review illustrates the proof-of-concept of nanotechnology in promoting a greater safety and efficacy profile through multiple in vitro and in vivo studies.

Inhaled prostacyclin therapy in the acute respiratory distress syndrome: a randomized controlled multicenter trial

BACKGROUND

Acute respiratory distress syndrome (ARDS) results in significant hypoxia, and ARDS is the central pathology of COVID-19. Inhaled prostacyclin has been proposed as a therapy for ARDS, but data regarding its role in this syndrome are unavailable. Therefore, we investigated whether inhaled prostacyclin would affect the oxygenation and survival of patients suffering from ARDS.

METHODS

We performed a prospective randomized controlled single-blind multicenter trial across Germany. The trial was conducted from March 2019 with final follow-up on 12th of August 2021. Patients with moderate to severe ARDS were included and randomized to receive either inhaled prostacyclin (3 times/day for 5 days) or sodium chloride (Placebo). The primary outcome was the oxygenation index in the intervention and control groups on Day 5 of therapy. Secondary outcomes were mortality, secondary organ failure, disease severity and adverse events.

RESULTS

Of 707 patients approached 150 patients were randomized to receive inhaled prostacyclin (n = 73) or sodium chloride (n = 77). Data from 144 patients were analyzed. The baseline PaO₂/FiO₂ ratio did not differ between groups. The primary analysis of the study was negative, and prostacyclin improved oxygenation by 20 mmHg more than Placebo (p = 0.17). Secondary analysis showed that the oxygenation was significantly improved in patients with ARDS who were COVID-19-positive (34 mmHg, p = 0.04). Mortality did not differ between groups. Secondary organ failure and adverse events were similar in the intervention and control groups.

CONCLUSIONS

The primary result of our study was negative. Our data suggest that inhaled prostacyclin might be beneficial treatment in patients with COVID-19 induced ARDS.

TRIAL REGISTRATION

The study was approved by the Institutional Review Board of the Research Ethics Committee of the University of Tübingen (899/2018AMG1) and the corresponding ethical review boards of all participating centers. The trial was also approved by the Federal Institute for Drugs and Medical Devices (BfArM, EudraCT No. 2016003168-37) and registered at clinicaltrials.gov (NCT03111212) on April 6th 2017.

Investigation of Novel Urinary Biomarkers in Hepatocellular Carcinoma Risk in a Predominantly African American Population: A Case-Control Study

Introduction

African Americans are at increased risk of hepatocellular carcinoma (HCC) compared to other racial and ethnic groups. We investigated the associations of four urinary biomarkers of prostaglandin E2 (PGE-M), prostacyclin (PGI-M), and thromboxane (11dTxB2) synthesis and the ratio of PGI-M to 11dTXB2 with HCC risk in a cohort of predominantly African American populations.

Methods

We conducted a nested case-control study (50 cases; 43 with HCC, 151 controls) in the Southern Community Cohort Study (SCCS), a large prospective cohort study including over 80,000 study participants, of whom two-thirds are African Americans. Urine samples were collected at enrollment and subsequently analyzed to assess biomarker levels. Multivariable regression models adjusted for age, race, sex, BMI, smoking status, NSAID use, education level, income, and alcohol consumption were used to assess the relationship between the biomarker and HCC risk.

Results

Only 11dTxB2 (OR = 11.50; 95% CI [2.34-56.47] for highest tertile vs. lowest tertile, p = 0.004) and the PGI-M/11dTXB2 ratio of the second quartile (0.25-0.49) (OR = 5.16; 95% CI [1.44-18.47]; p = 0.01) were significantly associated with increased risk of liver cancer.

Conclusion

11dTXB2 and PGI-M/11dTXB2 ratio may be urinary markers of HCC risk, particularly among African Americans, and future prospective studies are needed to evaluate this finding further and to develop accessible methods.

Anticoagulation in patients with acute kidney injury undergoing kidney replacement therapy

Kidney replacement therapy (KRT) is used to provide supportive therapy for critically ill patients with severe acute kidney injury and various other non-renal indications. Modalities of KRT include continuous KRT (CKRT), intermittent hemodialysis (HD), and sustained low efficiency daily dialysis (SLED). However, circuit clotting is a major complication that has been investigated extensively. Extracorporeal circuit clotting can cause reduction in solute clearances and can cause blood loss, leading to an upsurge in treatment costs and a rise in workload intensity. In this educational review, we discuss the pathophysiology of the clotting cascade within an extracorporeal circuit and the use of various types of anticoagulant methods in various pediatric KRT modalities.

Pulmonary vasodilator strategies in neonates with acute hypoxemic respiratory failure and pulmonary hypertension

The management of acute hypoxemic respiratory failure (AHRF) in newborns continues to be a clinical challenge with elevated risk for significant morbidities and mortality, especially when accompanied with persistent pulmonary hypertension of the newborn (PPHN). PPHN is a syndrome characterized by marked hypoxemia secondary to extrapulmonary right-to-left shunting across the ductus arteriosus and/or foramen ovale with high pulmonary artery pressure and increased pulmonary vascular resistance (PVR). After optimizing respiratory support, cardiac performance and systemic hemodynamics, targeting persistent elevations in PVR with inhaled nitric oxide (iNO) therapy has improved outcomes of neonates with PPHN physiology. Despite aggressive cardiopulmonary management, a significant proportion of patients have an inadequate response to iNO therapy, prompting consideration for additional pulmonary vasodilator therapy. This article reviews the pathophysiology and management of PPHN in term newborns with AHRF while highlighting both animal and human data to inform a physiologic approach to the use of PH-targeted therapies.

Characterization of prostanoids response to Bordetella pertussis antigen BscF and Tdap in LPS-challenged monocytes

Prostanoids are potent inflammatory mediators that play a regulatory role in the innate immune activation of the adaptive immune response to determine the duration of protection against infection. We aim to quantify the modulation of prostanoids profiles in lipopolysaccharide (LPS)-stimulated THP-1 cells treated with the novel pertussis antigen BscF. We compared the effect with pertussis antigens present in the current Tdap vaccine to understand the immunomodulatory effect that might contribute to the diminished Tdap vaccine effectiveness. The inflammatory challenge with LPS induced a robust elevation of most prostanoid family members compared to the control treatment. Treatment with BscF and Tdap significantly reduced the LPS-stimulated elevation of prostaglandins (PGs) D2, E2, and F2α, as well as thromboxane (TX) A2 levels. An opposite trend was observed for PGI2, as both antigens accelerated the LPS-stimulated upregulation. Further, we quantified cyclooxygenases (COXs) that catalyze the biosynthesis of prostanoids and found that both antigens significantly reduced LPS-stimulated COX-1 and COX-2, demonstrating that the waning of acellular pertussis vaccines' protective immunity may be due to other downstream enzymes not related to COXs. Our present study validates the potential role of BscF as an adjuvant, resulting in the next-generation pertussis vaccine discovery.

Contribution of cyclooxygenase-1-dependent prostacyclin synthesis to bradykinin-induced dermal extravasation

BACKGROUND

Non-allergic angioedema is a potentially life-threatening condition caused by accumulation of bradykinin and subsequent activation of bradykinin type 2 receptors (B2). Since COX activity plays a pivotal role in B2 signaling, the aim of this study was to determine which prostaglandins are the key mediators and which COX, COX-1 or COX-2, is predominantly involved.

METHODS

We used Miles assays to assess the effects of inhibitors of COX, 5-lipoxygenase, epoxyeicosatrienoic acid generation, cytosolic phospholipase A₂α and a variety of prostaglandin receptor antagonists on bradykinin-induced dermal extravasation in C57BL/6 and COX-1-deficient mice (COX-1^-/-). In addition, the prostacyclin metabolite 6-keto-PGF_1α was quantified by ELISA in subcutaneous tissue from C57BL/6 and human dermal microvascular endothelial cells. In the latter, 6-keto-PGF_1α was also quantified and identified by LC-MS/MS.

RESULTS

Unspecific COX inhibition by ibuprofen and diclofenac significantly reduced B2-mediated dermal extravasation in C57BL/6 but not COX-1^-/-. Likewise, inhibition of cytosolic phospholipase A₂α showed similar effects. Furthermore, extravasation in COX-1^-/- was generally lower than in C57BL/6. Of the prostaglandin antagonists used, only the prostacyclin receptor antagonist RO1138452 showed a significant reduction of dermal extravasation. Moreover, 6-keto-PGF_1α concentrations were increased after bradykinin treatment in subcutaneous tissue from C57BL/6 as well as in human dermal microvascular endothelial cells and this increase was abolished by diclofenac.

CONCLUSION

Our findings suggest that COX-1-dependent prostacyclin production is critically involved in dermal extravasation after activation of B2 in small dermal blood vessels. Targeting prostacyclin production and/or signaling appears to be a suitable option for acute treatment of non-allergic angioedema.

Omega-3 fatty acids decrease CRYAB, production of oncogenic prostaglandin E2 and suppress tumor growth in medulloblastoma

AIMS

Medulloblastoma (MB) is one of the most common malignant central nervous system tumors of childhood. Despite intensive treatments that often leads to severe neurological sequelae, the risk for resistant relapses remains significant. In this study we have evaluated the effects of the ω3-long chain polyunsaturated fatty acids (ω3-LCPUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on MB cell lines and in a MB xenograft model.

MAIN METHODS

Effects of ω3-LCPUFA treatment of MB cells were assessed using the following: WST-1 assay, cell death probes, clonogenic assay, ELISA and western blot. MB cells were implanted into nude mice and the mice were randomized to DHA, or a combination of DHA and EPA treatment, or to control group. Treatment effects in tumor tissues were evaluated with: LC-MS/MS, RNA-sequencing and immunohistochemistry, and tumors, erythrocytes and brain tissues were analyzed with gas chromatography.

KEY FINDINGS

ω3-LCPUFA decreased prostaglandin E2 (PGE₂) secretion from MB cells, and impaired MB cell viability and colony forming ability and increased apoptosis in a dose-dependent manner. DHA reduced tumor growth in vivo, and both PGE₂ and prostacyclin were significantly decreased in tumor tissue from treated mice compared to control animals. All ω3-LCPUFA and dihomo-γ-linolenic acid increased in tumors from treated mice. RNA-sequencing revealed 10 downregulated genes in common among ω3-LCPUFA treated tumors. CRYAB was the most significantly altered gene and the downregulation was confirmed by immunohistochemistry.

SIGNIFICANCE

Our findings suggest that addition of DHA and EPA to the standard MB treatment regimen might be a novel approach to target inflammation in the tumor microenvironment.

A novel prostaglandin I2 agonist, ONO-1301, attenuates liver inflammation and suppresses fibrosis in non-alcoholic steatohepatitis model mice

BACKGROUND

ONO-1301 is a novel long-lasting prostaglandin (PG) I₂ mimetic with inhibitory activity on thromboxane (TX) A₂ synthase. This drug can also induce endogenous prostaglandin (PG)I2 and PGE2 levels. Furthermore, ONO-1301 acts as a cytokine inducer and can initiate tissue repair in a variety of diseases, such as pulmonary hypertension, pulmonary fibrosis, cardiac infarction, and obstructive nephropathy. In this study, our aim was to evaluate the effect of ONO-1301 on liver inflammation and fibrosis in a mouse model of non-alcoholic steatohepatitis (NASH).

METHODS

The therapeutic effects of ONO-1301 against liver damage, fibrosis, and occurrence of liver tumors were evaluated using melanocortin 4 receptor-deficient (Mc4r-KO) NASH model mice. The effects of ONO-1301 against macrophages, hepatic stellate cells, and endothelial cells were also evaluated in vitro.

RESULTS

ONO-1301 ameliorated liver damage and fibrosis progression, was effective regardless of NASH status, and suppressed the occurrence of liver tumors in Mc4r-KO NASH model mice. In the in vitro study, ONO-1301 suppressed LPS-induced inflammatory responses in cultured macrophages, suppressed hepatic stellate cell (HSC) activation, upregulated vascular endothelial growth factor (VEGF) expression in HSCs, and upregulated hepatocyte growth factor (HGF) and VEGF expression in endothelial cells.

CONCLUSIONS

The results of our study highlight the potential of ONO-1301 to reverse the progression and prevent the occurrence of liver tumors in NASH using in vivo and in vitro models. ONO-1301 is a multidirectional drug that can play a key role in various pathways and can be further analyzed for use as a new drug candidate against NASH.

New strategy to resume and taper epoprostenol after lung transplant for pulmonary hypertension

OBJECTIVE

The perioperative outcome of lung transplantation (LTx) for patients with severe pulmonary hypertension (PH) remains poor due to the occurrence of primary graft dysfunction (PGD) from left ventricular failure. We hypothesized that tapering pretransplant use of epoprostenol rather than abrupt discontinuation after transplantation might improve perioperative outcomes.

METHODS

We performed 23 LTxs for patients with severe PH who received epoprostenol therapy from 2008 until 2021. In the discontinued group (n = 6), epoprostenol was discontinued after the establishment of extracorporeal circulation. In the tapered group (n = 17), epoprostenol was discontinued and resumed after reperfusion, and then gradually tapered over the following 2 weeks. We assessed survival, bleeding, blood transfusion, re-opening of the chest, oxygenation, PGD score, extracorporeal membrane oxygenation (ECMO) requirement for recovery after transplantation, and duration of mechanical ventilation.

RESULTS

The PGD score was significantly lower in the tapered group than in the discontinued group at 0 h, 24 h, and 48 h after LTx. In addition, the discontinued group required longer mechanical ventilation than the tapered group. Delayed chest closure and post-transplant ECMO use for recovery occurred significantly more frequently in the discontinued group.

CONCLUSIONS

To resume and taper epoprostenol administration after reperfusion in patients with severe PH may be a valuable new strategy associated with better perioperative outcomes.

Prostacyclin in Mechanically Ventilated Patients with COVID-19 and Severe Endotheliopathy: A Multicenter, Randomized, Clinical Trial

Rationale

The mortality in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who require mechanical ventilation remains high, and endotheliopathy has been implicated.

Objectives

To determine the effect of prostacyclin infusion in mechanically ventilated patients infected with SARS-CoV-2 with severe endotheliopathy.

Methods

We conducted a multicenter, randomized clinical trial in adults infected with coronavirus disease (COVID-19) who required mechanical ventilation and had a plasma level of thrombomodulin >4 ng/ml; patients were randomized to 72-hour infusion of prostacyclin 1 ng/kg/min or placebo.

Measurements and Main Results

The main outcome was the number of days alive and without mechanical ventilation within 28 days. Key secondary outcomes were 28-day mortality and serious adverse events within 7 days. Eighty patients were randomized (41 prostacyclin and 39 placebo). The median number of days alive without mechanical ventilation at 28 days was 16.0 days (SD, 12) versus 5.0 days (SD, 10) (difference of the medians, 10.96 days; 95% confidence interval [CI], −5 to 21; P = 0.07) in the prostacyclin and the placebo groups, respectively. The 28-day mortality was 21.9% versus 43.6% in the prostacyclin and the placebo groups, respectively (risk ratio, 0.50; 95% CI, 0.24 to 0.96; P = 0.06). The incidence of serious adverse events within 7 days was 2.4% versus 12.8% (risk ratio, 0.19; 95% CI, 0.001 to 1.11; P = 0.10) in the prostacyclin and the placebo groups, respectively.

Conclusions

Prostacyclin was not associated with a significant reduction in the number of days alive and without mechanical ventilation within 28 days. The point estimates, however, favored the prostacyclin group in all analyses, including 28-day mortality, warranting further investigation in larger trials.

Clinical trial registered with www.clinicaltrials.gov (NCT 04420741); EudraCT Identifier: 2020-001296-33.

Treprostinil alleviates hepatic mitochondrial injury during rat renal ischemia-reperfusion injury

BACKGROUND

Renal ischemia-reperfusion injury (IRI) causes acute kidney injury as well as liver injury. Renal IRI depletes hepatic antioxidants, promotes hepatic inflammation and dysfunction through Tlr9 upregulation. There is no treatment available for liver injury during renal IRI. This study examines the hepatoprotective role of treprostinil, a prostacyclin analog, during renal IRI.

METHODS

Male Sprague-Dawley rats were divided into four groups: control, sham, IRI-placebo, or IRI-treprostinil and subjected to bilateral ischemia (45 min) followed by reperfusion (1-72 h). Placebo or treprostinil (100 ng/kg/min) was administered subcutaneously via an osmotic minipump.

RESULTS

Treprostinil significantly reduced peak serum creatinine, BUN, ALT and AST levels vs. IRI-placebo. Treprostinil also restored hepatic levels of superoxide dismutase, glutathione, catalase, and Gclc expression to baseline, while reducing lipid peroxidation vs. IRI-placebo. Additionally, treprostinil significantly reduced elevated hepatic Tlr9, Il-1β, Ccl2, Vcam1, and Serpine1 mRNA expression. Renal IRI increased hepatic apoptosis which was inhibited by treprostinil through reduced cytochrome c and cleaved caspase-3 protein expression. Treprostinil enhanced hepatic ATP concentrations and mitochondrial DNA copy number and improved mitochondrial dynamics by restoring Pgc-1α expression and significantly upregulating Mfn1, Mfn2, and Sirt3 levels, while reducing Drp-1 protein vs. IRI-placebo. Non-targeted semi-quantitative proteomics showed improved oxidative stress indices and ATP subunits in the IRI-treprostinil group.

CONCLUSIONS

Treprostinil improved hepatic function and antioxidant levels, while suppressing the inflammatory response and alleviating Tlr9-mediated apoptotic injury during renal IRI. Our study provides evidence of treprostinil's hepatoprotective effect, which supports the therapeutic potential of treprostinil in reducing hepatic injury during renal IRI.

Inhaled prostacyclin analogues in COVID-19 associated acute respiratory distress syndrome: scientific rationale

BACKGROUND

COVID-19 associated acute respiratory distress syndrome (CARDS) is a severe form of SARS CoV-2 infection and affects about 15-30% of hospitalized patients with a high mortality rate. Growing research and data suggest several available drugs with appropriate pharmacological effects to treat COVID-19.

MAIN BODY

Prostacyclin analogues are regiments for pulmonary artery hypertension. Prostacyclin analogues are expected to be beneficial in treating CARDS based on at least four rationales: (1) inhaled prostacyclin analogues improve oxygenation, V/Q mismatch, and act as an ARDS therapy alternative; (2) it alleviates direct SARS-CoV-2-related coagulopathy; (3) increases nitric oxide production; and (4) possible anti-inflammatory effect. Prostacyclin analogues are available in oral, intravenous, and inhaled forms. The inhaled form has the advantage over other forms, such as parenteral administration risks. Previously, a meta-analysis demonstrated the beneficial effects of inhaled prostaglandins for ARDS treatment, such as improved PaO2/FiO2 and PaO2 along with reduced pulmonary artery pressure. Currently, two ongoing randomized controlled trials are evaluating inhaled epoprostenol (VPCOVID [NCT04452669]) and iloprost (ILOCOVID [NCT04445246]) for severe COVID-19 patients.

CONCLUSIONS

Inhaled prostacyclin could be considered in patients with refractory, life-threatening hypoxia despite standard management.

Low-dose Aspirin prevents hypertension and cardiac fibrosis when thromboxane A2 is unrestrained

Enhanced platelet activation has been reported in patients with essential hypertension and heart failure. The possible contribution of platelet-derived thromboxane (TX)A2 in their pathophysiology remains unclear. We investigated the systemic TXA2 biosynthesis in vivo and gene expression of its receptor TP in 22 essential hypertension patients and a mouse model of salt-sensitive hypertension. The contribution of platelet TXA2 biosynthesis on enhanced blood pressure (BP) and overload-induced cardiac fibrosis was explored in mice by treating with low-dose Aspirin, resulting in selective inhibition of platelet cyclooxygenase (COX)-1-dependent TXA2 generation. In essential hypertensive patients, systemic biosynthesis of TXA2 [assessed by measuring its urinary metabolites (TXM) reflecting predominant platelet source] was enhanced together with higher gene expression of circulating leukocyte TP and TGF-β, vs. normotensive controls. Similarly, in hypertensive mice with prostacyclin (PGI2) receptor (IP) deletion (IPKO) fed with a high-salt diet, enhanced urinary TXM, and left ventricular TP overexpression were detected vs. normotensive wildtype (WT) mice. Increased cardiac collagen deposition and profibrotic gene expression (including TGF-β) was found. Low-dose Aspirin administration caused a selective inhibition of platelet TXA2 biosynthesis and mitigated enhanced blood pressure, cardiac fibrosis, and left ventricular profibrotic gene expression in IPKO but not WT mice. Moreover, the number of myofibroblasts and extravasated platelets in the heart was reduced. In cocultures of human platelets and myofibroblasts, platelet TXA2 induced profibrotic gene expression, including TGF-β1. In conclusion, our results support tailoring low-dose Aspirin treatment in hypertensive patients with unconstrained TXA2/TP pathway to reduce blood pressure and prevent early cardiac fibrosis.

Treprostinil reduces mitochondrial injury during rat renal ischemia-reperfusion injury

BACKGROUND

Renal ischemia-reperfusion injury (IRI) is a major factor contributing to acute kidney injury and it is associated with a high morbidity and mortality if untreated. Renal IRI depletes cellular and tissue adenosine triphosphate (ATP), which compromises mitochondrial function, further exacerbating renal tubular injury. Currently, no treatment for IRI is available. This study investigates the protective role of treprostinil in improving mitochondria biogenesis and recovery during rat renal IRI.

METHODS

Male Sprague Dawley rats were randomly assigned to groups: control, sham, IRI-placebo or IRI-treprostinil and subjected to 45 min of bilateral renal ischemia followed by 1-72 h reperfusion. Placebo or treprostinil (100 ng/kg/min) was administered subcutaneously via an osmotic minipump.

RESULTS

Treprostinil significantly reduced peak elevated serum creatinine (SCr) levels and accelerated normalization relative to IRI-placebo (p < 0.0001). Treatment with treprostinil also inhibited IRI-mediated renal apoptosis, mitochondrial oxidative injury (p < 0.05), and the release of cytochrome c (p < 0.01) vs. IRI-placebo. In addition, treprostinil preserved renal mitochondrial DNA copy number (p < 0.0001) and renal ATP levels (p < 0.05) to nearly those of sham-operated animals. Non-targeted semi-quantitative proteomics showed reduced levels of ATP synthase subunits in the IRI-placebo group which were restored to sham levels by treprostinil treatment (p < 0.05). Furthermore, treprostinil reduced renal IRI-induced upregulated Drp1 and pErk protein levels, and restored Sirt3 and Pgc-1α levels to baseline (p < 0.05).

CONCLUSIONS

Treprostinil reduces mitochondrial-mediated renal apoptosis, inhibits mitochondria fission, and promotes mitochondria fusion, thereby accelerating mitochondrial recovery and protecting renal proximal tubules from renal IRI. These results support the clinical investigation of treprostinil as a viable therapy to reduce renal IRI.

Autoimmune hypophysitis as a cause of adrenocorticotropic hormone deficiency in pulmonary arterial hypertension: a case report

Background 

Severe pulmonary arterial hypertension (PAH) is generally treated with multiple PAH-specific vasodilators. If these agents are unsuccessful, additional treatment options are scarce, and the prognosis is poor due to right-sided heart failure. Some of these severe cases are also accompanied by endocrinological side effects. The most common side effect of prostacyclin is thyroid dysfunction, but in very few cases, adrenocorticotropic hormone (ACTH) deficiency may occur.

Case summary 

A 35-year-old woman was diagnosed with hereditary PAH 2 years ago. Since her mean pulmonary arterial pressure was high, combination therapy of vasodilators, including prostacyclin, was introduced. Several months later, she was hospitalized with a persistent fever. Laboratory tests showed no findings suggestive of infection. However, hypereosinophilia and decreased secretion of ACTH and cortisol were noted, which led to the diagnosis of ACTH deficiency. A multimodal diagnostic approach, including pituitary magnetic resonance imaging and axillary lymph node biopsy, indicated that the aetiology of the ACTH deficiency was likely autoimmune hypophysitis. She was treated with hydrocortisone supplementation, which significantly relieved her condition.

Discussion 

Endocrinological side effects in PAH patients using prostacyclin should be carefully addressed. If right-sided heart failure worsens during the administration of prostacyclin, it is essential to determine whether it is due to progression of pulmonary hypertension or endocrinological side effects. Careful diagnosis and treatment are important for managing the haemodynamics and symptoms of PAH patients given prostacyclin.

Beneficial effects of melatonin on prostanoids pathways in pulmonary hypertensive neonates

Pulmonary arterial hypertension of the newborn (PAHN) is a syndrome caused by chronic hypoxia, characterized by decreased vasodilator function, a marked vasoconstrictor activity, proliferation of smooth muscle cells (SMC) and thickening of the extracellular matrix in the pulmonary circulation, among other characteristics. Prostaglandins are derived from the arachidonic acid (AA) metabolism and are important regulators of pulmonary vascular tone. Since hypoxia induces oxidative stress and has been related to PAHN, a postnatal treatment with melatonin has been proposed due to its antioxidant properties. Here, we determined the effects of melatonin on pulmonary vascular homeostasis given by prostanoids. Ten PAHN newborn lambs were divided in two groups and treated either with vehicle or melatonin. After 1 week of treatment, we assessed pulmonary vascular prostanoids function and expression by wire myography, RT-PCR, Western Blot and immunohistochemistry. Melatonin improved in vivo and ex vivo pulmonary vasodilation. This was associated with an increased function and expression of vasodilator prostanoids at the expense of vasoconstrictor prostanoids. Our study demonstrates for the first time that melatonin may enhance the vasodilator prostanoid pathway in PAHN.

Coordinated action of microsomal prostaglandin E synthase-1 and prostacyclin synthase on contact hypersensitivity

Microsomal prostaglandin (PG) E synthase-1 (mPGES-1) and prostacyclin (PGI2) synthase (PGIS) are PG terminal synthases that work downstream of cyclooxygenase and synthesize PGE2 and PGI2, respectively. Although the involvement of PG receptors in acquired cutaneous immune responses was recently shown, the roles of these PG terminal synthases remain unclear. To identify the pathophysiological roles of mPGES-1 and PGIS in cutaneous immune systems, we applied contact hypersensitivity (CHS) to mPGES-1 and PGIS knockout (KO) mice as a model of acquired immune responses. Mice were treated with 1-fluoro-2,4-dinitrobenzene (DNFB) and evaluated for ear thickness and histopathological features. The results showed that the severity of ear swelling in both gene-deficient mice was much lower than that in wild-type (WT) mice. Histological examination of DNFB-treated ears showed that inflammatory cell infiltration and edema in the dermis were also less apparent in both genotypic mice. LC-MS analysis further showed that the increment in PGE2 levels in DNFB-treated ear tissue was reduced in mPGES-1 KO mice, and that 6-keto PGF1α (a stable metabolite of PGI2) was not detected in PGIS KO mice. Furthermore, we made bone marrow (BM) chimera and found that transplantation of WT mouse-derived BM cells restored the impaired CHS response in mPGES-1 KO mice but did not restore the response in PGIS KO mice. These results indicated that mPGES-1 in BM-derived cells and PGIS in non-BM-derived cells might play critical roles in DNFB-induced CHS. mPGES-1-derived PGE2 and PGIS-derived PGI2 might coordinately promote acquired cutaneous immune responses.

New regional drug delivery system by direct epicardial placement of slow-release prostacyclin agonist promise therapeutic angiogenesis in a porcine chronic myocardial infarction

Although prostacyclin is an endogenous factor for the protection and regeneration of damaged tissue, the use of clinically available prostacyclin analogues for treating chronic pathological conditions is limited owing to their short half-lives. A new reagent, ONO-1301SR, which is a unique synthetic prostacyclin agonist polymerized with lactic and glycolic acid, has been demonstrated to constitutively release prostacyclin analogues to adjacent tissues, suggesting its therapeutic potential via slow-release delivery into a specific organ. In this study, we investigated the regenerative effect of direct epicardial delivery of the ONO-1301SR on a heart with a chronic myocardial infarct. An ameroid constrictor was placed on the left anterior descending coronary artery of Göttingen minipigs for 4 weeks to induce ischemic cardiomyopathy; this was followed by direct epicardial placement of ONO-1301SR-immersed gelatinous sheet, or only a gelatinous sheet on the anterolateral surface of the heart. Epicardial placement of ONO-1301SR resulted in significant recovery of global cardiac functions and regional wall motion of the lateral wall. Importantly, after epicardial placement of ONO-1301SR for 4 weeks, the myocardial blood flow significantly increased in the lateral region as assessed by ¹³N-ammonia positron emission tomography; this finding was consistent with significantly increased capillary density in the peri-infarct area with up-regulated angiogenic cytokine expression. Conclusion: Use of the slow-release drug delivery system of prostacyclin agonist yielded regenerative angiogenesis, including increased regional blood perfusion and systolic function in a porcine model of chronic myocardial infarction.

Intravenous prostacyclin-analogue therapy in pulmonary arterial hypertension - A review of the past, present and future

Therapy with intravenous prostacyclin analogues in patients with pulmonary arterial hypertension (PAH) has been established for decades and is an integral component of the current guidelines for the treatment of pulmonary hypertension. Initially, these drugs were infused by external pump systems via tunnelled right atrial catheters with the need for cooling and frequent exchange of drug reservoirs. Associated complications included, among others, catheter-related infections. More recently, fully implantable pump systems have been developed with drug reservoirs that are filled transcutaneously, allowing intervals between refills of several weeks. This technique results in a low rate of infections. Epoprostenol, iloprost and treprostinil have all been used intravenously in PAH, but titration, dosing and dose escalation in long-term therapy are not standardized. Intravenous prostacyclin analogues are still under-used, despite available data suggesting that early and broad application of these therapies as part of risk-oriented, guideline-directed combination therapy for patients with PAH may lead to a survival benefit. This review provides a detailed overview of the drugs, infusion systems and dosing strategies used for intravenous therapy in patients with PAH.

Larger endothelium-dependent contractions in iliac arteries of adult SHRs are attributed to differential downregulation of TP and EP3 receptors in the vessels of WKYs and SHRs during the transition from adolescence to adulthood

This study was to determine how endothelium-dependent contractions (EDCs) change in iliac arteries of Wistar-Kyoto (WKYs) and spontaneously hypertensive rats (SHRs) during the transition from adolescence to adulthood and the underlying mechanism(s). We also aimed to elucidate effects of L-798106, an EP3 receptor antagonist, on EDCs and the blood pressure increase in adolescent SHRs. Blood vessels were isolated for functional and biochemical analyses. EDCs were comparable in adolescent iliac arteries of both strains, and contractions to ACh, prostacyclin (PGI2), the EP3 receptor agonist sulprostone and the TP receptor agonist U46619 in adult vessels were less prominent compared with those in the adolescents, while the attenuation of vasoconstrictions to ACh, PGI2 or U46619 with age was to a lesser extent in SHRs. PGI2 production was decreased to a similar level in adult arteries. TP and EP3 expressions were downregulated in adult vessels, whereas the extent of TP downregulation was less in SHRs. L-798106 partially suppressed the vasoconstrictions to U46619 and attenuated EDCs to a greater extent than SQ29548, and administration of L-798106 blunted the blood pressure increase with age in prehypertensive SHRs. These results demonstrate the comparable EDCs in iliac arteries of the adolescents are decreased in the adults, but relatively larger EDCs in adult SHRs can be a reflection of differential downregulation of TP and EP3 receptors during the transition from adolescence to adulthood. Also, our data suggest that blockade of both TP and EP3 receptors starting from the prehypertensive stage suppresses EDCs and the development of hypertension in SHRs.

Protective effects of luteolin on the venous endothelium

Luteolin is a flavonoid with antioxidant properties already demonstrated in studies related to inflammation, tumor, and cardiovascular processes; however, there are no available information regarding its antioxidant effects at the venous endothelial site. We investigated the effects of luteolin (10, 20, and 50 μmol/L) in cultures of rat venous endothelial cells. Nitric oxide (NO) and reactive oxygen species (ROS) were analyzed by fluorimetry; 3-nitrotyrosine (3-NT) residues were evaluated by immunofluorescence, and prostacyclin (PGI₂) release was investigated by colorimetry. Intracellular NO levels were significantly enhanced after 10 min of luteolin incubation, with a parallel decrease in ROS generation. These results were accompanied by a significant reduction in the expression of 3-NT residues and enhanced PGI₂ rates. Therefore, luteolin is effective in reducing ROS thereby improving NO availability in venous endothelial cells. Besides, luteolin-induced decrease in 3-NT residues may correlate with the enhancement in endothelial PGI₂ bioavailability. These findings suggest the future application of this flavonoid as a protective agent by improving endothelial function in several circulatory disorders related to venous insufficiency.

Epoprostenol up-regulates serum adiponectin level in patients with systemic sclerosis: therapeutic implications

INTRODUCTION

Adiponectin, resistin and leptin belong to adipokines, a group of molecules secreted mainly by the adipose tissue, which impaired expression may be a missing link between various manifestations of systemic sclerosis. Adiponectin, which is also released in small amounts by the endothelium, possesses anti-inflammatory, anti-fibrotic and protective against endothelial injury properties. Both leptin and resistin exhibit features which are contradictory to adiponectin, as they trigger inflammation and the activation of skin fibroblasts. Epoprostenol is a prostaglandin analogue with powerful vasodilator activity and inhibitory effect on platelet aggregation. The aim of the study was to evaluate whether epoprostenol may have an effect on serum adipokine levels in patients with systemic sclerosis.

METHODS

A total of 27 patients were included in the study and received epoprostenol intravenously (25 µg of per day for 3 consecutive days). Serum concentrations of total adiponectin, resistin and leptin were assessed with enzyme-linked immunosorbent essay (R&D Systems, Minneapolis, MN, USA).

RESULTS

In all SSc patients, the basal level of adiponectin was significantly lower compared to healthy controls (mean 6.00 [Formula: see text] 2.81 μg/ml vs. 8.8 [Formula: see text] 4.3 μg/ml, p = 0.02) and basal level of resistin (mean 11.12 [Formula: see text] 3.36 ng/ml vs. 8.54 [Formula: see text] 3.07 ng/ml p = 0.02) was significantly higher than in the control group. The serum concentration of adiponectin increased significantly after treatment with epoprostenol (6.00 [Formula: see text] 2.81 μg/ml vs 9.29 [Formula: see text] 6.05 μg/ml; P = 0.002). The level of resistin and leptin remained unchanged.

CONCLUSION

Epoprostenol infusions up-regulate the serum concentration of adiponectin in patients with systemic sclerosis. In our opinion, future studies on treatments in systemic sclerosis should address the issue of their effect on adipokine metabolism.

Contemporary Pharmacotherapeutic Approach in Pulmonary Arterial Hypertension

Since the 1973 World Symposium on Pulmonary Hypertension, advancements in the understanding of pathophysiology and pathobiology have led to a myriad of pharmacotherapies for the disease. This article journeys through the development of therapeutic approaches for pulmonary arterial hypertension.

Life-threatening PPHN refractory to nitric oxide: proposal for a rational therapeutic algorithm

Persistent pulmonary hypertension of the neonate (PPHN) refractory to inhaled nitric oxide still represents a frequent clinical challenge with negative outcomes in neonatal critical care. Several pulmonary vasodilators have become available thanks to improved understanding of pulmonary hypertension pathobiology. These drugs are commonly used in adults and there are numerous case series and small studies describing their potential usefulness in neonates, as well. New vasodilators act on different pathways, some of them can have additive effects and all have different pharmacology features. This information has never been summarized so far and no comprehensive pathobiology-driven algorithm is available to guide the treatment of refractory PPHN.Conclusion: We offer a rational clinical algorithm to guide the treatment of refractory PPHN based on expert advice and the more recent pathobiology and pharmacology knowledge. What is Known: • Refractory PPHN occurs in 30-40% of iNO-treated neonates and represents a significant clinical problem. Several pulmonary vasodilators have become available thanks to a better understanding of pulmonary hypertension pathobiology. What is New: • Available vasodilators have different pharmacology, mechanisms of action and may provide additive effect. We provide a rational clinical algorithm to guide the treatment of refractory PPHN based on expert advice and the more recent pathobiology and pharmacology knowledge.

Involvement of prostacyclin synthase in high-fat-diet-induced obesity

Prostacyclin (PGI₂) synthase (PGIS) functions downstream of inducible cyclooxygenase COX-2 in the PGI₂ biosynthetic pathway. Although COX-2 and PGI₂ receptor (IP) are known to be involved in adipogenesis and obesity, the involvement of PGIS has not been fully elucidated. In this study, we examined the role of PGIS in adiposity by using PGIS-deficient mice. Although PGIS deficiency did not affect in vitro adipocyte differentiation, when fed a high-fat diet (HFD), PGIS knockout (KO) mice showed reductions in both body weight gain and epididymal fat mass relative to wild-type (WT) mice. PGIS deficiency might reduce HFD-induced obesity by suppressing PGI₂ production. We further found that additional gene deletion of microsomal prostaglandin (PG) E synthase-1 (mPGES-1), one of the other PG terminal synthases that also functions downstream of COX-2, emphasized the metabolic phenotypes of PGIS-deficient mice. More marked reduction in obesity and improved insulin resistance were observed in PGIS/mPGES-1 double KO (DKO) mice. Since an additive increase in PGF_2α level in epididymal fat was observed in DKO mice, mPGES-1 deficiency might affect adiposity by enhancing the production of PGF_2α. Our immunohistochemical analysis further revealed that in adipose tissues, PGIS was expressed in vascular and stromal cells but not in adipocytes. These results suggested that PGI₂ produced from PGIS-expressed stromal tissues might enhance HFD-induced obesity by acting on IP expressed in adipocytes. The balance of expressions of PG terminal synthases and the subsequent production of prostanoids might be critical for adiposity.

An expert panel delphi consensus statement on patient selection and management for transitioning between oral and inhaled treprostinil

Treprostinil, a prostacyclin analogue used in the treatment of pulmonary arterial hypertension (PAH), is available for administration by parenteral, oral, or inhaled routes. Transitioning between routes may be beneficial for appropriate patients; however, there is little published data on transitions between oral and inhaled treprostinil. We used a modified Delphi process to develop expert consensus recommendations on transitions between these formulations. Three questionnaires were used to develop statements about relevant aspects of transition management, which the panelists rated, using a Likert scale, from -5 (strongly disagree) to +5 (strongly agree). Eleven physicians with expertise in PAH treatment modalities, participated in the panel. Of the 492 statements evaluated, consensus was reached on 215 (43.7%). Key consensus recommendations included (1) accurately defining successful transition, as stable or improved PAH with good tolerability and adherence, and (2) patients with stable, low-risk PAH showing insufficient response or tolerability to their existing treprostinil therapy (and due to restrictions in up titration of dosing), as appropriate candidates for transitions between treprostinil formulations. Panelists did not reach consensus for an overall strategy for performing these transitions, mainly because of variability in their practice parameters. Consensus was also achieved on recommendations for adverse event management, including reassurance, administration of oral treprostinil 3 times daily with food, and dosing inhaled treprostinil at intervals ≥3 hours apart. The Delphi process aided in developing expert consensus recommendations that may provide clinically useful guidance for transitioning between treprostinil formulations. However, additional data from centers with high volumes of PAH patients undergoing treprostinil transitions would be optimal for defining more complete and robust strategies to facilitate successful transition.

Management of Pulmonary Arterial Hypertension

Purpose of Review

This review focuses on the therapeutic management and individualized approach to Group 1 pulmonary arterial hypertension (PAH), utilizing Food and Drug Administration-approved PAH-specific therapies and various interventional and surgical options for PAH.

Recent Findings

The paradigm for the optimal management of PAH has shifted in recent years. Upfront combination therapy with an endothelin receptor antagonist and a phosphodiesterase 5 inhibitor is now widely accepted as standard of care. In addition, there is increasing emphasis on starting prostanoids early in order to delay time to clinical worsening. However, less is known regarding which prostanoid agent to initiate and the optimum time to do so. In order to facilitate shared decision-making, there is an increasing need for decision tools based on guidelines and collective clinical experiences to navigate between pharmacologic and interventional treatments, as well as explore innovative, therapeutic pathways for PAH.

Summary

The management of PAH has become increasingly complex. With a growing number of PAH-specific therapies, intimate knowledge of the therapeutics and the potential barriers to adherence are integral to providing optimal care for this high-risk patient population. While current PAH-specific therapies largely mediate their effects through pulmonary vasodilation, ongoing research efforts are focused on ways to disrupt the mechanisms leading to pulmonary vascular remodeling. By targeting aberrations identified in the metabolism and proliferative state of pulmonary vascular cells, novel PAH treatment pathways may be just on the horizon.

The sodium-glucose cotransporter-2 (SGLT2) inhibitors synergize with nitric oxide and prostacyclin to reduce human platelet activation

Gliflozins (canagliflozin, dapagliflozin and empagliflozin) are the newest anti-hyperglycemic class and have offered cardiovascular and renal benefits. Because platelets are involved in the atherothrombosis process, this study is aimed to evaluate the direct effect of gliflozins on platelet reactivity. Platelet-rich plasma (PRP) or washed platelets (WP) were obtained from healthy volunteers. Aggregation, flow cytometry for glycoprotein IIb/IIIa, cyclic nucleotides and intracellular calcium levels, Western blot, thromboxane B₂ (TXB₂) measurement and COX-1 activity were performed in the presence of gliflozins (1-30 μM) alone or in combination with sodium nitroprusside (SNP, 10 or 100 nM) + iloprost (ILO, 0.1 or 1 nM). SGLT2 protein is not expressed on human platelets. Gliflozins produced little inhibitory effect in agonists-induced aggregation and this effect was greatly potentiated by ~10-fold in the presence of SNP + ILO, accompanied by lower levels of TXB₂ (58.1 ± 5.1%, 47.1 ± 7.2% and 43.4 ± 9.2% inhibition for canagliflozin, dapagliflozin and empagliflozin, respectively). The activity of COX-1 was not affected by gliflozins. Collagen increased Ca²⁺ levels and α(IIb)β(3) activation, both of which were significantly reduced by gliflozins + SNP + ILO. The intracellular levels of cAMP and cGMP and the protein expression of p-VASPSer157 and p-VASPSer239 were not increased by gliflozins while the expression of the serine-threonine kinase, AktSer473 was markedly reduced. Our results showed that the antiplatelet activity of gliflozins were greatly enhanced by nitric oxide and prostacyclin, thus suggesting that the cardiovascular protection seen by this class of drugs could be in part due to platelet inhibition.

Novel anti-thrombotic mechanisms mediated by Mas receptor as result of balanced activities between the kallikrein/kinin and the renin-angiotensin systems

The risk of thrombosis, a globally growing challenge and a major cause of death, is influenced by various factors in the intravascular coagulation, vessel wall, and cellular systems. Among the contributors to thrombosis, the contact activation system and the kallikrein/kinin system, two overlapping plasma proteolytic systems that are often considered as synonymous, regulate thrombosis from different aspects. On one hand, components of the contact activation system such as factor XII initiates activation of the coagulation proteins promoting thrombus formation on artificial surfaces through factor XI- and possibly prekallikrein-mediated intrinsic coagulation. On the other hand, physiological activation of plasma prekallikrein in the kallikrein/kinin system on endothelial cells liberates bradykinin from associated high-molecular-weight kininogen to stimulate the constitutive bradykinin B2 receptor to generate nitric oxide and prostacyclin to induce vasodilation and counterbalance angiotensin II signaling from the renin-angiotensin system which stimulates vasoconstriction. In addition to vascular tone regulation, this interaction between the kallikrein/kinin and renin-angiotensin systems has a thrombo-regulatory role independent of the contact pathway. At the level of the G-protein coupled receptors of these systems, defective bradykinin signaling due to attenuated bradykinin formation and/or decreased B2 receptor expression, as seen in murine prekallikrein and B2 receptor null mice, respectively, leads to compensatory overexpressed Mas, the receptor for angiotensin-(1-7) of the renin-angiotensin system. Mas stimulation and/or its increased expression contributes to maintaining a healthy vascular homeostasis by generating graded elevation of plasma prostacyclin which reduces thrombosis through two independent pathways: (1) increasing the vasoprotective transcription factor Sirtuin 1 to suppress tissue factor expression, and (2) inhibiting platelet activation. This review will summarize the recent advances in this field that support these understandings. Appreciating these subtle mechanisms help to develop novel anti-thrombotic strategies by targeting the vascular receptors in the renin-angiotensin and the kallikrein/kinin systems to maintain healthy vascular homeostasis.

Mechanistic definition of the cardiovascular mPGES-1/COX-2/ADMA axis

AIMS

Cardiovascular side effects caused by non-steroidal anti-inflammatory drugs (NSAIDs), which all inhibit cyclooxygenase (COX)-2, have prevented development of new drugs that target prostaglandins to treat inflammation and cancer. Microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors have efficacy in the NSAID arena but their cardiovascular safety is not known. Our previous work identified asymmetric dimethylarginine (ADMA), an inhibitor of endothelial nitric oxide synthase, as a potential biomarker of cardiovascular toxicity associated with blockade of COX-2. Here, we have used pharmacological tools and genetically modified mice to delineate mPGES-1 and COX-2 in the regulation of ADMA.

METHODS AND RESULTS

Inhibition of COX-2 but not mPGES-1 deletion resulted in increased plasma ADMA levels. mPGES-1 deletion but not COX-2 inhibition resulted in increased plasma prostacyclin levels. These differences were explained by distinct compartmentalization of COX-2 and mPGES-1 in the kidney. Data from prostanoid synthase/receptor knockout mice showed that the COX-2/ADMA axis is controlled by prostacyclin receptors (IP and PPARβ/δ) and the inhibitory PGE2 receptor EP4, but not other PGE2 receptors.

CONCLUSION

These data demonstrate that inhibition of mPGES-1 spares the renal COX-2/ADMA pathway and define mechanistically how COX-2 regulates ADMA.