A Long-Acting Prostacyclin Agonist with Thromboxane Inhibitory Activity for Pulmonary Hypertension

Hypoxia-induced signaling in the cardiovascular system: pathogenesis and therapeutic targets

Hypoxia, characterized by reduced oxygen concentration, is a significant stressor that affects the survival of aerobic species and plays a prominent role in cardiovascular diseases. From the research history and milestone events related to hypoxia in cardiovascular development and diseases, The "hypoxia-inducible factors (HIFs) switch" can be observed from both temporal and spatial perspectives, encompassing the occurrence and progression of hypoxia (gradual decline in oxygen concentration), the acute and chronic manifestations of hypoxia, and the geographical characteristics of hypoxia (natural selection at high altitudes). Furthermore, hypoxia signaling pathways are associated with natural rhythms, such as diurnal and hibernation processes. In addition to innate factors and natural selection, it has been found that epigenetics, as a postnatal factor, profoundly influences the hypoxic response and progression within the cardiovascular system. Within this intricate process, interactions between different tissues and organs within the cardiovascular system and other systems in the context of hypoxia signaling pathways have been established. Thus, it is the time to summarize and to construct a multi-level regulatory framework of hypoxia signaling and mechanisms in cardiovascular diseases for developing more therapeutic targets and make reasonable advancements in clinical research, including FDA-approved drugs and ongoing clinical trials, to guide future clinical practice in the field of hypoxia signaling in cardiovascular diseases.

Pathogenic Mechanisms of Pulmonary Arterial Hypertension: Homeostasis Imbalance of Endothelium-Derived Relaxing and Contracting Factors

Pulmonary arterial hypertension (PAH) is a progressive and fatal disease. Sustained pulmonary vasoconstriction and concentric pulmonary vascular remodeling contribute to the elevated pulmonary vascular resistance and pulmonary artery pressure in PAH. Endothelial cells regulate vascular tension by producing endothelium-derived relaxing factors (EDRFs) and endothelium-derived contracting factors (EDCFs). Homeostasis of EDRF and EDCF production has been identified as a marker of the endothelium integrity. Impaired synthesis or release of EDRFs induces persistent vascular contraction and pulmonary artery remodeling, which subsequently leads to the development and progression of PAH. In this review, the authors summarize how EDRFs and EDCFs affect pulmonary vascular homeostasis, with special attention to the recently published novel mechanisms related to endothelial dysfunction in PAH and drugs associated with EDRFs and EDCFs.

Pulmonary hypertension associated with cardiopulmonary bypass and cardiac surgery

BACKGROUND AND AIM

Pulmonary hypertension (PH) is frequently associated with cardiovascular surgery and is a common complication that has been observed after surgery utilizing cardiopulmonary bypass (CPB). The purpose of this review is to explain the characteristics of PH, the mechanisms of PH induced by cardiac surgery and CPB, treatments for postoperative PH, and future directions in treating PH induced by cardiac surgery and CPB using up-to-date findings.

METHODS

The PubMed database was utilized to find published articles.

RESULTS

There are many mechanisms that contribute to PH after cardiac surgery and CPB which involve pulmonary vasomotor dysfunction, cyclooxygenase, the thromboxane A2 and prostacyclin pathway, the nitric oxide pathway, inflammation, and oxidative stress. Furthermore, there are several effective treatments for postoperative PH within different types of cardiac surgery.

CONCLUSIONS

By possessing a deep understanding of the mechanisms that contribute to PH after cardiac surgery and CPB, researchers can develop treatments for clinicians to use which target the mechanisms of PH and ultimately reduce and/or eliminate postoperative PH. Additionally, learning about the most up-to-date studies regarding treatments can allow clinicians to choose the best treatments for patients who are undergoing cardiac surgery and CPB.

Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension in preclinical models

Congenital diaphragmatic hernia (CDH)-related deaths are the largest contributor to in-hospital neonatal deaths in children with congenital malformations. Morbidity and mortality in CDH are directly related to the development of pulmonary hypertension (PH). Current treatment consists of supportive measures. To date, no pharmacotherapy has been shown to effectively reverse the hallmark finding of pulmonary vascular remodeling that is associated with pulmonary hypertension in CDH (CDH-PH). As such, there is a great need for novel therapies to effectively manage CDH-PH. Our review aims to evaluate emerging therapies, and specifically focuses on those that are still under investigation and not approved for clinical use by the Food and Drug Administration. Therapies were categorized into antenatal pharmacotherapies or antenatal regenerative therapies and assessed on their method of administration, safety profile, the effect on pulmonary vascular pathophysiology, and overall efficacy. In general, emerging antenatal pharmaceutical and regenerative treatments primarily aim to alleviate pulmonary vascular remodeling by restoring normal function and levels of key regulatory factors involved in pulmonary vascular development and/or in promoting angiogenesis. Overall, while these emerging therapies show great promise for the management of CDH-PH, most require further assessment of safety and efficacy in preclinical models before translation into the clinical setting. IMPACT: Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension (CDH-PH) show promise to effectively mitigate vascular remodeling in preclinical models. Further investigation is needed in preclinical and human studies to evaluate safety and efficacy prior to translation into the clinical arena. This review offers a comprehensive and up-to-date summary of emerging therapies currently under investigation in experimental animal models. There is no cure for CDH-PH. This review explores emerging therapeutic options for the treatment of CDH-PH and evaluates their impact on key molecular pathways and clinical markers of disease to determine efficacy in the preclinical stage.

Innovative therapeutic strategy using prostaglandin I2 agonist (ONO1301) combined with nano drug delivery system for pulmonary arterial hypertension

Clinical outcomes of pulmonary arterial hypertension (PAH) may be improved using targeted delivery system. We investigated the efficacy of ONO1301 (prostacyclin agonist) nanospheres (ONONS) in Sugen5416/hypoxia rat models of PAH. The rats were injected with saline (control) or ONONS (n = 10, each) on days 21 and 28, respectively. Hepatocyte growth factor (HGF)-expressing fibroblasts and inflammatory cytokines were measured. Cardiac performance was assessed and targeted delivery was monitored in vivo, using Texas red-labeled nanoparticles. Compared with control, HGF-expressing fibroblasts and HGF expression levels were significantly higher in the ONONS group, while the levels of interleukin-6, interleukin-1β, transforming growth factor-β, and platelet-derived growth factor were lower. Histological assessment revealed significant amelioration of the percent medial wall thickness in pulmonary vasculature of rats in the ONONS group. Rats in the ONONS group showed decreased proliferating cell nuclear antigen-positive smooth muscle cells and improved right ventricle pressure/left ventricle pressure. No difference was seen in the accumulation of Texas red-labeled nanoparticles in the brain, heart, liver, and spleen between PAH and normal rats. However, a significant area of nanoparticles was detected in the lungs of PAH rats. ONONS effectively ameliorated PAH, with selective delivery to the damaged lung.

Single injection of sustained-release prostacyclin analog ONO-1301-MS ameliorates hypoxic toxicity in the murine model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by several pathologies including oxidative stress, apoptosis, neuroinflammation, and glutamate toxicity. Although multiple reports suggest that ischemia and hypoxia in the spinal cord plays a pivotal role in the pathogenesis of ALS, the precise role of hypoxia in disease progression remains unknown. In this study, we detected higher expression levels of Hypoxia-inducible factor 1-alpha (HIF-1α), a key regulator of cellular responses to hypoxia, in the spinal cord of ALS patients and in the transgenic mice overexpressing the familial ALS-associated G93A SOD1 mutation (mSOD1^G93A mice) compared to controls. Single subcutaneous administration of sustained-release prostacyclin analog ONO-1301-MS to mSOD1^G93A mice abrogated the expression of HIF-1α in their spinal cords, as well as erythropoietin (EPO) and vascular endothelial growth factor (VEGF), both of which are downstream to HIF-1α. Furthermore, ONO-1301-MS increased the level of mature brain-derived neurotrophic factor (BDNF) and ATP production in the spinal cords of mSOD1^G93A mice. At late disease stages, the motor function and the survival of motor neurons of ONO-1301-MS-treated mSOD1^G93A mice was significantly improved compared to vehicle-treated mSOD1^G93A mice. Our data suggest that vasodilator therapy modulating local blood flow in the spinal cord has beneficial effects against ALS disease progression.

Enhanced Pulmonary Vascular and Alveolar Development via Prenatal Administration of a Slow-Release Synthetic Prostacyclin Agonist in Rat Fetal Lung Hypoplasia

Lung hypoplasia and pulmonary hypertension are the major causes of mortality in neonates with congenital diaphragmatic hernia (CDH). Although the prostaglandin pathway plays a pivotal role in lung development, the reported efficacy of postnatal prostaglandin agonist treatment is suboptimal. We hypothesized that prenatal treatment with ONO-1301SR, a slow-release form of a novel synthetic prostacyclin agonist with thromboxane inhibitory activity, might enhance the development of lungs exhibiting hypoplasia in the fetal period. On embryonic day (E) 9.5, nitrofen was given to pregnant Sprague-Dawley rats to establish a CDH-related lung hypoplasia model, whereas normal rats received the vehicle only. The same day, either ONO-1301SR or a placebo was also randomly administered. On E21.5, the fetuses of the normal group and those exhibiting CDH were analyzed. Prenatal ONO-1301SR administration had no influence on the incidence of nitrofen-induced CDH. The lung-to-body weight ratio in the CDH+ONO group was greater than that in the CDH group. Histologically, the medial wall in the CDH+ONO group was two-thirds thinner than that in the CDH group. In addition, the number of Ttf-1-positive cells and the capillary density were ≥1.5 times greater in the CDH+ONO group than in the CDH group, and this increase was associated with higher expression of vascular endothelial growth factor and stromal cell-derived factor in the CDH+ONO group, suggesting enhanced development of the alveolar and capillary networks. Thus, prenatal ONO-1301SR was protective against the progression of lung hypoplasia associated with CDH in a nitrofen-induced rat model, indicating the potential of this treatment for pathologies exhibiting lung hypoplasia.

A sustained-release drug-delivery system of synthetic prostacyclin agonist, ONO-1301SR: a new reagent to enhance cardiac tissue salvage and/or regeneration in the damaged heart

Cardiac failure is a major cause of mortality and morbidity worldwide, since the standard treatment for cardiac failure in the clinical practice is chiefly to focus on removal of insults against the heart or minimisation of additional factors to exacerbate cardiac failure, but not on regeneration of the damaged cardiac tissue. A synthetic prostacyclin agonist, ONO-1301, has been developed as a long-acting drug for acute and chronic pathologies related to regional ischaemia, inflammation and/or interstitial fibrosis by pre-clinical studies. In addition, poly-lactic co-glycolic acid-polymerised form of ONO-1301, ONO-1301SR, was generated to achieve a further sustained release of this drug into the targeted region. This unique reagent has been shown to act on fibroblasts, vascular smooth muscle cells and endothelial cells in the tissue via the prostaglandin IP receptor to exert paracrinal release of multiple protective factors, such as hepatocyte growth factor, vascular endothelial growth factor or stromal cell-derived factor-1, into the adjacent damaged tissue, which is salvaged and/or regenerated as a result. Our laboratory developed a new surgical approach to treat acute and chronic cardiac failure using a variety of animal models, in which ONO-1301SR is directly placed over the cardiac surface to maximise the therapeutic effects and minimise the systemic complications. This review summarises basic and pre-clinical information of ONO-1301 and ONO-1301SR as a new reagent to enhance tissue salvage and/or regeneration, with a particular focus on the therapeutic effects on acute and chronic cardiac failure and underlying mechanisms, to explore a potential in launching the clinical study.

The novel prostaglandin I2 mimetic ONO-1301 escapes desensitization in an antiplatelet effect due to its inhibitory action on thromboxane A2 synthesis in mice

ONO-1301 [(E)-[5-[2-[1-phenyl-1-(3-pyridyl)methylidene-aminooxy]ethyl]-7,8-dihydronaphthalene-1-yloxy]acetic acid] is a novel prostaglandin (PG) I2 mimetic with inhibitory activity on the thromboxane (TX) A2 synthase. Interestingly, ONO-1301 retains its inhibitory effect on platelet aggregation after repeated administration, while beraprost, a representative agonist for the PGI2 receptor (IP), loses its inhibitory effect after repeated administration. In the present study, we intended to clarify the mechanism by which ONO-1301 escapes desensitization of an antiplatelet effect. In platelets prepared from wild-type mice, ONO-1301 inhibited collagen-induced aggregation and stimulated cAMP production in an IP-dependent manner. In addition, ONO-1301 inhibited arachidonic acid-induced TXA2 production in platelets lacking IP. Despite the decrease in stimulatory action on cAMP production, the antiplatelet effect of ONO-1301 hardly changed after repeated administration for 10 days in wild-type mice. Noteworthy, beraprost could retain its antiplatelet effect after repeated administration in combination with a low dose of ozagrel, a TXA2 synthase inhibitor. Therefore, we hypothesized that chronic IP stimulation by beraprost induces an increase in TXA2 production, leading to reduction in the antiplatelet effect. As expected, repeated administration of beraprost increased the plasma and urinary levels of a TXA2 metabolite, while ONO-1301 did not increase them significantly. In addition, beraprost could retain the ability to inhibit platelet aggregation after repeated administration in mice lacking the TXA2 receptor (TP). These results indicate that TP-mediated signaling participates in platelet desensitization against IP agonists and that simultaneous inhibition of TXA2 production confers resistance against desensitization on IP agonists.

Optimal management of pulmonary arterial hypertension: prognostic indicators to determine treatment course

Pulmonary arterial hypertension (PAH) is a rapidly progressive pulmonary vascular disease with a multifactorial etiopathogenesis that can result in right-sided heart failure and death. A number of studies indicate that an early therapeutic intervention yields better results on disease progression as compared to delayed treatment. In this review, we will analyze treatment strategies that may be used for monitoring disease progression and for guiding treatment decisions. Several factors (ie, symptoms, functional class, exercise capacity as assessed by a walking test and cardiopulmonary stress testing, hemodynamic parameters, cardiac magnetic resonance imaging, and plasma levels of biochemical markers) have been prognostic of survival. These indicators may be used both at the time of diagnosis and during treatment follow-up. No resolutive therapy is currently available for PAH; however, in the last decade, the advent of specific pharmacological treatments has given new hope to patients suffering from this debilitating disease with a poor prognosis. Combination drug therapies offer increased benefits over monotherapy, and current guidelines recommend a sequential “add on” design approach for patients in functional class II–IV. The goal-oriented “treat to target” therapy sets the timing for treatment escalation in case of inadequate response to currently known prognostic indicators. To date, further longitudinal studies should be urgently conducted to identify new goals that may improve therapeutic strategies in order to optimize personalized treatment in PAH patients.

Novel long-acting prostacyclin agonist (ONO-1301) with an angiogenic effect: promoting synthesis of hepatocyte growth factor and increasing cyclic AMP concentration via IP-receptor signaling

The purpose of this study was to evaluate the angiogenic potency of ONO-1301, a novel prostacyclin agonist, using a murine sponge model. Solutions of ONO-1301 or hepatocyte growth factor (HGF), as a positive control, were injected into sponges in the backs of mice, daily for 14 days. Hemoglobin and HGF levels in the sponge were increased for up to 14 days on daily treatment with ONO-1301 while on HGF treatment, they peaked on day 7 and had decreased again by day 14. ONO-1301 also upregulated c-Met expression for 14 days in a dose-dependent manner. When the mice were pretreated with an antibody to HGF or the prostaglandin I (IP)-receptor antagonist CAY10441, the angiogenic effect of ONO-1301 was dramatically reduced. Plasma concentrations of cyclic adenosine monophosphate (cAMP) were increased in a dose-dependent manner by once daily treatment with ONO-1301 for 14 days. This effect was reduced by pretreatment with the IP-receptor antagonist. In conclusion, hemoglobin level was increased by repeated treatment with ONO-1301 for 14 days. It is suggested that ONO-1301 induced angiogenesis by promoting the synthesis of HGF and upregulated c-Met expression, followed by an increase in cAMP concentrations mediated by IP-receptor signaling.

A single injection of a sustained-release prostacyclin analog (ONO-1301MS) suppresses airway inflammation and remodeling in a chronic house dust mite-induced asthma model

ONO-1301, a novel prostacyclin agonist with thromboxane A2 synthase inhibitory activity, is a useful agent for ameliorating airway allergic inflammation; however, its short-action feature implies a requirement for the frequent administration of this drug. Therefore, we investigated the effects of ONO-1301-loaded poly (d,l-lactic-co-glycolic acid) microspheres (ONO-1301MS; to release ONO-1301 for 3 weeks) on the airway inflammation and remodeling in chronic house dust mite (HDM)-induced model. Balb/c mice were exposed to an HDM extract intranasally for 5 days/week for 5 consecutive weeks. The mice received a single subcutaneous injection of ONO-1301MS or vehicle after 3 weeks of HDM exposure, followed by 2 additional weeks of HDM exposure. Forty-eight hours after the last HDM exposure, airway hyperresponsiveness to methacholine was assessed and bronchoalveolar lavage was performed. Lung specimens were excised and stained to check for goblet cell metaplasia, airway smooth muscle hypertrophy, and submucosal fibrosis. Mice receiving ONO-1301MS showed significantly lower airway hyperresponsiveness, airway eosinophilia, and induced T helper 2 cytokine production compared with mice receiving the vehicle. Histological findings such as goblet cell metaplasia, airway smooth muscle hypertrophy, and submucosal fibrosis were decreased in ONO-1301MS-treated mice compared with vehicle-treated mice. A single administration of ONO-1301MS achieved sustained elevation of its circulating level for 3 weeks. These data suggest that a single administration of ONO-1301MS may suppress airway hyperresponsiveness, airway allergic inflammation, and development of airway remodeling in chronic HDM-induced asthma model. This agent may be effective as an anti-inflammatory and remodeling drug in the practical treatment of asthma.

A slow-releasing form of prostacyclin agonist (ONO1301SR) enhances endogenous secretion of multiple cardiotherapeutic cytokines and improves cardiac function in a rapid-pacing-induced model of canine heart failure

OBJECTIVES

Cardiac functional deterioration in dilated cardiomyopathy (DCM) is known to be reversed by intramyocardial up-regulation of multiple cardioprotective factors, whereas a prostacyclin analog, ONO1301, has been shown to paracrinally activate interstitial cells to release a variety of protective factors. We here hypothesized that intramyocardial delivery of a slow-releasing form of ONO1301 (ONO1301SR) might activate regional myocardium to up-regulate cardiotherapeutic factors, leading to regional and global functional recovery in DCM.

METHODS AND RESULTS

ONO1301 elevated messenger RNA and protein level of hepatocyte growth factor, vascular endothelial growth factor, and stromal-derived factor-1 of normal human dermal fibroblasts in a dose-dependent manner in vitro. Intramyocardial delivery of ONO1301SR, which is ONO1301 mixed with polylactic and glycolic acid polymer (PLGA), but not that of PLGA only, yielded significant global functional recovery in a canine rapid pacing-induced DCM model, assessed by echocardiography and cardiac catheterization (n = 5 each). Importantly, speckle-tracking echocardiography unveiled significant regional functional recovery in the ONO1301-delivered territory, consistent to significantly increased vascular density, reduced interstitial collagen accumulation, attenuated myocyte hypertrophy, and reversed mitochondrial structure in the corresponding area.

CONCLUSIONS

Intramyocardial delivery of ONO1301SR, which is a PLGA-coated slow-releasing form of ONO1301, up-regulated multiple cardiotherapeutic factors in the injected territory, leading to region-specific reverse left ventricular remodeling and consequently a global functional recovery in a rapid-pacing-induced canine DCM model, warranting a further preclinical study to optimize this novel drug-delivery system to treat DCM.

Gene transfer therapy by either type 1 or type 2 adeno-associated virus expressing human prostaglandin I2 synthase gene is effective for treatment of pulmonary arterial hypertension

Prostaglandin I(2) (PGI(2)) plays an important role in the clinical treatment of pulmonary arterial hypertension (PAH). However, the administration of PGI(2) involves continuous intravenous infusion using an indwelling catheter, which limits the patient's quality of life and increases the risk of infection. We therefore investigated whether human PGI(2) synthase (hPGIS) gene transfer using an adeno-associated virus (AAV) vector is still effective in a mouse model of PAH and tested for differences in the therapeutic efficacy of PAH among AAV serotypes. The PAH was induced by subjecting mice to hypoxia (10% O(2)). Type 1 AAV expressing hPGIS (AAV1-hPGIS) or type 2 AAV expressing hPGIS (AAV2-hPGIS) was injected into the thigh muscle of mice. Both vectors expressing hPGIS produced strong hPGIS protein expression in the mouse thigh skeletal muscles after 8 weeks of hypoxia. The administration of AAV1-hPGIS or AAV2-hPGIS also significantly inhibited the hypoxia-induced increase in right ventricular systolic pressure, the ratio of right ventricular weight to body weight (RV/BW), and the ratio of RV weight to left ventricular plus septal weight (RV/LV + S), and significantly attenuated the hypoxia-induced increase in medial wall thickness of peripheral pulmonary arteries. Furthermore, there were no significant differences in the degree of amelioration in RV systolic pressure, RV/BW, RV/LV + S, and percentage of wall thickness of peripheral pulmonary arteries between AAV1-hPGIS and AAV2-hPGIS administrations. In conclusion, we revealed that type 1 and type 2 AAV are equally effective for the treatment of PAH in a hypoxia-induced mouse model. Gene-transfer therapy using AAV expressing hPGIS is, therefore, a potential therapeutic breakthrough for PAH.

Sustained-release prostacyclin analog ONO-1301 ameliorates tubulointerstitial alterations in a mouse obstructive nephropathy model

Tubulointerstitial injuries are crucial histological alterations that predict the deterioration of renal function in chronic kidney disease. ONO-1301, a novel sustained-release prostacyclin analog, accompanied by thromboxane synthase activity, exerts therapeutic effects on experimental pulmonary hypertension, lung fibrosis, cardiomyopathy, and myocardial ischemia, partly associated with the induction of hepatocyte growth factor (HGF). In the present study, we examined the therapeutic efficacies of ONO-1301 on tubulointerstitial alterations induced by unilateral ureteral obstruction (UUO). After inducing unilateral ureteral obstruction in C57/BL6J mice, a single injection of sustained-release ONO-1301 polymerized with poly (D,L-lactic-co-glycolic acid) sustained-release ONO-1301 (SR-ONO) significantly suppressed interstitial fibrosis, accumulation of types I and III collagen, increase in the number of interstitial fibroblast-specific protein-1 (FSP-1)(+) cells, and interstitial infiltration of monocytes/macrophages (F4/80(+)) in the obstructed kidneys (OBK; day 7). Treatment with SR-ONO significantly suppressed the increase of the renal levels of profibrotic factor TGF-β and phosphorylation of Smad2/3, and elevated the renal levels of HGF in the OBK. In cultured mouse proximal tubular epithelial cells (mProx24), ONO-1301 significantly ameliorated the expression of fibroblast-specific protein-1 and α-smooth muscle actin as well as phosphorylation of Smad3 and increased the expression of zonula occludens-1 and E-cadherin in the presence of TGF-β1 as detected by immunoblot and immunocytochemistry, partly dependent on PGI(2) receptor-mediated signaling. Administration of rabbit anti-HGF antibodies, but not the control IgG, partly reversed the suppressive effects of SR-ONO on tubulointerstitial injuries in the OBK. Taken together, our findings suggest the potential therapeutic efficacies of ONO-1301 in suppressing tubulointerstitial alterations partly mediated via inducing HGF, an antifibrotic factor counteracting TGF-β.

Single injection of ONO-1301-loaded PLGA microspheres directly after ischaemia reduces ischaemic damage in rats subjected to middle cerebral artery occlusion

OBJECTIVES

ONO-1301 was developed as a novel long-acting prostacyclin agonist with thromboxane synthase inhibitory activity. In this study, we investigated the therapeutic time window of oral ONO-1301 and the effect of a single subcutaneous injection of ONO-1301-loaded poly(lactide-co-glycolide) (PLGA) microspheres (ONO-1301 PLGA MS) on infarction volume, functional deficits and plasma ONO-1301 levels following a 1 h middle cerebral artery occlusion (MCAO) in rats.

METHODS

Rats were treated with ONO-1301 (3 mg/kg) orally twice-daily starting 1 (directly), 6 or 24 h after MCAO. Rats received a single subcutaneous injection of ONO-1301 PLGA MS (10 mg/kg) directly after MCAO. Neurological scores were evaluated directly after, 1 and 6 h, 1, 2, and 3 days after MCAO. Infarct volume, oedema and plasma ONO-1301 levels were measured three days after MCAO.

KEY FINDINGS

Neurological scores, oedema and infarct volume were all significantly improved in rats repeatedly treated with oral ONO-1301 and subcutaneous ONO-1301 PLGA MS directly after MCAO. Plasma ONO-1301 levels were significantly lower in rats treated directly after MCAO (either with ONO-1301 or ONO-1301 PLGA MS) than in rats treated 6 h or 24 h after MCAO.

CONCLUSIONS

ONO-1301 PLGA MS subcutaneous treatment directly after MCAO showed a neuroprotective effect as well as oral ONO-1301. This treatment should be clinically more convenient than ONO-1301 oral administration since it is delivered as a single treatment after MCAO.

Prostacyclin: an inflammatory paradox

Prostacyclin (PGI₂) is a member of the prostaglandin family of bioactive lipids. Its best-characterized role is in the cardiovascular system, where it is released by vascular endothelial cells, serving as a potent vasodilator and inhibitor of platelet aggregation. In recent years, prostacyclin (PGI₂) has also been shown to promote differentiation and inhibit proliferation in vascular smooth muscle cells. In addition to these well-described homeostatic roles within the cardiovascular system, prostacyclin (PGI₂) also plays an important role as an inflammatory mediator. In this review, we focus on the contribution of prostacyclin (PGI₂) as both a pathophysiological mediator and therapeutic agent in three major inflammatory-mediated disease processes, namely rheumatoid arthritis, where it promotes disease progression (“pro-inflammatory”), along with pulmonary vascular disease and atherosclerosis, where it inhibits disease progression (“anti-inflammatory”). The emerging role of prostacyclin (PGI₂) in this context provides new opportunities for understanding the complex molecular basis for inflammatory-related diseases, and insights into the development of current and future anti-inflammatory treatments.

Intermittent administration of a sustained-release prostacyclin analog ONO-1301 ameliorates renal alterations in a rat type 1 diabetes model

Diabetic nephropathy is the most common pathological disorder predisposing end-stage renal disease. ONO-1301 is a novel sustained-release prostacyclin analog possessing thromboxane (TX) synthase inhibitory activity. Here, we aimed to investigate the therapeutic efficacies of ONO-1301 in a rat type 1 diabetic nephropathy model. Streptozotocin (STZ)-induced diabetic rats received injections of slow-release form of ONO-1301 (SR-ONO) every 3 weeks. Animals were sacrificed at Week 14. SR-ONO significantly suppressed albuminuria, glomerular hypertrophy, mesangial matrix accumulation, glomerular accumulation of monocyte/macrophage, increase in glomerular levels of pro-fibrotic factor transforming growth factor (TGF)-beta1 and the number of glomerular alpha-smooth muscle actin (SMA)(+) cells in diabetic animals. The glomerular levels of hepatocyte growth factor (HGF) were significantly increased in SR-ONO-treated diabetic animals. Taken together, these results suggest the potential therapeutic efficacy of intermittent administration of SR-ONO in treating diabetic nephropathy potentially via inducing HGF, thus counteracting the pro-fibrotic effects of TGF-beta1.

Novel approaches to treat experimental pulmonary arterial hypertension: a review

Background. Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by an increase in pulmonary artery pressure leading to right ventricular (RV) hypertrophy, RV failure, and ultimately death. Current treatments can improve symptoms and reduce severity of the hemodynamic disorder but gradual deterioration in their condition often necessitates a lung transplant. Methods and Results. In experimental models of PAH, particularly the model of monocrotaline-induced pulmonary hypertension, efficacious treatment options tested so far include a spectrum of pharmacologic agents with actions such as anti-mitogenic, proendothelial function, proangiogenic, antiinflammatory and antioxidative. Emerging trends in PAH treatment are gene and cell therapy and their combination, like (progenitor) cells enriched with eNOS or VEGF gene. More animal data should be collected to investigate optimal cell type, in vitro cell transduction, route of administration, and number of cells to inject. Several recently discovered and experimentally tested interventions bear potential for therapeutic purposes in humans or have been shown already to be effective in PAH patients leading to improved life expectation and better quality of life. Conclusion. Since many patients remain symptomatic despite therapy, we should encourage research in animal models of PAH and implement promising treatments in homogeneous groups of PAH patients.

A prostacyclin agonist with thromboxane inhibitory activity for airway allergic inflammation in mice

BACKGROUND

ONO-1301 is a novel drug that acts as a prostacyclin agonist with thromboxane A(2) (TxA(2)) synthase inhibitory activity. We investigated the effect of ONO-1301 on development of airway allergic inflammation.

METHODS

Mice sensitized and challenged to ovalbumin (OVA) received ONO-1301, OKY-046 (TxA(2) synthase inhibitor), beraprost, a prostacyclin receptor (IP) agonist, ONO-1301 plus CAY10449 (selective IP antagonist) or vehicle during the challenge period. Twenty-four hours after the OVA challenge, airway hyperresponsiveness (AHR) to methacholine was assessed and bronchoalveolar lavage was performed. Lung specimens were excised for goblet cell staining and analysis of lung dendritic cells (DCs). Bone marrow-derived dendritic cells (BMDCs) were generated, in the presence or absence of drugs, for analysis of DC function.

RESULTS

Mice that received ONO-1301 showed significantly lower AHR, airway eosinophilia, T-helper type 2 cytokine levels, mucus production and lung DCs numbers than vehicle-treated mice. These effects of ONO-1301 were mostly reversed by CAY10449. BMDCs treated with ONO-1301 alone showed lower DC functions, such as expression of costimulatory factors or stimulation to spleen T cells.

CONCLUSIONS

These data suggest that ONO-1301 may suppress AHR and airway allergic inflammation through modulation of DCs, mainly mediated through the IP receptor. This agent may be effective as an anti-inflammatory drug in the treatment of asthma.

AAV-PGIS gene transfer improves hypoxia-induced pulmonary hypertension in mice

Although prostaglandin I2 is used to treat pulmonary hypertension (PH), continuous intravenous administration is necessary. We investigated whether human PGIS (hPGIS) gene transfer using adeno-associated virus (AAV) vector was effective in treating an animal model of PH. PH was induced by subjecting mice to 10% O(2). Type 1-AAV-hPGIS was injected into the left thigh muscle after 24h. Significant PH was induced at 8 weeks, but AAV-hPGIS administration significantly inhibited the increase in RV systolic pressure. PH-induced BNP up-regulation in the RV was reduced to the control level. The severe medial thickening of pulmonary arteries in PH was significantly suppressed by AAV-hPGIS. The hPGIS gene was detected only on the injected side. No pathological changes were observed at the injected site. At 24 weeks, all PH mice were deceased, but 47% of AAV-hPGIS-treated mice survived. This study demonstrated that AAV-hPGIS administration was effective in treating PH and prolonging survival.

Emerging therapies for pulmonary arterial hypertension

Pulmonary arterial hypertension is characterised by increased pulmonary vascular resistance due to increased vascular tone and structural remodelling of pulmonary vessels. The therapies that are in use so far have been developed to correct endothelial dysfunction and reduce vasomotor tone. These treatments have a limited effect on the remodelling process and, increasingly, the focus is turning to potent strategies for inhibiting vascular proliferation and promoting vascular apoptosis. Multiple novel targets have been uncovered over the last 5 years and several are now in early clinical trials. At present, it is clear that there is no single treatment for the condition. Although this is the case, studies are investigating the role of combining therapies that are already established.

Pharmacologic treatment for pulmonary arterial hypertension

PURPOSE OF REVIEW

Pulmonary arterial hypertension (PAH) has been a disease with limited treatment options and poor prognosis. This article reviews the recent advances that took place in the medical management of PAH.

RECENT FINDINGS

Sildenafil is a type 5 cGMP-specific phosphodiesterase inhibitor originally developed to treat erectile dysfunction. Multiple uncontrolled and randomized controlled trials have proven that it is useful in the treatment of PAH and it was approved by the US Food and Drug Administration. The switch from continuous intravenous infusion of epoprostenol to subcutaneous infusion of treprostinil has been proven feasible and safe. Bosentan has been shown effective as a monotherapy and it also improves survival in patients with functional classes III and IV. In smaller clinical trials bosentan has improved symptoms in different forms of PAH. Combinations of drugs of different classes such as prostanoids, endothelin receptor blockers and sildenafil are tested, and such a strategy improves both symptoms and survival. Animal models and anecdotal clinical experience suggest the possibility of using imatinib mesylate in PAH.

SUMMARY

With the approval of sildenafil, treatment options for this difficult disease have improved significantly. Combinations of drugs of different groups are promising and need further exploration.

How valid are animal models to evaluate treatments for pulmonary hypertension?

Various animal models of pulmonary hypertension (PH) exist, among which injection of monocrotaline (MCT) and exposure to hypoxia are used most frequently. These animal models have not only been used to characterize the pathophysiology of PH and its sequelae such as right ventricular hypertrophy and failure, but also to test novel therapeutic strategies. This manuscript summarizes the available treatment studies in animal models of PH, and compares the findings to those obtained in patients with PH. The analysis shows that all approaches which have proven successful in patients, most notably prostacyclin and its analogs and endothelin receptor antagonists, are also effective in various animal models. However, the opposite it not always true. Therefore, promising results in animals have to be interpreted carefully until confirmed in clinical studies.