Cyclooxygenase-2 inhibition prevents renal toxicity but not hypertension during sunitinib treatment

BACKGROUND

Anticancer angiogenesis inhibitors cause hypertension and renal injury. Previously we observed in rats that high-dose aspirin (capable of blocking cyclooxygenase (COX)-1 and-2) was superior to low-dose aspirin (blocking COX-1 only) to prevent these side-effects during treatment with the angiogenesis inhibitor sunitinib, suggesting a role for COX-2. High-dose aspirin additionally prevented the rise in COX-derived prostacyclin (PGI2). Therefore, we studied the preventive effects of selective COX-2 inhibition and the hypothesized contributing role of PGI2 during angiogenesis inhibition.

METHODS

Male WKY rats received vehicle, sunitinib ((SU), 14 mg/kg/day) alone or combined with COX-2 inhibition (celecoxib, 10 mg/kg/day) or a PGI2 analogue (iloprost, 100 μg/kg/day) for 8 days (n = 8-9 per group). Mean arterial pressure (MAP) was measured via radiotelemetry, biochemical measurements were performed via ELISA and vascular function was assessed via wire myography.

RESULTS

SU increased MAP (17±1mmHg versus 3±1mmHg after vehicle on day 4, P < 0.002), which could not be significantly blunted by celecoxib (+12±3mmHg on day 4, P = 0.247), but was temporarily attenuated by iloprost (treatment days 1 + 2 only). Urinary PGI2 (996 ± 112 versus 51 ± 11ng/24h after vehicle, P < 0.001), but not circulating PGI2 increased during SU, which remained unaffected by celecoxib and iloprost. Celecoxib reduced sunitinib-induced albuminuria (0.36 ± 0.05 versus 0.58 ± 0.05mg/24h after SU, P = 0.005). Wire myography demonstrated increased vasoconstriction to endothelin-1 after SU (Emax P = 0.005 versus vehicle), which remained unaffected by celecoxib or iloprost.

CONCLUSION

Selective COX-2 inhibition ameliorates albuminuria during angiogenesis inhibition with sunitinib, which most likely acts independently of PGI2. To combat angiogenesis inhibitor-induced hypertension, dual rather than selective COX-1/2 blockade seems preferential.

Anti-inflammatory effects of the prostacyclin analogue iloprost in an in vitro model of inflamed human dental pulp cells

Iloprost's anti-inflammatory effects on human dental pulp stem cells (HDPCs) are currently unknown. We hypothesized that iloprost could downregulate the expression of inflammatory-related genes and protein in an inflamed HDPC in vitro model. To induce inflammation, the HDPCs were treated with a cocktail of interleukin-1 beta, interferon-gamma, and tumour necrosis alpha, at a ratio of 1:10:100. Iloprost (10-6  M) was then added or not to the cultures. Interleukin-6 (IL-6) and interleukin-12 (IL-12) mRNA expression were assessed by real-time polymerase chain reaction. IL-6 protein expression was assessed by enzyme-linked immunosorbent assay. The results were analysed using one-way ANOVA or the Kruskal-Wallis test. The cytokine cocktail induced more robust IL-6 expression than LPS treatment. Iloprost slightly, yet significantly, downregulated IL-6 and IL-12 mRNA expression. These findings suggest that iloprost might be used as a beneficial component in vital pulp therapy.

Diverse effects of prostacyclin on angiogenesis-related processes in the porcine endometrium

Angiogenesis is important for endometrial remodeling in mature females. The endometrium synthesizes high amounts of prostacyclin (PGI2) but the role of PGI2 in angiogenesis-related events in this tissue was not fully described. In the present study, porcine endometrial endothelial (pEETH) cells and/or a swine umbilical vein endothelial cell line (G1410 cells) were used to determine the regulation of PGI2 synthesis and PGI2 receptor (PTGIR) expression by cytokines and to evaluate the effect of PGI2 on pro-angiogenic gene expression, intracellular signaling activation, cell proliferation and migration, cell cycle distribution, and capillary-like structure formation. We found that IL1β, IFNγ, and/or TNFα increased PGI2 secretion and PTGIR expression in pEETH cells. Iloprost (a PGI2 analogue) acting through PTGIR enhanced the transcript abundance of KDR, FGFR2, and ANGPT2 and increased proliferation of pEETH cells. This latter was mediated by PI3K and mTOR activation. In support, transfection of G1410 cells with siRNA targeting PGI2 synthase decreased pro-angiogenic gene expression and cell proliferation. Furthermore, iloprost accelerated the gap closure and promoted cell cycle progression. Intriguingly, the formation of capillary-like structures was inhibited but not completely blocked by iloprost. These findings point to a complex pleiotropic role of PGI2 in angiogenesis-related events in the porcine uterus.

Precision Cut Lung Slices as a Preclinical Model for Non-Small Cell Lung Cancer Chemoprevention

Lung cancer chemoprevention is critical to addressing cancer burden in high-risk populations. Chemoprevention clinical trials rely on data from preclinical models; however, in vivo studies have high financial, technical, and staffing requirements. Precision cut lung slices (PCLS) provide an ex vivo model that maintains the structure and function of native tissues. This model can be used for mechanistic investigations and drug screenings and reduces the number of animals and time required to test hypotheses compared with in vivo studies. We tested the use of PCLS for chemoprevention studies, demonstrating recapitulation of in vivo models. Treatment of PCLS with the PPARγ agonizing chemoprevention agent iloprost produced similar effects on gene expression and downstream signaling as in vivo models. This occurred in both wild-type tissue and Frizzled 9 knockout tissue, a transmembrane receptor required for iloprost's preventive activity. We explored new areas of iloprost mechanisms by measuring immune and inflammation markers in PCLS tissue and media, and immune cell presence with immunofluorescence. To demonstrate the potential for drug screening, we treated PCLS with additional lung cancer chemoprevention agents and confirmed activity markers in culture. PCLS offers an intermediate step for chemoprevention research between in vitro and in vivo models that can facilitate drug screening prior to in vivo studies and support mechanistic studies with more relevant tissue environments and functions than in vitro models.

PREVENTION RELEVANCE

PCLS could be a new model for premalignancy and chemoprevention research, and this work evaluates the model with tissue from prevention-relevant genetic and carcinogen exposed in vivo mouse models, in addition to evaluating chemoprevention agents.

Prenatal exposure to alcohol impairs responses of cerebral arterioles to activation of potassium channels: Role of oxidative stress

BACKGROUND

Potassium channels play an important role in the basal tone and dilation of cerebral resistance arterioles in response to many stimuli. However, the effect of prenatal alcohol exposure (PAE) on specific potassium channel function remains unknown. The first goal of this study was to determine the influence of PAE on the reactivity of cerebral arterioles to activation of ATP-sensitive potassium (KATP ) and BK channels. Our second goal was to determine whether oxidative stress contributed to potassium channel dysfunction of cerebral arterioles following PAE.

METHODS

We fed Sprague-Dawley dams a liquid diet with or without alcohol (3% EtOH) for the duration of their pregnancy (21 to 23 days). We examined in vivo responses of cerebral arterioles in control and PAE male and female offspring (14 to 16 weeks after birth) to activators of potassium channels (Iloprost [BK channels] and pinacidil [KATP channels]), before and following inhibition of oxidative stress with apocynin.

RESULTS

We found that PAE impaired dilation of cerebral arterioles in response to activation of potassium channels with iloprost and pinacidil, and this impairment was similar in male and female rats. In addition, treatment with apocynin reversed the impaired vasodilation to iloprost and pinacidil in PAE rats to levels observed in control rats. This effect of apocynin also was similar in male and female rats.

CONCLUSIONS

PAE induces dysfunction in the ability of specific potassium channels to dilate cerebral arterioles which appears to be mediated by an increase in oxidative stress. We suggest that these alterations in potassium channel function may contribute to the pathogenesis of cerebral vascular abnormalities and/or behavioral/cognitive deficits observed in fetal alcohol spectrum disorders.

The Prostacyclin Analogue Iloprost Modulates CXCL10 in Systemic Sclerosis

The prostacyclin analogue iloprost is used to treat vascular alterations and digital ulcers, the early derangements manifesting in systemic sclerosis (SSc), an autoimmune disease leading to skin and organ fibrosis. Bioindicator(s) of SSc onset and progress are still lacking and the therapeutic approach remains a challenge. The T helper 1 (Th1) chemokine interferon (IFN)γ-induced protein 10 (IP-10/CXCL10) associates with disease progression and worse prognosis. Endothelial cells and fibroblasts, under Th1-dominance, release CXCL10, further enhancing SSc’s detrimental status. We analyzed the effect of iloprost on CXCL10 in endothelial cells, dermal fibroblasts, and in the serum of SSc patients. Human endothelial cells and dermal fibroblasts activated with IFNγ/Tumor Necrosis Factor (TNF)α, with/without iloprost, were investigated for CXCL10 secretion/expression and for intracellular signaling cascade underlying chemokine release (Signal Transducer and Activator of Transcription 1, STAT1; Nuclear Factor kappa-light-chain-enhancer of activated B cells, NF-kB; c-Jun NH₂-terminal kinase, JNK: Phosphatidyl-Inositol 3-kinase (PI3K)/protein kinase B, AKT; Extracellular signal-Regulated Kinase 1/2, ERK1/2). CXCL10 was quantified in sera from 25 patients taking iloprost, satisfying the American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) 2013 classification criteria for SSc, and in sera from 20 SSc sex/age-matched subjects without therapy, previously collected. In human endothelial cells and fibroblasts, iloprost targeted CXCL10, almost preventing IFNγ/TNFα-dependent cascade activation in endothelial cells. In SSc subjects taking iloprost, serum CXCL10 was lower. These in vitro and in vivo data suggest a potential role of iloprost to limit CXCL10 at local vascular/dermal and systemic levels in SSc and warrant further translational research aimed to ameliorate SSc understanding/management.

Adenosine diphosphate-induced aggregation is enhanced in platelets obtained from patients with thrombotic primary antiphospholipid syndrome (t-PAPS): Role of P2Y12 -cAMP signaling pathway

BACKGROUND

Thrombotic antiphospholipid syndrome (t-PAPS) is characterized by arterial, venous, or microvascular occlusions, which are explained, in part, by the presence of antiphospholipid (aPL) antibodies. Although there is much evidence indicating that isolated aPL antibodies increase the activity of platelets obtained from healthy volunteers, platelet function in t-PAPS has not been as widely studied.

OBJECTIVE

To evaluate platelet reactivity in t-PAPS patients.

METHODS

Platelet aggregation, protein expression, and cyclic nucleotide levels were carried out in platelet rich plasma (PRP) or washed platelets (WPs) obtained from t-PAPS or healthy volunteers.

RESULTS

ADP-induced aggregation was significantly higher in PRP obtained from t-PAPS than obtained from the control. The protein expression of P2Y12 receptor and Gs alpha was significantly higher and lower, respectively in WPs from t-PAPS patients. In PRP incubated with iloprost or sodium nitroprusside, the residual platelet reactivity induced by ADP was still higher in PRP from t-PAPS than from the control. Lower intracellular levels of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) were observed in unstimulated PRP from t-PAPS patients. The protein expression of soluble guanylate cyclase subunits and phosphodiesterases types 3 and 5 did not differ. The antiplatelet activity of ticagrelor was similar between the groups and cilostazol significantly potentiated this response. Isolated aPL antibodies obtained from t-PAPS patients potentiated ADP-induced aggregation in healthy platelets but did not affect the inhibitory responses induced by iloprost or sodium nitroprusside.

CONCLUSIONS

The overexpression of P2Y12 receptor, accompanied by lower levels of cAMP and cGMP levels produced greater amplitude of ADP aggregation in platelets from t-PAPS patients.

The impact of nebulized epoprostenol and iloprost on hemoglobin oxygen affinity: an ex vivo experiment

Inhalational prostacyclins act as strong vasodilators, potentially improving oxygenation by reducing shunt fraction and ventilation-perfusion mismatch. As prostacyclin receptors are known to be present on human erythrocytes, possible direct effects on hemoglobin oxygen transport were further explored by examining the sole in vitro influence of prostacyclins on hemoglobin oxygen (Hb-O2) affinity. Venous blood samples from 20 healthy volunteers were exposed in vitro to supramaximal doses of epoprostenol, iloprost, and compared with control. By high-throughput measurements, hemoglobin oxygen dissociation curves (ODCs) were derived. Hb-O2 affinity, expressed by P50 and Hill coefficient, was determined and analyzed for three subgroups: males (n = 10), females not taking oral contraceptives (n = 4), and females taking oral contraceptives (n = 6). Epoprostenol significantly decreased P50 in all (males, females without contraceptives, and females taking oral contraceptives) [27.5 (26.4-28.6) mmHg (control) vs. 24.2 (22.7-25.3) mmHg; P < 0.001. median (interquartile range, IQR)] thereby increasing Hb-O2 affinity. Inversely, iloprost only showed significant effects in females taking oral contraceptives where P50 was markedly increased and therefore Hb-O2 affinity decreased [28.4 (27.9-28.9) mmHg (control) vs. 34.4 (32.2-36.0) mmHg; P < 0.001]. Prostacyclin-receptor stimulation and subsequent cAMP-mediated ATP release from erythrocytes are discussed as a possible underlying mechanism for the effect of epoprostenol on Hb-O2 affinity. The reason for the sex hormone-modified iloprost effect remains unclear. Being aware of potentially differing effects on Hb-O2 affinity might help select the right prostacyclin (epoprostenol vs. iloprost) depending on the patient and the underlying disease (e.g., acute respiratory distress syndrome vs. peripheral arterial disease).

Prostacyclin is an endosteal bone marrow niche component and its clinical analog iloprost protects hematopoietic stem cell potential during stress

Hematopoietic stem cells (HSCs) with superior reconstitution potential are reported to be enriched in the endosteal compared to central bone marrow (BM) region. To investigate whether specific factors at the endosteum may contribute to HSC potency, we screened for candidate HSC niche factors enriched in the endosteal compared to central BM regions. Together with key known HSC supporting factors Kitl and Cxcl12, we report that prostacyclin/prostaglandin I₂ (PGI₂ ) synthase (Ptgis) was one of the most highly enriched mRNAs (>10-fold) in endosteal compared to central BM. As PGI₂ signals through receptors distinct from prostaglandin E₂ (PGE₂ ), we investigated functional roles for PGI₂ at the endosteal niche using therapeutic PGI₂ analogs, iloprost, and cicaprost. We found PGI₂ analogs strongly reduced HSC differentiation in vitro. Ex vivo iloprost pulse treatment also significantly boosted long-term competitive repopulation (LT-CR) potential of HSCs upon transplantation. This was associated with increased tyrosine-phosphorylation of transducer and activator of transcription-3 (STAT3) signaling in HSCs but not altered cell cycling. In vivo, iloprost administration protected BM HSC potential from radiation or granulocyte colony-stimulating factor-induced exhaustion, and restored HSC homing potential with increased Kitl and Cxcl12 transcription in the BM. In conclusion, we propose that PGI₂ is a novel HSC regulator enriched in the endosteum that promotes HSC regenerative potential following stress.

Dissecting the Cellular Mechanism of Prostacyclin Analog Iloprost in Reversing Vascular Dysfunction in Scleroderma

OBJECTIVE

Intravenous iloprost improves Raynaud's phenomenon (RP) and promotes healing of digital ulcers in systemic sclerosis (SSc; scleroderma). Despite a short half-life, its clinical efficacy lasts weeks. Endothelial adherens junctions, which are formed by VE-cadherin clustering between endothelial cells (ECs), regulate endothelial properties including barrier function, endothelial-to-mesenchymal transition (EndoMT), and angiogenesis. We undertook this study to investigate the hypothesis that junctional disruption contributes to vascular dysfunction in SSc, and that the protective effect of iloprost is mediated by strengthening of those junctions.

METHODS

Dermal ECs from SSc patients and healthy controls were isolated. The effect of iloprost on ECs was examined using immunofluorescence, permeability assays, Matrigel tube formation, and quantitative polymerase chain reaction.

RESULTS

Adherens junctions in SSc were disrupted compared to normal ECs, as indicated by reduced levels of VE-cadherin and increased permeability in SSc ECs (P < 0.05). Iloprost increased VE-cadherin clustering at junctions and restored junctional levels of VE-cadherin in SSc ECs (mean ± SD 37.3 ± 4.3 fluorescence units) compared to normal ECs (mean ± SD 29.7 ± 3.4 fluorescence units; P < 0.05), after 2 hours of iloprost incubation. In addition, iloprost reduced permeability of monolayers, increased tubulogenesis, and blocked EndoMT in both normal and SSc ECs (n ≥ 3; P < 0.05). The effects in normal ECs were inhibited by a function-blocking antibody that prevents junctional clustering of VE-cadherin.

CONCLUSION

Our data suggest that the long-lasting effects of iloprost reflect its ability to stabilize adherens junctions, resulting in increased tubulogenesis and barrier function and reduced EndoMT. These findings provide a mechanistic basis for the use of iloprost in treating SSc patients with RP and digital ulcers.

Thrombospondin-1 promotes hemostasis through modulation of cAMP signaling in blood platelets

Thrombospondin-1 (TSP-1) is released by platelets upon activation and can increase platelet activation, but its role in hemostasis in vivo is unclear. We show that TSP-1 is a critical mediator of hemostasis that promotes platelet activation by modulating inhibitory cyclic adenosine monophosphate (cAMP) signaling. Genetic deletion of TSP-1 did not affect platelet activation in vitro, but in vivo models of hemostasis and thrombosis showed that TSP-1-deficient mice had prolonged bleeding, defective thrombosis, and increased sensitivity to the prostacyclin mimetic iloprost. Adoptive transfer of wild-type (WT) but not TSP-1-/- platelets ameliorated the thrombotic phenotype, suggesting a key role for platelet-derived TSP-1. In functional assays, TSP-1-deficient platelets showed an increased sensitivity to cAMP signaling, inhibition of platelet aggregation, and arrest under flow by prostacyclin (PGI2). Plasma swap experiments showed that plasma TSP-1 did not correct PGI2 hypersensitivity in TSP-1-/- platelets. By contrast, incubation of TSP-1-/- platelets with releasates from WT platelets or purified TSP-1, but not releasates from TSP-1-/- platelets, reduced the inhibitory effects of PGI2. Activation of WT platelets resulted in diminished cAMP accumulation and downstream signaling, which was associated with increased activity of the cAMP hydrolyzing enzyme phosphodiesterase 3A (PDE3A). PDE3A activity and cAMP accumulation were unaffected in platelets from TSP-1-/- mice. Platelets deficient in CD36, a TSP-1 receptor, showed increased sensitivity to PGI2/cAMP signaling and diminished PDE3A activity, which was unaffected by platelet-derived or purified TSP-1. This scenario suggests that the release of TSP-1 regulates hemostasis in vivo through modulation of platelet cAMP signaling at sites of vascular injury.

Iloprost affects in vitro maturation and developmental competence of bovine oocytes

Prostacyclin (PGI2) is synthesised in oviductal fluid and enhance the embryo development during the preimplantation period. The objective of the present study was to determine the effect of an analogue of prostacyclin (iloprost) on the in vitro maturation (IVM) and the developmental competence of bovine oocytes. Cumulus oocyte complexes (COCs) were cultured in maturation medium with iloprost (0.5 μM) for 24 h. We found that iloprost assisted maturation rates and cumulus cell expansion of bovine oocytes, and it increased the mRNA expression of genes related to cumulus expansion: ADAM17, AREG, and TNFAIP6 and cathepsin genes (CTSK and CTSS). Moreover, iloprost reduced the occurrence of apoptosis in COCs and promoted an antiapoptotic balance in the transcription of genes involved in apoptosis (BAX and BCL2). COCs treatment with iloprost during IVM also reduced intracellular reactive oxygen species (ROS) levels, while glutathione (GSH) levels and the mRNA expression of antioxidant genes CAT and GPx4 were markedly increased. We also showed that an analogue of PGI2 influenced the mitochondrial status via distribution rates of mitochondria and mitochondrial membrane potential in oocytes. Although, iloprost-enhanced maturation had no direct effect on number of embryos cleaved, it increased blastocyst rates of bovine embryos as well as proportion of expanded blastocysts. These results indicate that the supplementation of maturation medium with iloprost is beneficial for the maturation efficiency and developmental competence of bovine oocytes.

Prostacyclin and EMT Pathway Markers for Monitoring Response to Lung Cancer Chemoprevention

Lung cancer is the leading cause of cancer death worldwide and global burden could be reduced through targeted application of chemoprevention. The development of squamous lung carcinoma has been linked with persistent, high-grade bronchial dysplasia. Bronchial histology improved in former smokers in a chemoprevention trial with the prostacyclin analogue iloprost. Prostacyclin acts through peroxisome proliferator-activated receptor gamma (PPARγ) to reverse epithelial to mesenchymal transition and promote anticancer signaling. We hypothesized that the prostacyclin signaling pathway and EMT could provide response markers for prostacyclin chemoprevention of lung cancer. Human bronchial epithelial cells were treated with cigarette smoke condensate (CSC) or iloprost for 2 weeks, CSC for 16 weeks, or CSC for 4 weeks followed by 4 weeks of CSC and/or iloprost, and RNA was extracted. Wild-type or prostacyclin synthase transgenic mice were exposed to 1 week of cigarette smoke or one injection of urethane, and RNA was extracted from the lungs. We measured potential markers of prostacyclin and iloprost efficacy in these models. We identified a panel of markers altered by tobacco carcinogens and inversely affected by prostacyclin, including PPARγ, 15PGDH, CES1, COX-2, ECADHERIN, SNAIL, VIMENTIN, CRB3, MIR34c, and MIR221 These data introduce a panel of potential markers for monitoring interception of bronchial dysplasia progression during chemoprevention with prostacyclin. Chemoprevention is a promising approach to reduce lung cancer mortality in a high-risk population. Identifying markers for targeted use is critical for success in future clinical trials of prostacyclin for lung cancer chemoprevention. Cancer Prev Res; 11(10); 643-54. ©2018 AACR.

Iloprost attenuates hyperoxia-mediated impairment of lung development in newborn mice

Cyclooxygenase-2 (COX-2/PTGS2) mediates hyperoxia-induced impairment of lung development in newborn animals and is increased in the lungs of human infants with bronchopulmonary dysplasia (BPD). COX-2 catalyzes the production of cytoprotective prostaglandins, such as prostacyclin (PGI2), as well as proinflammatory mediators, such as thromboxane A2. Our objective was to determine whether iloprost, a synthetic analog of PGI2, would attenuate hyperoxia effects in the newborn mouse lung. To test this hypothesis, newborn C57BL/6 mice along with their dams were exposed to normoxia (21% O2) or hyperoxia (85% O2) from 4 to 14 days of age in combination with daily intraperitoneal injections of either iloprost 200 µg·kg-1·day-1, nimesulide (selective COX-2 antagonist) 100 mg·kg-1·day-1, or vehicle. Alveolar development was estimated by radial alveolar counts and mean linear intercepts. Lung function was determined on a flexiVent, and multiple cytokines and myeloperoxidase (MPO) were quantitated in lung homogenates. Lung vascular and microvascular morphometry was performed, and right ventricle/left ventricle ratios were determined. We determined that iloprost (but not nimesulide) administration attenuated hyperoxia-induced inhibition of alveolar development and microvascular density in newborn mice. Iloprost and nimesulide both attenuated hyperoxia-induced, increased lung resistance but did not improve lung compliance that was reduced by hyperoxia. Iloprost and nimesulide reduced hyperoxia-induced increases in MPO and some cytokines (IL-1β and TNF-α) but not others (IL-6 and KC/Gro). There were no changes in pulmonary arterial wall thickness or right ventricle/left ventricle ratios. We conclude that iloprost improves lung development and reduces lung inflammation in a newborn mouse model of BPD.

Long-term effects of intravenous iloprost therapy in patients with bone marrow oedema of the hip

Bone marrow oedema (BMO) is a multifactorial condition. Various conservative treatment options include analgesic therapy, immobilisation of the affected joint and/or systemic intravenous iloprost or bisphosphonate therapy. Many studies confirm the positive effect of iloprost therapy in larger joints, e.g. the hip and knee joint, after short-term follow up. The objective of this study was to investigate that treatment with iloprost leads to positive long-term functional and radiological outcomes for BMO of the hip joint. Nineteen patients with BMO of the hip joint, ARCO stage 1-2, were included in this study. The Harris Hip Score, the SF-36, the WOMAC score and a visual analogue pain scale (VAS) were evaluated before and 29 ± 11 months after Ilomedin therapy. All patients underwent MRI for radiological follow-up monitoring three months after treatment. Significant improvements were found in the WOMAC Index and the VAS. In 79% of patients, follow-up MRI after three months showed complete regression of the oedema. Based on the positive results of our study, we support treatment with iloprost for BMO of the hip joint at ARCO stage 1-2.

The Effect of Iloprost in the Healing of Colonic Anastomosis in Rats under Chemotherapy with Irinotecan

PURPOSE

We have investigated the possible positive effect of iloprost in the healing of colonic anastomosis, in rats under intraperitoneal chemotherapy with irinotecan.

METHOD

Forty male Wistar rats have been divided into four groups. They underwent a partial colectomy and a termino-terminal anastomosis. They were administered, intraperitoneally, saline (group 1), irinotecan (group 2), iloprost (group 3), or irinotecan and iloprost (Group 4). After the sacrifice of the animals what followed was an autopsy, a macroscopic examination and the measurement of the anastomotic rupture pressure. A portion of the anastomosis was sent over for histological examination and determination of hydroxyproline levels. Results: The frequency of the leakage from the anastomosis was considered as significantly increased in group 2 compared with the other groups. In group 2, a significantly greater degree of adhesions, compared to all the remaining groups, was observed. The bursting pressure of the anastomosis was significantly lower in group 2, as compared with all the remaining groups, and significantly increased in the group 4 compared with group 2. Leukocytosis, fibroblasts, the neocollagen and the levels of hydroxyproline in group 4 showed significantly increased values, compared with group 2. The angiogenesis was significantly increased in groups 3 and 4 compared with group 2. Conclusions: Intraperitoneal administration of iloprost after colectomy, termino-terminal anastomosis and intraperitoneal administration of irinotecan promotes the healing process of the colon anastomoses as it competes the inhibitory effect of irinotecan.

Iloprost Induces Dental Pulp Angiogenesis in a Growth Factor-free 3-Dimensional Organ Culture System

INTRODUCTION

Angiogenesis is a key determinant in dental pulp regeneration. Iloprost is a synthetic prostacyclin that promotes angiogenesis. A three-dimensional culture that mimics the in vivo condition has been used in tissue engineering. This study investigated the effect of iloprost on promoting dental pulp angiogenesis by using the tooth slice organ culture system.

METHODS

Tooth slices with intact pulp tissue were cut from molars extracted from 12 patients. Dental pulp tissue viability was determined by live/dead staining. The tooth slices were cultured with iloprost for 1 or 3 days. The microvessel density and expression of vascular endothelial growth factor were determined by immunohistochemical staining. Collagen density was determined by using Masson trichrome and immunofluorescent staining.

RESULTS

The pulp tissue in the tooth slices remained viable when cultured in serum-free medium. Iloprost increased the microvessel density as shown by a higher number of von Willebrand factor-positive cells. A significant increase in vascular endothelial growth factor expression was observed in the tooth slices cultured with iloprost. Iloprost stimulated collagen deposition, and this effect was abolished after inhibition of protein kinase A activity.

CONCLUSIONS

Human tooth slices provide a valuable and easy-to-obtain model to investigate the effect of bioactive molecules used in dental pulp regeneration. This study showed for the first time that tooth slices could be kept viable under serum-free conditions for up to 3 days. Iloprost promoted angiogenesis, increased new vessel formation, and induced collagen deposition. This study proposes the clinical value of iloprost as a drug for inducing angiogenesis that can increase the success of pulp regeneration.

Increased neutrophil mediator release in patients with pulmonary hypertension – suppression by inhaled iloprost

Polymorphonuclear neutrophils (PMN) have been implicated in various vascular inflammatory processes. We isolated PMN from venous blood samples of 10 patients with severe primary pulmonary arterial hypertension (PPH), 7 patients with pulmonary hypertension secondary to chronic thromboembolism (CTEPH), and 12 healthy controls. When stimulated with the calcium-ionophore A23187, platelet activating factor (PAF) or the microbial agent n-formyl-Methionyl-Leucyl-Phenylalanine (fMLP), significantly increased release of elastase and super-oxide anion was noted in both groups with pulmonary hyper-tension. Moreover, the neutrophils of CTEPH patients responded with an enhanced liberation of leukotriene (LT) B4 and 5-hydroxyeicosatetraenoic acid (5-HETE). Inhalation of aerosolized iloprost (5 µg) caused a rapid decline in pulmonary vascular resistance, in both PPH and CTEPH. This hemodynamic response was paralleled by a significant suppression of ionophore- and ligand-induced elastase and superoxide release, as well as LTB4 and 5-HETE formation. The neutrophil inhibitory effect of the inhalation maneuver was fully reproduced by in vitro incubation of neutrophils with 1-10 pg/ml iloprost for 2 hours. This is the first study to demonstrate that circulating neutrophils from patients with PPH and CTEPH possess an enhanced readiness to respond with inflammatory mediator generation to different stimulatory agents ex-vivo, and that PMN respiratory burst, elastase secretion and leukotriene generation are promptly reduced by an iloprost inhalation maneuver. Neutrophils might participate in the inflammatory processes in pulmonary arterial hypertension.

Prostacyclin reverses the cigarette smoke-induced decrease in pulmonary Frizzled 9 expression through miR-31

Half of lung cancers are diagnosed in former smokers, leading to a significant treatment burden in this population. Chemoprevention in former smokers using the prostacyclin analogue iloprost reduces endobronchial dysplasia, a premalignant lung lesion. Iloprost requires the presence of the WNT receptor Frizzled 9 (Fzd9) for inhibition of transformed growth in vitro. To investigate the relationship between iloprost, cigarette smoke, and Fzd9 expression, we used human samples, mouse models, and in vitro studies. Fzd9 expression was low in human lung tumors and in progressive dysplasias. In mouse models and in vitro studies, tobacco smoke carcinogens reduced expression of Fzd9 while prostacyclin maintained or increased expression. Expression of miR-31 repressed Fzd9 expression, which was abrogated by prostacyclin. We propose a model where cigarette smoke exposure increases miR-31 expression, which leads to decreased Fzd9 expression and prevents response to iloprost. When smoke is removed miR-31 is reduced, prostacyclin can increase Fzd9 expression, and progression of dysplasia is inhibited. Fzd9 and miR-31 are candidate biomarkers for precision application of iloprost and monitoring of treatment progress. As we continue to investigate the mechanisms of prostacyclin chemoprevention and identify biomarkers for its use, we will facilitate clinical trials and speed implementation of this valuable prevention approach.

Iloprost administration in acrodermatitis of Hallopeau complicated by acquired toes syndactyly: a case report and review of the literature

OBJECTIVE

Acrodermatitis Continua of Hallopeau (ACH) is a variant of pustular psoriasis often very difficult to treat. Secondary syndactyly, also called "pseudosyndactyly", is rare and can be a complication of burns, dystrophic epidermolysis bullosa or trauma. If left untreated, joint complications and definitive functional impairments may occur.

CASE REPORT

We report a case of a 74-year-old man with acrodermatitis continua of Hallopeau involving the toes and complicated by syndactyly. ACH regression following Iloprost administration was also observed.

DISCUSSION

Published studies are mainly limited to case reports only, due to the rarity of the disease. Therefore, there are no clear-cut therapeutic management guidelines available for this chronic and sometimes debilitating disease. ACH is often recalcitrant to the available therapies. Topical and systemic treatments have been described in literature with no long-lasting results.

CONCLUSIONS

To our knowledge, this is the first report of foot syndactyly associated to ACH. In our patient, ACH symptoms regressed with Iloprost administration: this finding has never been previously described in literature. If confirmed by other clinical experiences, Iloprost could be a further therapeutic option in ACH.

Comparison of angiogenic and proliferative effects of three commonly used agents for pulmonary artery hypertension (sildenafil, iloprost, bosentan): is angiogenesis always beneficial?

OBJECTIVE

Pulmonary artery hypertension (PAH) is devastating disease that has very serious outcomes. Dysregulated angiogenesis is one of the main responsible courses in pathophysiology of disease. Our experimental research intends to find out and compare the angiogenic effects of medications used sildenafil, iloprost, and bosentan in the treatment of PAH.

MATERIALS AND METHODS

This study was performed in Department of Biochemistry and Cancer and Stem Cell Research Laboratory of our institutes between August and October 2014. Angiogenic activity of sildenafil, iloprost, and bosentan were examined in vivo in chick chorioallantoic membrane (CAM) model and in vitro tube formation assay of human umbilical vein endothelial cells (HUVECs). Proliferative activity of these three agents was also determined through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on HUVECs.

RESULTS

In CAM assay, when compared to the control and drug groups, treatment with sildenafil solutions resulted in a significant dose-dependent increase (budding, sprouting, extravasation) on CAM vessel growth. While there was no significant proliferative effect with iloprost and bosentan, presence of sildenafil caused a statistically significant proliferation on HUVECs following 24 and 48 h incubation (p < 0.05) compared to the control group. Comparing the tube length/area ratio values, there was statistically significant increase in sildenafil group with respect to the other 2 groups (p < 0.05). Iloprost and bosentan did not show a significant effect.

CONCLUSIONS

The results provide evidence that sildenafil but not iloprost and bosentan induces angiogenesis in vitro and in vivo. Dysregulated angiogenesis, as an important pathophysiological part in the progression of PAH, may be triggered by the chronic ingestion of sildenafil in the long treatment period and may cause negative effects.

[SPECIFICS OF INHALED ILOPROST PHARMACODYNAMICS IN PATIENTS WITH SEVERE LEFT VENTRICULAR SYSTOLIC DYSFUNCTION]

PURPOSE

To determine the specifics of inhaled iloprost effect on pulmonary and systemic hemodynamics in patients with pulmonary hypertension (PH) associated with left ventricular systolic dysfunction.

MATERIALS AND METHODS

47 vasore- activity tests (VRT) with 20 micrograms inhaled iloprost (Ventavis, Bayer) were performed in 39 candidates on heart transplantation. All patients had heart failure III-IV NYHA and PH with pulmonary vascular resistance (PVR) more than 2.5 Wood units. Hemodynamic parameters were evaluated at baseline and 15 minutes after inhalation of iloprost.

RESULTS

Iloprost significant decreased PAPmean: from 36.8 ± 8.5 mm Hg to 29.9 ± 9.4 mm Hg (p < 0.001). There was a significant decrease in PVR:from 4.5 1.6 Wood units to 3 ± 1 Wood units (p < 0.001). PVR dropped more than 20% in 34 cases (72.3%). Iloprost inhalation caused significant changes in systemic hemodynamic. There were decrease in sys- temic vascular resistance (SVR)from 1820 ± 527 dynes·sec·cm(-5) to 1423 ± 427 dynes·sec·cm(-5) (p < 0.001), increase in stroke volume index (SVI) from 26.1 ± 8.7 ml/m2 to 30.5 ± 9.5 ml/m2 (p < 0.001) and decrease in PCWP from 20.6 ± 5.9 mm Hg to 18.4 ± 6.6 mm Hg. (p = 0.016). We found significant negative correlation between systemic effects of iloprost and initial cardiac index (r = -0.63).

CONCLUSIONS

Inhaled iloprost caused significant changes in systemic hemodynamic when was used in patients with severe LV systolic dysfunction. Favorable changes in the left ventricle preload and after- load naturally increased its performance and decreased PCWP.

Hemodynamic effect of iloprost inhalation and oral sildenafil during acute vasoreactivity test in pulmonary arterial hypertension

BACKGROUND

The vasoreactivity test is usually performed to identify pulmonary arterial hypertension (PAH) patients who may benefit from long-term calcium channel blocker (CCB). The first and most commonly used agent is intravenous epoprostenol. A few other agents such as intravenous adenosine and inhaled nitric oxide are also used. In Thailand, epoprostenol is not available and the others are costly. Therefore, inhaled iloprost or oral sildenafil may be alternatives to test vasoreactivity.

OBJECTIVE

To evaluate the hemodynamic effect and response rate of inhaled iloprost and oral sildenafil during acute vasoreactivity test in PAH patients.

MATERIAL AND METHOD

In this retrospective descriptive study, the authors recruited patients with idiopathic PAH (IPAH) or PAHassociated with connective tissue disease (PAH-CNT) seen at the Medicine department Siriraj Hospital between January 2005 and December 2011 for whom acute vasoreactivity test was indicated. All patients used 20 microgram of inhaled iloprost via Delphinus® nebulizer for the test. Hemodynamic parameters were recorded before and after iloprost administration. Eight of those patients subsequently had a repeated test using 100 mg of oral sildenafil.

RESULTS

Fifteen patients had acute vasoreactivity testing. Eleven patients were IPAH and four were PAH-CNT Using ESC/ERS guidelines criteria for responsiveness to vasoreactivity test, the response rate was 13% (2 out of 15 patients) using inhaled iloprost. Hemodynamic change was seen as early as five minutes after the inhalation and the effect lasted up to 35 minutes. The response rate was 25% (2 out of 8 patients) using oral sildenafil. Hemodynamic change was seen as early as 30 minutes after sildenafil ingestion and lasted up to 480 minutes.

CONCLUSION

Inhaled iloprost can be used for acute vasoreactivity test in Thailand. The hemodynamic parameters should be recorded immediately after iloprost inhalation. Oral sildenafil, however, is not a suitable agent for acute vasoreactivity test due to its extended effect.

Iloprost donor treatment reduces ischemia-reperfusion injury in an isolated extracorporeal pig liver perfusion model

OBJECTIVES

Iloprost has the potential to protect the liver transplant graft before and during cold ischemia. We studied iloprost administration during organ procurement and reperfusion in an extracorporeal pig liver perfusion model.

MATERIALS AND METHODS

German Landrace pigs (n = 7/group; 22-26 kg each) were used as donors. Preservation was performed by aortic perfusion with 2 L Bretschneiders' Histidine-Tryptophan-Ketoglutarate solution HTK and cold ischemia time (4°C) 20 hours followed by normothermic extracorporeal perfusion for 8 hours. Untreated controls (1) were compared to iloprost (2) donor bolus-treatment (1 μg/kg body weight), (3) addition of iloprost to Bretschneiders' Histidine-Tryptophan-Ketoglutarate solution HTK (0.0125 μg/mL), (4) continuous infusion during reperfusion (2 ng/kg/min), and (5) combined treatment (2) and (4).

RESULTS

Iloprost donor treatment led to significantly higher bile production. Addition of iloprost to the preservation solution significantly improved hepatic artery perfusion and was accompanied by improvements of microcirculation and bile production. Iloprost reperfusion treatment alone significantly improved bile production. Enzyme levels were positively affected by all treatment regimens. Combined use of iloprost before and after ischemia improved hepatic artery flow and microcirculation and showed significantly lower hypoxia staining versus controls.

CONCLUSIONS

Iloprost donor treatment and use of iloprost in the preservation solution significantly improved graft perfusion and function. The effects of graft treatment seemed greater before than after reperfusion. Combined treatment did not reveal a synergistic advantage.

The effects of iloprost on lung injury induced by skeletal muscle ischemia-reperfusion

PURPOSE

The aim of this study was to investigate the effects of iloprost (I) on lung injury as a remote organ following skeletal muscle ischemia-reperfusion injury in a rat model.

MATERIALS AND METHODS

Twenty-four Wistar Albino rats were randomized into four groups (n = 6). Laparotomy was performed in all groups under general anesthesia. Only laparotomy was applied in Group S (Sham). Ischemia reperfusion group (Group I/R) underwent ischemia and reperfusion performed by clamping and declamping of the infrarenal abdominal aorta for 120 minutes. Group iloprost (Group I) received intravenous infusion of iloprost 0.5 ng/kg/min, without ischemia and reperfusion. Group I/R/I received intravenous infusion of iloprost 0.5 ng/kg/min immediately after 2 hours of ischemia. At the end of the study, lung tissue was obtained for determining total oxidant status (TOS) and total antioxidant status (TAS) levels, histochemical and immunohistochemical determination.

RESULTS

Diffuse lymphocyte infiltration was detected in immunohistochemical examination of lung tissue in Group I/R. The connective tissue around bronchi, bronchioles and vessel walls was found to be increased. Although minimal local lymphocyte infiltration was detected in some fields in Group I/R/I, the overall tissue was found to be similar to Group S. iNOS expression was significantly higher in Group I/R, when compared with Group S and significantly lower in Group I/R/I compared to Group I/R.TOS levels were significantly higher in Group I/R, when compared with groups S and I (p = 0.028, p = 0.016, respectively) and significantly lower in group I/R/I, when compared with Group I/R (p = 0.048). TAS levels were significantly higher in Group I/R, when compared with groups S, I (p = 0.014, p = 0.027, respectively) and significantly lower in Group I/R/I, when compared with Group I/R (p = 0.032).

CONCLUSION

These results indicate that administration of iloprost may have protective effects against ischemia reperfusion injury (Fig. 8, Tab. 1, Ref. 30)

The effects of iloprost on colonic anastomotic healing in rats under obstructive ileus conditions

BACKGROUND

The aim of this study was to investigate the effects of iloprost, on colonic anastomotic healing in rats, under obstructive ileus conditions.

MATERIALS AND METHODS

Eighty male Albino rats were randomized into four groups of 20 animals each. They underwent colonic resection followed by an inverted anastomosis. The rats of group 1 (control) and group 2 (ileus) received 3 mL of saline 0.9% intraperitoneally and those of group 3 (iloprost), and group 4 (ileus + iloprost) iloprost (2 μg/kg of body weight), immediately postoperatively and daily until the day of sacrifice. Each group was further divided into two equal subgroups, depending on the day of sacrifice. The animals of subgroup "a" were sacrificed on the fourth postoperative day, whereas those of "b" on the eighth day. Macroscopic and histologic assessment was performed, whereas anastomotic bursting pressures and the tissue concentrations in hydroxyproline and collagenase I were evaluated.

RESULTS

Means of bursting pressure, neoangiogenesis, fibroblast activity, and hydroxyproline concentration were significantly increased in group 4 compared with group 2. In addition, on the fourth postoperative day, the inflammatory cell infiltration and the collagenase I concentration were significantly decreased in group 4 compared with group 2. Moreover, on the eighth postoperative day, collagen deposition was significantly increased in group 4 compared with group 2.

CONCLUSIONS

Iloprost after intraperitoneal administration reverses the negative effect of obstructive ileus. It promotes not only the angiogenic activity but also collagen formation, resulting in increased bursting pressures on the fourth and eighth postoperative days.

Iloprost for idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension is a rare but serious and life-threatening disease that leads to right heart failure and death within 2.8 years without specific treatment. This review focuses on the stable prostacyclin analog iloprost, its biologic action and pharmacology and, finally, on its clinical development, efficacy and safety in patients with idiopathic pulmonary arterial hypertension, which led to its approval for this indication. Furthermore, this review assesses the role of iloprost compared with other newly developed drugs, such as the endothelin receptor antagonist bosentan and the phosphodiesterase-5 inhibitor sildenafil, as well as other modes of application of prostacyclin and its analogs for the treatment of idiopathic pulmonary arterial hypertension. Based on the different modes of action of these substances, a combination of these treatments could be most promising for the future.

Iloprost inhibits fracture repair in rats

BACKGROUND

Previous studies have shown that prostaglandins (PGs) dramatically stimulate healing processes in bone. However, the effect of prostaglandin I2 (PGI2) on fracture healing remains unclear. To investigate the effect of PGI2, a study on fracture healing process in closed tibia fractures was designed.

METHODS

Thirty-six Sprague-Dawley male rats were randomized into two groups. On the first day, their right tibias were fractured by three-point bending technique. The study group (n = 18) received a single injection of 10 µg/kg iloprost for 5 days, while the control group (n = 18) received saline solution in the same way. On the 7th, 14th and 28th days following the fracture, six rats were sacrificed and their right legs were harvested in each group. The progression of fracture healing was assessed for each specimen by the scores of radiography (by Lane-Sandhu) and histology (by Huo et al).

RESULTS

On the 7th day, the radiographic and histologic scores were equal. On the 14th day radiographic total score was 6 and histologic total score was 23 in the iloprost group, whereas radiographic total score was 11 and histologic total score was 33 in the control group. On the 14th day radiographic and histologic scores were significantly decreased in the iloprost group compared to the control group (P < 0.05). On the 28th day radiographic total score was 12 and histologic total score was 37 in the iloprost group, whereas radiographic total score was 15 and histologic total score was 40 in the control group. On the 28th day although there was a decrease in radiographic and histologic scores of the iloprost group acording to control group, it was not statistically significant (P > 0.05).

CONCLUSION

Iloprost delays fracture healing in early stage in rats.

Prostaglandin I2-IP signalling regulates human Th17 and Treg cell differentiation

Prostaglandin I2 (PGI2) is an important immunoregulatory lipid mediator. In this study, we analysed the effects of the PGI2 analogue (Iloprost) on the differentiation of Th17 cells and Tregs from human naïve CD4(+) T cells. PGI2 receptors (IP) are expressed on human naïve CD4(+) T cells. Via IP binding, the PGI2 analogue decreased the proportion of Tregs and Foxp3 mRNA expression but increased the percentage of Th17 cells, RORC mRNA and IL-17A production. The regulatory effects of Iloprost correlated with elevated intracellular cAMP levels. The effects were mimicked by a cAMP agonist (db-cAMP) but attenuated by a protein kinase A inhibitor (H-89). STAT3 and STAT5 signalling play direct and crucial roles in the development of Th17 and Tregs, respectively. The PGI2 analogue enhanced the activation of STAT3 in response to IL-6, whereas it decreased STAT5 activation in response to IL-2. Moreover, db-cAMP imitated the above effects of Iloprost, which were weakened by H-89. These results demonstrate that the PGI2-IP interaction promoted the phosphorylation of STAT3 and reduced the phosphorylation of STAT5, likely via the upregulation of cAMP-PKA signalling, thus facilitated Th17 differentiation and suppressed Treg differentiation. Together with previous results, these data suggest that prostanoids play an important role in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis.

Acute effects of aerosolized iloprost in COPD related pulmonary hypertension - a randomized controlled crossover trial

Background

Inhaled iloprost potentially improves hemodynamics and gas exchange in patients with chronic obstructive pulmonary disease (COPD) and secondary pulmonary hypertension (PH).

Objectives

To evaluate acute effects of aerosolized iloprost in patients with COPD-associated PH.

Methods

A randomized, double blind, crossover study was conducted in 16 COPD patients with invasively confirmed PH in a single tertiary care center. Each patient received a single dose of 10 µg iloprost (low dose), 20 µg iloprost (high dose) and placebo during distinct study-visits. The primary end-point of the study was exercise capacity as assessed by the six minute walking distance.

Results

Both iloprost doses failed to improve six-minute walking distance (p = 0.36). Low dose iloprost (estimated difference of the means −1.0%, p = 0.035) as well as high dose iloprost (−2.2%, p<0.001) significantly impaired oxygenation at rest. Peak oxygen consumption and carbon dioxide production differed significantly over the three study days (p = 0.002 and p = 0.003, accordingly). As compared to placebo, low dose iloprost was associated with reduced peak oxygen consumption (−76 ml/min, p = 0.002), elevated partial pressure of carbon dioxide (0.27 kPa, p = 0.040) and impaired ventilation during exercise (−3.0l/min, p<0.001).

Conclusions

Improvement of the exercise capacity after iloprost inhalation in patients with COPD-associated mild to moderate PH is very unlikely.

Trial Registration

Controlled-Trials.com ISRCTN61661881

Prostaglandin I(2) analogues enhance already exuberant Th17 cell responses in systemic sclerosis

OBJECTIVE

Among pleiotropic effects, the capacity of prostaglandin I(2) (PGI(2)) analogues to affect adaptive immunity remains poorly characterised. The purpose of this study was to assess whether PGI(2) analogues could affect T helper (Th) cell responses in patients with systemic sclerosis (SSc) and healthy donors (HD).

METHODS

Peripheral blood mononuclear cells (PBMC) were obtained from 33 patients with SSc and 29 HD. Cytokine levels in PBMC and monocyte/CD4 T cell cultures were quantified by immunoassays. The frequencies of interleukin (IL)-17A, IL-22, interferon γ (IFNγ) and IL-4-producing CD4 T cells were assessed by multiparametric flow cytometry. Selective receptor antagonists, cytokine blocking antibodies and signalling protein inhibitors were used to identify the receptors and signalling pathways mediating PGI(2) analogue effects.

RESULTS

Th17 and Th22 cells were more abundant in individuals with SSc than in HD. PGI(2) analogues (iloprost, treprostinil and beraprost) significantly increased IL-17A and IL-22 in vitro while decreasing IFNγ production both in SSc and HD PBMC. These effects relied on the specific expansion of Th17 and Th22 and inhibition of Th1 cells. The enhanced Th17 cell responses depended on increased IL-23 production by monocytes, involved the IP prostacyclin receptor and required protein kinase A activation. Importantly, in vivo administration of iloprost in individuals with SSc presenting with digital ulcers resulted in a significant increase in the frequency of Th17 cells.

CONCLUSIONS

These findings demonstrate that PGI(2) analogues affect Th cell differentiation/expansion programmes, favouring Th17 and inhibiting Th1 cell responses in SSc. The impact of these changes on the disease course needs to be taken into consideration and further exploited to improve SSc.

Prostanoid receptors involved in regulation of the beating rate of neonatal rat cardiomyocytes

Although prostanoids are known to be involved in regulation of the spontaneous beating rate of cultured neonatal rat cardiomyocytes, the various subtypes of prostanoid receptors have not been investigated in detail. In our experiments, prostaglandin (PG)F_2α and prostanoid FP receptor agonists (fluprostenol, latanoprost and cloprostenol) produced a decrease in the beating rate. Two prostanoid IP receptor agonists (iloprost and beraprost) induced first a marked drop in the beating rate and then definitive abrogation of beating. In contrast, the prostanoid DP receptor agonists (PGD₂ and BW245C) and TP receptor agonists (U-46619) produced increases in the beating rate. Sulprostone (a prostanoid EP₁ and EP₃ receptor agonist) induced marked increases in the beating rate, which were suppressed by SC-19220 (a selective prostanoid EP₁ antagonist). Butaprost (a selective prostanoid EP₂ receptor agonist), misoprostol (a prostanoid EP₂ and EP₃ receptor agonist), 11-deoxy-PGE₁ (a prostanoid EP₂, EP₃ and EP₄ receptor agonist) did not alter the beating rate. Our results strongly suggest that prostanoid EP₁ receptors are involved in positive regulation of the beating rate. Prostanoid EP₁ receptor expression was confirmed by western blotting with a selective antibody. Hence, neonatal rat cardiomyocytes express both prostanoid IP and FP receptors (which negatively regulate the spontaneous beating rate) and prostanoid TP, DP₁ and EP₁ receptors (which positively regulate the spontaneous beating rate).

No additive effects of inhaled iloprost and prone positioning on pulmonary hypertension and oxygenation in acute respiratory distress syndrome

BACKGROUND

In acute respiratory distress syndrome (ARDS), pulmonary hypertension is associated with a poor prognosis. Prone position is effective to improve oxygenation whereas inhaled iloprost can treat pulmonary hypertension. However, combination of these interventions has not been examined before. The hypothesis was that this combination had additive effects on oxygenation and pulmonary hemodynamics as compared with each intervention alone.

METHODS

In a prospective, randomized cross-over study, ten pigs were anesthetized, intubated and ventilated with volume controlled ventilation. Carotid, jugular venous and pulmonary artery catheters were inserted. ARDS was induced with oleic acid (0.20 mL/kg). Measurements were repeated in randomized different sequences of prone or supine positions with or without iloprost inhalation (220 ng/kg/min) (four combinations). Systemic and pulmonary arterial pressures; arterial and mixed venous blood gases; and Qs/Qt and the resistances were recorded.

RESULTS

Iloprost decreased pulmonary artery pressures (for MPAP: P=0.034) in both supine (37±10 vs. 31±8 mmHg; P<0.05) and prone positions (38±9 vs. 29±8 mmHg; P<0.05); but did not obtain a significant improvement in oxygenation in both positions. Prone position improved the oxygenation (p<0.0001) compared to supine position in both with (361±140 vs. 183±158 mmHg, P<0.05) or without iloprost application (331±112 vs. 167±117 mmHg, P<0.05); but did not achieve a significant decrease in MPAP.

CONCLUSION

Although iloprost reduced pulmonary arterial pressures, and prone positioning improved oxygenation; there are no additive effects of the combination of both interventions on both parameters. To treat both pulmonary hypertension and hypoxemia, application of iloprost in prone position is suggested.

The prostacyclin agonist iloprost aggravates fibrosis and enhances viral replication in enteroviral myocarditis by modulation of ERK signaling and increase of iNOS expression

Enteroviruses, such as coxsackieviruses of group B (CVB), are able to induce a chronic inflammation of the myocardium, which may finally lead to the loss of functional tissue, remodeling processes and the development of fibrosis, thus affecting the proper contractile function of the heart. In other fibrotic diseases like scleroderma, the prostacyclin agonist iloprost was found to inhibit the extracellular signal-regulated kinase (ERK, p44/42 MAPK), a mitogen-activated protein kinase, and consecutively, the expression of the profibrotic cytokine connective tissue growth factor (CTGF), thereby preventing the development of fibrosis. As CTGF was found to mediate fibrosis in chronic CVB3 myocarditis as well, we evaluated whether the in vivo application of iloprost is capable to reduce the development of ERK/CTGF-mediated fibrosis in enteroviral myocarditis. Unexpectedly, the application of iloprost resulted in a prolonged myocardial inflammation and an aggravated fibrosis and failed to reduce activation of ERK and expression of CTGF at later stages of the disease. In addition, viral replication was found to be increased in iloprost-treated mice. Notably, the expression of cardiac inducible nitric oxide synthase (iNOS), which is known to aggravate myocardial damage in CVB3-infected mice, was strongly enhanced by iloprost. Using cultivated bone marrow macrophages (BMM), we confirmed these results, proving that iloprost potentiates the expression of iNOS mRNA and protein in CVB3-infected and IFN-gamma stimulated BMM. In conclusion, these results suggest a critical reflection of the clinical use of iloprost, especially in patients possibly suffering from an enteroviral myocarditis.

Prostaglandin I2 signaling drives Th17 differentiation and exacerbates experimental autoimmune encephalomyelitis

Background

Prostaglandin I₂ (PGI₂), a lipid mediator currently used in treatment of human disease, is a critical regulator of adaptive immune responses. Although PGI₂ signaling suppressed Th1 and Th2 immune responses, the role of PGI₂ in Th17 differentiation is not known.

Methodology/Principal Findings

In mouse CD4⁺CD62L⁺ naïve T cell culture, the PGI₂ analogs iloprost and cicaprost increased IL-17A and IL-22 protein production and Th17 differentiation in vitro. This effect was augmented by IL-23 and was dependent on PGI₂ receptor IP signaling. In mouse bone marrow-derived CD11c⁺ dendritic cells (BMDCs), PGI₂ analogs increased the ratio of IL-23/IL-12, which is correlated with increased ability of BMDCs to stimulate naïve T cells for IL-17A production. Moreover, IP knockout mice had delayed onset of a Th17-associated neurological disease, experimental autoimmune encephalomyelitis (EAE), and reduced infiltration of IL-17A-expressing mononuclear cells in the spinal cords compared to wild type mice. These results suggest that PGI₂ promotes in vivo Th17 responses.

Conclusion

The preferential stimulation of Th17 differentiation by IP signaling may have important clinical implications as PGI₂ and its analogs are commonly used to treat human pulmonary hypertension.

Modafinil inhibits K(Ca)3.1 currents and muscle contraction via a cAMP-dependent mechanism

Modafinil has been used as a psychostimulant for the treatment of narcolepsy. However, its primary mechanism of action remains elusive. Therefore, we examined the effects of modafinil on K(Ca)3.1 channels and vascular smooth muscle contraction. K(Ca)3.1 currents and channel activity were measured using a voltage-clamp technique and inside-out patches in mouse embryonic fibroblast cell line, NIH-3T3 fibroblasts. Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) concentration was measured, and the phosphorylation of K(Ca)3.1 channel protein was examined using western blotting in NIH-3T3 fibroblasts and/or primary cultured mouse aortic smooth muscle cells (SMCs). Muscle contractions were recorded from mouse aorta and rat pulmonary artery by using a myograph developed in-house. Modafinil was found to inhibit K(Ca)3.1 currents in a concentration-dependent manner, and the half-maximal inhibition (IC(50)) of modafinil for the current inhibition was 6.8 ± 0.7 nM. The protein kinase A (PKA) activator forskolin also inhibited K(Ca)3.1 currents. The inhibitory effects of modafinil and forskolin on K(Ca)3.1 currents were blocked by the PKA inhibitors PKI(14-22) or H-89. In addition, modafinil relaxed blood vessels (mouse aorta and rat pulmonary artery) in a concentration-dependent manner. Modafinil increased cAMP concentrations in NIH-3T3 fibroblasts or primary cultured mouse aortic SMCs and phosphorylated K(Ca)3.1 channel protein in NIH-3T3 fibroblasts. However, open probability and single-channel current amplitudes of K(Ca)3.1 channels were not changed by modafinil. From these results, we conclude that modafinil inhibits K(Ca)3.1 channels and vascular smooth muscle contraction by cAMP-dependent phosphorylation, suggesting that modafinil can be used as a cAMP-dependent K(Ca)3.1 channel blocker and vasodilator.

Two non-vesicular ATP release pathways in the mouse erythrocyte membrane

Erythrocytes are exceptionally suited for analysis of non-exocytotic release mechanisms of ATP, because these cells under physiological conditions lack vesicles. Previous studies have indicated, that Pannexin1 (Panx1) provides a key ATP permeation pathway in many cell types, including human and frog erythrocytes. Here we show that erythrocytes of Panx1(-/-) mice lend further support to this conclusion. However, ATP release, although attenuated, was still observed in Panx1(-/-) mouse erythrocytes. In contrast to Panx1(+/+) cells, this release was not correlated with uptake of extracellularly applied dyes, was insensitive to Panx1 channel blockers, and was inhibited by dipyridamole and stimulated by iloprost. Thus, in erythrocytes, two independent pathways mediate the release of ATP. We also show that glyburide is a strong inhibitor of Panx1 channels.

Prostacyclin administration as a beneficial supplement to the conventional cancer chemotherapy

Prostacyclin (PGI(2)) and its analogues protect from cardiovascular disease through pleiotropic effects such as vasodilation, inhibition of platelet aggregation, leukocyte adhesion, and vascular smooth muscle cell (VSMC) proliferation. Additionally, prostacyclin synthase (PGIS) and PGI(2) also possess anti-cancer properties. As of late (2009-2010), numerous studies have identified the deleterious side-effects of chemotherapy on the cardiovascular system, which have been deemed as a serious clinical issue. Cardiomyocyte damage, induced by oxidative stress, is one of the clinical consequences caused by routine cancer chemotherapy. Previous studies indicate iloprost, a PGI(2) analogue, can protect against doxorubicin-induced (DOX) cardiomyocyte injury in vitro and in vivo without compromising tumor suppression. Therefore, we hypothesize PGI(2) can be used as a cardioprotective supplement to attenuate the damaging cardiac effects caused by the traditional cancer chemotherapy regimen.

[Immediately effects of inhaled aerosolised iloprost in adult patients with severe pulmonary hypertension secondary to congenital heart diseases]

OBJECTIVE

To investigate the immediately effects of inhaled aerosolized iloprost in adult patients with severe pulmonary arterial hypertension (PAH) secondary to congenital heart diseases (CHD).

METHODS

Adult patients with severe PAH secondary to CHD (n = 165) were included in this study. Right heart catheterization was performed, Pulmonary and systemic blood flow, the oxygen consumption VO(2) (ml/min) were calculated using Fick's principle. Pulmonary vascular resistances (PVR) were calculated with standard formulas and indexed to body surface area. Hemodynamic parameters were measured before and after iloprost inhalation (20 µg).

RESULTS

Post iloprost inhalation, heart rate, mean aortic pressure, pulmonary systolic pressure to aortic systolic pressure ratio all remained un changed (P > 0.05), while pulmonary artery pressure (PAP) were significantly reduced and Qp significantly increased from (7.2 ± 4.8) L/min to (9.9 ± 7.2) L/min (P < 0.01), PVR was also significantly reduced from (13.4 ± 8.7) Wood units to (9.5 ± 6.6) Wood units (P < 0.01), and left-to-right shunt volume increased from (3.2 ± 4.4) L/min to (5.5 ± 7.0) L/min (P < 0.01) and right-to-left shunt volume decreased from (1.0 ± 1.0) L/min to (0.7 ± 0.7) L/min (P < 0.01). Subgroup analysis showed that adult patients with patent ductus arteriosus and/or ventricular septal defects are more likely to develop severe pulmonary arterial hypertension or Eisenmenger syndrome than patients with atrial septal defects.

CONCLUSIONS

Inhaled Aerosolised iloprost use is effective and safe for adult patients with severe pulmonary arterial hypertension secondary to congenital heart diseases.

Prostaglandin I(2) analogues enhance growth-related oncogene-alpha expression in human monocyte-derived dendritic cells

Chemokines for neutrophils such as growth-related oncogene-alpha (GRO-alpha) are important in patients with refractory or severe asthma. Prostaglandin I(2) (PGI(2)) analogues were regarded as potential treatments for asthma. Dendritic cells (DCs) are the professional antigen-presenting cells and play a critical role in regulating immune response. However, it is unknown whether PGI(2) analogues have regulatory effects on GRO-alpha expression in human monocyte-derived DCs (MDDCs). The human MDDCs were pretreated with iloprost and treprostinil (two PGI(2) analogues) or forskolin, a cyclic adenosine monophosphate (cAMP) activator, before stimulation with lipopolysaccharide (LPS). In some cases, I prostanoid (IP) receptor and E prostanoid (EP) antagonists were pretreated before PGI(2) analogue treatment. To investigate the intracellular signaling, nuclear factor (NF)-kappaB inhibitor and the mitogen-activated protein kinase (MAPK) inhibitors were pretreated before PGI(2) analogue treatment. GRO-alpha was measured by enzyme-linked immunosorbent assay. Intracellular signaling was also investigated by Western blot. Iloprost and treprostinil enhanced LPS-induced GRO-alpha expression in MDDCs. This effect could be reversed by an I prostanoid receptor antagonist, CAY10449, but not EP receptor antagonists. Forskolin conferred a similar modulating effect as that noted in iloprost- and treprostinil-treated MDDCs. PGI(2) analogue-enhanced LPS-induced GRO-alpha expression was reduced by MAPK-p38 inhibitor, SB203580. PGI(2) analogues enhanced LPS-induced phospho-p38 expression. PGI(2) analogues enhanced LPS-induced GRO-alpha expression via the IP receptor-cAMP and p38-MAPK pathways in human MDDCs, which may further recruit neutrophil accumulation and adversely affect patients with refractory or severe asthma because of airway neutrophilia. These effects should be considered for PGI(2) analogues as candidates for the treatment of asthma.

Smooth muscle proliferation and role of the prostacyclin (IP) receptor in idiopathic pulmonary arterial hypertension

RATIONALE

Prostacyclin analogs, used to treat idiopathic pulmonary arterial hypertension (IPAH), are assumed to work through prostacyclin (IP) receptors linked to cyclic AMP (cAMP) generation, although the potential to signal through peroxisome proliferator-activated receptor-γ (PPARγ) exists.

OBJECTIVES

IP receptor and PPARγ expression may be depressed in IPAH. We wished to determine if pathways remain functional and if analogs continue to inhibit smooth muscle proliferation.

METHODS

We used Western blotting to determine IP receptor expression in peripheral pulmonary arterial smooth muscle cells (PASMCs) from normal and IPAH lungs and immunohistochemistry to evaluate IP receptor and PPARγ expression in distal arteries.

MEASUREMENTS AND MAIN RESULTS

Cell proliferation and cAMP assays assessed analog responses in human and mouse PASMCs and HEK-293 cells. Proliferative rates of IPAH cells were greater than normal human PASMCs. IP receptor protein levels were lower in PASMCs from patients with IPAH, but treprostinil reduced replication and treprostinil-induced cAMP elevation appeared normal. Responses to prostacyclin analogs were largely dependent on the IP receptor and cAMP in normal PASMCs, although in IP(-/-) receptor cells analogs inhibited growth in a cAMP-independent, PPARγ-dependent manner. In IPAH cells, antiproliferative responses to analogs were insensitive to IP receptor or adenylyl cyclase antagonists but were potentiated by a PPARγ agonist and inhibited (∼ 60%) by the PPARγ antagonist GW9662. This coincided with increased PPARγ expression in the medial layer of acinar arteries.

CONCLUSIONS

The antiproliferative effects of prostacyclin analogs are preserved in IPAH despite IP receptor down-regulation and abnormal coupling. PPARγ may represent a previously unrecognized pathway by which these agents inhibit smooth muscle proliferation.

[Inhaled iloprost during acute pulmonary vasodilator testing for preoperative assessment of surgical operability of congenital heart disease with severe pulmonary hypertension]

OBJECTIVE

To evaluate the efficacy of iloprost in acute vasodilatation test during cardiac catheterization and to explore a useful hemodynamic indication regarding operability in the patients with severe pulmonary hypertension (PH) related to congenital heart disease (CHD).

METHODS

The clinical data of 46 patients [mean age (12 ± 9) years] with severe PH related to CHD from June 2006 to December 2008 was retrospectively analyzed. All patients underwent standard right and left cardiac catheterization and a trial of inhaled iloprost test during cardiac catheterization. The mean pulmonary arterial pressure was (80 ± 13) mm Hg (1 mm Hg = 0.133 kPa) and pulmonary vascular resistance index was (17 ± 10) wood.m². A positive response to inhaled iloprost was defined as a decrease of at least 20% in pulmonary vascular resistance index (PVRI) without changes on systemic artery pressure. Patients with positive response to iloprost underwent cardiac surgical repair. The pulmonary artery pressure and PVRI was monitored by Swan-Ganz catheter postoperatively.

RESULTS

Of the 46 patients, 29 (63.1%) showed a positive response after iloprost inhalation, defined by a significant reduction in PVRI from (15 ± 6) wood.m(2) at baseline to (9 ± 4) wood.m² in response to iloprost inhalation therapy (P < 0.05). The ratio of pulmonary to systemic resistance (Rp/Rs) decreased from 0.7 ± 0.2 to 0.4 ± 0.2 (P < 0.05). Seventeen patients (36.9%) didn't respond to iloprost displayed only little changes in PVRI [from (21 ± 10) wood.m(2) to (19 ± 9) wood.m²] and Rp/Rs (from 1.0 ± 0.5 to 0.9 ± 0.5). Out of 29 positive patients, 21 (72%) underwent successful cardiac surgical repair with a reduction of mean pulmonary arterial pressure (mPAP) to an average of (27 ± 10) mm Hg after the operation. Only 2 patients out of the 17 patients from the negative group were referred to surgery. Their mPAP was greater than 45 mm Hg.

CONCLUSIONS

A significant reduction in pulmonary artery pressure after cardiac surgery was observed in patients with positive response to inhaled iloprost. Inhaled iloprost may be a valuable tool in the preoperative evaluation of patients with severe PH related to CHD.

In central obesity, weight loss restores platelet sensitivity to nitric oxide and prostacyclin

Central obesity shows impaired platelet responses to the antiaggregating effects of nitric oxide (NO), prostacyclin, and their effectors--guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP). The influence of weight loss on these alterations is not known. To evaluate whether a diet-induced body-weight reduction restores platelet sensitivity to the physiological antiaggregating agents and reduces platelet activation in subjects affected by central obesity, we studied 20 centrally obese subjects before and after a 6-month diet intervention aiming at reducing body weight by 10%, by measuring (i) insulin sensitivity (homeostasis model assessment of insulin resistance (HOMA(IR))); (ii) plasma lipids; (iii) circulating markers of inflammation of adipose tissue and endothelial dysfunction, and of platelet activation (i.e., soluble CD-40 ligand (sCD-40L) and soluble P-selectin (sP-selectin)); (iv) ability of the NO donor sodium nitroprusside (SNP), the prostacyclin analog Iloprost and the cyclic nucleotide analogs 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) and 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) to reduce platelet aggregation in response to adenosine-5-diphosphate (ADP); and (v) ability of SNP and Iloprost to increase cGMP and cAMP. The 10 subjects who reached the body-weight target showed significant reductions of insulin resistance, adipose tissue, endothelial dysfunction, and platelet activation, and a significant increase of the ability of SNP, Iloprost, 8-Br-cGMP, and 8-Br-cAMP to reduce ADP-induced platelet aggregation and of the ability of SNP and Iloprost to increase cyclic nucleotide concentrations. No change was observed in the 10 subjects who did not reach the body-weight target. Changes of platelet function correlated with changes of HOMA(IR). Thus, in central obesity, diet-induced weight loss reduces platelet activation and restores the sensitivity to the physiological antiaggregating agents, with a correlation with improvements in insulin sensitivity.

The in vitro effects of iloprost with other vasodilators on the human internal thoracic artery

PURPOSE

We aimed (a) to analyze the effects of iloprost as a vasodilator on the human internal thoracic artery (ITA) and (b) to compare these effects with the effects of other vasodilators now being used in the clinic.

METHODS

Following transfer into only Krebs solution or into Krebs solution containing papaverine or iloprost, human ITA strips were then incubated only in Krebs or in Krebs with vasodilators that are generally used in clinical practice, such as diltiazem or glyceryl trinitrate. Cumulative concentration-contraction curves for noradrenaline (NA) and KCl were then established for these strips. Student's t-test and one-way analysis of variance followed by Tukey-Kramer tests were used to compare differences between groups. A p <0.05 was used to indicate significance.

RESULTS

Among the transfer solutions, papaverine (6.50 ± 0.20) and iloprost (7.33 ± 0.13) were significantly more potent than Krebs (8.46 ± 0.75, p <0.001 and p <0.05) with regard to preventive effect on precontracted ITA with NA. Iloprost significantly relaxed the NA-induced precontracted ITA strips in the Krebs, papaverine, and iloprost groups. Diltiazem significantly relaxed the precontracted ITA with KCl in all storage groups.

CONCLUSION

Iloprost may also prevent perioperative ITA spasm, but should be tested in the clinical setting.

[The acute effects of inhaled iloprost on hemodynamics and oxygenation in chronic thromboembolic pulmonary hypertension]

OBJECTIVE

To evaluate the acute effects of inhaled iloprost on hemodynamics and oxygenation in chronic thromboembolic pulmonary hypertension (CTEPH).

METHODS

A prospective study was made. Eighteen patients with CTEPH were enrolled. At right heart catheterisation, iloprost was inhaled at 20 microg for 10 - 15 min. Compare the value of heart rate (HR), mean blood pressure (mBP), mean pulmonary arterial hypertension (mPAP), right atrium pressure (RAP), pulmonary arterial wedge pressure (PAWP), cardiac output (CO), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), arterial partial pressure of oxygen (PaO2), arterial oxygen saturation (SaO2), mixed venous saturation (SvO2), pulmonary shunt fraction (Qs/Qt), alveolar-arterial partial pressure of oxygen [P ( A-a) O2] before to after inhaled iloprost in these patients.

RESULTS

Significant changes (before to after inhalation): mPAP, (53 +/- 11) to (47 +/- 14) mm Hg (P < 0.01); PVR, (821 +/- 194) to (681 +/- 199) dyn x s x cm(-5) (P < 0.01); RAP, (10 +/- 6) to (7 +/- 6) mm Hg (P < 0.01). However, HR, PAWP, mBP, CO and SVR had no significant changes. At the same time, inhaled iloprost significantly decreased PaO2 from (58 +/- 11) to (52 +/- 6) mm Hg (P < 0.01) and increased Qs/Qt from (27 +/- 11)% to (33 +/- 9)% (P < 0.01)and P(A-a) O2 from (86 +/-39) to (93 +/- 38) mm Hg (P < 0.01).

CONCLUSION

Inhaled iloprost might instantly improve hemodynamics in CTEPH, but at the same time it increased arteriovenous shunts which resulted in lower PaO2.

[The oxygen kinetic effect of inhaled iloprost in pulmonary artery hypertension and chronic thromboembolic pulmonary hypertension]

OBJECTIVE

To study the acute oxygen kinetic effect of inhaled iloprost in pulmonary artery hypertension and chronic thromboembolic pulmonary hypertension.

METHODS

Twenty-two and 24 patients who were admitted to our hospital between June 2006 and January 2009 with confirmed diagnosis of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) respectively were enrolled to this study. During right heart catheterization, the hemodynamics and oxygen kinetics were monitored at baseline and after inhaling Iloprost (20 micrograms).

RESULTS

At baseline, the arterial partial pressure of oxygen (PaO2) was (63 +/- 10) mm Hg (1 mm Hg = 0.133 kPa) and (59 +/- 10) mm Hg respectively in PAH and CTEPH patients, and the oxygen delivery index (DO2I) and oxygen consumption index (VO2I) were (458 +/- 136) ml x min(-1) x m(-2) and (135 +/- 53) ml x min(-1) x m(-2) in PAH patients respectively, and (386 +/- 92) ml x min(-1) x m(-2) and (131 +/- 43) ml x min(-1) x m(-2) in CTEPH patients respectively. Three minutes after inhaling Iloprost, for PAH and CTEPH patients, the pulmonary shunt rate (Qs/Qt) all increased significantly (all P < 0.05, respectively) as well as the difference of oxygen partial pressure between pulmonary alveoli and artery (P[A-a]O2, all P < 0.05, respectively), and the arterial oxygen content (CaO2) all decreased significantly (all P < 0.05, respectively). The oxygenation parameters of mixed venous blood, oxygen extractive rate and DO2I did not change significantly, but VO2I declined to different extent. The extent of change after inhaling Iloprost for all oxygen kinetic parameters were similar between PAH and CTEPH patients. At baseline, mixed venous oxygen saturation (SvO2), venous oxygen content (CvO2) and DO2I in CTEPH patients were lower than those in PAH patients. After inhaling Iloprost, in CTEPH patients, PaO2, SvO2 and CvO2 were lower than those in PAH patients.

CONCLUSION

There were hypoxemia and abnormality of oxygen kinetics in PAH and CTEPH patients. After inhaling Iloprost, pulmonary shunt increased without improvement in oxygen kinetics. Oxygenation should be monitored closely and supply oxygen supplied for CTEPH when inhaling Iloprost.

Prostacyclin analogue iloprost influences endothelial cell-associated soluble adhesion molecules and growth factors in patients with systemic sclerosis: a time course study of serum concentrations

Systemic sclerosis is a connective tissue disorder with unclear aetiology and pathogenesis. However, there is evidence that microvascular changes belong to the early symptoms of the disease. These are associated with increased serum levels of markers of endothelium activation, such as adhesion molecules and growth factors. The stable prostacyclin analogue iloprost is licensed for vascular symptoms (Raynaud's phenomenon) and was recently shown to exert short-term effects on these markers. In this study, serum samples (n = 13) from patients with systemic sclerosis were examined for serum levels of vascular cell adhesion molecule-1 (VCAM-1), intercellular cell adhesion molecule-1, E-selectin, endothelin-1 and vascular endothelial growth factor over 6 months after iloprost infusions in order to detect possible long-term effects. Iloprost significantly reduced initially elevated levels of these markers, partly until the end of the observation period (E-selectin, VCAM-1, endothelin-1). These effects provide serological evidence for the benefits of iloprost infusions that are seen clinically in patients with systemic sclerosis.

Donor heart preservation with iloprost supplemented St. Thomas Hospital cardioplegic solution in isolated rat hearts

This study was designed to assess the influence of St. Thomas Hospital cardioplegic solution (St. Th.) on heart preservation in rat hearts subjected to 6h ischemia when supplemented with iloprost. In the control group (n=8), nothing was added to St. Th., whereas 10 or 1000 nmol L(-1) iloprost was added in the second (n=7) and third (n=8) groups, respectively. Mechanical contraction parameters, cardiac tissue damage and oxidative stress markers were evaluated. The 10 nmol/L iloprost group peak systolic pressure (71.0+/-30.9 versus 41.0+/-9.4 mm Hg) and -dp/dtmax (1103.8+/-94.3 versus 678.6+/-156.8 mm Hg s(-1)) were significantly higher than control group at 30 min of reperfusion (p<0.05). Iloprost supplemented groups had higher GSH and catalase levels of coronary perfusate at reperfusion, in comparison with initial values (p<0.05). AST, CK, CK-MB values increased at 0 min of reperfusion and cTnI values at 45 min of reperfusion (p<0.05) in all groups with no difference between groups. According to our results, iloprost supplementation had mild but significant improvement in postischemic values in mechanical and oxidative stress parameters, resulting in better heart preservation.