Iloprost

BackgroundMetabolites of arachidonic acid such as prostacyclin (PGI2) have been shown to participate in the pathogenesis of pulmonary fibrosis by inhibiting the expression of pro-inflammatory and pro-fibrotic mediators. In this investigation, we examined whether iloprost, a stable PGI2 analogue, could prevent bleomycin-induced pulmonary inflammation and fibrosis in a mouse model.MethodsMice received a single intratracheal injection of bleomycin with or without intraperitoneal iloprost. Pulmonary inflammation and fibrosis were analysed by histological evaluation, cellular composition of bronchoalveolar lavage (BAL) fluid, and hydroxyproline content. Lung mechanics were measured. We also analysed the expression of inflammatory mediators in BAL fluid and lung tissue.ResultsAdministration of iloprost significantly improved survival rate and reduced weight loss in the mice induced by bleomycin. The severe inflammatory response and fibrotic changes were significantly attenuated in the mice treated with iloprost as shown by reduction in infiltration of inflammatory cells into the airways and pulmonary parenchyma, diminution in interstitial collagen deposition, and lung hydroxyproline content. Iloprost significantly improved lung static compliance and tissue elastance. It increased the expression of IFNgamma and CXCL10 in lung tissue measured by RT-PCR and their levels in BAL fluid as measured by ELISA. Levels of TNFalpha, IL-6 and TGFbeta1 were lowered by iloprost.ConclusionsIloprost prevents bleomycin-induced pulmonary fibrosis, possibly by upregulating antifibrotic mediators (IFNgamma and CXCL10) and downregulating pro-inflammatory and pro-fibrotic cytokines (TNFalpha, IL-6, and TGFbeta1). Prostacyclin may represent a novel pharmacological agent for treating pulmonary fibrotic diseases.

Within an aging population, fracture incidences will rise and with the augmented risks of impaired healing the overall risk of delayed bone regeneration will substantially increase in elderly patients. Thus, new strategies to rescue fracture healing in the elderly are highly warranted. Modulating the initial inflammatory phase toward a reduced pro-inflammation launches new treatment options for delayed or impaired healing specifically in the elderly. Here, we evaluated the capacity of the prostacyclin analog Iloprost to modulate the inflammatory phase toward a pro-regenerative milieu using in vitro as well as in vivo model systems. In vitro, Iloprost administration led to a downregulation of potential unfavorable CD8+ cytotoxic T cells as well as their pro-inflammatory cytokine secretion profile. Furthermore, Iloprost increased the mineralization capacity of osteogenic induced mesenchymal stromal cells through both direct as well as indirect cues. In an in vivo approach, Iloprost, embedded in a biphasic fibrin scaffold, decreased the pro-inflammatory and simultaneously enhanced the anti-inflammatory phase thereby improving bone healing outcome. Overall, our presented data confirms a possible strategy to modulate the early inflammatory phase in aged individuals toward a physiological healing by a downregulation of an excessive pro-inflammation that otherwise would impair healing. Further confirmation in phase I/II trials, however, is needed to validate the concept in a broader clinical evaluation.

IntroductionBone marrow oedema (BME) and avascular osteonecrosis (AVN) are disorders of unclear origin. Although there are numerous operative and non-operative treatments for AVN, pain management in patients with AVN remains challenging. Prostaglandins play an important role in inflammatory responses and cell differentiation. It is thought that prostaglandin I2 ([PGI2] or synonoma prostacyclin) and its analogues promote bone regeneration on a cellular or systemic level. The purpose of this study was to assess the curative and symptomatic efficacy of the prostacyclin analogue iloprost in BME and AVN patients.MethodWe are reporting on 50 patients (117 bones) affected by BME/AVN who were treated with iloprost. Pain levels before, during and 3 and 6 months after iloprost application were evaluated by a visual analogue scale (VAS). The short form(SF)-36 health survey served to judge general health status before and after treatment. Harris Hip Score (HHS) and Knee Society Score (KSS) were performed as functional scores and MRI and X-rays before and 3 and 6 months after iloprost application served as objective parameters for morphological changes of the affected bones.ResultsWe found a significant improvement in pain, functional and radiological outcome in BME and early AVN stages after iloprost application, whereas patients with advanced AVN stages did not benefit from iloprost infusions. Mean pain level decreased from 5.26 (day 0) to 1.63 (6 months) and both HHS and KSS increased during follow-up. Moreover, the SF-36 increased from 353.2 (day 0) to 560.5 points (6 months). We found a significant decrease in BME on MRI scans after iloprost application.ConclusionsIn addition to other drugs, iloprost may be an alternative substance which should be considered in the treatment of BME/AVN-associated pain.

Iloprost, a prostacyclin (PGI2) analogue, stimulates the IP receptor (PTGIR) to interact with the Gsα β/γ complex, leading to the activation of adenylate cyclase, which enzyme produces the second messenger cAMP. Elevation in cAMP triggers intracellular signalling events and regulates a wide variety of cellular activities. Thus, we evaluated the effects of Iloprost on platelet function and apoptosis and in vivo haemostasis and thrombosis, as well as the underlying mechanisms. Firstly, we showed that Iloprost concentration-dependently inhibited agonist-induced P-selectin exposure, integrin αIIbβ3 activation, platelet aggregation, ATP release, platelet spreading, and clot retraction. Moreover, Iloprost dose-dependently inhibited FeCl3-induced mouse mesenteric arteriole thrombosis and markedly prolonged the tail bleeding time. Iloprost also concentration-dependently inhibited mitochondrial membrane potential (ΔΨm) depolarisation and phosphatidylserine (PS) externalisation in platelets, thereby inhibiting platelet apoptosis, and Iloprost at concentrations lower than 2 nM inhibited only platelet apoptosis but not platelet function. Importantly, Iloprost at low doses markedly elevated peripheral platelet counts in GPIbα antibody-induced immune thrombocytopenia (ITP). Mechanistic studies showed that Iloprost concentration-dependently antagonised agonist-induced decline of protein kinase A (PKA) activity and elevation of cytoplasmic Ca2+ in platelets, thereby attenuating platelet activation and aggregation. Elevation in PKA activity inhibited dephosphorylation of proapoptotic protein BAD and reduced caspase-3 activity, thus retarding platelet apoptosis. These data demonstrate that Iloprost dose-dependently inhibits platelet function and apoptosis by elevating PKA activity. Moderate-dose Iloprost impairs haemostasis and thrombosis via suppression of platelet function, and low-dose Iloprost elevates peripheral platelet levels by inhibiting platelet apoptosis while having no effects on platelet function.