Inhaled nitric oxide combined with prostacyclin and adrenomedullin in acute respiratory failure with pulmonary hypertension in piglets

Sustained Activation of CLR/RAMP Receptors by Gel-Forming Agonists

Background: Adrenomedullin (ADM), adrenomedullin 2 (ADM2), and CGRP family peptides are important regulators of vascular vasotone and integrity, neurotransmission, and fetoplacental development. These peptides signal through CLR/RAMP1, 2, and 3 receptors, and protect against endothelial dysfunction in disease models. As such, CLR/RAMP receptor agonists are considered important therapeutic candidates for various diseases. Methods and Results: Based on the screening of a series of palmitoylated chimeric ADM/ADM2 analogs, we demonstrated a combination of lipidation and accommodating motifs at the hinge region of select peptides is important for gaining an enhanced receptor-activation activity and improved stimulatory effects on the proliferation and survival of human lymphatic endothelial cells when compared to wild-type peptides. In addition, by serendipity, we found that select palmitoylated analogs self-assemble to form liquid gels, and subcutaneous administration of an analog gel led to the sustained presence of the peptide in the circulation for >2 days. Consistently, subcutaneous injection of the analog gel significantly reduced the blood pressure in SHR rats and increased vasodilation in the hindlimbs of adult rats for days. Conclusions: Together, these data suggest gel-forming adrenomedullin analogs may represent promising candidates for the treatment of various life-threatening endothelial dysfunction-associated diseases such as treatment-resistant hypertension and preeclampsia, which are in urgent need of an effective drug.

Orotracheal treprostinil administration attenuates bleomycin-induced lung injury, vascular remodeling, and fibrosis in mice

Pulmonary fibrosis is a progressive disease characterized by disruption of lung architecture and deregulation of the pulmonary function. Prostacyclin, a metabolite of arachidonic acid, is a potential disease mediator since it exerts anti-inflammatory and anti-fibrotic actions. We investigated the effect of treprostinil, a prostacyclin analogue, in bleomycin-induced experimental pulmonary fibrosis. Bleomycin sulfate or saline was administrated intratracheally to mice (n = 9-10/group) at day 0. Orotracheal aspiration of treprostinil or vehicle was administered daily and started 24 h prior to bleomycin challenge. Evaluation of lung pathology was performed in tissue samples and bronchoalveolar lavage fluid collected 7, 14 and 21 days after bleomycin exposure. Lung injury was achieved due to bleomycin exposure at all time points as indicated by impaired lung mechanics, pathologic lung architecture (from day 14), and cellular and protein accumulation in the alveolar space accompanied by a minor decrease in lung tissue VE-cadherin at day 14. Treprostinil preserved lung mechanics, and reduced lung inflammation, fibrosis, and vascular remodeling (day 21); reduced cellularity and protein content of bronchoalveolar lavage fluid were additionally observed with no significant effect on VE-cadherin expression. Bleomycin-induced collagen deposition was attenuated by treprostinil from day 14, while treprostinil involvement in regulating inflammatory processes appears mediated by NF-κB signaling. Overall, prophylactic administration of treprostinil, a stable prostacyclin analogue, maintained lung function, and prevented bleomycin-induced lung injury, and fibrosis, as well as vascular remodeling, a hallmark of pulmonary hypertension. This suggests potential therapeutic efficacy of treprostinil in pulmonary fibrosis and possibly in pulmonary hypertension related to chronic lung diseases.

Inhaled nitric oxide for the treatment of preterm infants with respiratory distress syndrome

Many authors have hypothesized that inhaled nitric oxide (iNO) might acutely improve oxygenation in preterm neonates with infant respiratory distress syndrome (iRDS) and decrease the risk of bronchopulmonary dysplasia. The studies on the effects of iNO in preterm infants with iRDS have given contradictory results. We report their main methodological characteristics and the observed effects of iNO in preterm infants. Moreover, we discuss the infants' age at the beginning of the study, the dose and duration of iNO therapy, its potential effect on neurodevelopment, its relationship with surfactant properties, and the need to identify patients who are likely to respond to this therapy. We advise caution against the widespread use of iNO in preterm infants with iRDS. At present, it appears to be premature to have specific recommendations regarding the indications for iNO therapy in this group of patients. The conclusion of current trials and the follow-up studies of recently completed trials will give further data to guide neonatologists' decisions, and until then it is likely that clinicians will continue to make case-by-case decisions for the treatment of iNO in preterm infants with hypoxia that is unresponsive to other therapies. However, this decision should always be discussed with the parents.