Efectos y terapias con surfactante pulmonar en el tratamiento de patologías respiratorias

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, Departamento de Bioquímica y Biología Molecular, leída el 19-04-2021Respiratory diseases are one of the primary causes of death, disability and health costs worldwide. In this framework, the lack and dysfunction of lung surfactant may result in airless collapsed alveoli and difficulty for breathing, being the primary trigger or a contributing factor of severe respiratory disorders, such as neonatal respiratory distress syndrome (RDS) and acute respiratory distress syndrome (ARDS). RDS is a common cause of morbidity in preterm neonates, associated to immature lungs and an impaired secretion of pulmonary surfactant. The latter is, instead, present but inactivated during ARDS, a quickly progressive severe respiratory failure characterised by widespread acute lung inflammation. In both diseases, the leading role of pulmonary surfactant is due to its specific properties, which permit to maintain reduced surface tension values at the alveolar spaces, particularly upon exhalation. To accomplish this function, its lipid-protein complexes are secreted by pneumocyte type II cells and distribute, as a dense network of membranes, at the air liquid-interface that is generated between the aqueous layer covering the pulmonary epithelium and the alveolar air space. The resulting efficient adsorption, spreading and reorganisation of lung surfactant prevent alveolar collapse and depend on its particular composition: ~90% lipids, mainly disaturated phospholipids (~50%), and 10% of hydrophilic (SP-A and SP-D) and highly hydrophobic proteins (SP-B and SP-C)...Las enfermedades respiratorias son una de las principales causas de muerte, discapacidad y gasto sanitario en todo el mundo. En este contexto, la falta o disfunción del surfactante pulmonar puede ser el desencadenante principal o un factor contribuyente de trastornos respiratorios graves, como el síndrome de dificultad respiratoria neonatal (RDS) y el síndrome de dificultad respiratoria aguda (ARDS). Gracias a su composición, estructura y actividad interfacial, el surfactante pulmonar cumple una función vital durante el proceso de la respiración, reduciendo la tensión superficial del fluido alveolar y minimizando la energía necesaria especialmente durante la exhalación. Aproximadamente el 90% del surfactante pulmonar son lípidos, principalmente fosfolípidos disaturados (~ 50%). El 10% restante lo componen fundamentalmente proteínas, dos hidrofílicas (SP-A y SP-D) y otras dos altamente hidrofóbicas (SP-B y SP-C). Para lograr esta función vital, los complejos lipoproteícos del surfactante se distribuyen como una densa red de membranas en la interfase aire-líquido generada entre la capa acuosa que recubre el epitelio pulmonar y el espacio aéreo alveolar. El resultado es una eficiente adsorción, propagación y reorganización del material tensoactivo que previene el colapso alveolar...Fac. de Ciencias BiológicasTRUEunpu

Techniques to evaluate surfactant activity for a personalized therapy of RDS neonates

According to both European and American Guidelines, preterm neonates have to be treated by nasal continuous air pressure (CPAP) early in the delivery room. The administration of surfactant should be reserved only for babies with respiratory distress syndrome (RDS) with increased oxygen requirement, according to different thresholds of FiO2. However, these oxygenation thresholds do not fully take into consideration the lung physiopathology and mechanics or the lung surfactant biology of RDS neonates. Since surfactant replacement therapy (SRT) seems to be more effective if it is initiated within the first 3 hours after birth, the use of a reliable bench-to-bedside biological test able to predict as soon as possible the necessity of SRT will help optimise individualised therapies and personalise the actual collective strategy used to treat RDS neonates. With this in mind, in the present review several quantitative and qualitative biological tests to assess the surfactant status in RDS neonates are introduced as potential candidates for the early prediction of SRT requirement, summarising the state-of-the-art in the evaluation of surfactant activity

Strategies to protect surfactant and enhance its activity

The knowledge about surfactant biology is now deeper and recent research has allowed to clarify its role in several human lung disorders. The balance between surfactant production and consumption is better known and the same applies to their regulatory mechanisms. This has allowed to hypothesize and investigate several new and original strategies to protect surfactant and enhance its activity. These interventions are potentially useful for several disorders and particularly for acute respiratory distress syndrome. We here highlight the mechanisms regulating surfactant consumption, encompassing surfactant catabolism but also surfactant injury due to other mechanisms, in a physiopathologydriven fashion. We then analyze each corresponding strategy to protect surfactant and enhance its activity. Some of these strategies are more advanced in terms of research & development pathway, some others are still investigational, but all are promising and deserve a joint effort from clinical-academic researchers and the industry

In Vitro functional and structural characterization of a synthetic clinical pulmonary surfactant with enhanced resistance to inhibition

CHF5633 is a novel synthetic clinical pulmonary surfactant preparation composed by two phospholipid species, dipalmitoyl phosphatidylcholine (DPPC) and palmitoyloleoyl phosphatidylglycerol (POPG), and synthetic analogues of the hydrophobic surfactant proteins SP-B and SP-C. In this study, the interfacial properties of CHF5633 in the absence and in the presence of inhibitory serum proteins have been assessed in comparison with a native surfactant purifed from porcine lungs and with poractant alpha, a widely used clinical surfactant preparation. The study of the spreading properties of CHF5633 in a Wilhelmy balance, its ability to adsorb and accumulate at air-liquid interfaces as revealed by a multiwell fuorescence assay, and its dynamic behavior under breathing-like compression-expansion cycling in a Captive Bubble Surfactometer (CBS), all revealed that CHF5633 exhibits a good behavior to reduce and sustain surface tensions to values below 5 mN/m. CHF5633 shows somehow slower initial interfacial adsorption than native surfactant or poractant alpha, but a better resistance to inhibition by serum proteins than the animal-derived clinical surfactant, comparable to that of the full native surfactant complex. Interfacial CHF5633 flms formed in a Langmuir-Blodgett balance coupled with epifuorescence microscopy revealed similar propensity to segregate condensed lipid domains under compression than flms made by native porcine surfactant or poractant alpha. This ability of CHF5633 to segregate condensed lipid phases can be related with a marked thermotropic transition from ordered to disordered membrane phases as exhibited by diferential scanning calorimetry (DSC) of CHF5633 suspensions, occurring at similar temperatures but with higher associated enthalpy than that shown by poractant alpha. The good interfacial behavior of CHF5633 tested under physiologically meaningful conditions in vitro and its higher resistance to inactivation by serum proteins, together with its standardized and well-defned composition, makes it a particularly useful therapeutic preparation to be applied in situations associated with lung infammation and edema, alone or in combined strategies to exploit surfactant-facilitated drug delivery

Molecular and biophysical mechanisms behind the enhancement of lung surfactant function during controlled therapeutic hypothermia

Therapeutic hypothermia (TH) enhances pulmonary surfactant performance in vivo by molecular mechanisms still unknown. Here, the interfacial structure and the composition of lung surfactant flms have been analysed in vitro under TH as well as the molecular basis of its improved performance both under physiological and inhibitory conditions. The biophysical activity of a purifed porcine surfactant was tested under slow and breathing-like dynamics by constrained drop surfactometry (CDS) and in the captive bubble surfactometer (CBS) at both 33 and 37 °C. Additionally, the temperaturedependent surfactant activity was also analysed upon inhibition by plasma and subsequent restoration by further surfactant supplementation. Interfacial performance was correlated with lateral structure and lipid composition of flms made of native surfactant. Lipid/protein mixtures designed as models to mimic diferent surfactant contexts were also studied. The capability of surfactant to drastically reduce surface tension was enhanced at 33 °C. Larger DPPC-enriched domains and lower percentages of less active lipids were detected in surfactant flms exposed to TH-like conditions. Surfactant resistance to plasma inhibition was boosted and restoration therapies were more efective at 33 °C. This may explain the improved respiratory outcomes observed in cooled patients with acute respiratory distress syndrome and opens new opportunities in the treatment of acute lung injury

Antileukotrienes Improve Naso-Ocular Symptoms and Biomarkers inPatients With NARES and Asthma

Objective: The aim of our study was to analyze the montelukast effectiveness in improving oculonasal symptoms, patient-reported outcomes (PROs), and eosinophilic biomarkers in patients with nonallergic rhinitis eosinophilic syndrome (NARES).Methods: We enrolled prospectively 80 symptomatic patients treated with 10 mg once a day of montelukast in mono-therapy for 2 months. All patients were investigated before and after treatment. Nasal symptoms (nasal obstruction, rhinor-rhoea, sneezing, nasal itching), ocular symptoms (redness/puffiness, watery eyes), and other PROs (olfactory dysfunction,difficulty going to sleep, nighttime awakenings, and nasal congestion on awakening) were scored by visual analogic scale. Thefollowing clinical scores were assessed: Total Nasal Symptom Score (T4NSS), Total Ocular Symptom Score (T2OSS), TotalSymptom Score of Patient-Reported Outcomes (TSS-PROs), and a Composite Symptoms Score (CSS). Patients were classified asresponders when a reduction of at least 50% of the CSS was observed. Before and after treatment, the eosinophilic biomarkersin nasal lavage were analyzed: nasal eosinophilia (number of eosinophils per high power field), eotaxin-1 and eotaxin-2.Results: Aft er tre atment, s ig nificant reductions were observed for all the symptom scores. Forty-two of 78 patients were con-sidered responders. A significant reduction of eosinophils in nasal mucosa and of levels of eotaxin-1 and eotaxin-2 in nasal lavagewere observed after treatment in responder patients. Patients with asthma had an increased probability to be responders.Conclusion: NARES patients may benefit from treatment with montelukast. In particular, the presence of concomitantasthma may be predictive of a greater efficacy

Restoring pulmonary surfactant membranes and films at the respiratory surface

Pulmonary surfactant is a complex of lipids and proteins assembled and secreted by the alveolar epithelium into the thin layer of fluid coating the respiratory surface of lungs. There, surfactant forms interfacial films at the airwater interface, reducing dramatically surface tension and thus stabilizing the air-exposed interface to prevent alveolar collapse along respiratory mechanics. The absence or deficiency of surfactant produces severe lung pathologies. This review describes some of the most important surfactant-related pathologies, which are a cause of high morbidity and mortality in neonates and adults. The review also updates current therapeutic approaches pursuing restoration of surfactant operative films in diseased lungs, mainly through supplementation with exogenous clinical surfactant preparations. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá