Inhalation therapies in acute respiratory distress syndrome

Acute respiratory distress syndrome: A review of ARDS across the life course

Acute respiratory distress syndrome (ARDS) is a multifactorial, inflammatory lung disease with significant morbidity and mortality that predominantly requires supportive care in its management. Although initially described in adult patients, the diagnostic definitions for ARDS have evolved over time to accurately describe this disease process in pediatric and, more recently, neonatal patients. The management of ARDS in each age demographic has converged in the application of lung-protective ventilatory strategies to mitigate the primary disease process and prevent its exacerbation by limiting ventilator-induced lung injury. However, differences arise in the preferred ventilatory strategies or adjunctive pulmonary therapies used to mitigate each type of ARDS. In this review, we compare and contrast the epidemiology, common etiologies, pathophysiology, diagnostic criteria, and outcomes of ARDS across the lifespan. Additionally, we discuss in detail the different management strategies used for each subtype of ARDS and spotlight how these strategies were applied to mitigate poor outcomes during the COVID-19 pandemic. This review is geared toward both clinicians and clinician-scientists as it not only summarizes the latest information on disease pathogenesis and patient management in ARDS across the lifespan but also highlights knowledge gaps for further investigative efforts. We conclude by projecting how future studies can fill these gaps in research and what improvements may be envisioned in the management of NARDS and PARDS based on the current breadth of literature on adult ARDS treatment strategies.

Steroids in acute respiratory distress syndrome: A panacea or still a puzzle?

Acute respiratory distress syndrome (ARDS) is a unique entity marked by various etiologies and heterogenous pathophysiologies. There remain concerns regarding the efficacy of particular medications for each severity level apart from respiratory support. Among several pharmacotherapies which have been examined in the treatment of ARDS, corticosteroids, in particular, have demonstrated potential for improving the resolution of ARDS. Nevertheless, it is imperative to consider the potential adverse effects of hyperglycemia, susceptibility to hospital-acquired infections, and the development of intensive care unit acquired weakness when administering corticosteroids. Thus far, a multitude of trials spanning several decades have investigated the role of corticosteroids in ARDS. Further stringent trials are necessary to identify particular subgroups before implementing corticosteroids more widely in the treatment of ARDS. This review article provides a concise overview of the most recent evidence regarding the role and impact of corticosteroids in the management of ARDS.

Hybrid biomineralized nanovesicles to enhance inflamed lung biodistribution and reduce side effect of glucocorticoid for ARDS therapy

Acute respiratory distress syndrome (ARDS) is a critical illness characterized by severe lung inflammation. Improving the delivery efficiency and achieving the controlled release of anti-inflammatory drugs at the lung inflammatory site are major challenges in ARDS therapy. Taking advantage of the increased pulmonary vascular permeability and a slightly acidic-inflammatory microenvironment, pH-responsive mineralized nanoparticles based on dexamethasone sodium phosphate (DSP) and Ca2+ were constructed. By further biomimetic modification with M2 macrophage membranes, hybrid mineralized nanovesicles (MM@LCaP) were designed to possess immunomodulatory ability from the membranes and preserve the pH-sensitivity from core nanoparticles for responsive drug release under acidic inflammatory conditions. Compared with healthy mice, the lung/liver accumulation of MM@LCaP in inflammatory mice was increased by around 5.5 times at 48 h after intravenous injection. MM@LCaP promoted the polarization of anti-inflammatory macrophages, calmed inflammatory cytokines, and exhibited a comprehensive therapeutic outcome. Moreover, MM@LCaP improved the safety profile of glucocorticoids. Taken together, the hybrid mineralized nanovesicles-based drug delivery strategy may offer promising ideas for enhancing the efficacy and reducing the toxicity of clinical drugs.

Aerosol Delivery of a Novel Recombinant Modified Superoxide Dismutase Protein Reduces Oxidant Injury and Attenuates Escherichia coli Induced Lung Injury in Rats

Background: Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory failure syndrome with diverse etiologies characterized by increased permeability of alveolar-capillary membranes, pulmonary edema, and acute onset hypoxemia. During the ARDS acute phase, neutrophil infiltration into the alveolar space results in uncontrolled release of reactive oxygen species (ROS) and proteases, overwhelming antioxidant defenses and causing alveolar epithelial and lung endothelial injury. Objectives: To investigate the therapeutic potential of a novel recombinant human Cu-Zn-superoxide dismutase (SOD) fusion protein in protecting against ROS injury and for aerosolized SOD delivery to treat Escherichia coli induced ARDS. Methods: Fusion proteins incorporating human Cu-Zn-SOD (hSOD1), with (pep1-hSOD1-his) and without (hSOD1-his) a fused hyaluronic acid-binding peptide, were expressed in E. coli. Purified proteins were evaluated in in vitro assays with human bronchial epithelial cells and through aerosolized delivery to the lung of an E. coli-induced ARDS rat model. Results: SOD proteins exhibited high SOD activity in vitro and protected bronchial epithelial cells from oxidative damage. hSOD1-his and pep1-hSOD1-his retained SOD activity postnebulization and exhibited no adverse effects in the rat. Pep1-hSOD1-his administered through instillation or nebulization to the lung of an E. coli-induced pneumonia rat improved arterial oxygenation and lactate levels compared to vehicle after 48 hours. Static lung compliance was improved when the pep1-hSOD1-his protein was delivered by instillation. White cell infiltration to the lung was significantly reduced by aerosolized delivery of protein, and reduction of cytokine-induced neutrophil chemoattractant-1, interferon-gamma, and interleukin 6 pro-inflammatory cytokine concentrations in bronchoalveolar lavage was observed. Conclusions: Aerosol delivery of a novel recombinant modified SOD protein reduces oxidant injury and attenuates E. coli induced lung injury in rats. The results provide a strong basis for further investigation of the therapeutic potential of hSOD1 in the treatment of ARDS.

Expression of circulating angiotensin-converting enzyme 2 in children with asthma and the effects of inhaled corticosteroids

BACKGROUND

The global spread of coronavirus disease 2019 (COVID-19) has resulted in a significant disease burden, yet asthma patients do not have the expected high morbidity and mortality rates in the pandemics of COVID-19.

OBJECTIVE

To find the difference of angiotensin-converting enzyme 2 (ACE2) in asthma and nonasthma children and evaluate the effect of inhaled corticosteroids (ICS) on its expression.

METHODS

The ACE2, immunoglobulin E (IgE), and eosinophils were tested in different children.

RESULTS

A total of 157 children aged 3-16 years were enrolled. The expression of ACE2 in asthma children were lower than nonasthma children (T = -2.512, p = .013). Allergic nonasthma children had a significant higher ACE2 expression than children with allergic asthma (p = .013) and nonallergic asthma (p = .029). The expression of ACE2 had no significant difference between first-diagnosed asthma children and that had been treated with ICS for ≥6 months (F = 0.028, p = .598). The allergic asthma children showed a significantly higher eosinophils cells (EC) count than the allergic nonasthma (W = 200, p < .001) and nonallergic nonasthma children (W = 1089, p < .001). Nonallergic asthma children also had a significant higher EC count than the allergic non-asthma (W = 182.5, p < .001) and nonallergic non-asthma (W = 200.5, p < .001) children. There was no significant difference in IgE levels between asthmatic children and non-asthmatic children (W = 2792.5, p = .18).

CONCLUSION

Circulating ACE2 levels in asthmatic children were lower than those in non-asthmatic children and ICS treatment for ≥6 months did not affect the expression of ACE2 in peripheral blood in the asthma children.

The Epithelial Sodium Channel-An Underestimated Drug Target

Epithelial sodium channels (ENaC) are part of a complex network of interacting biochemical pathways and as such are involved in several disease states. Dependent on site and type of mutation, gain- or loss-of-function generated symptoms occur which span from asymptomatic to life-threatening disorders such as Liddle syndrome, cystic fibrosis or generalized pseudohypoaldosteronism type 1. Variants of ENaC which are implicated in disease assist further understanding of their molecular mechanisms in order to create models for specific pharmacological targeting. Identification and characterization of ENaC modifiers not only furthers our basic understanding of how these regulatory processes interact, but also enables discovery of new therapeutic targets for the disease conditions caused by ENaC dysfunction. Numerous test compounds have revealed encouraging results in vitro and in animal models but less in clinical settings. The EMA- and FDA-designated orphan drug solnatide is currently being tested in phase 2 clinical trials in the setting of acute respiratory distress syndrome, and the NOX1/ NOX4 inhibitor setanaxib is undergoing clinical phase 2 and 3 trials for therapy of primary biliary cholangitis, liver stiffness, and carcinoma. The established ENaC blocker amiloride is mainly used as an add-on drug in the therapy of resistant hypertension and is being studied in ongoing clinical phase 3 and 4 trials for special applications. This review focuses on discussing some recent developments in the search for novel therapeutic agents.

Aerosolized Pulmonary Delivery of mRNA Constructs Attenuates Severity of Escherichia coli Pneumonia in the Rat

Acute respiratory distress syndrome (ARDS), a rapid onset inflammatory lung disease with no effective specific therapy, typically has pathogenic etiology termed pneumonia. In previous studies nuclear factor-κB (NF-κB) inhibitor α super-repressor (IκBα-SR) and extracellular superoxide dismutase 3 (SOD3) reduced pneumonia severity when prophylactically delivered by viral vector. In this study, mRNA coding for green fluorescent protein, IκBα-SR, or SOD3 was complexed with cationic lipid, passed through a vibrating mesh nebulizer, and delivered to cell culture or directly to rats undergoing Escherichia coli pneumonia. Injury level was then assessed at 48 h. In vitro, expression was observed as early as 4 h in lung epithelial cells. IκBα-SR and wild-type IκBα mRNAs attenuated inflammatory markers, while SOD3 mRNA induced protective and antioxidant effects. In rat E. coli pneumonia, IκBα-SR mRNA reduced arterial carbon dioxide (pCO2) and reduced lung wet/dry ratio. SOD3 mRNA improved static lung compliance and alveolar-arterial oxygen gradient (AaDO2) and decreased bronchoalveolar lavage (BAL) bacteria load. White cell infiltration and inflammatory cytokine concentrations in BAL and serum were reduced by both mRNA treatments compared to scrambled mRNA controls. These findings indicate nebulized mRNA therapeutics are a promising approach to ARDS therapy, with rapid expression of protein and observable amelioration of pneumonia symptoms.

Acinetobacter baumannii among Patients Receiving Glucocorticoid Aerosol Therapy during Invasive Mechanical Ventilation, China

Acinetobacter baumannii is a nosocomial pathogen associated with severe illness and death. Glucocorticoid aerosol is a common inhalation therapy in patients receiving invasive mechanical ventilation. We conducted a prospective cohort study to analyze the association between glucocorticoid aerosol therapy and A. baumannii isolation from ventilator patients in China. Of 497 enrolled patients, 262 (52.7%) received glucocorticoid aerosol, and A. baumannii was isolated from 159 (32.0%). Glucocorticoid aerosol therapy was an independent risk factor for A. baumannii isolation (hazard ratio 1.5, 95% CI 1.02-2.28; p = 0.038). Patients receiving glucocorticoid aerosol had a higher cumulative hazard for A. baumannii isolation and analysis showed that glucocorticoid aerosol therapy increased A. baumannii isolation in most subpopulations. Glucocorticoid aerosol was not a direct risk factor for 30-day mortality, but A. baumannii isolation was independently associated with 30-day mortality in ventilator patients. Physicians should consider potential A. baumannii infection when prescribing glucocorticoid aerosol therapy.

Fluorescent PLGA Nanocarriers for Pulmonary Administration: Influence of the Surface Charge

Nearly four million yearly deaths can be attributed to respiratory diseases, prompting a huge worldwide health emergency. Additionally, the COVID-19 pandemic’s death toll has surpassed six million, significantly increasing respiratory disease morbidity and mortality rates. Despite recent advances, it is still challenging for many drugs to be homogeneously distributed throughout the lungs, and specifically to reach the lower respiratory tract with an accurate sustained dose and minimal systemic side effects. Engineered nanocarriers can provide increased therapeutic efficacy while lessening potential biochemical adverse reactions. Poly(lactic-co-glycolic acid) (PLGA), a biodegradable polymer, has attracted significant interest as an inhalable drug delivery system. However, the influence of the nanocarrier surface charge and its intratracheal instillation has not been addressed so far. In this study, we fabricated red fluorescent PLGA nanocapsules (NCs)—Cy5/PLGA—with either positive (Cy5/PLGA+) or negative surface charge (Cy5/PLGA-). We report here on their excellent colloidal stability in culture and biological media, and after cryo-storage. Their lack of cytotoxicity in two relevant lung cell types, even for concentrations as high as 10 mg/mL, is also reported. More importantly, differences in the NCs’ cell uptake rates and internalization capacity were identified. The uptake of the anionic system was faster and in much higher amounts—10-fold and 2.5-fold in macrophages and epithelial alveolar cells, respectively. The in vivo study demonstrated that anionic PLGA NCs were retained in all lung lobules after 1 h of being intratracheally instilled, and were found to accumulate in lung macrophages after 24 h, making those nanocarriers especially suitable as a pulmonary immunomodulatory delivery system with a marked translational character.

Impact of Coronavirus Disease 2019 on the Pediatric Population with Aerodigestive Disease

OBJECTIVE

To determine the impact of the coronavirus disease 2019 (COVID-19) quarantine on baseline health, medication use, health anxiety, and healthcare use in pediatric patients with aerodigestive disease and to evaluate for associations of commonly prescribed medications with the risk of COVID-19 illness.

STUDY DESIGN

Prospective study of patients presenting in person to pediatric neurogastroenterology clinics between July 2020 and March 2021.

RESULTS

Of 202 recruited patients, 71.3% were seen in the aerodigestive diseases center and 28.7% in the functional abdominal pain (FAP)/motility clinic. Of all patients, 25.1% reported improved overall health during quarantine; patients with aerodigestive disease (35.3%) reported higher rates of improved overall health compared with patients with FAP/motility disorders (3.6%, P = .0001). Patients with aerodigestive disease had fewer airway symptoms (P < .05) and less medication use during quarantine (inhaled steroids, P < .05 and albuterol, P < .05). Despite objective improvement, there was significant health-related anxiety, with greater anxiety scores reported during and at the end of quarantine (P < .05), with no difference between patient groups (P > .11). Patients continued to access healthcare during quarantine. In total, 28.7% of patients were seen in the emergency department (patients with FAP more than patients with aerodigestive disease, P = .02), and 19.8% were hospitalized. COVID-19 testing was performed in 58.4% of patients and 2.0% (n = 4) of the entire cohort tested positive.

CONCLUSIONS

Patients with aerodigestive disease show improvement of airway symptoms and decreased use of medications during the pandemic, despite increased health-related anxiety. Despite complexities of accessing care due to the widespread lockdown, all patient groups continued to access healthcare.

Sevoflurane Dampens Acute Pulmonary Inflammation via the Adenosine Receptor A2B and Heme Oxygenase-1

Acute respiratory distress syndrome is a life-threatening disease associated with high mortality. The adenosine receptor A2B (Adora2b) provides anti-inflammatory effects, which are also associated with the intracellular enzyme heme oxygenase-1 (HO-1). Our study determined the mechanism of sevoflurane’s protective properties and investigated the link between sevoflurane and the impact of a functional Adora2b via HO-1 modulation during lipopolysaccharide (LPS)-induced lung injury. We examined the LPS-induced infiltration of polymorphonuclear neutrophils (PMNs) into the lung tissue and protein extravasation in wild-type and Adora2b−/− animals. We generated chimeric animals, to identify the impact of sevoflurane on Adora2b of hematopoietic and non-hematopoietic cells. Sevoflurane decreased the LPS-induced PMN-infiltration and diminished the edema formation in wild-type mice. Reduced PMN counts after sevoflurane treatment were detected only in chimeric mice, which expressed Adora2b exclusively on leukocytes. The Adora2b on hematopoietic and non-hematopoietic cells was required to improve the permeability after sevoflurane inhalation. Further, sevoflurane increased the protective effects of HO-1 modulation on PMN migration and microvascular permeability. These protective effects were abrogated by specific HO-1 inhibition. In conclusion, our data revealed new insights into the protective mechanisms of sevoflurane application during acute pulmonary inflammation and the link between sevoflurane and Adora2b, and HO-1 signaling, respectively.

Pulmonary delivery of siRNA against acute lung injury/acute respiratory distress syndrome

The use of small interfering RNAs (siRNAs) has been under investigation for the treatment of several unmet medical needs, including acute lung injury/acute respiratory distress syndrome (ALI/ARDS) wherein siRNA may be implemented to modify the expression of pro-inflammatory cytokines and chemokines at the mRNA level. The properties such as clear anatomy, accessibility, and relatively low enzyme activity make the lung a good target for local siRNA therapy. However, the translation of siRNA is restricted by the inefficient delivery of siRNA therapeutics to the target cells due to the properties of naked siRNA. Thus, this review will focus on the various delivery systems that can be used and the different barriers that need to be surmounted for the development of stable inhalable siRNA formulations for human use before siRNA therapeutics for ALI/ARDS become available in the clinic.

Inhaled β2 Adrenergic Agonists and Other cAMP-Elevating Agents: Therapeutics for Alveolar Injury and Acute Respiratory Disease Syndrome?

Inhaled long-acting β-adrenergic agonists (LABAs) and short-acting β-adrenergic agonists are approved for the treatment of obstructive lung disease via actions mediated by β2 adrenergic receptors (β2-ARs) that increase cellular cAMP synthesis. This review discusses the potential of β2-AR agonists, in particular LABAs, for the treatment of acute respiratory distress syndrome (ARDS). We emphasize ARDS induced by pneumonia and focus on the pathobiology of ARDS and actions of LABAs and cAMP on pulmonary and immune cell types. β2-AR agonists/cAMP have beneficial actions that include protection of epithelial and endothelial cells from injury, restoration of alveolar fluid clearance, and reduction of fibrotic remodeling. β2-AR agonists/cAMP also exert anti-inflammatory effects on the immune system by actions on several types of immune cells. Early administration is likely critical for optimizing efficacy of LABAs or other cAMP-elevating agents, such as agonists of other Gs-coupled G protein-coupled receptors or cyclic nucleotide phosphodiesterase inhibitors. Clinical studies that target lung injury early, prior to development of ARDS, are thus needed to further assess the use of inhaled LABAs, perhaps combined with inhaled corticosteroids and/or long-acting muscarinic cholinergic antagonists. Such agents may provide a multipronged, repurposing, and efficacious therapeutic approach while minimizing systemic toxicity. SIGNIFICANCE STATEMENT: Acute respiratory distress syndrome (ARDS) after pulmonary alveolar injury (e.g., certain viral infections) is associated with ∼40% mortality and in need of new therapeutic approaches. This review summarizes the pathobiology of ARDS, focusing on contributions of pulmonary and immune cell types and potentially beneficial actions of β2 adrenergic receptors and cAMP. Early administration of inhaled β2 adrenergic agonists and perhaps other cAMP-elevating agents after alveolar injury may be a prophylactic approach to prevent development of ARDS.

A Randomized Controlled Trial to Evaluate the Safety and Efficacy of a Novel Inhaled Biologic Therapeutic in Adults with Respiratory Distress Secondary to COVID-19 Infection

INTRODUCTION

Inhaled therapeutics may act to directly target and attenuate lung inflammation due to COVID-19. An inhalation form of a novel biologic drug, AMP5A, is being developed as an immunomodulatory agent to treat dysregulated immune responses and is being studied in hospitalized patients to treat respiratory complications due to COVID-19.

METHODS

A randomized, controlled, phase I trial was conducted to evaluate hospitalized adults with respiratory distress secondary to COVID-19. Patients received the standard care (SOC) for COVID-19, including respiratory therapy, corticosteroids, and antiviral therapies such as remdesivir. Patients were randomized 1:1 to inhalation treatment with AMP5A as an adjunct to SOC or to SOC alone (control). AMP5A was administered via inhalation daily for 5 days via hand-held nebulizer, non-invasive ventilator, or mechanical ventilation. Safety and clinical efficacy endpoints were evaluated.

RESULTS

Forty subjects were enrolled and randomized (n = 19 AMP5A, n = 21 control). Remdesivir was used in fewer AMP5A subjects (26%) than control (52%), and dexamethasone was administered for most subjects (84% AMP5A, 71% control). The study met its primary endpoint with no AMP5A treatment-related adverse events (AEs), and the incidence and severity of AEs were comparable between groups: 18 AEs for control (8 mild, 1 moderate, 9 severe) and 19 AEs for AMP5A (7 mild, 7 moderate, 5 severe). Notably, subjects treated with AMP5A had fewer deaths (5% vs. 24%), shorter hospital stay (8 days vs. 12 days), fewer ICU admissions (21% vs. 33%), and a greater proportion with improved clinical outcomes than control.

CONCLUSION

The phase I clinical results indicate inhaled AMP5A is safe, is well tolerated, and could lead to fewer patients experiencing deterioration or death. Based on the treatment effect (i.e., reduced mortality), a phase II trial has been initiated.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT04606784.

Asthma and COVID-19: lessons learned and questions that remain

INTRODUCTION

Asthma is one of the most common chronic diseases worldwide. As a disease of the respiratory tract, the site of entry for the SARS-CoV-2 virus, there may be an important interplay between asthma and COVID-19 disease.

AREAS COVERED

We report asthma prevalence among hospitalized cohorts with COVID-19. Those with non-allergic and severe asthma may be at increased risk of a worsened clinical outcome from COVID-19 infection. We explore the epidemiology of asthma as a risk factor for the severity of COVID-19 infection. We then consider the role COVID-19 may play in leading to exacerbations of asthma. The impact of asthma endotype on outcome is discussed. Lastly, we address the safety of common asthma therapeutics. A literature search was performed with relevant terms for each of the sections of the review using PubMed, Google Scholar, and Medline.

EXPERT OPINION

Asthma diagnosis may be a risk factor for severe COVID-19 especially for those with severe disease or nonallergic phenotypes. COVID-19 does not appear to provoke asthma exacerbations and asthma therapeutics should be continued for patients with exposure to COVID-19. Clearly much regarding this topic remains unknown and we identify some key questions that may be of interest for future researchers.[Figure: see text].

Inhalationally Administered Semifluorinated Alkanes (SFAs) as Drug Carriers in an Experimental Model of Acute Respiratory Distress Syndrome

Aerosol therapy in patients suffering from acute respiratory distress syndrome (ARDS) has so far failed in improving patients' outcomes. This might be because dependent lung areas cannot be reached by conventional aerosols. Due to their physicochemical properties, semifluorinated alkanes (SFAs) could address this problem. After induction of ARDS, 26 pigs were randomized into three groups: (1) control (Sham), (2) perfluorohexyloctane (F6H8), and (3) F6H8-ibuprofen. Using a nebulization catheter, (2) received 1 mL/kg F6H8 while (3) received 1 mL/kg F6H8 with 6 mg/mL ibuprofen. Ibuprofen plasma and lung tissue concentration, bronchoalveolar lavage (BAL) fluid concentration of TNF-α, IL-8, and IL-6, and lung mechanics were measured. The ibuprofen concentration was equally distributed to the dependent parts of the right lungs. Pharmacokinetic data demonstrated systemic absorption of ibuprofen proofing a transport across the alveolo-capillary membrane. A significantly lower TNF-α concentration was observed in (2) and (3) when compared to the control group (1). There were no significant differences in IL-8 and IL-6 concentrations and lung mechanics. F6H8 aerosol seemed to be a suitable carrier for pulmonary drug delivery to dependent ARDS lung regions without having negative effects on lung mechanics.

Thrombosis and Haemostasis challenges in COVID-19 - Therapeutic perspectives of heparin and tissue-type plasminogen activator and potential toxicological reactions-a mini review

The coronavirus disease (COVID)-19 pandemic is a major challenge for the health systems worldwide. Acute respiratory distress syndrome (ARDS), is one of the most common complications of the COVID-19 infection. The activation of the coagulation system plays an important role in the pathogenesis of ARDS. The development of lung coagulopathy involves thrombin generation and fibrinolysis inhibition.

Unfractionated heparin and its recently introduced counterpart low molecular weight heparin (LMWH), are widely used anticoagulants with a variety of clinical indications allowing for limited and manageable physio-toxicologic side effects while the use of protamine sulfate, heparin's effective antidote, has made their use even safer. Tissue-type plasminogen activator (tPA) is approved as intravenous thrombolytic treatment. The present narrative review discusses the use of heparin and tPA in the treatment of COVID-19-induced ARDS and their related potential physio-toxicologic side effects. The article is a quick review of articles on anticoagulation in COVID infection and the potential toxicologic reactions associated with these drugs.

Cognitive impact of COVID-19: looking beyond the short term

COVID-19 is primarily a respiratory disease but up to two thirds of hospitalised patients show evidence of central nervous system (CNS) damage, predominantly ischaemic, in some cases haemorrhagic and occasionally encephalitic. It is unclear how much of the ischaemic damage is mediated by direct or inflammatory effects of virus on the CNS vasculature and how much is secondary to extracranial cardiorespiratory disease. Limited data suggest that the causative SARS-CoV-2 virus may enter the CNS via the nasal mucosa and olfactory fibres, or by haematogenous spread, and is capable of infecting endothelial cells, pericytes and probably neurons. Extracranially, SARS-CoV-2 targets endothelial cells and pericytes, causing endothelial cell dysfunction, vascular leakage and immune activation, sometimes leading to disseminated intravascular coagulation. It remains to be confirmed whether endothelial cells and pericytes in the cerebral vasculature are similarly targeted. Several aspects of COVID-19 are likely to impact on cognition. Cerebral white matter is particularly vulnerable to ischaemic damage in COVID-19 and is also critically important for cognitive function. There is accumulating evidence that cerebral hypoperfusion accelerates amyloid-β (Aβ) accumulation and is linked to tau and TDP-43 pathology, and by inducing phosphorylation of α-synuclein at serine-129, ischaemia may also increase the risk of development of Lewy body disease. Current therapies for COVID-19 are understandably focused on supporting respiratory function, preventing thrombosis and reducing immune activation. Since angiotensin-converting enzyme (ACE)-2 is a receptor for SARS-CoV-2, and ACE inhibitors and angiotensin receptor blockers are predicted to increase ACE-2 expression, it was initially feared that their use might exacerbate COVID-19. Recent meta-analyses have instead suggested that these medications are protective. This is perhaps because SARS-CoV-2 entry may deplete ACE-2, tipping the balance towards angiotensin II-ACE-1-mediated classical RAS activation: exacerbating hypoperfusion and promoting inflammation. It may be relevant that APOE ε4 individuals, who seem to be at increased risk of COVID-19, also have lowest ACE-2 activity. COVID-19 is likely to leave an unexpected legacy of long-term neurological complications in a significant number of survivors. Cognitive follow-up of COVID-19 patients will be important, especially in patients who develop cerebrovascular and neurological complications during the acute illness.

Acetylcholine Regulates Pulmonary Pathology During Viral Infection and Recovery

Introduction

This study was designed to explore the role of acetylcholine (ACh) in pulmonary viral infection and recovery. Inflammatory control is critical to recovery from respiratory viral infection. ACh secreted from non-neuronal sources, including lymphocytes, plays an important, albeit underappreciated, role in regulating immune-mediated inflammation.

Methods

ACh and lymphocyte cholinergic status in the lungs were measured over the course of influenza infection and recovery. The role of ACh was examined by inhibiting ACh synthesis in vivo. Pulmonary inflammation was monitored by Iba1 immunofluorescence, using a novel automated algorithm. Tissue repair was monitored histologically.

Results

Pulmonary ACh remained constant through the early stage of infection and increased during the peak of the acquired immune response. As the concentration of ACh increased, cholinergic lymphocytes appeared in the BAL and lungs. Cholinergic capacity was found primarily in CD4 T cells, but also in B cells and CD8 T cells. The cholinergic CD4⁺ T cells bound to influenza-specific tetramers and were retained in the resident memory regions of the lung up to 2 months after infection. Histologically, cholinergic lymphocytes were found in direct physical contact with activated macrophages throughout the lung. Inflammation was monitored by ionized calcium-binding adapter molecule 1 (Iba1) immunofluorescence, using a novel automated algorithm. When ACh production was inhibited, mice exhibited increased tissue inflammation and delayed recovery. Histologic examination revealed abnormal tissue repair when ACh was limited.

Conclusion

These findings point to a previously unrecognized role for ACh in the transition from active immunity to recovery and pulmonary repair following respiratory viral infection.

Design of polymeric core-shell carriers for combination therapies

Particle engineering for co-delivery of drugs has the potential to combine multiple drugs with different pharmaceutical mechanisms within the same carrier, increasing the therapeutic efficiency while improving patient compliance. This work proposes a novel approach for producing polymer-polymer core-shell microparticles by multi-step processing of emulsion and spray drying. The particle core was obtained by an oil-in-water emulsion of poly(ε-caprolactone) (PCL) loaded with curcumin (CM), followed by the resuspension in poly(vinyl alcohol) (PVA) containing ciprofloxacin (CPx) forming the shell layer by spray-drying. The obtained core-shell particles showed an average size of 3.8 ± 1.2 μm, which is a suitable size for inhalation therapies. The spatial distribution of the drugs was studied using synchrotron-based macro attenuated total reflection Fourier transform infrared (macro ATR-FTIR) microspectroscopy to map the chemical distribution of the components within the particles and supported the presence of CM and CPx in the core and shell layers, respectively. The formation of the core-shell structure was further supported by the differences in the release profile of CM from these particles, when compared to the release profile observed for the single particle structure (PCL-CM). Both empty and drug-loaded carriers (up to 100 μg.mL^-1) showed no cytotoxic effects on A549 cells while exhibiting the antibacterial activity of CPx against Gram-positive and Gram-negative bacteria. These polymer core-shell microparticles provide a promising route for the combination and sequential drug release therapies, with the potential to be used in inhalation therapies.

The Potential Role of Coagulation Factor Xa in the Pathophysiology of COVID-19: A Role for Anticoagulants as Multimodal Therapeutic Agents

SARS-CoV-2 infection (COVID-19) results in local and systemic activation of inflammation and coagulation. In this review article, we will discuss the potential role of coagulation factor Xa (FXa) in the pathophysiology of COVID-19. FXa, a serine protease, has been shown to play a role in the cleavage of SARS-CoV-1 spike protein (SP), with the inhibition of FXa resulting in the inhibition of viral infectivity. FX is known to be primarily produced in the liver, but it is also expressed by multiple cells types, including alveolar epithelium, cardiac myocytes, and macrophages. Considering that patients with preexisting conditions, including cardiopulmonary disease, are at an increased risk of severe COVID-19, we discuss the potential role of increased levels of FX in these patients, resulting in a potential increased propensity to have a higher infectious rate and viral load, increased activation of coagulation and inflammation, and development of fibrosis. With these observations in mind, we postulate as to the potential therapeutic role of FXa inhibitors as a prophylactic and therapeutic treatment for high-risk patients with COVID-19.

Future Trends in Nebulized Therapies for Pulmonary Disease

Aerosol therapy is a key modality for drug delivery to the lungs of respiratory disease patients. Aerosol therapy improves therapeutic effects by directly targeting diseased lung regions for rapid onset of action, requiring smaller doses than oral or intravenous delivery and minimizing systemic side effects. In order to optimize treatment of critically ill patients, the efficacy of aerosol therapy depends on lung morphology, breathing patterns, aerosol droplet characteristics, disease, mechanical ventilation, pharmacokinetics, and the pharmacodynamics of cell-drug interactions. While aerosol characteristics are influenced by drug formulations and device mechanisms, most other factors are reliant on individual patient variables. This has led to increased efforts towards more personalized therapeutic approaches to optimize pulmonary drug delivery and improve selection of effective drug types for individual patients. Vibrating mesh nebulizers (VMN) are the dominant device in clinical trials involving mechanical ventilation and emerging drugs. In this review, we consider the use of VMN during mechanical ventilation in intensive care units. We aim to link VMN fundamentals to applications in mechanically ventilated patients and look to the future use of VMN in emerging personalized therapeutic drugs.

Adjunctive therapies during veno-venous extracorporeal membrane oxygenation

Veno-venous extracorporeal membrane oxygenation (VV ECMO) restores gas exchanges in severely hypoxemic patients. The need for adjunctive therapies usually originates either from refractory hypoxemia during ECMO (defined as the persistence of low blood oxygen levels despite extracorporeal support) or from the attempt to give a specific therapy for acute respiratory distress syndrome (ARDS). In this review, therapeutic strategies to treat refractory and persistent hypoxemia during ECMO are evaluated. In the second part, therapies that can be added on top of VV ECMO to address inflammation and altered vascular permeability in ARDS are examined. The therapies currently available often allow for an effective treatment of hypoxemia during ECMO. ARDS is still lacking a specific therapy, with low-grade evidence sustaining the majority of currently used drugs.

Identification of three classes of acute respiratory distress syndrome using latent class analysis

Acute respiratory distress syndrome (ARDS) is a highly heterogeneous syndrome that can exhibit significant differences in the underlying causes, leading to different responses to treatment. It is required to identify subtypes of ARDS to guideline clinical treatment and trial design. The study aimed to identify subtypes of ARDS using latent class analysis (LCA). The study was a secondary analysis of the EDEN study, which was a randomized, controlled, multicenter trial conducted from January 2, 2008 to April 12, 2011. The primary study endpoint was death through 90-day follow up. LCA was performed incorporating variables on day 0 before randomization. The number of classes was chosen by a bootstrapped likelihood ratio test, Bayesian information criterion and the number of patients in each class. A total of 943 patients were enrolled in the study, including 219 (23.2%) non-survivors and 724 (76.8%) survivors. The LCA identified three classes of ARDS. Class 1 (hemodynamically unstable type) had significantly higher mortality rate (p = 0.003) than class 2 (intermediate type) and 3 (stable type) through 90 days follow up. There was significant interaction between cumulative fluid balance and the class (p = 0.02). While more fluid balance was beneficial for class 1, it was harmful for class 2 and 3. In conclusion, the study identified three classes of ARDS, which showed different clinical presentations, responses to fluid therapy and prognosis. The classification system used simple clinical variables and could help to design ARDS trials in the future.

Anticoagulant therapy in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) presents a complex pathophysiology characterized by pulmonary activated coagulation and reduced fibrinolysis. Despite advances in supportive care of this syndrome, morbidity and mortality remains high, leading to the need of novel therapies to combat this disease. Focus these therapies in the inhibition of ARDS development pathophysiology is essential. Beneficial effects of anticoagulants in ARDS have been proved in preclinical and clinical trials, thanks to its anticoagulant and anti-inflammatory properties. Moreover, local administration by nebulization in the alveolar compartment increases local efficacy and does not produce systemic bleeding. In this review the coagulation and fibrinolytic pathway and its pharmacological targets to treat ARDS are summarized.