The Basic Science and Molecular Mechanisms of Lung Injury and Acute Respiratory Distress Syndrome

Fragment-Based Anti-inflammatory Agent Design and Target Identification: Discovery of AF-45 as an IRAK4 Inhibitor to Treat Ulcerative Colitis and Acute Lung Injury

UC and ALI are inflammatory diseases with limited treatment in the clinic. Herein, fragment-based anti-inflammatory agent designs were carried out deriving from cyclohexylamine/cyclobutylamine and several fragments from anti-inflammatory agents in our lab. AF-45 (IC50 = 0.53/0.60 μM on IL-6/TNF-α in THP-1 macrophages) was identified as the optimal molecule using ELISA and MTT assays from the 33 synthesized compounds. Through mechanistic studies and a systematic target search process, AF-45 was found to block the NF-κB/MAPK pathway and target IRAK4, a promising target for inflammation and autoimmune diseases. The selectivity of AF-45 targeting IRAK4 was validated by comparing its effects on other kinase/nonkinase proteins. In vivo, AF-45 exhibited a good therapeutic effect on UC and ALI, and favorable PK proprieties. Since there are currently no clinical or preclinical trials for IRAK4 inhibitors to treat UC and ALI, AF-45 provides a new lead compound or candidate targeting IRAK4 for the treatment of these diseases.

Sulfasalazine ameliorates lipopolysaccharide-induced acute lung injury by inhibiting oxidative stress and nuclear factor-kappaB pathways

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) has a high mortality rate and incidence of complications. The pathophysiology of ALI/ARDS is still not fully understood. The lipopolysaccharide (LPS)-induced mouse model of ALI has been widely used to study human ALI/ARDS. Sulfasalazine (SASP) has antibacterial and anti-inflammatory effects and is used for treating inflammatory bowel and rheumatic diseases. However, the effect of SASP on LPS-induced ALI in mice has not yet been reported. Therefore, we aimed to investigate the effect of SASP on LPS-induced ALI in mice. Mice were intraperitoneally injected with SASP 2 h before or 4 h after LPS modeling. Pulmonary pathological damage was measured based on inflammatory factor expression (malondialdehyde and superoxide dismutase levels) in the lung tissue homogenate and alveolar lavage fluid. The production of inflammatory cytokines and occurrence of oxidative stress in the lungs induced by LPS were significantly mitigated after the prophylactic and long-term therapeutic administration of SASP, which ameliorated ALI caused by LPS. SASP reduced both the production of inflammatory cytokines and occurrence of oxidative stress in RAW264.7 cells, which respond to LPS. Moreover, its mechanism contributed to the suppression of NF-κB and nuclear translocation. In summary, SASP treatment ameliorates LPS-induced ALI by mediating anti-inflammatory and antioxidant effects, which may be attributed to the inhibition of NF-κB activation and promotion of antioxidant defenses. Thus, SASP may be a promising pharmacologic agent for ALI therapy.

ICAM-1 targeted and ROS-responsive nanoparticles for the treatment of acute lung injury

Acute lung injury (ALI) is an inflammatory disease caused by multiple factors such as infection, trauma, and chemicals. Without effective intervention during the early stages, it usually quickly progresses to acute respiratory distress syndrome (ARDS). Since ordinary pharmaceutical preparations cannot precisely target the lungs, their clinical application is limited. In response, we constructed a γ3 peptide-decorated and ROS-responsive nanoparticle system encapsulating therapeutic dexamethasone (Dex/PSB-γ3 NPs). In vitro, Dex/PSB-γ3 NPs had rapid H2O2 responsiveness, low cytotoxicity, and strong intracellular ROS removal capacity. In a mouse model of ALI, Dex/PSB-γ3 NPs accumulated at the injured lung rapidly, alleviating pulmonary edema and cytokine levels significantly. The modification of NPs by γ3 peptide achieved highly specific positioning of NPs in the inflammatory area. The ROS-responsive release mechanism ensured the rapid release of therapeutic dexamethasone at the inflammatory site. This combined approach improves treatment accuracy, and drug bioavailability, and effectively inhibits inflammation progression. Our study could effectively reduce the risk of ALI progressing to ARDS and hold potential for the early treatment of ALI.

Synergistic Pulmonoprotective Effect of Natural Prolyl Oligopeptidase Inhibitors in In Vitro and In Vivo Models of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a highly morbid inflammatory lung disease with limited pharmacological interventions. The present study aims to evaluate and compare the potential pulmonoprotective effects of natural prolyl oligopeptidase (POP) inhibitors namely rosmarinic acid (RA), chicoric acid (CA), epigallocatechin-3-gallate (EGCG) and gallic acid (GA), against lipopolysaccharide (LPS)-induced ARDS. Cell viability and expression of pro-inflammatory mediators were measured in RAW264.7 cells and in primary murine lung epithelial and bone marrow cells. Nitric oxide (NO) production was also assessed in unstimulated and LPS-stimulated RAW264.7 cells. For subsequent in vivo experiments, the two natural products (NPs) with the most favorable effects, RA and GA, were selected. Protein, cell content and lipid peroxidation levels in bronchoalveolar lavage fluid (BALF), as well as histopathological changes and respiratory parameters were evaluated in LPS-challenged mice. Expression of key mediators involved in ARDS pathophysiology was detected by Western blotting. RA and GA favorably reduced gene expression of pro-inflammatory mediators in vitro, while GA decreased NO production in macrophages. In LPS-challenged mice, RA and GA co-administration improved respiratory parameters, reduced cell and protein content and malondialdehyde (MDA) levels in BALF, decreased vascular cell adhesion molecule-1 (VCAM-1) and the inducible nitric oxide synthase (iNOS) protein expression, activated anti-apoptotic mechanisms and down-regulated POP in the lung. Conclusively, these synergistic pulmonoprotective effects of RA and GA co-administration could render them a promising prophylactic/therapeutic pharmacological intervention against ARDS.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Dexmedetomidine Attenuates LPS-Stimulated Alveolar Type II Cells’ Injury through Upregulation of miR-140-3p and Partial Suppression of PD-L1 Involving Inactivating JNK-Bnip3 Pathway

Dexmedetomidine (DEX), which is reported to be a newly discovered, novel α-2 adrenoceptor agonist, is known to exhibit anti-inflammatory properties in several diseases. DEX regulates inflammation-related signaling pathways and genes through interactions with several miRNAs. This study verified that expression levels of miR-140-3p were diminished when alveolar type II cells were exposed to LPS. However, the levels of miR-140-3p were confirmed as showing an increase with DEX treatment. These observations revealed that the expression of miR-140-3p was related to the beneficial effects that accompanied the DEX treatment of LPS-induced ALI. In addition, PD-1/PD-L1 expression increased extensively when RLE-6TN cells were induced by LPS. The increased expression was reduced after treatment with DEX. Thus, it appears that the PD-L1 expression was targeted directly by miR-140-3p, resulting in the partial repression of PD-L1 levels, which involved the inhibition of p-JNK and Bnip3 expression. Therefore, DEX was shown to inhibit the PD-L1 expression by promoting partially increased miR-140-3p levels in RLE-6TN cells. DEX also inactivated the JNK-Bnip3 pathway, resulting in the inhibition of inflammation and alleviating alveolar type II cell injury.

Nanoscale Porphyrin Metal-Organic Frameworks Deliver siRNA for Alleviating Early Pulmonary Fibrosis in Acute Lung Injury

Acute lung injury (ALI) has high mortality and still lacks novel and efficient therapies. Zinc finger E-box binding homeobox 1 and 2 (ZEB1/2) are highly expressed in the early stage of ALI and are positively correlated with the progression of pulmonary fibrosis. Herein, we developed a nanoscale Zr(IV)-based porphyrin metal-organic (ZPM) framework to deliver small interfering ZEB1/2 (siZEB1/2) to alleviate early pulmonary fibrosis during ALI. This pH-responsive nano-ZPM system could effectively protect siRNAs during lung delivery until after internalization and rapidly trigger siRNA release under the mildly acidic environment of the endo/lysosome (pH 4.0–6.5) for transfection and gene silencing. Furthermore, the in vivo studies confirmed that this nano-ZPM system could anchor in inflamed lungs. Moreover, the ZEB1/2 silencing led to increased E-cadherin and decreased α-SMA levels. Overall, the nano-ZPM system was an excellent non-viral vector system to deliver siRNAs to alleviate early pulmonary fibrosis during ALI.

Progress in non-viral localized delivery of siRNA therapeutics for pulmonary diseases

Emerging therapies based on localized delivery of siRNA to lungs have opened up exciting possibilities for treatment of different lung diseases. Localized delivery of siRNA to lungs has shown to result in severalfold higher lung accumulation than systemic route, while minimizing non-specific distribution in other organs. However, to date, only 2 clinical trials have explored localized delivery of siRNA for pulmonary diseases. Here we systematically reviewed recent advances in the field of pulmonary delivery of siRNA using non-viral approaches. We firstly introduce the routes of local administration and analyze the anatomical and physiological barriers towards effective local delivery of siRNA in lungs. We then discuss current progress in pulmonary delivery of siRNA for respiratory tract infections, chronic obstructive pulmonary diseases, acute lung injury, and lung cancer, list outstanding questions, and highlight directions for future research. We expect this review to provide a comprehensive understanding of current advances in pulmonary delivery of siRNA.

Identification of kidney injury released circulating osteopontin as causal agent of respiratory failure

Tissue injury can drive secondary organ injury; however, mechanisms and mediators are not well understood. To identify interorgan cross-talk mediators, we used acute kidney injury (AKI)-induced acute lung injury (ALI) as a clinically important example. Using kidney and lung single-cell RNA sequencing after AKI in mice followed by ligand-receptor pairing analysis across organs, kidney ligands to lung receptors, we identify kidney-released circulating osteopontin (OPN) as a novel AKI-ALI mediator. OPN release from kidney tubule cells triggered lung endothelial leakage, inflammation, and respiratory failure. Pharmacological or genetic OPN inhibition prevented AKI-ALI. Transplantation of ischemic wt kidneys caused AKI-ALI, but not of ischemic OPN-global knockout kidneys, identifying kidney-released OPN as necessary interorgan signal to cause AKI-ALI. We show that OPN serum levels are elevated in patients with AKI and correlate with kidney injury. Our results demonstrate feasibility of using ligand-receptor analysis across organs to identify interorgan cross-talk mediators and may have important therapeutic implications in human AKI-ALI and multiorgan failure.

GM-CSF: Orchestrating the Pulmonary Response to Infection

This review summarizes the structure and function of the alveolar unit, comprised of alveolar macrophage and epithelial cell types that work in tandem to respond to infection. Granulocyte-macrophage colony-stimulating factor (GM-CSF) helps to maintain the alveolar epithelium and pulmonary immune system under physiological conditions and plays a critical role in restoring homeostasis under pathologic conditions, including infection. Given the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and global spread of coronavirus disease 2019 (COVID-19), with subsequent acute respiratory distress syndrome, understanding basic lung physiology in infectious diseases is especially warranted. This review summarizes clinical and preclinical data for GM-CSF in respiratory infections, and the rationale for sargramostim (yeast-derived recombinant human [rhu] GM-CSF) as adjunctive treatment for COVID-19 and other pulmonary infectious diseases.

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.

Therapeutic and protective potential of mesenchymal stem cells, pharmaceutical agents and current vaccines against covid-19

It has been almost 18 months since the first outbreak of COVID-19 disease was reported in Wuhan, China. This unexpected devastating phenomenon, raised a great deal of concerns and anxiety among people around the world and imposed a huge economic burden on the nations' health care systems. Accordingly, clinical scientists, pharmacologists and physicians worldwide felt an urgent demand for a safe, effective therapeutic agent, treatment strategy or vaccine in order to prevent or cure the recently-emerged disease. Initially, due to lack of specific pharmacological agents and approved vaccines to combat the COVID-19, the disease control in the confirmed cases was limited to supportive care. Accordingly, repositioning or repurposing current drugs and examining their possible therapeutic efficacy received a great deal of attention. Despite revealing promising results in some clinical trials, the overall results are conflicting. For this reason, there is an urgent to seek and investigate other potential therapeutics. Mesenchymal stem cells (MSC) representing immunomodulatory and regenerative capacity to treat both curable and intractable diseases, have been investigated in COVID-19 clinical trials carried out in different parts of the world. Nevertheless, up to now, none of MSC-based approaches has been approved in controlling COVID-19 infection. Thanks to the fact that the final solution for defeating the pandemic is developing a safe, effective vaccine, enormous efforts and clinical research have been carried out. In this review, we will concisely discuss the safety and efficacy of the most relevant pharmacological agents, MSC-based approaches and candidate vaccines for treating and preventing COVID-19 infection.

Proposal for the use of anakinra in acute respiratory distress secondary to COVID-19

The outcome of the SARS-CoV-2 (COVID-19) infection fundamentally affects the lung field, causing ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS). This process is an inflammatory picture, involving an NLRP3 INFLAMOSOME-triggered cytokine storm, the main player in alveolar destruction. IL-1 beta stands out among the cytokines that are triggered in this picture. ANAKINRA is a potent biological drug, capable of blocking this IL 1 beta. We propose its use in controlling ARDS secondary to COVID-19 infection.

[Proposal for the use of anakinra in acute respiratory distress secondary to COVID-19]

The outcome of the SARS-CoV-2 (COVID-19) infection fundamentally affects the lung field, causing acute respiratory distress syndrome (ARDS). This process is an inflammatory picture, involving an NLRP3 inflamosome-triggered cytokine storm, the main player in alveolar destruction. IL-1 beta stands out among the cytokines that are triggered in this picture. Anakinra is a potent biological drug, capable of blocking this IL-1ß. We propose its use in controlling ARDS secondary to COVID-19 infection.

Construction of mannose-modified polyethyleneimine-block-polycaprolactone cationic polymer micelles and its application in acute lung injury

This study evaluated the D-mannose modified polyethyleneimine-block-polycaprolactone biomacromolecule copolymer micelles (PCL-PEI-mannose) as a targeted delivery of the glucocorticoid dexamethasone (DXM) to lung inflammation tissues and enhances the vehicle for its anti-inflammatory effects. Dexamethasone was encapsulated in the hydrophobic core of cationic polymer micelles by solvent evaporation. The polymeric micelles exhibited sustained-release within 48 h, good blood compatibility, and colloidal stability in vitro. The cellular uptake of mannose-modified micelles was higher compared with the non-modified micelles. And drug-loaded targeted micelles could inhibit the production of inflammatory factors in activated RAW264.7 cells. The distribution results indicated that drug-loaded targeted micelles highly improved the lung targeting ability, reduced the wet/dry ratio of injured lung tissue, and relieved the lung inflammation, accompanied by the decrease of inflammatory cell infiltration, myeloperoxidase activity, and inflammatory mediator levels in bronchoalveolar lavage fluid. These findings suggested that PCL-PEI-mannose delivery system could facilitate the lung-specific delivery and inhibit the inflammatory response. Collectively, PCL-PEI-mannose polymer micelles could be used as a potential delivery system for the treatment of acute lung injury (ALI).

Attenuation of ventilator-induced lung injury through suppressing the pro-inflammatory signaling pathways: A review on preclinical studies

Mechanical ventilation (MV) is a relatively common medical intervention in ICU patients. The main side effect of MV is the so-called "ventilator-induced lung injury" (VILI). The pathogenesis of VILI is not completely understood; however, it has been reported that MV might be associated with up-regulation of various inflammatory mediators within the lung tissue and that these mediators might act as pathogenic factors in lung tissue injury. One potential mechanism for the generation of inflammatory mediators is through the release of endogenous molecules known as damage associated molecular patterns (DAMPs). These molecules are released from injured tissues and can bind to pattern recognition receptors (PRRs). PRR activation generally leads to the production and release of inflammation-related molecules including innate immune cytokines and chemokines. It has been suggested that blocking DAMP/PRR signaling pathways might diminish the progression of VILI. Herein, we review the latest findings with regard to the effects of DAMP/PRRs and their blockade, as well as the potential therapeutic targets and future research directions in VILI. Results of studies performed on human samples, animal models of disease, as well as relevant in vitro systems will be discussed.

Pharmacological management of adult patients with acute respiratory distress syndrome

INTRODUCTION

There is still no definite drug for acute respiratory distress syndrome (ARDS) that is capable of reducing either short-term or long-term mortality. Therefore, great efforts are being made to identify a pharmacological approach that can be really effective.

AREAS COVERED

This review focuses on current challenges and future directions in the pharmacological management of ARDS, regardless of anti-infective treatments. The authors have excluded small randomized controlled trials (RCTs) with less than 60 patients because those studies do not have statistical power for outcome data, and also anecdotal trials but have considered the last meta-analysis on any drug.

EXPERT OPINION

There has been substantial progress in our knowledge of ARDS over the past two decades and many drugs have been used in its treatment. Nevertheless, effective targeted pharmacological treatments for ARDS are still lacking. The likely reason why a pharmacological approach is beneficial for some patients, but harmful for others is that ARDS is an extremely heterogeneous syndrome. To overcome this issue, a precision approach for ARDS, whereby therapies are specifically targeted to patients most likely to benefit, has been proposed. At present, however, the application of this approach seems to be a difficult task.

Novel noncoding RNAs biomarkers in acute respiratory distress syndrome

Introduction: Acute respiratory distress syndrome (ARDS) is a very common condition associated with critically ill patients, which causes substantial morbidity and mortality. Currently, there is no effective clinical ARDS treatment strategy. Novel targets that effectively treat ARDS need to be found.Areas covered: Data sources were published articles through June 2019 in PubMed using the following keywords: 'acute respiratory distress syndrome,' 'miRNAs,' 'lncRNAs,' and 'biomarkers.' The selection of studies focused on in cellular model, animal model, and clinical studies of ARDS.Expert commentary: Accumulated evidence revealed that some specific miRNAs and lncRNAs could regulate the signaling pathways of the pathophysiology by targeting specific molecule in ARDS. The differentially expressed miRNAs exert a crucial role in apoptosis of neutrophil, antigen-presenting cells and lung epithelial cell, and the dysfunction of mitochondrial. Recently, the influence of lncRNAs upon miRNA function is also rapidly emerging. In some cases, lncRNA MALAT1 target TLR4 to mediate the p38 MAPK and NF-κB signaling pathway in ARDS rat model. In other cases, lncRNA CASC2 was found to act as a ceRNA of miR-144-3p which directly targeted AQP1 in LPS-induced A549 cell. In addition, other miRNA-lncRNA regulatory patterns in ARDS and novel biomarkers still require deeper research.