Simvastatin Treatment Modulates Mechanically-Induced Injury and Inflammation in Respiratory Epithelial Cells

A micro-scale humanized ventilator-on-a-chip to examine the injurious effects of mechanical ventilation

Patients with compromised respiratory function frequently require mechanical ventilation to survive. Unfortunately, non-uniform ventilation of injured lungs generates complex mechanical forces that lead to ventilator induced lung injury (VILI). Although investigators have developed lung-on-a-chip systems to simulate normal respiration, modeling the complex mechanics of VILI as well as the subsequent recovery phase is a challenge. Here we present a novel humanized in vitro ventilator-on-a-chip (VOC) model of the lung microenvironment that simulates the different types of injurious forces generated in the lung during mechanical ventilation. We used transepithelial/endothelial electrical impedance measurements to investigate how individual and simultaneous application of mechanical forces alters real-time changes in barrier integrity during and after injury. We find that compressive stress (i.e. barotrauma) does not significantly alter barrier integrity while over-distention (20% cyclic radial strain, volutrauma) results in decreased barrier integrity that quickly recovers upon removal of mechanical stress. Conversely, surface tension forces generated during airway reopening (atelectrauma), result in a rapid loss of barrier integrity with a delayed recovery relative to volutrauma. Simultaneous application of cyclic stretching (volutrauma) and airway reopening (atelectrauma), indicates that the surface tension forces associated with reopening fluid-occluded lung regions are the primary driver of barrier disruption. Thus, our novel VOC system can monitor the effects of different types of injurious forces on barrier disruption and recovery in real-time and can be used to interogate the biomechanical mechanisms of VILI.

Magnetic Resonance Elastography and Computational Modeling Identify Heterogeneous Lung Biomechanical Properties during Cystic Fibrosis

The lung is a dynamic mechanical organ and several pulmonary disorders are characterized by heterogeneous changes in the lung's local mechanical properties (i.e. stiffness). These alterations lead to abnormal lung tissue deformation (i.e. strain) which have been shown to promote disease progression. Although heterogenous mechanical properties may be important biomarkers of disease, there is currently no non-invasive way to measure these properties for clinical diagnostic purposes. In this study, we use a magnetic resonance elastography technique to measure heterogenous distributions of the lung's shear stiffness in healthy adults and in people with Cystic Fibrosis. Additionally, computational finite element models which directly incorporate the measured heterogenous mechanical properties were developed to assess the effects on lung tissue deformation. Results indicate that consolidated lung regions in people with Cystic Fibrosis exhibited increased shear stiffness and reduced spatial heterogeneity compared to surrounding non-consolidated regions. Accounting for heterogenous lung stiffness in healthy adults did not change the globally averaged strain magnitude obtained in computational models. However, computational models that used heterogenous stiffness measurements predicted significantly more variability in local strain and higher spatial strain gradients. Finally, computational models predicted lower strain variability and spatial strain gradients in consolidated lung regions compared to non-consolidated regions. These results indicate that spatial variability in shear stiffness alters local strain and strain gradient magnitudes in people with Cystic Fibrosis. This imaged-based modeling technique therefore represents a clinically viable way to non-invasively assess lung mechanics during both health and disease.

A Micro-scale Humanized Ventilator-on-a-Chip to Examine the Injurious Effects of Mechanical Ventilation

Patients with compromised respiratory function frequently require mechanical ventilation to survive. Unfortunately, non-uniform ventilation of injured lungs generates complex mechanical forces that lead to ventilator induced lung injury (VILI). Although investigators have developed lung-on-a-chip systems to simulate normal respiration, modeling the complex mechanics of VILI as well as the subsequent recovery phase is a challenge. Here we present a novel humanized in vitro ventilator-on-a-chip (VOC) model of the lung microenvironment that simulates the different types of injurious forces generated in the lung during mechanical ventilation. We used transepithelial/endothelial electrical resistance (TEER) measurements to investigate how individual and simultaneous application of the different mechanical forces alters real-time changes in barrier integrity during and after injury. We find that compressive stress (i.e. barotrauma) does not significantly alter barrier integrity while over-distention (20% cyclic radial strain, volutrauma) results in decreased barrier integrity that quickly recovers upon removal of mechanical stress. Conversely, surface tension forces generated during airway reopening (atelectrauma), result in a rapid loss of barrier integrity with a delayed recovery relative to volutrauma. Simultaneous application of cyclic stretching (volutrauma) and airway reopening (atelectrauma), indicate that the surface tension forces associated with reopening fluid-occluded lung regions is the primary driver of barrier disruption. Thus, our novel VOC system can monitor the effects of different types of injurious forces on barrier disruption and recovery in real-time and can be used to identify the biomechanical mechanisms of VILI.

Pressure-controlled ventilation-volume guaranteed mode improves bronchial mucus transport velocity in patients during laparoscopic surgery for gynecological oncology: a randomized controlled study

BACKGROUND

Mechanical ventilation during general anesthesia may impair airway mucosal function. This study aimed to investigate the effect of pressure-controlled ventilation-volume guaranteed (PCV-VG) on bronchial mucus transport velocity (BTV) in patients during laparoscopic surgery for gynecological oncology compared with volume controlled ventilation (VCV).

METHODS

66 patients undergoing elective a laparoscopic surgery for gynecological oncology. The patients were randomized into two group receiving either PCV-VG or VCV. a drop of methylene blue was placed on the surface of the airway mucosa under the bronchoscopeand, then the distance the dye movement was measured after 2, 4, and 6 min. Outcomes were assessed at T0 (5 min after endotracheal intubation and before initiation of pneumoperitoneum), T1 and T2 (1 and 2 h after stabilization of pneumoperitoneum respectively). BTV at T0, T1 and T2 was the primary outcome. Secondary outcomes included heart rate (HR), mean arterial pressure (MAP), body temperature, end-tidal CO2 pressure (PETCO2), tidal volume(VT), peak inspiratory pressure (PIP), mean inspiratory pressure (Pmean), respiratory rate (RR), and dynamic compliance (CDyn) at T0, T1, and T2.

RESULTS

64 patients were included in the analysis. The median [interquartile range] BTV was significantly lower in VCV group at T1 and T2 that at T0 (P < 0.05). Furthermore, BTV was slightly reduced in PCV-VG compared with VCV. BTV in PCV-VG was significantly decreased at T2 compared with BTV at T0 (P < 0.05) and slightly decreased at T1 compared with T0(P > 0.05). Compared with the PCV-VG group, BTV in VCV group significantly decreased at T2 (P < 0.05). No participants experienced respiratory complications.

CONCLUSIONS

PCV-VG is more suitable for patients undergoing laparoscopic surgery for gynecological oncology than VCV since it can protect mucociliary clearance function.

TRIAL REGISTRATION

This trial is registered on https://www.chictr.org.cn/ in Chinese Clinical Trial Registry (ChiCTR.2200064564: Date of registration 11/10/2022).

Sepsis-Induced Acute Lung Injury Is Alleviated by Small Molecules from Dietary Plants via Pyroptosis Modulation

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality, and it has three major pathogeneses, namely alveolar-capillary barrier destruction, elevated gut permeability, and reduced neutrophil extracellular traps (NETS), all of which are pyroptosis-involved. Due to limitations of current agents like adverse reaction superposition, inevitable drug resistance, and relatively heavier financial burden, naturally extracted small-molecule compounds have a broad market even though chemically modified drugs have straightforward efficacy. Despite increased understanding of the molecular biology and mechanism underlying sepsis-induced ARDS, there are no specific reviews concerning how small molecules from dietary plants alleviate sepsis-induced acute lung injury (ALI) via regulating pyroptotic cell death. Herein, we traced and reviewed the molecular underpinnings of sepsis-induced ALI with a focus on small-molecule compounds from dietary plants, the top three categories of which are respectively flavonoids and flavone, terpenoids, and polyphenol and phenolic acids, and how they rescued septic ALI by restraining pyroptosis.

Pulmonary drug delivery for acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a life-threatening condition that causes respiratory failure. Despite numerous clinical trials, there are no molecularly targeted pharmacologic therapies to prevent or treat ARDS. Drug delivery during ARDS is challenging due to the heterogenous nature of lung injury and occlusion of lung units by edema fluid and inflammation. Pulmonary drug delivery during ARDS offers several potential advantages including limiting the off-target and off-organ effects and directly targeting the damaged and inflamed lung regions. In this review we summarize recent ARDS clinical trials using both systemic and pulmonary drug delivery. We then discuss the advantages of pulmonary drug delivery and potential challenges to its implementation. Finally, we discuss the use of nanoparticle drug delivery and surfactant-based drug carriers as potential strategies for delivering therapeutics to the injured lung in ARDS.

Mechanobiology of Pulmonary Diseases: A Review of Engineering Tools to Understand Lung Mechanotransduction

Cells within the lung micro-environment are continuously subjected to dynamic mechanical stimuli which are converted into biochemical signaling events in a process known as mechanotransduction. In pulmonary diseases, the abrogated mechanical conditions modify the homeostatic signaling which influences cellular phenotype and disease progression. The use of in vitro models has significantly expanded our understanding of lung mechanotransduction mechanisms. However, our ability to match complex facets of the lung including three-dimensionality, multicellular interactions, and multiple simultaneous forces is limited and it has proven difficult to replicate and control these factors in vitro. The goal of this review is to (a) outline the anatomy of the pulmonary system and the mechanical stimuli that reside therein, (b) describe how disease impacts the mechanical micro-environment of the lung, and (c) summarize how existing in vitro models have contributed to our current understanding of pulmonary mechanotransduction. We also highlight critical needs in the pulmonary mechanotransduction field with an emphasis on next-generation devices that can simulate the complex mechanical and cellular environment of the lung. This review provides a comprehensive basis for understanding the current state of knowledge in pulmonary mechanotransduction and identifying the areas for future research.

Nitric Oxide Releasing Hydrogel Nanoparticles Decreases Epithelial Cell Injuries Associated With Airway Reopening

Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung condition. It is characterized by disruption of gas exchange inside the alveoli, accumulation of protein edema, and an increase in lung stiffness. One major cause of ARDS is a lung infection, such as SARS-COV-2 infection. Lungs of ARDS patients need to be mechanically ventilated for airway reopening. Consequently, ventilation might damage delicate lung tissue leading to excess edema, known as ventilator-induced lung injury (VILI). Mortality of COVID-19 patients under VILI seems to be higher than non-COVID patients, necessitating effective preventative therapies. VILI occurs when small air bubbles form in the alveoli, injuring epithelial cells (EPC) due to shear stress. Nitric oxide (NO) inhalation was suggested as a therapy for ARDS, however, it was shown that it is not effective because of the extremely short half-life of NO. In this study, NO-releasing nanoparticles were produced and tested in an in vitro model, representing airways in the deep lung. Cellular injuries were quantified via fluorescent live/dead assay. Atomic force microscopy (AFM) was used to assess cell morphology. qRT-PCR was performed to assess the expression of inflammatory markers, specifically IL6 and CCL2. ELISA was performed to assess IL6 and confirm qRT-PCR results at the protein level. Finally, ROS levels were assessed in all groups. Here, we show that NO delivery via nanoparticles enhanced EPC survival and recovery, AFM measurements revealed that NO exposure affect cell morphology, while qRT-PCR demonstrated a significant downregulation in IL6 and CCL2 expression when treating the cells to NO both before and after shear exposure. ELISA results for IL6 confirmed qRT-PCR data. ROS experiment results support our findings from previous experiments. These findings demonstrate that NO-releasing nanoparticles can be used as an effective delivery approach of NO to deep lung to prevent/reduce ARDS associated inflammation and cell injuries. This information is particularly useful to treat severe ARDS due to COVID-19 infection. These nanoparticles will be useful when clinically administrated to COVID-19 patients to reduce the symptoms originating from lung distress.

Integrating molecular pathogenesis and clinical translation in sepsis-induced acute respiratory distress syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality and arises after lung infection or infection at extrapulmonary sites. An aberrant host response to infection leads to disruption of the pulmonary alveolar-capillary barrier, resulting in lung injury characterized by hypoxemia, inflammation, and noncardiogenic pulmonary edema. Despite increased understanding of the molecular biology underlying sepsis-induced ARDS, there are no targeted pharmacologic therapies for this devastating condition. Here, we review the molecular underpinnings of sepsis-induced ARDS with a focus on relevant clinical and translational studies that point toward novel therapeutic strategies.

Using a Novel Microfabricated Model of the Alveolar-Capillary Barrier to Investigate the Effect of Matrix Structure on Atelectrauma

The alveolar-capillary barrier is composed of epithelial and endothelial cells interacting across a fibrous extracelluar matrix (ECM). Although remodeling of the ECM occurs during several lung disorders, it is not known how fiber structure and mechanics influences cell injury during cyclic airway reopening as occurs during mechanical ventilation (atelectrauma). We have developed a novel in vitro platform that mimics the micro/nano-scale architecture of the alveolar microenvironment and have used this system to investigate how ECM microstructural properties influence epithelial cell injury during airway reopening. In addition to epithelial-endothelial interactions, our platform accounts for the fibrous topography of the basal membrane and allows for easy modulation of fiber size/diameter, density and stiffness. Results indicate that fiber stiffness and topography significantly influence epithelial/endothelial barrier function where increased fiber stiffness/density resulted in altered cytoskeletal structure, increased tight junction (TJ) formation and reduced barrier permeability. However, cells on rigid/dense fibers were also more susceptible to injury during airway reopening. These results indicate that changes in the mechanics and architecture of the lung microenvironment can significantly alter cell function and injury and demonstrate the importance of implementing in vitro models that more closely resemble the natural conditions of the lung microenvironment.

Effects of Simvastatin Beyond Dyslipidemia: Exploring Its Antinociceptive Action in an Animal Model of Complex Regional Pain Syndrome-Type I

Simvastatin is a lipid-lowering agent that blocks the production of cholesterol through inhibition of 3-hydroxy-methyl-glutaryl coenzyme A (HMG-CoA) reductase. In addition, recent evidence has suggested its anti-inflammatory and antinociceptive actions during inflammatory and pain disorders. Herein, we investigated the effects of simvastatin in an animal model of complex regional pain syndrome-type I, and its underlying mechanisms. Chronic post-ischemia pain (CPIP) was induced by ischemia and reperfusion (IR) injury of the left hind paw. Our findings showed that simvastatin inhibited mechanical hyperalgesia induced by CPIP model in single and repeated treatment schedules, respectively; however simvastatin did not alter inflammatory signs during CPIP model. The mechanisms underlying those actions are related to modulation of transient receptor potential (TRP) channels, especially TRMP8. Moreover, simvastatin oral treatment was able to reduce the nociception induced by acidified saline [an acid-sensing ion channels (ASICs) activator] and bradykinin (BK) stimulus, but not by TRPA1, TRPV1 or prostaglandin-E2 (PGE2). Relevantly, the antinociceptive effects of simvastatin did not seem to be associated with modulation of the descending pain circuits, especially noradrenergic, serotoninergic and dopaminergic systems. These results indicate that simvastatin consistently inhibits mechanical hyperalgesia during neuropathic and inflammatory disorders, possibly by modulating the ascending pain signaling (TRPM8/ASIC/BK pathways expressed in the primary sensory neuron). Thus, simvastatin open-up new standpoint in the development of innovative analgesic drugs for treatment of persistent pain, including CRPS-I.