Alveolar Inflammation Research Articles

A glimpse in post-COVID pathophysiology: the role of exhaled breath condensate pH as an early marker of residual alveolar inflammation

ABSTRACT Background Residual alveolar inflammation seems to be paramount in post-COVID pathophysiology. Currently, we still lack a reliable marker to detect and track alveolar phlogosis in these patients. Exhaled Breath Condensate (EBC) pH has robust evidences highlighting its correlation with lung phlogosis in various diseases. We aim to define the reliability of alveolar and bronchial EBC pH in the assessment and in the follow up of post-COVID-related inflammation. Research design and methods We enrolled 10 patients previously hospitalized due to COVID-19 pneumonia. We performed a complete follow-up after 3 months and 6 months from discharge. Each visit included routine blood tests, arterial blood gas analysis, 6-minute walking test, spirometry, diffusing capacity and body plethysmography. Finally, bronchial and alveolar EBC were collected at the end of each visit. Results Alveolar EBC pH was significantly lower than bronchial EBC pH at T1, alveolar EBC pH tended to be more acid after 3 months from hospital discharge compared to the same sample 6 months later. Serum inflammatory biomarkers showed no significant differences from T1 to T2. Alveolar EBC pH was positively correlated with neutrophil-lymphocyte ratio. Conclusions Collecting EBC pH could help to understand pathophysiologic mechanism as well as monitoring alveolar inflammation in the post-COVID syndrome.

Distal Lung Inflammation Assessed by Alveolar Concentration of Nitric Oxide Is an Individualised Biomarker of Severe COVID-19 Pneumonia.

Pulmonary sequelae as assessed by pulmonary function tests (PFTs) are often reported in patients infected by SARS-CoV-2 during the post-COVID-19 period. Little is known, however, about the status of pulmonary inflammation during clinical recovery after patients’ discharge from the hospitals. We prospectively measured PFTs coupled with the exhaled nitric oxide (NO) stemming from the proximal airways (FeNO) and the distal lung (CaNO) in 169 consecutive patients with varying degrees of the severity of COVID-19 six weeks to one year after acute infection by SARS-CoV-2. The proportions of patients with abnormal PFTs, defined as the presence of either obstructive/restrictive patterns or impaired lung gas transfer, or both, increased with the severity of the initial lung disease (15, 30, and 52% in patients with mild, moderate, and severe COVID-19). FeNO values remained within normal ranges and did not differ between the three groups of patients. CaNO, however, was significantly higher in patients with severe or critical COVID-19, compared with patients with milder forms of the disease. There was also an inverse relationship between CaNO and DLCO. We conclude that the residual inflammation of the distal lung is still present in the post-COVID-19 follow-up period, in particular, in those patients with an initially severe form of COVID-19. This long-lasting alveolar inflammation might contribute to the long-term development of pulmonary fibrosis and warrants the regular monitoring of exhaled NO together with PFTs in patients with COVID-19.

The impact of platelets on pulmonary microcirculation throughout COVID-19 and its persistent activating factors.

Patients with COVID-19 often have hypoxemia, impaired lung function, and abnormal imaging manifestations in acute and convalescent stages. Alveolar inflammation, pulmonary vasculitis, and thromboembolism synergistically damage the blood-air barrier, resulting in increased pulmonary permeability and gas exchange disorders. The incidence of low platelet counts correlates with disease severity. Platelets are also involved in the impairment of pulmonary microcirculation leading to abnormal lung function at different phases of COVID-19. Activated platelets lose the ability to protect the integrity of blood vessel walls, increasing the permeability of pulmonary microvasculature. High levels of platelet activation markers are observed in both mild and severe cases, short and long term. Therefore, the risk of thrombotic events may always be present. Vascular endothelial injury, immune cells, inflammatory mediators, and hypoxia participate in the high reactivity and aggregation of platelets in various ways. Microvesicles, phosphatidylserine (PS), platelets, and coagulation factors are closely related. The release of various cell-derived microvesicles can be detected in COVID-19 patients. In addition to providing a phospholipid surface for the synthesis of intrinsic factor Xase complex and prothrombinase complex, exposed PS also promotes the decryption of tissue factor (TF) which then promotes coagulant activity by complexing with factor VIIa to activate factor X. The treatment of COVID-19 hypercoagulability and thrombosis still focuses on early intervention. Antiplatelet therapy plays a role in relieving the disease, inhibiting the formation of the hypercoagulable state, reducing thrombotic events and mortality, and improving sequelae. PS can be another potential target for the inhibition of hypercoagulable states.

D-tagatose protects against oleic acid-induced acute respiratory distress syndrome in rats by activating PTEN/PI3K/AKT pathway.

Acute respiratory distress syndrome (ARDS) is characterized by disruption of the alveolar–capillary barrier, resulting in severe alveolar edema and inflammation. D-tagatose (TAG) is a low-calorie fructose isomer with diverse biological activities whose role in ARDS has never been explored. We found that TAG protects lung tissues from injury in the oleic acid-induced rat model of ARDS. Seventeen male Sprague–Dawley rats were randomly assigned to 3 groups: Sham (n = 5), ARDS (n = 6), and TAG + ARDS (n = 6). The treatment groups were injected with oleic acid to induce ARDS, and the TAG + ARDS group was given TAG 3 days before the induction. After the treatments, the effect of TAG was evaluated by blood gas analysis and observing the gross and histological structure of the lung. The results showed that TAG significantly improved the oxygenation function, reduced the respiratory acidosis and the inflammatory response. TAG also improved the vascular permeability in ARDS rats and promoted the differentiation of alveolar type II cells, maintaining the stability of the alveolar structure. This protective effect of TAG on the lung may be achieved by activating the PTEN/PI3K/AKT pathway. Thus, TAG protects against oleic acid-induced ARDS in rats, suggesting a new clinical strategy for treating the condition.

Assessment of vessels endothelial dysfunction by protease-activated receptors (PARs) signaling in COVID-19 patients

PAR-1-mediated the endothelial disruption that occurs in the context of thromboinflammation. In addition, PAR1 promotes a profibrotic phenotype in fibroblasts, alveolar inflammation, and apoptosis. This is an active area of research; more data are needed to clarify similarities and differences of the PARs and their modulators in Post and Critical cases of COVID-19. Such issues are especially relevant given the potential use PAR-1 as a marker of promote thrombosis and tissue injury through a proposed mechanism between inflammation and thrombosis that was reported previously. This paper would track the theoretical role of PAR-1 as a marker of promote thrombosis in COVID-19 cases by looking for the following questions: What is the Cross Talk Between Thromboinflammation and Protease-activated receptors during Post and Critical cases of COVID-19?

Predicting asthma exacerbations: is there utility in noninvasive assessment of distal airway inflammation using multiple flowFENO?

<b>Alveolar inflammation, as assessed by partitioned exhaled nitric oxide, appears to provide promising insights into small airway disease relevant to asthma exacerbation</b>https://bit.ly/38KqyCk

Early Isolates of SARS-CoV-2 Result in Different Pathogenesis in the Transduced Mouse Model of COVID-19.

A transduced mouse model of SARS-CoV-2 infection was established using Balb/c mice. This was achieved through the adenovirus-vectored delivery of the hACE2 gene, to render the mice transiently susceptible to the virus. The model was characterised in terms of the dissemination of hACE2 receptor expression, the dissemination of three SARS-CoV-2 virus variants in vivo up to 10 days following challenge, the resulting histopathology and the clinical signs induced in the mice. In transduced mice, the infection was short-term, with a rapid loss in body weight starting at day 2 with maximum weight loss at day 4, followed by subsequent recovery until day 10. The induced expression of the hACE2 receptor was evident in the lungs, but, upon challenge, the SARS-CoV-2 virus disseminated beyond the lungs to spleen, liver and kidney, peaking at day 2 post infection. However, by day 10 post infection, the virus was undetectable. The lung histopathology was characterised by bronchial and alveolar inflammation, which was still present at day 10 post infection. Transduced mice had differential responses to viral variants ranking CVR-Glasgow 1 > Victoria-1 > England-2 isolates in terms of body weight loss. The transduced mouse model provides a consistent and manipulatable model of SARS-CoV-2 infection to screen viral variants for their relative virulence and possible interventions.

Abstract P2102: EB3 Inhibitor VT-109 Activated FOXM1 Pathways To Promote Resolution Of Acute Lung Injury

Acute respiratory distress syndrome (ARDS) is the acute onset of non-cardiogenic pulmonary edema, hypoxemia, and respiratory failure, conditions associated with a high mortality rate. ARDS is frequently caused by lung infections including SARS-CoV-2. In light of the COVID-19 pandemic, development of therapeutic approaches to combat ARDS have become an urgent unmet medical need. As increased vascular leakage is a culprit of alveolar damage and lung inflammation, we hypothesize that an effective therapy against vascular leakage should improve the clinical outcome of ARDS patients. We have identified a drug candidate Vascular Therapeutics (VT)-109, an allosteric inhibitor of End Binding protein 3, which contributes to vascular leakage by amplifying pathological calcium signaling in endothelial cells. Treatment of mice with VT-109 reduced the leakage of proteinous fluids in lungs to 55.4% (n=7, p&lt;0.05) after endotoxin challenge, 77.7% (n=6, p&lt;0.01) after exposure to high volume mechanical ventilation, and 42.5% (n=7, p&lt;0.05) in the two-hit model, a combination of polymicrobial sepsis with normal tidal volume mechanical ventilation. VT-109 reduced the mortality of both septic (n=10, p&lt;0.01) and endotoxin-challenged (n=10, p&lt;0.05) mice. Furthermore, treatment with VT-109 in mice expressing human ACE2 receptor blocked diffuse alveolar damage (n=5, p&lt;0.0001) caused by SARS-CoV-2 infection. In this COVID-19 model, the therapeutic benefits of VT-109 were observed when treatment was initiated at either day 1 or day 3 post-viral infection. Transcriptome analysis of lung endothelial cells in mice challenged with endotoxin showed that VT-109 upregulated 23 FOXM1 target genes (&gt;2-fold) suggesting that it promotes endothelial cell regeneration by activating the FOXM1 pathway. Our data demonstrate that VT-109 successfully treats vascular leakage and is a promising drug candidate for future clinical studies. Funding for this work is provided by the Congressionally Directed Medical Research Programs through the Peer Reviewed Medical Research Program (PRMRP) under award No. W81XWH-21-1-0639. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the Department of Defense.

Differences in the characteristics and pulmonary toxicity of nano- and micron-sized respirable coal dust

BackgroundThe characteristics of coal dust (CD) particles affect the inhalation of CD, which causes coal worker’s pneumoconiosis (CWP). CD nanoparticles (CD-NPs, < 500 nm) and micron particles (CD-MPs, < 5 μm) are components of the respirable CD. However, the differences in physicochemical properties and pulmonary toxicity between CD-NPs and CD-MPs remain unclear.MethodsCD was analyzed by scanning electron microscopy, Malvern nanoparticle size potentiometer, energy dispersive spectroscopy, infrared spectroscopy, and electron paramagnetic resonance spectroscopy. CCK-8 assay, ELISA, transmission electron microscope, JC-1 staining, reactive oxygen species activity probe, calcium ion fluorescent probe, AO/EB staining, flow cytometry, and western blot were used to determine the differences between CD-NPs and CD-MPs on acute pulmonary toxicity. CCK-8, scratch healing and Transwell assay, hematoxylin–eosin and Masson staining, immunohistochemistry, immunofluorescence, and western blot were applied to examine the effects of CD-NPs and CD-MPs on pneumoconiosis.ResultsAnalysis of the size distribution of CD revealed that the samples had been size segregated. The carbon content of CD-NPs was greater than that of CD-MPs, and the oxygen, aluminum, and silicon contents were less. In in vitro experiments with A549 and BEAS-2B cells, CD-NPs, compared with CD-MPs, had more inflammatory vacuoles, release of pro-inflammatory cytokines (IL-6, IL-1β, TNFα) and profibrotic cytokines (CXCL2, TGFβ1), mitochondrial damage (reactive oxygen species and Ca2+ levels and decreased mitochondrial membrane potential), and cell death (apoptosis, pyroptosis, and necrosis). CD-NPs-induced fibrosis model cells had stronger proliferation, migration, and invasion than did CD-MPs. In in vivo experiments, lung coefficient, alveolar inflammation score, and lung tissue fibrosis score (mean: 1.1%, 1.33, 1.33) of CD-NPs were higher than those of CD-MPs (mean: 1.3%, 2.67, 2.67). CD-NPs accelerated the progression of pulmonary fibrosis by upregulating the expression of pro-fibrotic proteins and promoting epithelial–mesenchymal transition. The regulatory molecules involved were E-cadherin, N-cadherin, COL-1, COL-3, ZO-1, ZEB1, Slug, α-SMA, TGFβ1, and Vimentin.ConclusionsStimulation with CD-NPs resulted in more pronounced acute and chronic lung toxicity than did stimulation with CD-MPs. These effects included acute inflammatory response, mitochondrial damage, pyroptosis, and necrosis, and more pulmonary fibrosis induced by epithelial–mesenchymal transition.

ALVEOLAR HEMORRHAGE: AN UNUSUAL PRESENTATION FOR BIRD EXPOSURE-HYPERSENSITIVITY PNEUMONITIS

TYPE: Late Breaking Abstract TOPIC: Occupational and Environmental Lung Diseases INTRODUCTION: Hypersensitivity pneumonitis (HP) is caused by an inhaled agent. Usual cytopathologic findings include peri-bronchial and alveolar lymphocytic inflammation, poorly formed granulomas, and scattered areas of organizing pneumonia. Alveolar hemorrhage is a rare presentation. CASE PRESENTATION: 63 y/o male with history of asthma and multiple hospital visits due to respiratory distress, presented with shortness of breath and hypoxemia for 2 weeks. Physical exam, showed O2Sat: 85% (RA), tachypnea, and bilateral wheezes. Chest CT Angiography showed no evidence of pulmonary embolism but demonstrated bilateral patchy peribronchovascular groundglass consolidation in a mosaic attenuation, centrilobular nodules and focal areas of airspace consolidation. Laboratories remarkable for leukocytosis with eosinophilia and elevated procalcitonin. He was admitted with diagnosis of Pneumonia and treated with antibiotics without improvement. Bronchoalveolar lavage showed granulomatous inflammation and iron stain strongly positive in numerous alveolar macrophages. All cultures were negative. Further investigation revealed that he had multiple birds inside the house. Systemic steroids were started with rapid improvement of clinical presentation. Upon removal of the birds from home, he has not further exacerbations for the next 6 months. A diagnosis of non-fibrotic HP secondary to bird exposure was done. DISCUSSION: HP can be misdiagnosed as a viral illnesses, pneumonia, or asthma. Poor response to pneumonia treatment can be a clue during exacerbations, although the use of steroids for conditions as asthma can mask the condition. Also, atypical pathologic presentations as alveolar hemorrhage can occur. CONCLUSIONS: The diagnosis of HP requires a high index of suspicion and careful attention to exposure history, and possible atypical histopathologic findings. DISCLOSURE: No significant relationships. KEYWORD: Hypersensitivity Pneumonitis

A VERY RARE CASE OF ISOLATED SPONTANEOUS PNEUMOPERICARDIUM SECONDARY TO COVID-19

TYPE: Case Report TOPIC: Cardiovascular Disease INTRODUCTION: During the COVID-19 pandemic, new and atypical clinical manifestations and complications of this disease continue to emerge. One of these rare complications is spontaneous pneumopericardium. CASE PRESENTATION: A 75-year-old male presented to our hospital with fever, productive cough, and fatigue for 3 days. Physical exam demonstrated crackles at the right and left lung bases. Nasopharyngeal severe acute respiratory syndrome coronavirus 2(SARS-C0V-2) reverse transcriptase-polymerase chain reaction was positive. A chest CT scan was ordered and demonstrated pneumopericardium without subcutaneous emphysema, pneumomediastinum or pneumothorax. On day seven of hospitalization, he had acutely increased work of breathing and had desaturations. He was intubated. Two days later the patient died of severe respiratory insufficiency. DISCUSSION: The most common causes of pneumopericardium are chest trauma, mechanical ventilation, and cardiothoracic operations. After alveolar damage, air enters interstitial tissue spaces or continue dissecting along with the perivascular and peribronchial connective tissue. In COVID-19, alveolar rupture, hyperinflammatory response and hypercoagulability, could increase the risk of pneumopericardium, and pneumomediastinum. Alveolar rupture and inflammation in the setting of COVID-19 could have resulted in the fistulous communication between the lung and pericardium leading to isolated pneumopericardium in this patient. Most patients with pneumopericardium remain asymptomatic but can sometimes develop the complication of tension pneumopericardium leading to hemodynamic instability. Pneumopericardium is usually a self-limiting condition and is managed conservatively. CONCLUSIONS: It is very important that clinicians must be aware of this rare but potentially fatal complication of COVID-19. Further studies are needed to establish the association between the presence of spontaneous pneumopericardium and outcomes in COVID-19. DISCLOSURE: Nothing to declare. KEYWORD: pneumopericardium

Aerobic exercise training engages cholinergic signaling to improve emphysema induced by cigarette smoke exposure in mice

Lung inflammation is modulated by cholinergic signaling and exercise training protects mice against pulmonary emphysema development; however, whether exercise training engages cholinergic signaling is unknown. AimsAs cholinergic signaling is directly linked to the vesicular acetylcholine transporter (VAChT) levels, we evaluated whether the effects of aerobic exercise training depend on the VAChT levels in mice with pulmonary emphysema. Main methodsWild-type (WT) and mutant (KDHOM) mice (65–70% of reduction in VAChT levels) were exposed to cigarette smoke (30 min, 2×/day, 5×/week, 12 weeks) and submitted or not to aerobic exercise training on a treadmill (60 min/day, 5×/week, 12 weeks). Lung function and inflammation were evaluated. Key findingsCigarette smoke reduced body mass in mice (p < 0.001) and increased alveolar diameter (p < 0.001), inflammation (p < 0.001) and collagen deposition (p < 0.01) in lung tissue. Both trained groups improved their performance in the final physical test compared to the initial test (p < 0.001). In WT mice, exercise training protected against emphysema development (p < 0.05), reduced mononuclear cells infiltrate (p < 0.001) and increased MAC-2 positive cells in lung parenchyma (p < 0.05); however, these effects were not observed in KDHOM mice. The exercise training reduced iNOS-positive cells (p < 0.001) and collagen fibers deposition (p < 0.05) in lung parenchyma of WT and KDHOM mice, although KDHOM mice showed higher levels of iNOS-positive cells. SignificanceOur data suggest that the protective effects of aerobic exercise training on pulmonary emphysema are, at least in part, dependent on the integrity of the lung cholinergic signaling.

Novel aerosol treatment of airway hyper-reactivity and inflammation in a murine model of asthma with a soluble epoxide hydrolase inhibitor.

Asthma currently affects more than 339 million people worldwide. In the present preliminary study, we examined the efficacy of a new, inhalable soluble epoxide hydrolase inhibitor (sEHI), 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), to attenuate airway inflammation, mucin secretion, and hyper-responsiveness (AHR) in an ovalbumin (OVA)-sensitized murine model. Male BALB/c mice were divided into phosphate-buffered saline (PBS), OVA, and OVA+TPPU (2- or 6-h) exposure groups. On days 0 and 14, the mice were administered PBS or sensitized to OVA in PBS. From days 26-38, seven challenge exposures were performed with 30 min inhalation of filtered air or OVA alone. In the OVA+TPPU groups, a 2- or 6-h TPPU inhalation preceded each 30-min OVA exposure. On day 39, pulmonary function tests (PFTs) were performed, and biological samples were collected. Lung tissues were used to semi-quantitatively evaluate the severity of inflammation and airway constriction and the volume of stored intracellular mucosubstances. Bronchoalveolar lavage (BAL) and blood samples were used to analyze regulatory lipid mediator profiles. Significantly (p < 0.05) attenuated alveolar, bronchiolar, and pleural inflammation; airway resistance and constriction; mucosubstance volume; and inflammatory lipid mediator levels were observed with OVA+TPPU relative to OVA alone. Cumulative findings indicated TPPU inhalation effectively inhibited inflammation, suppressed AHR, and prevented mucosubstance accumulation in the murine asthmatic model. Future studies should determine the pharmacokinetics (i.e., absorption, distribution, metabolism, and excretion) and pharmacodynamics (i.e., concentration/dose responses) of inhaled TPPU to explore its potential as an asthma-preventative or -rescue treatment.

Inflammation and Oxidative Stress as Common Mechanisms of Pulmonary, Autonomic and Musculoskeletal Dysfunction after Spinal Cord Injury.

Simple SummaryWhen a spinal cord injury occurs, the neurons that regulate our voluntary movements, those involved in environment and somatic perception and those that regulate vegetative functions are affected. Once neuronal damage is established, the cells of other tissues are also affected in their functions, altering the interaction between organs and altering the proper functioning of the organism. Multiple studies in animal models, as well as in humans, have recognized as factors involved in organ damage the imbalance between the formation of highly reactive molecules called pro-oxidants and defensive mechanisms called antioxidants. Closely associated with this phenomenon, the inflammatory response is also pathologically activated. In this narrative review, we have analyzed the information involving these pathological processes at the level of the lung, the autonomic nervous system and the skeletal musculature after spinal cord injury. Knowing the abnormal functioning mechanisms that occur after a spinal cord injury not only offers a better understanding of the organic events but also offers future possibilities for therapeutic interventions that may benefit the thousands of patients suffering this pathology.One of the etiopathogenic factors frequently associated with generalized organ damage after spinal cord injury corresponds to the imbalance of the redox state and inflammation, particularly of the respiratory, autonomic and musculoskeletal systems. Our goal in this review was to gain a better understanding of this phenomenon by reviewing both animal and human studies. At the respiratory level, the presence of tissue damage is notable in situations that require increased ventilation due to lower thoracic distensibility and alveolar inflammation caused by higher levels of leptin as a result of increased fatty tissue. Increased airway reactivity, due to loss of sympathetic innervation, and levels of nitric oxide in exhaled air that are similar to those seen in asthmatic patients have also been reported. In addition, the loss of autonomic control efficiency leads to an uncontrolled release of catecholamines and glucocorticoids that induce immunosuppression, as well as a predisposition to autoimmune reactions. Simultaneously, blood pressure regulation is altered with vascular damage and atherogenesis associated with oxidative damage. At the muscular level, chronically elevated levels of prooxidants and lipoperoxidation associated with myofibrillar atrophy are described, with no reduction or reversibility of this process through antioxidant supplementation.

The Protective Effects and Mechanism of Doxepin on Radiation-Induced Lung Injury in Rats.

Radiation-induced lung injuries (RILI) is one of the serious complications of radiotherapy posed by the damage of alveolar cells and inflammation over-reaction. We aimed to investigate the potential protective effects of doxepin on RILI (20 Gy total dose at 3 Gy/min of X-ray irradiation), as well as its underlying mechanism. For animal experiments, such parameters as Immunohistochemistry and hematoxylin and eosin (H&E) staining, WBC (white blood cell), CRP (C-reactive protein), Western blot, and q-PCR were detected. The results indicated that both survival status and weight increase of irradiated rats treated by doxepin (3 mg/kg/day, rat) were higher than those of treated with irradiation alone (Dosing started the day before irradiation). Further, histological examinations showed doxepin could tenuate the radiation injury, as indicated as alveolar inflammatory exudation and there was only mild interstitial inflammation infiltration. Western blotting and q-PCR showed that expression of NF-κβ in X group were higher than that in XMD group. For the first time, we reported doxepin functioned as a radioprotectant candidate, which provide a promising application of doxepin for protecting radiotherapy injuries.

GSPE Protects against Bleomycin-Induced Pulmonary Fibrosis in Mice via Ameliorating Epithelial Apoptosis through Inhibition of Oxidative Stress.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease of unknown cause which leads to alveolar epithelial cell apoptosis followed by basement membrane disruption and accumulation of extracellular matrix, destroying the lung architecture. Oxidative stress is involved in the development of alveolar injury, inflammation, and fibrosis. Oxidative stress-mediated alveolar epithelial cell (AEC) apoptosis is suggested to be a key process in the pathogenesis of IPF. Therefore, the present study investigated whether grape seed proanthocyanidin extract (GSPE) could inhibit the development of pulmonary fibrosis via ameliorating epithelial apoptosis through the inhibition of oxidative stress. We found that GSPE significantly ameliorated the histological changes and the level of collagen deposition in bleomycin (BLM)-induced lungs. Moreover, GSPE attenuated lung inflammation by reducing the total number of cells in bronchoalveolar lavage (BAL) fluid and decreasing the expression of IL-6. We observed that the levels of H2O2 leading to oxidative stress were increased following BLM instillation, which significantly decreased with GSPE treatment both in vivo and in vitro. These findings showed that GSPE attenuated BLM-induced epithelial apoptosis in the mouse lung and A549 alveolar epithelial cell through the inhibition of oxidative stress. Furthermore, GSPE could attenuate mitochondrial-associated cell apoptosis via decreasing the Bax/Bcl-2 ratio. The present study demonstrates that GSPE could ameliorate bleomycin-induced pulmonary fibrosis in mice via inhibition of epithelial apoptosis through the inhibition of oxidative stress.

The Heat Shock Protein 90 Inhibitor, AT13387, Protects the Alveolo-Capillary Barrier and Prevents HCl-Induced Chronic Lung Injury and Pulmonary Fibrosis.

Hydrochloric acid (HCl) exposure causes asthma-like conditions, reactive airways dysfunction syndrome, and pulmonary fibrosis. Heat Shock Protein 90 (HSP90) is a molecular chaperone that regulates multiple cellular processes. HSP90 inhibitors are undergoing clinical trials for cancer and are also being studied in various pre-clinical settings for their anti-inflammatory and anti-fibrotic effects. Here we investigated the ability of the heat shock protein 90 (HSP90) inhibitor AT13387 to prevent chronic lung injury induced by exposure to HCl in vivo and its protective role in the endothelial barrier in vitro. We instilled C57Bl/6J mice with 0.1N HCl (2 µL/g body weight, intratracheally) and after 24 h began treatment with vehicle or AT13387 (10 or 15 mg/kg, SC), administered 3×/week; we analyzed histological, functional, and molecular markers 30 days after HCl. In addition, we monitored transendothelial electrical resistance (TER) and protein expression in a monolayer of human lung microvascular endothelial cells (HLMVEC) exposed to HCl (0.02 N) and treated with vehicle or AT13387 (2 µM). HCl provoked persistent alveolar inflammation; activation of profibrotic pathways (MAPK/ERK, HSP90); increased deposition of collagen, fibronectin and elastin; histological evidence of fibrosis; and a decline in lung function reflected in a downward shift in pressure–volume curves, increased respiratory system resistance (Rrs), elastance (Ers), tissue damping (G), and hyperresponsiveness to methacholine. Treatment with 15 mg/kg AT13387reduced alveolar inflammation, fibrosis, and NLRP3 staining; blocked activation of ERK and HSP90; and attenuated the deposition of collagen and the development of chronic lung injury and airway hyperreactivity. In vitro, AT13387 prevented HCl-induced loss of barrier function and AKT, ERK, and ROCK1 activation, and restored HSP70 and cofilin expression. The HSP90 inhibitor, AT13387, represents a promising drug candidate for chronic lung injury that can be administered subcutaneously in the field, and at low, non-toxic doses.

RETRACTED ARTICLE: Rubusoside relieves lipopolysaccharide-induced acute lung injury via modulating inflammatory responses: in vitro and in vivo studies

Acute lung injury (ALI) is a common respiratory disease characterized by the alveolar edema and pulmonary inflammation, which results in the respiratory failure and even death. The current research study was planned to assess the beneficial properties of rubusoside against the LPS-provoked ALI in mice through the alleviation of oxidative stress and inflammatory responses. The viability of lipopolysaccharide (LPS)-provoked RAW 264.7 cells were assessed by MTT assay. The ALI was initiated to the mice via administering the LPS (5 mg/kg) for 3 days and supplemented with the 30 mg/kg of rubusoside. The lung edema, total cells, and protein content were assessed by standard methods. The pro-inflammatory markers level was investigated by assay kits and the antioxidant biomarkers were analyzed by standard techniques. The levels of inflammatory biomarkers in the LPS-provoked RAW 264.7 cells and lung tissues of ALI mice were studied by RT-PCR assay. The lung tissues were analyzed microscopically to identify the histological alterations. The rubusoside treatment effectively decreased the RAW 264.7 cells viability. The rubusoside also inhibited the lung edema, IL-6, and TNF-α content, ROS accumulation, and TBARS level in the LPS-challenged ALI mice. Rubusoside also improved the GSH content and CAT activity in the ALI mice. The levels of TLR-4, COX-2, iNOS, and IL-1β were effectively down-regulated by the rubusoside in both LPS-challenged RAW 264.7 cells and lung tissues. The finding of lung tissue histopathology was also proved the therapeutic action of rubusoside. Altogether, our results suggest that rubusoside demonstrates therapeutic property against the LPS-challenged ALI in mice via inhibiting the inflammatory responses and it can be an effective drug to treat the ALI in future.

Bone mesenchymal stem cell-derived extracellular vesicles inhibit DAPK1-mediated inflammation by delivering miR-191 to macrophages

Alveolar macrophage activation and apoptosis are vital contributors to sepsis-associated acute lung injury (ALI). However, the mechanisms of alveolar macrophage activation are yet to be clarified. Death-associated protein kinase 1 (DAPK1) is one of the potential candidates that play crucial roles in regulating alveolar macrophage inflammation. Herein, we found that primary human bone mesenchymal stem cell (BMSC)-derived extracellular vesicles (EVs) antagonize LPS-induced inflammation in the THP-1 human macrophage-like cell line. Mechanistically, LPS stimulation elevates the expression of DAPK1 and the inflammation markers in THP-1 cells, while BMSC-derived EVs inhibit the expression of DAPK1 and inflammation through delivering miR-191, which can target the 3′-UTR of the DAPK1 mRNA and therefore suppress its translation. The importance of DAPK1 in the activation of THP-1 is also stressed in this study. Our findings provide evidence that BMSC-derived EVs regulate the alveolar macrophage inflammation and highlight BMSC-derived EVs as a potential vehicle to deliver biomacromolecules to macrophages.

Dihydroartemisinin attenuates pulmonary inflammation and fibrosis in rats by suppressing JAK2/STAT3 signaling.

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has induced a worldwide pandemic since early 2020. COVID-19 causes pulmonary inflammation, secondary pulmonary fibrosis (PF); however, there are still no effective treatments for PF. The present study aimed to explore the inhibitory effect of dihydroartemisinin (DHA) on pulmonary inflammation and PF, and its molecular mechanism. Morphological changes and collagen deposition were analyzed using hematoxylin-eosin staining, Masson staining, and the hydroxyproline content. DHA attenuated early alveolar inflammation and later PF in a bleomycin-induced rat PF model, and inhibited the expression of interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNFα), and chemokine (C-C Motif) Ligand 3 (CCL3) in model rat serum. Further molecular analysis revealed that both pulmonary inflammation and PF were associated with increased transforming growth factor-β1 (TGF-β1), Janus activated kinase 2 (JAK2), and signal transducer and activator 3(STAT3) expression in the lung tissues of model rats. DHA reduced the inflammatory response and PF in the lungs by suppressing TGF-β1, JAK2, phosphorylated (p)-JAK2, STAT3, and p-STAT3. Thus, DHA exerts therapeutic effects against bleomycin-induced pulmonary inflammation and PF by inhibiting JAK2-STAT3 activation. DHA inhibits alveolar inflammation, and attenuates lung injury and fibrosis, possibly representing a therapeutic candidate to treat PF associated with COVID-19.