Role of extracellular vesicles in cell-cell communication and inflammation following exposure to pulmonary toxicants

Bioinformatics-Guided Identification and Quantification of Biomarkers of Crotalus atrox Envenoming and its Neutralization by Antivenom

Quantitative mass spectrometry-based proteomics of extracellular vesicles (EVs) provides systems-level exploration for the analysis of snakebite envenoming (SBE) as the venom progresses, causing injuries such as hemorrhage, trauma, and death. Predicting EV biomarkers has become an essential aspect of this process, offering an avenue to explore the specific pathophysiological changes that occur after envenoming. As new omics approaches emerge to advance our understanding of SBE, further bioinformatics analyses are warranted to incorporate the use of antivenom or other therapeutics to observe their global impact on various biological processes. Herein, we used an in vivo BALB/c mouse model and proteomics approach to analyze the physiological impacts of SBE and antivenom neutralization in intact animals; this was followed by bioinformatics methods to predict potential EV biomarkers. Groups of mice (n=5) were intramuscularly injected with Saline or Crotalus atrox venom. After 30 minutes, the mice received saline or antivenom (ANTIVIPMYN®) by intravenous injection. After 24 hours, blood was collected to extract the plasma to analyze the EV content and determine the exposome of C. atrox venom as well as the neutralizing capabilities of the antivenom. The predicted biomarkers consistently and significantly sensitive to antivenom treatment are Slc25a4, Rps8, Akr1c6, Naa10, Sult1d1, Hadha, Mbl2, Zc3hav, Tgfb1, Prxl2a, Coro1c, Tnni1, Ryr3, C8b, Mycbp, and Cfhr4. These biomarkers pointed towards specific physiological alterations, causing significant metabolic changes in mitochondrial homeostasis, lipid metabolism, immunity, and cytolysis, indicating hallmarks of traumatic injury. Here, we present a more comprehensive view of murine plasma EV proteome and further identify significant changes in abundance for potential biomarkers associated with antivenom treatment. The predicted biomarkers have the potential to enhance current diagnostic tools for snakebite management, thereby contributing significantly to the evolution of treatment strategies in the diagnosis and prognosis of SBE.

Respiratory extracellular vesicle isolation optimization through proteomic profiling of equine samples and identification of candidates for cell-of-origin studies

Growing evidence supports the importance of extracellular vesicle (EV) as mediators of communication in pathological processes, including those underlying respiratory disease. However, establishing methods for isolating and characterizing EVs remains challenging, particularly for respiratory samples. This study set out to address this challenge by comparing different EV isolation methods and evaluating their impacts on EV yield, markers of purity, and proteomic signatures, utilizing equine/horse bronchoalveolar lavage samples. Horses can serve as effective translational animal models for respiratory studies due to similarities with human immune responses, shared environmental exposures, and naturally occurring respiratory diseases including asthma. Further, horses are long-lived large animals that allow for longitudinal sample collection, and provide large sample volume and cell yield, which are particularly useful since EV research is commonly limited by low sample yields. Here, EVs were isolated from horse bronchoalveolar lavage fluid (BALF) using four different methods (ultracentrifugation, microcentrifugation, and two sizes of size exclusion chromatography columns) and characterized by measuring particle counts, EV purity, total protein yield, and proteomic cargo, with a specific focus on vesicle surface marker expression potentially informing cell type of origin. We found that size exclusion chromatography yielded the highest particle counts, greatest EV purity markers and elevated vesicle surface marker expression. Overall proteomic profiles differed across isolation methods, with size exclusion chromatography clustering separately from centrifugation. Taken together, our results demonstrate that different isolation methods impact characteristics of EVs, notably that size exclusion chromatography, compared to centrifugation methods, resulted in higher EV purity and better characterized proteomic diversity, including information on EV cell-of-origin. This is the first study to characterize proteomic profiles of EVs following different isolation methods using equine BALF. The results of this study will pave the way for future studies using equine and human samples to characterize respiratory tract EVs.

Epigenetic mechanisms of alveolar macrophage activation in chemical-induced acute lung injury

Airways, alveoli and the pulmonary tissues are the most vulnerable to the external environment including occasional deliberate or accidental exposure to highly toxic chemical gases. However, there are many effective protective mechanisms that maintain the integrity of the pulmonary tissues and preserve lung function. Alveolar macrophages form the first line of defense against any pathogen or chemical/reactant that crosses the airway mucociliary barrier and reaches the alveolar region. Resident alveolar macrophages are activated or circulating monocytes infiltrate the airspace to contribute towards inflammatory or reparative responses. Studies on response of alveolar macrophages to noxious stimuli are rapidly emerging and alveolar macrophage are also being sought as therapeutic target. Here such studies have been reviewed and put together for a better understanding of the role pulmonary macrophages in general and alveolar macrophage in particular play in the pathogenesis of disease caused by chemical induced acute lung injury.

Neuroinflammatory responses and blood-brain barrier injury in chronic alcohol exposure: role of purinergic P2 × 7 Receptor signaling

Alcohol consumption leads to neuroinflammation and blood‒brain barrier (BBB) damage, resulting in neurological impairment. We previously demonstrated that ethanol-induced disruption of barrier function in human brain endothelial cells was associated with mitochondrial injury, increased ATP and extracellular vesicle (EV) release, and purinergic receptor P2 × 7R activation. Therefore, we aimed to evaluate the effect of P2 × 7R blockade on peripheral and neuro-inflammation in ethanol-exposed mice. In a chronic intermittent ethanol (CIE)-exposed mouse model, P2 × 7R was inhibited by two different methods: Brilliant Blue G (BBG) or gene knockout. We assessed blood ethanol concentration (BEC), brain microvessel gene expression by using RT2 PCR array, plasma P2 × 7R and P-gp, serum ATP, EV-ATP, number of EVs, and EV mtDNA copy numbers. An RT2 PCR array of brain microvessels revealed significant upregulation of proinflammatory genes involved in apoptosis, vasodilation, and platelet activation in CIE-exposed wild-type animals, which were decreased 15-50-fold in BBG-treated-CIE-exposed animals. Plasma P-gp levels and serum P2 × 7R shedding were significantly increased in CIE-exposed animals. Pharmacological or genetic suppression of P2 × 7R decreased receptor shedding to levels equivalent to those in control group. The increase in EV number and EV-ATP content in the CIE-exposed mice was significantly reduced by P2 × 7R inhibition. CIE mice showed augmented EV-mtDNA copy numbers which were reduced in EVs after P2 × 7R inhibition or receptor knockout. These observations suggested that P2 × 7R signaling plays a critical role in ethanol-induced brain injury. Increased extracellular ATP, EV-ATP, EV numbers, and EV-mtDNA copy numbers highlight a new mechanism of brain injury during alcohol exposure via P2 × 7R and biomarkers of such damage. In this study, for the first time, we report the in vivo involvement of P2 × 7R signaling in CIE-induced brain injury.

Oral arsenite exposure induces inflammation and apoptosis in pulmonary tissue: acute and chronic evaluation in young and adult mice

Inorganic arsenic is a well-known environmental toxicant, and exposure to this metalloid is strongly linked with severe and extensive toxic effects in various organs including the lungs. In the present study, we aimed to investigate the acute and chronic effects of arsenite exposure on pulmonary tissue in young and adult mice. In brief, young and adult female Balb/C mice were exposed to 3 and 30 ppm arsenite daily via drinking water for 30 and 90 days. Subsequently, the animals were sacrificed and various histological and immunohistochemistry (IHC) analyses were performed using lung tissues. Our findings showed arsenite was found to cause dose-dependent pathological changes such as thickening of the alveolar septum, inflammatory cell infiltrations and lung fibrosis in young and adult mice. In addition, arsenite exposure significantly increased the expression of inflammatory markers NF-κB and TNF-α, indicating that arsenite-exposed mice suffered from severe lung inflammation. Moreover, the IHC analysis of fibrotic proteins demonstrated an increased expression of TGF-β1, α-SMA, vimentin and collagen-I in the arsenite-exposed mice compared to the control mice. This was accompanied by apoptosis, which was indicated by the upregulated expression of caspase-3 in arsenite-exposed mice compared to the control. Adult mice were generally found to be more prone to arsenite toxicity during chronic exposure relative to their younger counterparts. Overall, our findings suggest that arsenite in drinking water may induce dose-dependent and age-dependent structural and functional impairment in the lungs through elevating inflammation and fibrotic proteins.

Environmental pollutants and exosomes: A new paradigm in environmental health and disease

This study investigates the intricate interplay between environmental pollutants and exosomes, shedding light on a novel paradigm in environmental health and disease. Cellular stress, induced by environmental toxicants or disease, significantly impacts the production and composition of exosomes, crucial mediators of intercellular communication. The heat shock response (HSR) and unfolded protein response (UPR) pathways, activated during cellular stress, profoundly influence exosome generation, cargo sorting, and function, shaping intercellular communication and stress responses. Environmental pollutants, particularly lipophilic ones, directly interact with exosome lipid bilayers, potentially affecting membrane stability, release, and cellular uptake. The study reveals that exposure to environmental contaminants induces significant changes in exosomal proteins, miRNAs, and lipids, impacting cellular function and health. Understanding the impact of environmental pollutants on exosomal cargo holds promise for biomarkers of exposure, enabling non-invasive sample collection and real-time insights into ongoing cellular responses. This research explores the potential of exosomal biomarkers for early detection of health effects, assessing treatment efficacy, and population-wide screening. Overcoming challenges requires advanced isolation techniques, standardized protocols, and machine learning for data analysis. Integration with omics technologies enhances comprehensive molecular analysis, offering a holistic understanding of the complex regulatory network influenced by environmental pollutants. The study underscores the capability of exosomes in circulation as promising biomarkers for assessing environmental exposure and systemic health effects, contributing to advancements in environmental health research and disease prevention.

Neuroinflammatory Responses and Blood-Brain Barrier Injury in Chronic Alcohol Exposure: Role of Purinergic P2X7 Receptor Signaling

Alcohol consumption leads to neuroinflammation and blood-brain barrier (BBB) damage, resulting in neurological impairment. We previously demonstrated that ethanol-induced disruption of barrier function in human brain endothelial cells was associated with mitochondrial injury, increased ATP and extracellular vesicle (EV) release, and purinergic receptor P2X7R activation. Therefore, we aimed to evaluate the effect of P2X7r blockade on peripheral and neuro-inflammation in EtOH-exposed mice. In a chronic intermittent ethanol (CIE)-exposed mouse model, P2X7R was inhibited by two different methods: Brilliant Blue G (BBG) or gene knockout. We assessed blood ethanol concentration (BEC), plasma P2X7R and P-gp, number of extra-cellular vesicles (EV), serum ATP and EV-ATP levels. Brain microvessel gene expression and EV mtDNA copy numbers were measured by RT2 PCR array and digital PCR, respectively. A RT2 PCR array of brain microvessels revealed significant upregulation of proinflammatory genes involved in apoptosis, vasodilation, and platelet activation in CIE-exposed animals, which were decreased 15-50-fold in BBG-treated CIE-exposed animals. Plasma P-gp levels and serum P2X7R shedding were significantly increased in CIE-exposed animals. Pharmacological or genetic suppression of P2X7R decreased P2X7R shedding to levels equivalent to those in control group. The increase in EV number and EV-ATP content in the CIE-exposed mice was significantly reduced by P2X7R inhibition. CIE mice showed augmented EV-mtDNA copy numbers which were reduced in EVs after P2X7R inhibition or receptor knockout. These observations suggested that P2X7R signaling plays a critical role in ethanol-induced brain injury. Increased eATP, EV-ATP, EV numbers, and EV-mtDNA copy numbers highlight a new mechanism of brain injury during alcohol exposure via P2X7R and biomarkers of such damage. In this study, for the first time, we report the in vivo involvement of P2X7R signaling in CIE-induced brain injury.

Endothelial extracellular vesicles induce acute lung injury via follistatin-like protein 1

Cardiopulmonary bypass has been speculated to elicit systemic inflammation to initiate acute lung injury (ALI), including acute respiratory distress syndrome (ARDS), in patients after cardiac surgery. We previously found that post-operative patients showed an increase in endothelial cell-derived extracellular vesicles (eEVs) with components of coagulation and acute inflammatory responses. However, the mechanism underlying the onset of ALI owing to the release of eEVs after cardiopulmonary bypass, remains unclear. Plasma plasminogen-activated inhibitor-1 (PAI-1) and eEV levels were measured in patients with cardiopulmonary bypass. Endothelial cells and mice (C57BL/6, Toll-like receptor 4 knockout (TLR4-/-) and inducible nitric oxide synthase knockout (iNOS-/-)) were challenged with eEVs isolated from PAI-1-stimulated endothelial cells. Plasma PAI-1 and eEVs were remarkably enhanced after cardiopulmonary bypass. Plasma PAI-1 elevation was positively correlated with the increase in eEVs. The increase in plasma PAI-1 and eEV levels was associated with post-operative ARDS. The eEVs derived from PAI-1-stimulated endothelial cells could recognize TLR4 to stimulate a downstream signaling cascade identified as the Janus kinase 2/3 (JAK2/3)-signal transducer and activator of transcription 3 (STAT3)-interferon regulatory factor 1 (IRF-1) pathway, along with iNOS induction, and cytokine/chemokine production in vascular endothelial cells and C57BL/6 mice, ultimately contributing to ALI. ALI could be attenuated by JAK2/3 or STAT3 inhibitors (AG490 or S3I-201, respectively), and was relieved in TLR4-/- and iNOS-/- mice. eEVs activate the TLR4/JAK3/STAT3/IRF-1 signaling pathway to induce ALI/ARDS by delivering follistatin-like protein 1 (FSTL1), and FSTL1 knockdown in eEVs alleviates eEV-induced ALI/ARDS. Our data thus demonstrate that cardiopulmonary bypass may increase plasma PAI-1 levels to induce FSTL1-enriched eEVs, which target the TLR4-mediated JAK2/3/STAT3/IRF-1 signaling cascade and form a positive feedback loop, leading to ALI/ARDS after cardiac surgery. Our findings provide new insight into the molecular mechanisms and therapeutic targets for ALI/ARDS after cardiac surgery.

Epigenetic regulation of pulmonary inflammation

Pulmonary disease such as chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis and pulmonary hypertension are the leading cause of deaths. More importantly, lung diseases are on the rise and environmental factors induced epigenetic modifications are major players on this increased prevalence. It has been reported that dysregulation of genes involved in epigenetic regulation such as the histone deacetylase (HDACs) and histone acetyltransferase (HATs) play important role in lung health and pulmonary disease pathogenesis. Inflammation is an essential component of respiratory diseases. Injury and inflammation trigger release of extracellular vesicles that can act as epigenetic modifiers through transfer of epigenetic regulators such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), proteins and lipids, from one cell to another. The immune dysregulations caused by the cargo contents are important contributors of respiratory disease pathogenesis. N6 methylation of RNA is also emerging to be a critical mechanism of epigenetic alteration and upregulation of immune responses to environmental stressors. Epigenetic changes such as DNA methylation are stable and often long term and cause onset of chronic lung conditions. These epigenetic pathways are also being utilized for therapeutic intervention in several lung conditions.

Naringenin regulates cigarette smoke extract-induced extracellular vesicles from alveolar macrophage to attenuate the mouse lung epithelial ferroptosis through activating EV miR-23a-3p/ACSL4 axis

BACKGROUND

Alveolar macrophages are one of the momentous regulators in pulmonary inflammatory responses, which can secrete extracellular vesicles (EVs) packing miRNAs. Ferroptosis, an iron-dependent cell death, is associated with cigarette smoke-induced lung injury, and EVs have been reported to regulate ferroptosis by transporting intracellular iron. However, the regulatory mechanism of alveolar macrophage-derived EVs has not been clearly illuminated in smoking-related pulmonary ferroptosis. Despite the known anti-ferroptosis effects of naringenin in lung injury, whether naringenin controls EVs-mediated ferroptosis has not yet been explored.

PURPOSE

We explore the effects of EVs from cigarette smoke-stimulated alveolar macrophages in lung epithelial ferroptosis, and elucidate the EV miRNA-mediated pharmacological mechanism of naringenin.

STUDY DESIGN AND METHODS

Differential and ultracentrifugation were conducted to extract EVs from different alveolar macrophages treatment groups in vitro. Both intratracheal instilled mice and treated epithelial cells were used to investigate the roles of EVs from alveolar macrophages involved in ferroptosis. Small RNA sequencing analysis was performed to distinguish altered miRNAs in EVs. The ferroptotic effects of EV miRNAs were examined by applying dual-Luciferase reporter assay and miRNA inhibitor transfection experiment.

RESULTS

Here, we firstly reported that EVs from cigarette smoke extract-induced alveolar macrophages (CSE-EVs) provoked pulmonary epithelial ferroptosis. The ferroptosis inhibitor ferrostatin-1 treatment reversed these changes in vitro. Moreover, EVs from naringenin and CSE co-treated alveolar macrophages (CSE+Naringenin-EVs) markedly attenuated the lung epithelial ferroptosis compared with CSE-EVs. Notably, we identified miR-23a-3p as the most dramatically changed miRNA among Normal-EVs, CSE-EVs, and CSE+Naringenin-EVs. Further experimental investigation showed that ACSL4, a pro-ferroptotic gene leading to lipid peroxidation, was negatively regulated by miR-23a-3p. The inhibition of miR-23a-3p diminished the efficacy of CSE+Naringenin-EVs.

CONCLUSION

Our findings firstly provided evidence that naringenin elevated the EV miR-23a-3p level from CSE-induced alveolar macrophages, thereby inhibiting the mouse lung epithelial ferroptosis via targeting ACSL4, and further complemented the mechanism of cigarette-induced lung injury and the protection of naringenin in a paracrine manner. The administration of miR-23a-3p-enriched EVs has the potential to ameliorate pulmonary ferroptosis.

Alcohol and e-cigarette damage alveolar-epithelial barrier by activation of P2X7r and provoke brain endothelial injury via extracellular vesicles

BACKGROUND

Use of nicotine containing products like electronic cigarettes (e-Cig) and alcohol are associated with mitochondrial membrane depolarization, resulting in the extracellular release of ATP, and mitochondrial DNA (mtDNA), mediating inflammatory responses. While nicotine effects on lungs is well-known, chronic alcohol (ETH) exposure also weakens lung immune responses and cause inflammation. Extracellular ATP (eATP) released by inflammatory/stressed cells stimulate purinergic P2X7 receptors (P2X7r) activation in adjacent cells. We hypothesized that injury caused by alcohol and e-Cig to pulmonary alveolar epithelial cells (hPAEpiC) promote the release of eATP, mtDNA and P2X7r in circulation. This induces a paracrine signaling communication either directly or via EVs to affect brain cells (human brain endothelial cells - hBMVEC).

METHODS

We used a model of primary human pulmonary alveolar epithelial cells (hPAEpiC) and exposed the cells to 100 mM ethanol (ETH), 100 µM acetaldehyde (ALD), or e-Cig (1.75 µg/mL of 1.8% or 0% nicotine) conditioned media, and measured the mitochondrial efficiency using Agilent Seahorse machine. Gene expression was measured by Taqman RT-qPCR and digital PCR. hPAEpiC-EVs were extracted from culture supernatant and characterized by flow cytometric analysis. Calcium (Ca2+) and eATP levels were quantified using commercial kits. To study intercellular communication via paracrine signaling or by EVs, we stimulated hBMVECs with hPAEpiC cell culture medium conditioned with ETH, ALD or e-cig or hPAEpiC-EVs and measured Ca2+ levels.

RESULTS

ETH, ALD, or e-Cig (1.8% nicotine) stimulation depleted the mitochondrial spare respiration capacity in hPAEpiC. We observed increased expression of P2X7r and TRPV1 genes (3-6-fold) and increased intracellular Ca2+ accumulation (20-30-fold increase) in hPAEpiC, resulting in greater expression of endoplasmic reticulum (ER) stress markers. hPAEpiC stimulated by ETH, ALD, and e-Cig conditioned media shed more EVs with larger particle sizes, carrying higher amounts of eATP and mtDNA. ETH, ALD and e-Cig (1.8% nicotine) exposure also increased the P2X7r shedding in media and via EVs. hPAEpiC-EVs carrying P2X7r and eATP cargo triggered paracrine signaling in human brain microvascular endothelial cells (BMVECs) and increased Ca2+ levels. P2X7r inhibition by A804598 compound normalized mitochondrial spare respiration, reduced ER stress and diminished EV release, thus protecting the BBB function.

CONCLUSION

Abusive drugs like ETH and e-Cig promote mitochondrial and endoplasmic reticulum stress in hPAEpiC and disrupts the cell functions via P2X7 receptor signaling. EVs released by lung epithelial cells against ETH/e-cig insults, carry a cargo of secondary messengers that stimulate brain cells via paracrine signals.

Air Pollution and Lung Cancer: Contributions of Extracellular Vesicles as Pathogenic Mechanisms and Clinical Utility

PURPOSE OF REVIEW

This review addresses the pressing issue of air pollution's threat to human health, focusing on its connection to non-small cell lung cancer (NSCLC) development. The aim is to explore the role of extracellular vesicles (EVs) as potential pathogenic mechanisms in lung cancer, including NSCLC, induced by air pollutants.

RECENT FINDINGS

Recent research highlights EVs as vital mediators of intercellular communication and key contributors to cancer progression. Notably, this review emphasizes the cargo of EVs released by both cancerous and non-cancerous lung cells, shedding light on their potential role in promoting various aspects of tumor development. The review underscores the importance of comprehending the intricate interplay between air pollution, biological damage mechanisms, and EV-mediated communication during NSCLC development. Major takeaways emphasize the significance of this understanding in addressing air pollution-related lung cancer. Future research avenues are also highlighted, aiming to enhance the applicability of EVs for diagnosis and targeted therapies, ultimately mitigating the inevitable impact of air pollution on NSCLC development and treatment.

Alcohol and e-cigarette damage alveolar-epithelial barrier by activation of P2X7r and provoke brain endothelial injury via extracellular vesicles

Background

Use of nicotine containing products like electronic cigarettes (e-Cig) and alcohol are associated with mitochondrial membrane depolarization, resulting in the extracellular release of ATP, and mitochondrial DNA (mtDNA), mediating inflammatory responses. While nicotine effects on lungs is well-known, chronic alcohol (ETH) exposure also weakens lung immune responses and cause inflammation. Extracellular ATP (eATP) released by inflammatory/stressed cells stimulate purinergic P2X7 receptors (P2X7r) activation in adjacent cells. We hypothesized that injury caused by alcohol and e-Cig to pulmonary alveolar epithelial cells (hPAEpiC) promote the release of eATP, mtDNA and P2X7r in circulation. This induces a paracrine signaling communication either directly or via EVs to affect brain cells (human brain endothelial cells - hBMVEC).

Methods

We used a model of primary human pulmonary alveolar epithelial cells (hPAEpiC) and exposed the cells to 100 mM ethanol (ETH), 100 μM acetaldehyde (ALD), or e-Cig (1.75μg/mL of 1.8% or 0% nicotine) conditioned media, and measured the mitochondrial efficiency using Agilent Seahorse machine. Gene expression was measured by Taqman RT-qPCR and digital PCR. hPAEpiC-EVs were extracted from culture supernatant and characterized by flow cytometric analysis. Calcium (Ca2+) and eATP levels were quantified using commercial kits. To study intercellular communication via paracrine signaling or by EVs, we stimulated hBMVECs with hPAEpiC cell culture medium conditioned with ETH, ALD or e-cig or hPAEpiC-EVs and measured Ca2+ levels.

Results

ETH, ALD, or e-Cig (1.8% nicotine) stimulation depleted the mitochondrial spare respiration capacity in hPAEpiC. We observed increased expression of P2X7r and TRPV1 genes (3-6-fold) and increased intracellular Ca2+ accumulation (20-30-fold increase) in hPAEpiC, resulting in greater expression of endoplasmic reticulum (ER) stress markers. hPAEpiC stimulated by ETH, ALD, and e-Cig conditioned media shed more EVs with larger particle sizes, carrying higher amounts of eATP and mtDNA. ETH, ALD and e-Cig (1.8% nicotine) exposure also increased the P2X7r shedding in media and via EVs. hPAEpiC-EVs carrying P2X7r and eATP cargo triggered paracrine signaling in human brain microvascular endothelial cells (BMVECs) and increased Ca2+ levels. P2X7r inhibition by A804598 compound normalized mitochondrial spare respiration, reduced ER stress and diminished EV release, thus protecting the BBB function.

Conclusion

Abusive drugs like ETH and e-Cig promote mitochondrial and endoplasmic reticulum stress in hPAEpiC and disrupts the cell functions via P2X7 receptor signaling. EVs released by lung epithelial cells against ETH/e-cig insults, carry a cargo of secondary messengers that stimulate brain cells via paracrine signals.

ACE2/ACE imbalance mediates bisphenol A-induced lung injury in Wistar rats: Results from captopril versus losartan histo-biochemical study

Bisphenol-A (BPA) is a synthetic chemical compound broadly used in the plastic and epoxy resin industries with a considerable potential for food contamination. Literary reports have suggested that the altered renin-angiotensin system (RAS) is a mechanism for lung injury and inflammation caused by variable agents. The current study sought to investigate the contribution of RAS to BPA-induced lung damage. Moreover, the study assessed whether angiotensin II and/or bradykinin pathways were involved. For this aim, the angiotensin-converting enzyme (ACE) inhibitor captopril (Cap), either alone or combined with bradykinin receptor antagonist icatibant (Icat), was attempted versus the angiotensin receptor blocker losartan (Los). An eight-week study was conducted on forty Wistar male albino rats randomly divided into five equal groups: control, BPA, BPA/Cap, BPA/Los, and BPA/Cap/Icat groups. Captopril (100 mg/mL) and losartan (200 mg/mL) were given orally in drinking water, but icatibant (Icat) was injected subcutaneously (250 μg/kg) during the last two weeks of captopril treatment. Biochemical analysis of bronchoalveolar lavage fluid (BALF) and lung tissues, polymerase chain reaction (PCR) assay for ACE, ACE2, and caspase-3 genes expression, and histological and immunohistochemical studies were carried out to evaluate BPA-mediated pulmonary inflammation/apoptosis. BPA impaired the histological structure of the lungs, increased ACE, ACE2, and caspase-3 expressions at both gene/protein levels, and increased BALF inflammatory cytokines and lung oxidative markers. Inhibiting the ACE activity by captopril maintained the histological lung injury score, restored inflammation and the ACE2/ACE balance, and decreased apoptosis. Further improvement was obtained by the angiotensin II receptor (ATR1) blocker losartan. Icatibant (bradykinin B2 receptor blocker) didn't counteract the observed captopril effects. It was strongly suggested that RAS contributed to BPA-induced lung damage via alteration of ACE2 and ACE expression mediating angiotensin II generation rather than bradykinin.

Annexin A5 Inhibits Endothelial Inflammation Induced by Lipopolysaccharide-Activated Platelets and Microvesicles via Phosphatidylserine Binding

Sepsis is caused by a dysregulated immune response to infection and is a leading cause of mortality globally. To date, no specific therapeutics are available to treat the underlying septic response. We and others have shown that recombinant human annexin A5 (Anx5) treatment inhibits pro-inflammatory cytokine production and improves survival in rodent sepsis models. During sepsis, activated platelets release microvesicles (MVs) with externalization of phosphatidylserine to which Anx5 binds with high affinity. We hypothesized that recombinant human Anx5 blocks the pro-inflammatory response induced by activated platelets and MVs in vascular endothelial cells under septic conditions via phosphatidylserine binding. Our data show that treatment with wildtype Anx5 reduced the expression of inflammatory cytokines and adhesion molecules induced by lipopolysaccharide (LPS)-activated platelets or MVs in endothelial cells (p < 0.01), which was not observed with Anx5 mutant deficient in phosphatidylserine binding. In addition, wildtype Anx5 treatment, but not Anx5 mutant, improved trans-endothelial electrical resistance (p < 0.05) and reduced monocyte (p < 0.001) and platelet (p < 0.001) adhesion to vascular endothelial cells in septic conditions. In conclusion, recombinant human Anx5 inhibits endothelial inflammation induced by activated platelets and MVs in septic conditions via phosphatidylserine binding, which may contribute to its anti-inflammatory effects in the treatment of sepsis.

Lung injury and oxidative stress induced by inhaled chlorine in mice is associated with proinflammatory activation of macrophages and altered bioenergetics

Chlorine (Cl2) gas is a highly toxic and oxidizing irritant that causes life-threatening lung injuries. Herein, we investigated the impact of Cl2-induced injury and oxidative stress on lung macrophage phenotype and function. Spontaneously breathing male C57BL/6J mice were exposed to air or Cl2 (300 ppm, 25 min) in a whole-body exposure chamber. Bronchoalveolar lavage (BAL) fluid and cells, and lung tissue were collected 24 h later and analyzed for markers of injury, oxidative stress and macrophage activation. Exposure of mice to Cl2 resulted in increases in numbers of BAL cells and levels of IgM, total protein, and fibrinogen, indicating alveolar epithelial barrier dysfunction and inflammation. BAL levels of inflammatory proteins including surfactant protein (SP)-D, soluble receptor for glycation end product (sRAGE) and matrix metalloproteinase (MMP)-9 were also increased. Cl2 inhalation resulted in upregulation of phospho-histone H2A.X, a marker of double-strand DNA breaks in the bronchiolar epithelium and alveolar cells; oxidative stress proteins, heme oxygenase (HO)-1 and catalase were also upregulated. Flow cytometric analysis of BAL cells revealed increases in proinflammatory macrophages following Cl2 exposure, whereas numbers of resident and antiinflammatory macrophages were not altered. This was associated with increases in numbers of macrophages expressing cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS), markers of proinflammatory activation, with no effect on mannose receptor (MR) or Ym-1 expression, markers of antiinflammatory activation. Metabolic analysis of lung cells showed increases in glycolytic activity following Cl2 exposure in line with proinflammatory macrophage activation. Mechanistic understanding of Cl2-induced injury will be useful in the identification of efficacious countermeasures for mitigating morbidity and mortality of this highly toxic gas.

Short-term air pollution and temperature exposure and changes in the extracellular microRNA profile of Normative Aging Study (NAS) participants

BACKGROUND

While the health effects of air pollution and temperature are widely studied, the molecular effects are poorly understood. Extracellular microRNAs (ex-miRNAs) have the potential to serve as diagnostic or prognostic biomarkers and/or to act as intercellular signaling molecules that mediate the effects of environmental exposures on health outcomes.

METHODS

We examined the relationship between short-term exposure to air pollution and ambient temperature and the ex-miRNA profiles of participants in the Normative Aging Study (NAS) from 1999 to 2015. Our exposures were defined as same-day, two-day, three-day, one-week, two-week, and three-week moving averages of PM2.5, NO2, O3, and temperature which were derived from high-resolution spatio-temporal models. The ex-miRNA profiles of the subjects were obtained during follow-up visits. We analyzed the data using a longitudinal quantile regression model adjusted for individual covariates, batch effects, and time trends. We adjusted for multiple comparisons using a false discovery rate (FDR) correction. Ex-miRNAs that were significantly associated with exposures were further investigated using pathway analyses.

RESULTS

We found that all the examined exposures were associated with changes in ex-miRNA profiles in our study, particularly PM2.5 which was responsible for most of the statistically significant results. We found 110 statistically significant exposure-outcome relationships that revealed associations with the levels of 52 unique ex-miRNAs. Pathway analyses showed these ex-miRNAs have been linked to target mRNAs, genes, and biological mechanisms that could affect virtually every organ system, and as such may be linked to multiple clinical disease presentations such as cardiovascular disease, respiratory disease, and neurological disease.

CONCLUSIONS

Air pollution and temperature exposures were significantly associated with alterations in the ex-miRNA profiles of NAS subjects with possible biological consequences.

Inflammation resolution in environmental pulmonary health and morbidity

Inflammation and resolution are dynamic processes comprised of inflammatory activation and neutrophil influx, followed by mediator catabolism and efferocytosis. These critical pathways ensure a return to homeostasis and promote repair. Over the past decade research has shown that diverse mediators play a role in the active process of resolution. Specialized pro-resolving mediators (SPMs), biosynthesized from fatty acids, are released during inflammation to facilitate resolution and are deficient in a variety of lung disorders. Failed resolution results in remodeling and cellular deposition through pro-fibrotic myofibroblast expansion that irreversibly narrows the airways and worsens lung function. Recent studies indicate environmental exposures may perturb and deregulate critical resolution pathways. Environmental xenobiotics induce lung inflammation and generate reactive metabolites that promote oxidative stress, injuring the respiratory mucosa and impairing gas-exchange. This warrants recognition of xenobiotic associated molecular patterns (XAMPs) as new signals in the field of inflammation biology, as many environmental chemicals generate free radicals capable of initiating the inflammatory response. Recent studies suggest that unresolved, persistent inflammation impacts both resolution pathways and endogenous regulatory mediators, compromising lung function, which over time can progress to chronic lung disease. Chronic ozone (O3) exposure overwhelms successful resolution, and in susceptible individuals promotes asthma onset. The industrial contaminant cadmium (Cd) bioaccumulates in the lung to impair resolution, and recurrent inflammation can result in chronic obstructive pulmonary disease (COPD). Persistent particulate matter (PM) exposure increases systemic cardiopulmonary inflammation, which reduces lung function and can exacerbate asthma, COPD, and idiopathic pulmonary fibrosis (IPF). While recurrent inflammation underlies environmentally induced pulmonary morbidity and may drive the disease process, our understanding of inflammation resolution in this context is limited. This review aims to explore inflammation resolution biology and its role in chronic environmental lung disease(s).

Microvesicle-Derived miRNAs Regulate Proinflammatory Macrophage Activation in the Lung Following Ozone Exposure

Ozone is a ubiquitous air pollutant that causes lung damage and altered functioning. Evidence suggests that proinflammatory macrophages contribute to ozone toxicity. Herein, we analyzed the role of extracellular vesicles (EVs) and microRNA (miRNA) cargo in ozone-induced macrophage activation. Exposure of mice to ozone (0.8 ppm, 3 h) resulted in increases in bronchoalveolar lavage fluid EVs, which were comprised predominantly of microvesicles (MVs). NanoFACS analysis revealed that MVs generated following both air and ozone exposure was largely from CD45+ myeloid cells; these MVs were readily taken up by macrophages. Functionally, MVs from ozone, but not air treated mice, upregulated mRNA expression of inflammatory proteins in macrophages including inducible nitric oxide synthase (iNOS), CXCL-1, CXCL-2, and interleukin (IL)-1β. The miRNA profile of MVs in bronchoalveolar lavage fluid (BALF) was altered after ozone exposure; thus, increases in miR-21, miR-145, miR320a, miR-155, let-7b, miR744, miR181, miR-17, miR-92a, and miR-199a-3p were observed, whereas miR-24-3p and miR-20 were reduced. Ingenuity pathway analysis revealed that these miRNAs regulate pathways that promote inflammatory macrophage activation, and predicted that let-7a-5p/let-7b, miR-24-3p, miR-21-5p, miR-17, and miR-181a-5p are key upstream regulators of inflammatory proteins. After ozone exposure, miR-199a-3p, but not precursor miR-199a-3p, was increased in lung macrophages, indicating that it is derived from MV-mediated delivery. Furthermore, lung macrophage mRNA expression of IL-1β was upregulated after administration of MVs containing miR-199a-3p mimic but downregulated by miR-199a-3p inhibitor. Collectively, these data suggest that MVs generated following ozone exposure contribute to proinflammatory macrophage activation via MV-derived miRNAs including miR-199a-3p. These findings identify a novel pathway regulating macrophage inflammatory responses to inhaled ozone.

Interleukin-9 attenuates inflammatory response and hepatocyte apoptosis in alcoholic liver injury

Alcoholic liver injury is a liver cell dysfunction disease caused by long-term or excessive alcohol consumption. Inhibiting the production of inflammatory factors is an important way to alleviate liver injury. Interleukin-9 (IL-9) is one of the members of IL-2Rγc family. It has multiple biological functions. Previous studies have shown that IL-9 is a cytokine that is closely related to inflammatory disease, allergic diseases, autoimmune diseases, and parasitic infections. However, no systematic studies have been performed to address the role of IL-9 in ALI. This project aims to investigate the effects of IL-9 on macrophage-related inflammatory response and hepatocyte apoptosis in alcohol-induced liver injury by injecting adeno-associated virus (AAV9) into tail vein. In the ALI model group, western blot and ELISA assays demonstrated that the expression of IL-9 was reduced. Overexpression of IL-9 relieved the injury and reduced the serum levels of IL-6, TNF-α in EtOH-induced ALI mouse model. Moreover, by using western blot, it was indicated that IL-9 can inhibit the expression of pro-apoptotic protein, such as cleaved caspase 3 and Bax. In vitro, mouse recombinant protein IL-9 inhibited the expression of IL-6, TNF-α in EtOH-induced RAW264.7 cells. Moreover, flow cytometry and western blot results displayed that macrophage-derived IL-9 inhibited hepatocyte apoptosis. After silencing STAT3 in AML-12 cells, the anti-apoptotic effect of macrophage-derived IL-9 was further enhanced. These results indicate that IL-9 reduces the production of pro-inflammatory factors in ALI. Furthermore, macrophage-derived IL-9 can reduce hepatocyte apoptosis by inhibiting the activation of the STAT3 pathway.

Vesicular and extravesicular protein analyses from the airspaces of ozone-exposed mice revealed signatures associated with mucoinflammatory lung disease

Lung epithelial lining fluid (ELF) harbors a variety of proteins that influence homeostatic and stress responses in the airspaces. Exosomes, nano-sized extracellular vesicles, contain many proteins that vary in abundance and composition based on the prevailing conditions. Ozone causes inflammatory responses in the airspaces of experimental animals and humans. However, the exosomal protein signatures contained within the ELF from ozone-exposed lung airspaces remain poorly characterized. To explore this, we hypothesized that ozone triggers the release of exosome-bound inflammatory proteins from various cells that reflect mucoobstructive lung disease. Accordingly, we repetitively exposed adult male and female C57BL/6 mice to HEPA-filtered air (air) or 0.8 ppm ozone (4 h per day) for 14 days (five consecutive days of exposure, 2 days of rest, five consecutive days of exposure, 2 days of rest, four consecutive days of exposure). Exosome-bound proteomic signatures, as well as the levels of soluble inflammatory mediators in the bronchoalveolar lavage fluid (BALF), were determined 12-16 h after the last exposure. Principal component analyses of the exosome-bound proteome revealed a clear distinction between air-exposed and ozone-exposed mice, as well as between ozone-exposed males and ozone-exposed females. In addition to 575 proteins that were enriched in both sexes upon ozone exposure, 243 and 326 proteins were enriched uniquely in ozone-exposed males and females, respectively. Ingenuity pathway analyses on enriched proteins between ozone- and air-exposed mice revealed enrichment of pro-inflammatory pathways. More specifically, macrophage activation-related proteins were enriched in exosomes from ozone-exposed mice. Cytokine analyses on the BALF revealed elevated levels of G-CSF, KC, IP-10, IL-6, and IL-5 in ozone-exposed mice. Finally, the histopathological assessment revealed significantly enhanced intracellular localization of mucoinflammatory proteins including MUC5B and FIZZ1 in ozone-exposed mice in a cell-specific manner indicating the cellular sources of the proteins that are ferried in the exosomes upon ozone-induced lung injury. Collectively, this study identified exosomal, secretory, and cell-specific proteins and biological pathways following repetitive exposure of mice to ozone.

Impact of the Main Cardiovascular Risk Factors on Plasma Extracellular Vesicles and Their Influence on the Heart's Vulnerability to Ischemia-Reperfusion Injury

The majority of cardiovascular deaths are associated with acute coronary syndrome, especially ST-elevation myocardial infarction. Therapeutic reperfusion alone can contribute up to 40 percent of total infarct size following coronary artery occlusion, which is called ischemia-reperfusion injury (IRI). Its size depends on many factors, including the main risk factors of cardiovascular mortality, such as age, sex, systolic blood pressure, smoking, and total cholesterol level as well as obesity, diabetes, and physical effort. Extracellular vesicles (EVs) are membrane-coated particles released by every type of cell, which can carry content that affects the functioning of other tissues. Their role is essential in the communication between healthy and dysfunctional cells. In this article, data on the variability of the content of EVs in patients with the most prevalent cardiovascular risk factors is presented, and their influence on IRI is discussed.

Ozone-induced changes in the murine lung extracellular vesicle small RNA landscape

Inhalation exposure to ozone (O3 ) causes adverse respiratory health effects that result from airway inflammation, a complex response mediated in part by changes to airway cellular transcriptional programs. These programs may be regulated by microRNAs transferred between cells (e.g., epithelial cells and macrophages) via extracellular vesicles (EV miRNA). To explore this, we exposed female C57BL/6J mice to filtered air (FA), 1, or 2 ppm O3 by inhalation and collected bronchoalveolar lavage fluid (BALF) 21 h later for markers of airway inflammation, EVs, and EV miRNA. Both concentrations of O3  significantly increased markers of inflammation (neutrophils), injury (total protein), and the number of EV-sized particles in the BALF. Imagestream analysis indicated a substantial portion of particles was positive for canonical EV markers (CD81, CD51), and Siglec-F, a marker of alveolar macrophages. Using high-throughput small RNA sequencing, we identified several differentially expressed (DE) BALF EV miRNAs after 1 ppm (16 DE miRNAs) and 2 ppm (99 DE miRNAs) O3 versus FA exposure. O3 concentration-response patterns in EV miRNA expression were apparent, particularly for miR-2137, miR-126-3p, and miR-351-5p. Integrative analysis of EV miRNA expression and airway cellular mRNA expression identified EV miR-22-3p as a candidate regulator of transcriptomic responses to O3 in airway macrophages. In contrast, we did not identify candidate miRNA regulators of mRNA expression data from conducting airways (predominantly composed of epithelial cells). In summary, our data show that O3 exposure alters EV release and EV miRNA expression, suggesting that further investigation of EVs may provide insight into their effects on airway macrophage function and other mechanisms of O3 -induced respiratory inflammation.

Regulation of Lung Macrophage Activation and Oxidative Stress Following Ozone Exposure by Farnesoid X Receptor

Inflammatory macrophages are known to contribute to ozone toxicity. Farnesoid X receptor (FXR) is a nuclear receptor involved in regulating bile acid and lipid homeostasis; it also exerts anti-inflammatory activity by suppressing macrophage NF-κB. Herein, we analyzed the role of FXR in regulating macrophage activation in the lung following ozone exposure. Treatment of wild-type (WT) mice with ozone (0.8 ppm, 3 h) resulted in increases in proinflammatory (F4/80+CD11c+CD11b+Ly6CHi) and anti-inflammatory (F4/80+CD11c+CD11b+Ly6CLo) macrophages in the lung. The accumulation of proinflammatory macrophages was increased in FXR-/- mice compared with WT mice; however, anti-inflammatory macrophage activation was blunted as reflected by reduced arginase and mannose receptor expression, a response correlated with decreased Nur77. This was associated with prolonged oxidative stress, as measured by 4-hydroxynonenal-modified proteins in the lung. Loss of FXR was accompanied by protracted increases in lung NF-κB activity and its target, inducible nitric oxide synthase in response to ozone. Levels of Tnf-α, Il-1β, Ccr2, Ccl2, Cx3cr1, and Cx3cl1 were also increased in lungs of FXR-/- relative to WT mice; conversely, genes regulating lipid homeostasis including Lxrα, Apoe, Vldlr, Abcg1, and Abca1 were downregulated, irrespective of ozone exposure. In FXR-/- mice, ozone caused an increase in total lung phospholipids, with no effect on SP-B or SP-D. Dyslipidemia was correlated with blunting of ozone-induced increases in positive end-expiratory pressure-dependent quasi-static pressure volume curves indicating a stiffer lung in FXR-/- mice. These findings identify FXR as a regulator of macrophage activation following ozone exposure suggesting that FXR ligands may be useful in mitigating inflammation and oxidative stress induced by pulmonary irritants.

Emerging Cell-Based Therapies in Chronic Lung Diseases: What About Asthma?

Asthma is a widespread disease characterized by chronic airway inflammation. It causes substantial disability, impaired quality of life, and avoidable deaths around the world. The main treatment for asthmatic patients is the administration of corticosteroids, which improves the quality of life; however, prolonged use of corticosteroids interferes with extracellular matrix elements. Therefore, cell-based therapies are emerging as a novel therapeutic contribution to tissue regeneration for lung diseases. This study aimed to summarize the advancements in cell therapy involving mesenchymal stromal cells, extracellular vesicles, and immune cells such as T-cells in asthma. Our findings provide evidence that the use of mesenchymal stem cells, their derivatives, and immune cells such as T-cells are an initial milestone to understand how emergent cell-based therapies are effective to face the challenges in the development, progression, and management of asthma, thus improving the quality of life.

Role of extracellular vesicles in chronic lung disease

To explore the role of extracellular vesicles (EVs) in chronic lung diseases.

EVs are emerging as mediators of intercellular communication and possible diagnostic markers of disease. EVs harbour cargo molecules including RNA, lipids and proteins that they transfer to recipient cells. EVs are intercellular communicators within the lung microenvironment. Due to their disease-specific cargoes, EVs have the promise to be all-in-one complex multimodal biomarkers. EVs also have potential as drug carriers in chronic lung disease.

Descriptive discussion of key studies of EVs as contributors to disease pathology, as biomarkers and as potential therapies with a focus on chronic obstructive pulmonary disorder (COPD), cystic fibrosis (CF), asthma, idiopathic pulmonary fibrosis and lung cancer.

We provide a broad overview of the roles of EV in chronic respiratory disease. Recent advances in profiling EVs have shown their potential as biomarker candidates. Further studies have provided insight into their disease pathology, particularly in inflammatory processes across a spectrum of lung diseases. EVs are on the horizon as new modes of drug delivery and as therapies themselves in cell-based therapeutics.

EVs are relatively untapped sources of information in the clinic that can help further detail the full translational nature of chronic lung disorders.

Extracellular Vesicles from Airway Secretions: New Insights in Lung Diseases

Lung diseases (LD) are one of the most common causes of death worldwide. Although it is known that chronic airway inflammation and excessive tissue repair are processes associated with LD such as asthma, chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibrosis (IPF), their specific pathways remain unclear. Extracellular vesicles (EVs) are heterogeneous nanoscale membrane vesicles with an important role in cell-to-cell communication. EVs are present in general biofluids as plasma or urine but also in secretions of the airway as bronchoalveolar lavage fluid (BALF), induced sputum (IS), nasal lavage (NL) or pharyngeal lavage. Alterations of airway EV cargo could be crucial for understanding LD. Airway EVs have shown a role in the pathogenesis of some LD such as eosinophil increase in asthma, the promotion of lung cancer in vitro models in COPD and as biomarkers to distinguishing IPF in patients with diffuse lung diseases. In addition, they also have a promising future as therapeutics for LD. In this review, we focus on the importance of airway secretions in LD, the pivotal role of EVs from those secretions on their pathophysiology and their potential for biomarker discovery.