- Open Access
Emerging role of exosomes in the pathology of chronic obstructive pulmonary diseases; destructive and therapeutic properties
Stem Cell Research & Therapy volume 13, Article number: 144 (2022)
Chronic obstructive pulmonary disease (COPD) is known as the third leading cause of human death globally. Enhanced chronic inflammation and pathological remodeling are the main consequences of COPD, leading to decreased life span. Histological and molecular investigations revealed that prominent immune cell infiltration and release of several cytokines contribute to progressive chronic remodeling. Recent investigations have revealed that exosomes belonging to extracellular vesicles are involved in the pathogenesis of COPD. It has been elucidated that exosomes secreted from immune cells are eligible to carry numerous pro-inflammatory factors exacerbating the pathological conditions. Here, in this review article, we have summarized various and reliable information about the negative role of immune cell-derived exosomes in the remodeling of pulmonary tissue and airways destruction in COPD patients.
COPD is a chronic inflammatory condition with progressive bronchopneumonitis, leading to difficulty breathing and limitation of daily tasks . Recent works established the importance and critical role of innate and adaptive immune systems in the pathology of COPD . Prolonged inflammatory response accounts for excessive mucus production, generation of emphysematous foci, obstruction/narrowing of airways, and remodeling of the extracellular matrix (ECM) within the lung parenchyma . The innate immune system response is stimulated in COPD patients coincides with the expression of cytokines such as interleukin-8 (IL-8), matrix metalloproteinase protein-9 (MMP-9), and neutrophil elastase (NE) in certain micro-anatomical regions of pulmonary parenchyma and intra-alveolar septum. These features may associate with reduced airflow capacity and gas exchange between blood and respiratory system . Regardless of the presence of different subsets of immune cells in the COPD pulmonary niche, it is believed that the release of degrading enzymes and inflammatory mediators can regulate the bioactivity of other cells in close or remote sites . Previous works have provided evidence of exosomal cytokines and modulatory effects under pathological conditions . For example, several cytokines have been indicated inside the lumen of Exo released from inflammatory cells, progenitors, and certain stem cell types. Unlike several types of immune cells, mesenchymal stem cells (MSCs) can produce extracellular vesicles (EVs) with a large content of anti-inflammatory cytokines compared to the other cell lineages .
Exo are known as nano-sized communication vehicles, playing an interesting role in the paracrine activity of almost all cells under physiological and pathological conditions [8, 9]. Exo can cross all-natural barriers within the body and transfer their cargo to remote sites . Their communicative facilities and components such as microRNAs (miRNAs) make key players in the dynamic activity of cells under pathological conditions [10, 11]. Besides, the critical role of Exo inside the body, using them directly or as a delivery agent is an undeniable part of almost the majority of experimental and clinical studies [12,13,14]. As expected, immune cells like other cells can actively secret Exo for reciprocal communication . Exo exchange between the immune cells can be assessed from two distinct aspects. Whether and how these Exo can exacerbate the inflammation and remodeling process or trained immune cell Exo may contain certain growth factors that accelerate the regeneration of injured pulmonary microenvironment is the subject of area. It seems that the cellular source and cargo type is determinant in Exo activity under pathological conditions. For instance, under pathological conditions such as sepsis macrophages can release Exo with the ability to increase the expression of intercellular adhesion molecule-1 (ICAM-1) in alveolar epithelial cells and trafficking of immune cells from the blood side into the pulmonary niche, leading to subsequent tissue damage and deleterious outcomes [16, 17]. Unlike these effects, inflamed monocyte-derived Exo contain mitochondrial-associated DAMPs which can diminish neutrophil infiltration into injured sire via the suppression of Toll-like receptor-9 (TLR-9) . It can be hypothesized immune cell Exo possess pleiotropic properties related to pathological state and intensity of inflammation . In this review article, we collected comprehensive information about the role of immune- and stem cell-derived Exo on the pathology of COPD disease.
EVs are distributed in different biofluids and are involved in paracrine cross talk between the cells in higher organisms . Generally, the term EVs include a heterogeneous population of vesicles shed by the majority of cell types and can be detected in biofluids. Based on ultrastructural analyses, EVs are classified into different subsets based on size, mechanism of biogenesis, density, function, and origins . EVs include Exo, microvesicles, and apoptotic bodies . Unlike Exo, microvesicles, and apoptotic bodies are directly generated via the protrusion plasma membrane, and their sizes are ranged between 500 to 2000 nm . Among all subtypes of EVs, Exo, with a mean diameter of 40 to 160 nm, are classified as the smallest vesicles with an endosomal origin . In physiological and pathological conditions, several factors such as proteins, nucleic acids (including mRNA and miRNA), viral genetic materials, and lipids are sorted into the Exo lumen, harbored in biofluids, and transferred to the nearby acceptor cells or distant sites .
Exo appear relatively spherical and are enclosed by the lipid bilayer membrane, making them stable bioshuttles . One reason would be that distinct factors such as tetraspanins (CD9, 63, 81, and 82), microvesicular bodies (MVB) biogenesis-associated proteins [ALG-2 interacting protein X (Alix)], tumor susceptibility gene 101 (TSG101), clathrin), tumor necrosis factor receptor-1 (TNFR-1), flotillin, docking, and membrane fusion proteins [RABs, adenosine diphosphate ribosylation factor (ARF)], and heat shock proteins [HSPs (Hsp90, Hsp70, and Hsp60)] are tightly attached to Exo membrane during biogenesis . Besides proteins, several lipid elements such as sphingomyelin, cholesterol, ganglioside GM3, and ceramides are distributed in the Exo membrane. The amount of Exo membrane lipids and protein can be different in terms of cell origin and physiological and pathological conditions . In collaboration with ESCRT machinery, lipids can participate in cargo sorting, Exo secretion, and induction of specified signaling pathways in acceptor cells [26, 29]. Nucleic acids such as mRNA, microRNA (miRNA), non-coding RNA, and DNA are other important elements sorted into Exo lumen [26, 29]. In the cytosol, Exo are formed inside MVBs and an endosomal compartment with the collaboration of several machinery systems (Fig. 1) [26, 29]. In a very simple language, the Exo biogenesis consists of MVB formation, intraluminal budding, and cargo sorting. The invagination of cell membrane leads to the generation of early endosomes and further morphological changes lead to inward budding at the vesicle membrane and the formation of late endosomes and MVBs, respectively . Numerous intraluminal vesicles (ILVs), Exo ancestors, are seen inside the MVBs. In the next step, MVBs can fuse with lysosomes or follow the endocytic/exocytic pathway where the membrane of MVBs coalesce with the plasma membrane and protrude the ILVs into the ECM hereafter referred to as Exo . It was suggested that Exo biogenesis happens via two distinct pathways including endosomal sorting complex transport (ESCRT) required for transport (ESCRT)-dependent and -independent mechanisms . The ESCRT system is composed of four different proteins ESCRT-0, -1, -2, and -3 . These proteins are in close contact with other factors like vascular protein sorting associated protein-4 (VPS4), vesicle trafficking 1 protein (VTA1), and ALIX to promote MVBs. Of note, ESCRT-0 and -1 belonging to the ESCRT system possess ubiquitin domains with the ability to recognize ubiquitinated protein and sort into the ILVs lumen . Following cargo sorting, ESCRT-2 and -3 are recalled accelerating intraluminal budding via enzymatic de-ubiquitination of cytosolic proteins which leads to MVBs formation. The activation of the latter protein (ESCRT-3) is also associated with the recycling of the ESCRT system . Suppression of the ESCRT complex does not completely inhibit the Exo biogenesis which is the main reason for the existence of the ESCRT-independent system. Interestingly, in the absence of ESCRT-0, -1, -2, and -3, the process of intraluminal budding continues, indicating an alternative pathway involved in Exo biogenesis . In the ESCRT-independent pathway, the vesicle formation is orchestrated by the regulation of lipid and cargo domains via engaging HSPs, tetraspanins and lipids . Along with these mechanisms, a recently introduced pathway so-called lipid raft participates in Exo biogenesis inside the cells . In this pathway, changes are initiated in the lipid composition of the endosomal compartment, leading to lipid clustering, known as lipid rafts, allowing vesicle formation and intraluminal budding. It is thought that both flotillins and tetraspanins are involve in this mechanism . The Exo secretion in this pathway is not affected by the downregulation of ESCRT components such as hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs), Alix, or Tsg101 proteins, proving that this pathway is not associated with the ESCRT-dependent pathway .
Once MVBs are formed, they harbor Exo in their membranes. To be specific, Exo have two distinct directions. They could either be degraded by the lysosomes or fused with plasma membrane resulting in the release of Exo into the ECM. If the MVB is targeted for lysosomal degradation, it will fuse with the lysosome and result in the release of the internal Exo and the macromolecules contained within them, into the lumen of the lysosome. These components will later be exposed to the hydrolytic enzymes and be degraded . As a second fate, the MVBs will move to the plasma membrane and release their ILVs to the extracellular environment. There is molecular machinery involved in the transportation of MVBs to the cell periphery and fusion with the plasma membrane. This molecular machinery mediates the secretion of Exo .
Some studies proved that pathways for the secretion of Exo are mediated by Rab GTPases [37, 38]. Even though the mechanism has not been fully understood yet, it has been shown that a GTPase, RAL-1, mediates the fusion of the MVB membrane with the plasma membrane of the cell which results in the release of the Exo into the extracellular space . It has also been shown in another study that some of the Rab family components such as Rab27A and Rab27B are the crucial mediators of Exo release. This process happens by inducing MVBs transfer to the cell periphery and finally ends with their fusion with the plasma membrane . Soluble N-ethylmaleimide-sensitive factor attachment proteins receptor (SNARE) proteins are also thought to have a role in the fusion of vesicles with the plasma membrane . Other molecular regulators, such as Rab11, Rab35, and cortactin, have been implicated in different steps of Exo release from different cells [38, 41,42,43]. Other than these regulators, Ca2+ levels within the cells are directly proportional to the release of Exo . It has also been seen that low pH in the microenvironment affects the release of Exo and also their uptake too .
As mentioned above, Exo contain several signaling biomolecules and can affect target signaling pathways inside the acceptor cells. Exo can exploit several mechanisms for internalization. In short, this procedure includes the mutual interaction of exosomal ligands with cell surface receptors, membrane fusion, and endocytosis . To this end, several mechanisms consisted of macropinocytosis, clathrin-, caveolin-, and lipid raft-mediated endocytosis . It was suggested that the membrane distribution of specific factors such as CD9, CD81, ICAM-1, heparan sulfate proteoglycans, annexins, and integrins can affect the internalization rate of Exo [48,49,50]. Upon Exo uptake, these elements are internalized into early endosomes and most of the early and late endosomes are directed to fusion with lysosomes. It is thought that the degradation metabolites are then released into the cytosol and affect several signaling cascades .
COPD and immune system reaction
From a clinical perspective, COPD is commonly diagnosed with progressive dyspnea, cough, and sputum production . COPD is responsible for the third leading cause of human mortality globally mainly in low-income and middle-income countries . It is estimated that the number of COPD deaths to increase with the aging human population shortly, while the exposure of individuals to risk factors and allergens can speed up casualties . The occurrence of chronic inflammatory response and relatively irreversible changes in airway conduits, known as bronchopneumonia, bronchitis/bronchiolitis, coincided emphysema limits airflow . As a correlate, treatments have been mainly focused on the modulation of immune responses . Importantly, airway conduits with an internal diameter less than 2 mm are touted to be major sites for obstruction following progressive COPD . The increase in airway wall thickness due to epithelial metaplasia, bronchial mucocele, hypertrophy of surrounding smooth muscle cells, and the recruitment of immune cells are common pathological findings during COPD . The activation of both innate and adaptive immunity has been documented following COPD and progressive inflammation . Evidence points to the local infiltration of CD8+ lymphocytes in air ducts . There is a close association between pulmonary CD8+ lymphocytes and the severity of COPD . As mentioned above, exposure to irritants, such as smoking, and air pollutants can intensify pathological remodeling and COPD symptoms [59, 60]. Following the exposure to irritants and allergens, the coordination of the oxidant/antioxidant system is interrupted, leading to oxidative and nitrosative stress, leading to activation of certain factors such as NF-κB and AP-1 [61,62,63]. The apparent accumulation of free radicals predisposes the host cells to injury via triggering apoptotic changes . Several lines of documents have shown both endothelial cells (ECs) and alveolar epithelial cells displayed apoptotic changes, indicated with enhanced P53 and Caspase activity, after the onset of COPD [65, 66]. Histological examinations have indicated that pulmonary ECM like basement membranes and the interstitial matrix is degraded, leading to the lack of suitable elasticity and mechanical stability . The progressive turnover in the ECM components supports prominent structural modifications and pathological remodeling . Along with these changes, induction of proteolytic activity and insufficient α1-antitrypsin level can result in the demolition of lung parenchyma and emphysematous appearance [69, 70]. It is confirmed that infiltration of immune cells or activation of local inflammatory cells such as dust cells (alveolar macrophages) and neutrophils is associated with notable proteolytic enzymes like MMP-12, MMP-2, MMP-9, elastase, cathepsin L, and neutrophil-derived protease 3 involved in pathological remodeling (Fig. 2) . In normal lungs, neutrophils are dominant inflammatory cells while the onset of chronic inflammation indicated with the elevation of pulmonary lymphocytes and macrophages that likely leads to emphysema [72, 73]. In the support of this claim, lung macrophages CD8+ lymphocytes are dominant inflammatory cells in the proximity of emphysematous foci . Likewise, several cytokines and chemokines such as tumor necrosis factor-α (TNF-α), IL-1β, IL-6, granulocyte macrophage colony-stimulating matrix (GM-CSF), and IL-8 were actively released to the inflammatory niche . The prolonged inflammatory condition results in local fibrosis by the over-production and release of tumor growth factor-β (TGF-β) from small airway epithelial cells . It is important to remember that macrophages have a critical role in the development of COPD. Using ultrastructural studies, a marked increase in the number of macrophages has been indicated in pulmonary parenchyma, bronchoalveolar lavage fluid (BALF), and sputum of COPD patients [77, 78]. In addition to the proliferation of local macrophages, a large number of pulmonary macrophages are associated with enhanced monocyte recruitment to the inflamed microenvironment . The apparent increase in local macrophage number is proportional to the severity of COPD. Frustrated macrophages are potent enough to release TNF-α, leukotriene B4 (LTB-4), monocyte chemoattractant protein-1 (MCP-1), reactive oxygen species, elastase, and IL-8 [80,81,82]. By contrast, most subsets of MMPs are released by neutrophils. Except in airway or lung parenchyma, the number of activated neutrophils is increased in sputum, bronchoalveolar lavage fluid, and airway smooth muscles of COPD patients. It would correlate with rapid transition through these tissues . The expression of adhesion molecules like E-selectin on the endothelial layer can increase the intra-pulmonary entrance of blood neutrophils in COPD patients . Concurrently, the concentration gradients of factors such as IL-8, LTB-4, and chemokines (C-X-C motif chemokine ligand (CXCL1) and CXCL8), and C-X-C motif chemokine 5 (ENA-78 or CXCL5) released by macrophages, T lymphocytes, and epithelial cells are involved in neutrophils chemotaxis . Continuous release of IL-8, granulocyte colony stimulating factor (G-CSF), and GM-CSF can increase neutrophil's survival rate inside inflamed niches .
Pathological changes following COPD
Prolonged pulmonary diseases mainly COPD are indicated with several abnormalities ranging from irreversible widespread pathological conditions in airway conduits and lung parenchyma to the alteration of broncho-pulmonary function . The continuity of chronic conditions allows ciliary dysfunction, the proliferation of goblet cells, and mucous secretion . Due to the airflow obstruction or narrowing, both emphysematous (excessive alveolar dilation) and atelectatic foci are detectable in gross and microscopic examinations . The increased recruitment of immune cells, neutrophils, eosinophils, and further activation of alveolar macrophages coincides with the release of MMPs and lung destruction and ECM remodeling . Within the lung parenchyma, the exposure of furnishing epithelial cells to pro-inflammatory cytokines leads to mitochondrial dysfunction and squamous metaplasia (Fig. 3) . Recent works have established the lack of normal mitochondrial function, incomplete oxidative phosphorylation, leading to intracellular accumulation of ROS in COPD patients . As a consequence, the initiation of the mitochondrial damage-associated molecular pattern (DAMPs) triggers inflammation and apoptotic changes in epithelial cells. These pathological findings are consistent with the promotion of autophagic response via mitochondrial injury which is so-called mitophagy. Ultrastructural imaging reveals the disintegration of mitochondrial membranes and localization of injured mitochondria in the periphery of the nucleus [91, 92]. These features support excessive ROS production and DNA injury. Commensurate with these descriptions, one could hypothesize that autophagic response, induced by mitophagy, can contribute to epithelial cell loss and subsequent pathologies such as apoptosis and necroptosis [93, 94]. The loss of cilia would closely relate to mitochondrial dysfunction properties as the motility of these nano-sized structures is dependent on the energy supply provided by mitochondria. The reduction of mucociliary clearance per se triggers goblet cell hyperplasia . The increase of ROS was concurrent with the activation of the Akt/mTOR/sirtulin-1 axis. Sirtuin1 (SIRT-1) is a histone deacetylase linked to oxidative stress, inflammation, and cellular senescence in COPD [96, 97]. Given the highly intricate nature of COPD, the ECM network within the lung parenchyma is likely to change in COPD patients, leading to the alteration of blood-pulmonary barrier integrity. Likewise, activation of Rho-associated protein kinase and reduction of E-cadherin can lose cell-to-cell connection . In the pulmonary system, ECM is the main component of basal membrane (type IV collagen and laminin) and lamina propria, and alveolar interstitium (collagens, fibronectin, elastin, and fibronectin) [99, 100]. It is thought that fibroblasts and myofibroblasts are the main ECM producers inside the pulmonary niche . Reconstruction of ECM is tightly regulated by the activity of MMPs and tissue inhibitors of metalloproteinase (TIMPs) . Excessive production of MMP-2, -9, and -12 increases elastin degradation and emphysema formation . Histological examinations have shown less elastic fiber content in the lungs of COPD patients compared to normal tissues. . In response to the reduction of elastin fibers, enhanced gene expression of elastin and fibulin-5 is normal in COPD cases . The reduction of elastin is compensated with the production and deposition of type I collagen in COPD . Excessive collagen leads to the loss of elasticity in alveolar structure and airway collapsibility .
Role of Exo on the progression of COPD
The release of Exo by immune cells is done to maintain cell-to-cell communication while these bio-carriers can also spread the effectors associated with pathological conditions. To be specific, tissue progenitor/stem cells exit from quiescence, migrate and differentiate into the mature cell type in response to Exo released from immune cells and injured cells with pro-inflammatory response . It has been shown that various types of progenitor cells can be detected within pulmonary in terms of micro-anatomical sites, specific biomarkers, and activities (Table 1). Lung progenitor cells are quiescent during the physiological condition. Shortly after the occurrence of pathological circumstances, these cells proliferate and subsequently differentiate into mature cells . Among these progenitor cells, tracheal basal cells commonly express cytokeratins such as cytokeratin-14 and -5 as well as P63 [109, 110]. In response to insulting conditions such as chemical irritants (sulfur dioxide and naphthalene) and injury of the pseudostratified epithelial layer, basal cells proliferate and differentiate into both ciliated and non-ciliated luminal epithelial cells . In COPD patients and cigarette smokers, an untamed proliferation of basal cells can lead to pathological hyperplasia and lack of mucociliary epithelia restoration . Type 2 alveolar pneumocytes (AT2) are other lung progenitor cells with the ability to secret surfactant proteins. Under pathological conditions like inhalation of toxic gas NO2, proliferate and differentiate into type 1 alveolar pneumocytes (AT1) . Interestingly, AT2 cells can be adversely affected by various types of respiratory disorders like idiopathic pulmonary fibrosis, leading to early cellular senescence and reduction of regenerative capacity in the pulmonary tissue . Similarly, COPD can prone AT2 cells to DNA damage with the possibility of apoptotic changes . Goblet cells are also known as secretory progenitor cells and produce mucus in collaboration with serous cells . Like AT2 cells, goblet cells function is mainly affected by inflammation, resulting in mucus overproduction. Histological examination has shown that inflammatory compositions followed by COPD dictate goblet cells hyperplasia and consequently mucus hypersecretion  (Table 2).
Whether or how inflammatory Exo or immune cell Exo can predetermine pathological remodeling and/or regeneration status need further investigations. It is also possible the molecular identity of stem/progenitor cell Exo can be different rather than that of immune cell Exo. For instance, it has been indicated that the administration of epithelial progenitor cells (EPCs) Exo in acute lung injury using lipopolysaccharide ameliorates the pathological condition. This work revealed that the regenerative effects can be associated with exosomal miRNA-126 and inhibition of sprout-related EVH1 domain-containing protein-1 (SPRED-1) via the RAF/ERK signaling axis . Within the lung parenchyma, alveolar epithelial type II cells are the source of surfactant with an inherent capacity to mature into type I alveolar epithelial cells . Besides differentiation into functional cells, type II epithelial cells secret a significant amount of Exo that can lead to the delivery of chemotactic factors recall mesenchymal stem cells (MSCs) under inflammatory conditions. Upon migration of MSCs into lung parenchyma, the intensity of inflammation is diminished via mitochondrial donation and improving bioenergetics . This indicates that the tissue stem/progenitor cell Exo mighty blunt the pro-inflammatory condition and regenerate the injured area. However, the physiological significance of this claim is the subject of debate.
It also suggests that various immune cells like neutrophils, macrophages, resident dendritic cells (DCs), and B lymphocytes can release Exo during COPD. The activity of several enzymes, hydrolases, lysozymes, proteinases, collagenase, etc., inside neutrophils, eosinophils, and basophils granules is closely related to the tissue damage and ECM remodeling [121, 122]. In line with the active secretion of granules, the critical role of polymorphonuclear cells (PMNs) Exo has been indicated in the pathogenesis of COPD. These Exo distribute neutrophil elastase, and α1-antitrypsin, into the COPD inflammatory sites where active ECM destruction occurs. In vitro investigations revealed that this enzyme digests type I collagen and elastin. Noteworthy, intratracheally injection of neutrophil Exo into the mouse airway conduits led to alveolar enlargement following the ECM remodeling . The close interaction of Exo-containing neutrophil elastase with type I collagen is associated with surface Mac-1 protein (integrin αMβ2) . In late COPD, extensive ECM destruction and pathological remodeling can be detectable. Under these conditions, the activity of specific cell lineages such as alveolar macrophages is increased as well . The secretion of cytokines by alveolar macrophages into the pulmonary niche induces bronchial epithelial cells proliferation and migration. Exo isolated from alveolar macrophages are enriched in miRNA-380 a specific genetic element that tends to regulate the target cell cycle . On basis of immunomodulatory properties of antigen-presenting cell Exo, such as B lymphocytes and DCs, it is postulated that these cells in line with the innate immune cell system participate in the COPD pathogenesis . These immunomodulatory properties highly correlate with Exo cargo and surface antigenic molecules. For example, it has been indicated that the exosomal levels of major histocompatibility complex I and II (MHC-I and II) and heat shock proteins (70 and 90) . In support of this notion, Rapaso and colleagues showed that B lymphocyte- and DC-derived Exo can activate CD4+ and CD8+ lymphocytes [128, 129]. Indeed, these Exo can harbor processed antigens to the T lymphocytes using integrins and ICAM . Of note, the Exo releasing capacity of these cells can be altered according to developmental steps. For example, it has been indicated that mature DCs possess less cytosolic MVB compared to mature DCs, showing the reduction of released Exo in mature DCs. Therefore, it is logical to postulate that Exo can promote specific cell bioactivity in the target cells depending on cargo type and intracellular origination [131, 132]. Regarding the activation of T lymphocytes after exposure to DC Exo, one reason would be that DC-derived Exo contain CD86, T cell stimulator, αMβ2, milk fat globule-epidermal growth factor 8, ICAM-1/CD45, and Ig family member protein . Besides, molecular investigations have shown that HSP70 family member heat shock cognate protein (HSC73) is a chaperon protein involved in MHC II presentation which is abundant in DC-derived Exo . Along with this protein, the content of HSP90 is also high in DC Exo, leading to immunogenicity of Exo and activation of T lymphocytes . Further analyses showed that B lymphocyte Exo harbor a large amount of ICAM-1/CD45 too, late endosomal lyso-bis-phosphatidic acid, and sphingomyelin . Importantly, it is noteworthy to mention that Exo from other cell types rather than immune cells can regulate pathological response in COPD patients. In the line with this claim, Xu et al. showed that Exo derived from human bronchial epithelial cells (BECs) can induce myofibroblasts differentiation through transporting overexpressed miRNA-21 in cigarette smoke-induced COPD . It is thought that differentiation of bronchial fibroblasts to myofibroblasts and aggregation of myofibroblasts is one of the main reasons for the narrowing of the small airways in conditions that coincided with the inflammatory response. The abundance of specific genetic elements such as miRNA-21 in BECs Exo can lead to the deterioration of connection between BECs and fibroblasts, promoting myofibroblasts differentiation and fibrosis via modifying Von Hippel Lindau/ Hypoxia-Inducible Factor-1 (VHL/HIF-1α) signaling . The increase of miRNA-21 can exacerbate COPD-related pathologies via enhanced polarization of macrophages toward M2 type and epithelial cell metaplasia via epithelial to mesenchymal transition (EMT) . It seems that BECs can release Exo with distinct cargo in response to an inflammatory condition, exacerbating the conditions. The secretion of miRNA-210 via Exo can suppress autophagic response in pulmonary fibroblasts via targeting autophagy-related protein-7 (ATG7) . As a correlate, prominent fibrosis and ECM remodeling occur, showing the critical role of autophagy in the regulation of COPD-related inflammatory response .
Taken together, the promotion of COPD can affect the production rate and exosomal cargo mainly via the alteration of the miRNA profile. Of course, the duration of disease and severity of immune responses can directly or indirectly affect exosomal content. In line with this claim, it was determined that the content of miR-122-5p was significantly reduced in bronchoalveolar fluid taken from COPD patients compared to the control group . Due to the existence of active inflammatory response and recruitment of different immune cells into a pulmonary niche, it is logical to mention that the content of inflammatory Exo are high in inflamed site compared to the systemic circulation. It was suggested that sputum and bronchoalveolar lavage fluid EVs, more importantly, Exo, are indicative of inflammatory composition during the occurrence of pulmonary pathologies . Of note, transcription of specific miRNAs can be modulated following the progression of different pathological conditions within the pulmonary niche. For instance, it has been shown that miR-145 and miR-338 contents were altered in conditions such as COPD, asthma, and asthma-COPD overlap syndrome, indicating that these miRNAs are common biomarkers for the detection of inflamed pulmonary tract . As mentioned above, it seems that the pulmonary content of these genetic elements was higher than that of blood . Whether continued inflammatory conditions can lead to balances in blood and respiratory content of specific miRNAs needs further investigation. Additionally, the specificity and sensitivity of each biomarker in response to pulmonary disease should be indicated.
Immunomodulatory effects of stem cell Exo on COPD niche
Putative therapeutic effects of stem cells and their Exo have been proved under inflammatory conditions via juxtacrine and paracrine activities . It was suggested that a part of these restorative impacts correlates with anti-inflammatory, and immunomodulatory properties of release Exo . Stem cell-derived Exo are comprehensively applicable in studies ranging from pharmacological to clinical settings (Table 3). In addition to their therapeutic effects, the application of stem cell Exo as a delivery vehicle is one of the most prominent approaches in this area . For instance, Fonseca and coworkers tried to deliver micro-bubbles to the respiratory tract via Exo. To this end, ultrasound signals were used to penetrate tissue to provide a way for Exo-containing micro-bubbles to reach the alveoli. They postulated that the combination of ultrasound signals and Exo administration can help in an emergency, such as COVID-19 patients, to decrease pulmonary injury . It is accepted that Exo can be touted as a natural carrier for the transfer of mRNA and other genetic elements under pathological conditions. Exo can be used for the delivery of mRNA-based COVID-19 vaccines and are superior in comparison with lipid nanoparticles (LNPs) based delivery .
Up to now, there are few studies related to the application of stem cell Exo in COPD patients. In a study conducted by Maremanda et al., authors applied intraperitoneally the combination of MSCs and Exo in COPD mice. Data showed that the number of recruited neutrophils, CD4+ lymphocytes, and macrophages was reduced in bronchoalveolar lavage, indicating the protective role of MSCs and Exo against COPD inflammation. One reason related to the therapeutic effects of MSCs would be due to the reduction of adiponectin, keratinocytes-derived chemokine following MSCs, and Exo administration . In another experiment, intra-tracheal administration of umbilical MSCs Exo in COPD rats suppressed inflammatory cytokines such as NF-κB and inhibition of alveolar septum thickening. These features coincided with the reduction of goblet cell hyperplasia compared to control asthmatic rats . Like these studies, the application of placental MSCs Exo in COPD mice reduced the number of infiltrating leukocytes, diminished vascular inflammation, and suppressed local secretion of TNF-α, IL-1β, IL-12, and interferon-γ. Histological examination revealed the number of local CD80/F4+ macrophages in the pulmonary tract . Small airway fibrosis is another complication of COPD; the underlying mechanism for this phenomenon is related to activation of myofibroblasts by the TGF-β signaling pathway . One possible way to cope with this side effect might be using stem cells derived Exo; according to previous studies, effective role of this kind of Exo in fibrosis has been strongly confirmed (Table 3).
Due to the pleiotropic effects of Exo from different cell sources and the complexity of underlying mechanisms in therapeutic properties of these nano-sized vesicles, there are few reports related to the application of Exo in COPD patients (Table 4). As shown in Table 3, Exo were used only for monitoring for the prediction of pathological changes and detection of valid biomarkers in COPD patients. Lack of enough knowledge related to whole Exo dose (single or repeat injection), route and time of administration, lack of standard GMP protocol, and the possibility of side effects limit the extensive application of Exo in COPD patients. Besides, standard methods have not been introduced for Exo isolation and purification, leading to heterogeneity in Exo population and content .
The majority of previously published data have indicated the critical role of immune cell-derived Exo in the progression of COPD. It seems that the exosomal cargo and activity of host cells can predetermine the inflammatory/therapeutic role of Exo in specific tissue niches. In contrary to immune cell-derived Exo, stem cell-derived Exo exhibit prominent anti-inflammatory and regenerative properties under pathological conditions. Regarding the existence of few studies monitoring stem cell Exo, many comprehensive studies are needed for confirming therapeutic effects in COPD patients.
Availability of data and materials
Activator protein 1
Adenosine diphosphate ribosylation factor
ALG-2 interacting protein X
Alveolar type 1
Alveolar type 2
Autophagy-related protein 7
Bronchoalveolar lavage fluid
Chronic obstructive pulmonary disease
- CXCL1 CXCL8:
C-X-C motif chemokine ligand
- ENA-78 or CXCL5:
C-X-C motif chemokine 5
Damage-associated molecular patterns
Endosomal sorting complex transport
Endothelial progenitor cell
Epithelial to mesenchymal transition
Granulocyte colony stimulating factor
Granulocyte–macrophage colony-stimulating factor
Heat shock protein
Hepatocyte growth factor-regulated tyrosine kinase substrate
Human bronchial epithelial cells
Idiopathic pulmonary fibrosis
Intercellular adhesion molecule
- MHC I, II:
Major histocompatibility complex I and II
Mesenchymal stem cells
Mitochondrial damage-associated molecular patterns
Monocyte chemoattractant protein-1
Reactive oxygen species
Soluble N-ethylmaleimide-sensitive factor attachment proteins receptor
Sprout-related EVH1 domain-containing protein-1
Tissue inhibitors of metalloproteinase
Transforming growth factor beta
Tumor necrosis factor receptor 1
Tumor necrosis factor-α
Tumor susceptibility gene 101
Vascular protein sorting associated protein-4
Vesicle trafficking 1 protein
Von Hippel Lindau/ Hypoxia-Inducible Factor-1
Mannino DMJC. COPD: epidemiology, prevalence, morbidity and mortality, and disease heterogeneity. Chest. 2002;121(5):121S-126S.
Liew FYJI. Cigarette smoke resets the alarmin IL-33 in COPD. Immunity. 2015;42(3):401–3.
Papaioannou AI, et al. Systemic and airway inflammation and the presence of emphysema in patients with COPD. Respir Med. 2010;104(2):275–82.
Baines KJ, Simpson JL, Gibson PG. Innate immune responses are increased in chronic obstructive pulmonary disease. PLoS ONE. 2011;6(3): e18426.
Hogg JC, et al. The nature of small-airway obstruction in chronic obstructive pulmonary disease. N Engl J Med. 2004;350(26):2645–53.
Mirershadi F, et al. Unraveling the therapeutic effects of mesenchymal stem cells in asthma. Stem Cell Res Ther. 2020;11(1):400.
Harrell CR, et al. Mesenchymal stem cell-derived exosomes and other extracellular vesicles as new remedies in the therapy of inflammatory diseases. Cells. 2019;8(12):1605.
Russell D, et al. Inhibition of Mac-1 Associated with PMN Exosomes Attenuates Emphysema in a COPD Mouse Model, in C93. Mechanisms of airway inflammation in asthma and COPD 2019. American Thoracic Society. p A5561–A5561.
Rezaie J, et al. Diabetic sera disrupted the normal exosome signaling pathway in human mesenchymal stem cells in vitro. Cell Tissue Res. 2018;374(3):555–65.
Phinney DG, et al. Mesenchymal stem cells use extracellular vesicles to outsource mitophagy and shuttle microRNAs. Nat Commun. 2015;6(1):1–15.
Shokrollahi E, et al. Treatment of human neuroblastoma cell line SH-SY5Y with HSP27 siRNA tagged-exosomes decreased differentiation rate into mature neurons. J Cell Physiol. 2019;234(11):21005–13.
Kahlert C, et al. Identification of double-stranded genomic DNA spanning all chromosomes with mutated KRAS and p53 DNA in the serum exosomes of patients with pancreatic cancer. J Biol Chem. 2014;289(7):3869–75.
Kwon HH, et al. Combination treatment with human adipose tissue stem cell-derived exosomes and fractional CO2 laser for acne scars: a 12-week prospective, double-blind, randomized, split-face study. Acta Derm Venereol. 2020;100(11):adv00310.
Zhang J, et al. The interferon-stimulated exosomal hACE2 potently inhibits SARS-CoV-2 replication through competitively blocking the virus entry. Signal Transduct Target Ther. 2021;6(1):1–11.
Tavasolian F, et al. The impact of immune cell-derived exosomes on immune response initiation and immune system function. Curr Pharm Des. 2021;27(2):197–205.
Qi Y, et al. M1 macrophage-derived exosomes transfer miR-222 to induce bone marrow mesenchymal stem cell apoptosis. Lab Invest. 2021;101:1318–26.
Qiu P, et al. Exosome: the regulator of the immune system in sepsis. Front Pharmacol. 2021;12: 671164.
Konecna B, et al. Monocyte exocytosis of mitochondrial danger-associated molecular patterns in sepsis suppresses neutrophil chemotaxis. J Trauma Acute Care Surg. 2021;90(1):46–53.
Wu R, et al. Roles of exosomes derived from immune cells in cardiovascular diseases. Front Immunol. 2019;10:648–648.
Mason TE, et al. Association of CD14 variant with prostate cancer in African American men. Prostate. 2010;70(3):262–9.
Kajimoto T, et al. Ongoing activation of sphingosine 1-phosphate receptors mediates maturation of exosomal multivesicular endosomes. Nat Commun. 2013;4(1):1–13.
Crescitelli R, et al. Distinct RNA profiles in subpopulations of extracellular vesicles: apoptotic bodies, microvesicles and exosomes. J Extacell Vesicles. 2013;2(1):20677.
Hessvik NP, Llorente AJC, Sciences ML. Current knowledge on exosome biogenesis and release. Cell Mol Life Sci. 2018;75(2):193–208.
Kalluri R, LeBleu VSJS. The biology, function, and biomedical applications of exosomes. Science. 2020;367(6478):eaau6977.
Wu J, et al. Construction and topological analysis of an endometriosis-related exosomal circRNA-miRNA-mRNA regulatory network. Aging. 2021;13(9):12607.
Zhang Y, et al. Exosomes: biogenesis, biologic function and clinical potential. Cell Biosci. 2019;9(1):1–18.
Simons M, Raposo G. Exosomes–vesicular carriers for intercellular communication. Curr Opin Cell Biol. 2009;21(4):575–81.
Donoso-Quezada J, Ayala-Mar S, González-Valdez J. The role of lipids in exosome biology and intercellular communication: Function, analytics and applications. Traffic. 2021;22(7):204–20.
Pant S, Hilton H, Burczynski ME. The multifaceted exosome: biogenesis, role in normal and aberrant cellular function, and frontiers for pharmacological and biomarker opportunities. Biochem Pharmacol. 2012;83(11):1484–94.
Jadli AS, et al. Inside (sight) of tiny communicator: exosome biogenesis, secretion, and uptake. Mol Cell Biochem. 2020;467(1):77–94.
Urbanelli L, et al. Signaling pathways in exosomes biogenesis, secretion and fate. Genes. 2013;4(2):152–70.
Rahmati S, et al. An overview of current knowledge in biological functions and potential theragnostic applications of exosomes. Chem Phys Lipids. 2020;226: 104836.
Farooqi AA, et al. Exosome biogenesis, bioactivities and functions as new delivery systems of natural compounds. Biotechnol Adv. 2018;36(1):328–34.
Kowal J, Tkach M, Théry C. Biogenesis and secretion of exosomes. Curr Opin Cell Biol. 2014;29:116–25.
Skryabin G, et al. Lipid rafts in exosome biogenesis. Biochemistry (Mosc). 2020;85(2):177–91.
Isola AL, Chen S. Exosomes: the link between GPCR activation and metastatic potential? Front Genet. 2016;7:56.
Ostrowski M, et al. Rab27a and Rab27b control different steps of the exosome secretion pathway. Nat Cell Biol. 2010;12(1):19–30.
Hsu C, et al. Regulation of exosome secretion by Rab35 and its GTPase-activating proteins TBC1D10A–C. J Cell Biol. 2010;189(2):223–32.
Hyenne V, et al. RAL-1 controls multivesicular body biogenesis and exosome secretion. J Cell Biol. 2015;211(1):27–37.
Bonifacino JS, Glick BS. The mechanisms of vesicle budding and fusion. Cell. 2004;116(2):153–66.
Savina A, Vidal M, Colombo MI. The exosome pathway in K562 cells is regulated by Rab11. J Cell Sci. 2002;115(12):2505–15.
Sinha S, et al. Cortactin promotes exosome secretion by controlling branched actin dynamics. J Cell Biol. 2016;214(2):197–213.
Mica Y, et al. Modeling neural crest induction, melanocyte specification, and disease-related pigmentation defects in hESCs and patient-specific iPSCs. Cell Rep. 2013;3(4):1140–52.
Savina A, et al. Exosome release is regulated by a calcium-dependent mechanism in K562 cells. J Biol Chem. 2003;278(22):20083–90.
Parolini I, et al. Microenvironmental pH is a key factor for exosome traffic in tumor cells. J Biol Chem. 2009;284(49):34211–22.
He C, et al. Exosome theranostics: biology and translational medicine. Theranostics. 2018;8(1):237.
Mulcahy L, Pink R, Carter DF. Routes and mechanisms of extracellular vesicle uptake. J Extracell Vesicles. 2014;3:24641.
Amigorena S, et al. ICAM-1 on exosomes from mature dendritic cells is critical for efficient.
Christianson HC, et al. Cancer cell exosomes depend on cell-surface heparan sulfate proteoglycans for their internalization and functional activity. Proc Natl Acad Sci. 2013;110(43):17380–5.
Rana S, Zöller M. Exosome target cell selection and the importance of exosomal tetraspanins: a hypothesis. Biochem Soc Trans. 2011;39(2):559–62.
Wei H, et al. Regulation of exosome production and cargo sorting. Int J Biol Sci. 2021;17(1):163–77.
Riley CM, Sciurba FCJJ. Diagnosis and outpatient management of chronic obstructive pulmonary disease: a review. JAMA. 2019;321(8):786–97.
Halpin DM, et al. Global initiative for the diagnosis, management, and prevention of chronic obstructive lung disease. The 2020 GOLD science committee report on COVID-19 and chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2021;203(1):24–36.
Agustí A, Hogg JC. Update on the pathogenesis of chronic obstructive pulmonary disease. N Engl J Med. 2019;381(13):1248–56.
Zuo L, et al. Interrelated role of cigarette smoking, oxidative stress, and immune response in COPD and corresponding treatments. Am J Physiol Lung Cell Mol Physiol. 2014;307(3):L205–18.
Higham A, et al. The pathology of small airways disease in COPD: historical aspects and future directions. Respir Res. 2019;20(1):1–11.
Holloway RA, Donnelly LE. Immunopathogenesis of chronic obstructive pulmonary disease. Curr Opin Pulm Med. 2013;19(2):95–102.
Olloquequi J, et al. Differential lymphocyte infiltration in small airways and lung parenchyma in COPD patients. Respir Med. 2010;104(9):1310–8.
Baumann BC, MacArthur KM, Baumann JC. Emotional support animals on commercial flights: a risk to allergic patients. Lancet Respir Med. 2016;4(7):544–5.
Ruvuna L, Sood A. Epidemiology of chronic obstructive pulmonary disease. Clin Chest Med. 2020;41(3):315–27.
Aslani MR, et al. Modification of lung endoplasmic reticulum genes expression and NF-kB protein levels in obese ovalbumin-sensitized male and female rats. Life Sci. 2020;247: 117446.
Heidarzadeh M, et al. Toll-like receptor bioactivity in endothelial progenitor cells. Cell Tissue Res. 2020;379(2):223–30.
Hikichi M, et al. Pathogenesis of chronic obstructive pulmonary disease (COPD) induced by cigarette smoke. J Thorac Dis. 2019;11(Suppl 17):S2129.
Kroemer G. Mitochondrial control of apoptosis: an introduction. Biochem Biophys Res Commun. 2003;304(3):433–5.
Segura-Valdez L, et al. Upregulation of gelatinases A and B, collagenases 1 and 2, and increased parenchymal cell death in COPD. Chest. 2000;117(3):684–94.
Imai K, et al. Correlation of lung surface area to apoptosis and proliferation in human emphysema. Eur Respir J. 2005;25(2):250–8.
Karakioulaki M, Papakonstantinou E, Stolz D. Extracellular matrix remodelling in COPD. Eur Respir Rev. 2020;29(158): 190124.
Sand JM, et al. Accelerated extracellular matrix turnover during exacerbations of COPD. Respir Res. 2015;16(1):1–8.
Mitzner W. Emphysema: a disease of small airways or lung parenchyma? N Engl J Med. 2011;365(17):1637.
Petrache I, et al. A novel antiapoptotic role for α1-antitrypsin in the prevention of pulmonary emphysema. Am J Respir Crit Care Med. 2006;173(11):1222–8.
Travis J, et al. The role of proteolytic enzymes in the development of pulmonary emphysema and periodontal disease. Am J Respir Crit Care Med. 1994;150(6):S143.
Majo J, Ghezzo H, Cosio MG. Lymphocyte population and apoptosis in the lungs of smokers and their relation to emphysema. Eur Respir J. 2001;17(5):946–53.
Wallace AM, et al. Matrix metalloproteinase expression by human alveolar macrophages in relation to emphysema. COPD. 2008;5(1):13–23.
Maeno T, et al. CD8+ T Cells are required for inflammation and destruction in cigarette smoke-induced emphysema in mice. J Immunol. 2007;178(12):8090–6.
Gao W, et al. Bronchial epithelial cells: the key effector cells in the pathogenesis of chronic obstructive pulmonary disease? Respirology. 2015;20(5):722–9.
Kitamura H, et al. Mouse and human lung fibroblasts regulate dendritic cell trafficking, airway inflammation, and fibrosis through integrin αvβ8–mediated activation of TGF-β. J Clin Invest. 2011;121(7):2863–75.
George L, Brightling CE. Eosinophilic airway inflammation: role in asthma and chronic obstructive pulmonary disease. Ther Adv Chronic Dis. 2016;7(1):34–51.
Di Stefano A, et al. Severity of airflow limitation is associated with severity of airway inflammation in smokers. Am J Respir Crit Care Med. 1998;158(4):1277–85.
Rovina N, Koutsoukou A, Koulouris NG. Inflammation and immune response in COPD: where do we stand? Mediators Inflamm. 2013;2013: 413735.
Barnes PJ. Mediators of chronic obstructive pulmonary disease. Pharmacol Rev. 2004;56(4):515–48.
Russell RE, et al. Alveolar macrophage-mediated elastolysis: roles of matrix metalloproteinases, cysteine, and serine proteases. Am J Physiol Lung Cell Mol Physiol. 2002;283(4):L867–73.
Amini H, et al. Cytoprotective and cytofunctional effect of polyanionic polysaccharide alginate and gelatin microspheres on rat cardiac cells. Int J Biol Macromol. 2020;161:969–76.
Tanino M, et al. Increased levels of interleukin-8 in BAL fluid from smokers susceptible to pulmonary emphysema. Thorax. 2002;57(5):405–11.
Di Stefano A, et al. Upregulation of adhesion molecules in the bronchial mucosa of subjects with chronic obstructive bronchitis. Am J Respir Crit Care Med. 1994;149(3):803–10.
Traves S, et al. Increased levels of the chemokines GROα and MCP-1 in sputum samples from patients with COPD. Thorax. 2002;57(7):590–5.
Kany S, Vollrath JT, Relja B. Cytokines in inflammatory disease. Int J Mol Sci. 2019;20(23):6008.
Ma J, Rubin BK, Voynow JAJC. Mucins, mucus, and goblet cells. Chest. 2018;154(1):169–76.
Dirksen A. Monitoring the progress of emphysema by repeat computed tomography scans with focus on noise reduction. Proc Am Thorac Soc. 2008;5(9):925–8.
Hoffmann RF, et al. Prolonged cigarette smoke exposure alters mitochondrial structure and function in airway epithelial cells. Respir Res. 2013;14(1):1–13.
Gosker HR, et al. Exercise training restores uncoupling protein-3 content in limb muscles of patients with chronic obstructive pulmonary disease. Am J Physiol Endocrinol Metab. 2006;290(5):E976–81.
Ito S, et al. PARK2-mediated mitophagy is involved in regulation of HBEC senescence in COPD pathogenesis. Autophagy. 2015;11(3):547–59.
Ahmad T, et al. Impaired mitophagy leads to cigarette smoke stress-induced cellular senescence: implications for chronic obstructive pulmonary disease. FASEB J. 2015;29(7):2912–29.
Aggarwal S, et al. Differential regulation of autophagy and mitophagy in pulmonary diseases. Am J Physiol Lung Cell Mol Physiol. 2016;311(2):L433–52.
Ryter SW, et al. Mitochondrial dysfunction as a pathogenic mediator of chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. Ann Am Thorac Soc. 2018;15(Supplement 4):S266–72.
Shaykhiev R. Emerging biology of persistent mucous cell hyperplasia in COPD. Thorax. 2019;74(1):4–6.
Wang L, et al. Chlorpyrifos induces the apoptosis and necroptosis of L8824 cells through the ROS/PTEN/PI3K/AKT axis. J Hazard Mater. 2020;398: 122905.
Chilosi M, et al. Premature lung aging and cellular senescence in the pathogenesis of idiopathic pulmonary fibrosis and COPD/emphysema. Transl Res. 2013;162(3):156–73.
Forteza RM, et al. Hyaluronan and layilin mediate loss of airway epithelial barrier function induced by cigarette smoke by decreasing E-cadherin. J Biol Chem. 2012;287(50):42288–98.
Dunsmore SE, Rannels DE. Extracellular matrix biology in the lung. Am J Physiol. 1996;270(1):L3-27.
Nguyen NM, et al. Laminin α5 is required for lobar septation and visceral pleural basement membrane formation in the developing mouse lung. Dev Biol. 2002;246(2):231–44.
Burgess JK, et al. Dynamic reciprocity: the role of the extracellular matrix microenvironment in amplifying and sustaining pathological lung fibrosis. In: Willis M, Yates C, Schisler J, editors., et al., Fibrosis in disease. Berlin: Springer; 2019. p. 239–70.
Brandsma CA, et al. Recent advances in chronic obstructive pulmonary disease pathogenesis: from disease mechanisms to precision medicine. J Pathol. 2020;250(5):624–35.
Yao H, et al. SIRT1 redresses the imbalance of tissue inhibitor of matrix metalloproteinase-1 and matrix metalloproteinase-9 in the development of mouse emphysema and human COPD. Am J Physiol Lung Cell Mol Physiol. 2013;305(9):L615–24.
Brusselle G. Dysregulated fibulin-5 expression and elastogenesis in COPD lungs: pyromaniac or fire fighter? Thorax. 2015;70(1):1–2.
Brandsma CA, et al. A large lung gene expression study identifying fibulin-5 as a novel player in tissue repair in COPD. Thorax. 2015;70(1):21–32.
Santos S, et al. Characterization of pulmonary vascular remodelling in smokers and patients with mild COPD. Eur Respir J. 2002;19(4):632–8.
Yu H, et al. Bone marrow mesenchymal stem cell-derived exosomes promote tendon regeneration by facilitating the proliferation and migration of endogenous tendon stem/progenitor cells. Acta Biomater. 2020;106:328–41.
Driscoll B, et al. Isolation and characterization of distal lung progenitor cells. In: Singh S, editor., et al., Somatic stem cells. Berlin: Springer; 2012. p. 109–22.
Pardo-Saganta A, et al. Injury induces direct lineage segregation of functionally distinct airway basal stem/progenitor cell subpopulations. Cell Stem Cell. 2015;16(2):184–97.
Reis-Filho JS, et al. Distribution of p63, cytokeratins 5/6 and cytokeratin 14 in 51 normal and 400 neoplastic human tissue samples using TARP-4 multi-tumor tissue microarray. Virchows Arch. 2003;443(2):122–32.
Hong KU, et al. Basal cells are a multipotent progenitor capable of renewing the bronchial epithelium. Am J Pathol. 2004;164(2):577–88.
Staudt MR, et al. Airway Basal stem/progenitor cells have diminished capacity to regenerate airway epithelium in chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2014;190(8):955–8.
Evans MJ, et al. Transformation of alveolar type 2 cells to type 1 cells following exposure to NO2. Exp Mol Pathol. 1975;22(1):142–50.
Yao C, et al. Senescence of alveolar type 2 cells drives progressive pulmonary fibrosis. Am J Respir Crit Care Med. 2021;203(6):707–17.
Olajuyin AM, Zhang X, Ji HL. Alveolar type 2 progenitor cells for lung injury repair. Cell Death Discov. 2019;5:63.
Van Es JH, et al. Dll1+ secretory progenitor cells revert to stem cells upon crypt damage. Nat Cell Biol. 2012;14(10):1099–104.
Kim V, et al. Chronic bronchitis and current smoking are associated with more goblet cells in moderate to severe COPD and smokers without airflow obstruction. PLoS ONE. 2015;10(2): e0116108.
Wu X, et al. Exosomes derived from endothelial progenitor cells ameliorate acute lung injury by transferring miR-126. Exp Cell Res. 2018;370(1):13–23.
Fehrenbach H. Alveolar epithelial type II cell: defender of the alveolus revisited. Respir Res. 2001;2(1):1–20.
Song L, Peng J, Guo XJLS. Exosomal lncRNA TCONS_00064356 derived from injured alveolar epithelial type II cells affects the biological characteristics of mesenchymal stem cells. Life Sci. 2021;278: 119568.
Serhan CN, Levy BD. Resolvins in inflammation: emergence of the pro-resolving superfamily of mediators. J Clin Invest. 2018;128(7):2657–69.
Arnhold J. The Dual Role of Myeloperoxidase in Immune Response. Int J Mol Sci. 2020;21(21):8057.
Genschmer KR, et al. Activated PMN exosomes: pathogenic entities causing matrix destruction and disease in the lung. Cell. 2019;176(1–2):113-126. e15.
Houghton AM. Mechanistic links between COPD and lung cancer. Nat Rev Cancer. 2013;13(4):233–45.
Li G, et al. Coronavirus infections and immune responses. J Med Virol. 2020;92(4):424–32.
Häusser-Kinzel S, Weber MS. The role of B cells and antibodies in multiple sclerosis, neuromyelitis optica, and related disorders. Front Immunol. 2019;10:201.
Chaput N, et al. Exosome-based immunotherapy. Cancer Immunol Immmunother. 2004;53(3):234–9.
Raposo G, et al. B lymphocytes secrete antigen-presenting vesicles. J Exp Med. 1996;183(3):1161–72.
Wang N, et al. The potential roles of exosomes in chronic obstructive pulmonary disease. Front Med (Lausanne). 2020;7:1095.
Pitt JM, et al. Dendritic cell-derived exosomes for cancer therapy. J Clin Invest. 2016;126(4):1224–32.
Chaput N, et al. Dendritic cell derived-exosomes: biology and clinical implementations. J Leukoc Biol. 2006;80(3):471–8.
Kowal J, Tkach M. Dendritic cell extracellular vesicles. Int Rev Cell Mol Biol. 2019;349:213–49.
Panjwani N, et al. The HSC73 molecular chaperone: involvement in MHC class II antigen presentation. J Immunol. 1999;163(4):1936–42.
Xu H, et al. Exosomal microRNA-21 derived from bronchial epithelial cells is involved in aberrant epithelium-fibroblast cross-talk in COPD induced by cigarette smoking. Theranostics. 2018;8(19):5419.
He S, et al. Bronchial epithelial cell extracellular vesicles ameliorate epithelial–mesenchymal transition in COPD pathogenesis by alleviating M2 macrophage polarization. Nanomedicine. 2019;18:259–71.
Fujita Y, et al. Suppression of autophagy by extracellular vesicles promotes myofibroblast differentiation in COPD pathogenesis. J Extracell Vesicles. 2015;4(1):28388.
Fujii S, et al. Insufficient autophagy promotes bronchial epithelial cell senescence in chronic obstructive pulmonary disease. Oncoimmunology. 2012;1(5):630–41.
Kaur G, et al. Distinct exosomal miRNA profiles from BALF and lung tissue of COPD and IPF patients. Int J Mol Sci. 2021;22(21):11830.
Cañas JA, et al. Exosomes: a key piece in asthmatic inflammation. Int J Mol Sci. 2021;22(2):963.
Lacedonia D, et al. Expression profiling of miRNA-145 and miRNA-338 in serum and sputum of patients with COPD, asthma, and asthma–COPD overlap syndrome phenotype. Int J Chron Obstruct Pulmon Dis. 2017;12:1811.
Malmhäll C, et al. Altered miR-155 expression in allergic asthmatic airways. Scand J Immunol. 2017;85(4):300–7.
Mirershadi F, et al. Unraveling the therapeutic effects of mesenchymal stem cells in asthma. Stem Cell Res Ther. 2020;11(1):1–12.
Lai RC, et al. Exosomes for drug delivery—a novel application for the mesenchymal stem cell. Biotechnol Adv. 2013;31(5):543–51.
Fonseca B, et al. Ultrasound-based control of micro-bubbles for exosome delivery in treating COVID-19 lung damage. 2021.
Tsai SJ, et al. Exosome-mediated mRNA delivery for SARS-CoV-2 vaccination. 2021.
Maremanda KP, et al. Protective role of mesenchymal stem cells and mesenchymal stem cell-derived exosomes in cigarette smoke-induced mitochondrial dysfunction in mice. Toxicol Appl Pharmacol. 2019;385: 114788.
Ridzuan N, et al. Human umbilical cord mesenchymal stem cell-derived extracellular vesicles ameliorate airway inflammation in a rat model of chronic obstructive pulmonary disease (COPD). Stem Cell Res Ther. 2021;12(1):1–21.
Harrell CR, et al. Molecular and cellular mechanisms responsible for beneficial effects of mesenchymal stem cell-derived product “Exo-d-MAPPS” in attenuation of chronic airway inflammation. Anal Cell Pathol (Amst). 2020;2020:3153891.
Rao W, et al. Regenerative metaplastic clones in COPD lung drive inflammation and fibrosis. Cell. 2020;181(4):848-864. e18.
Rezabakhsh A, Sokullu E, Rahbarghazi R. Applications, challenges and prospects of mesenchymal stem cell exosomes in regenerative medicine. Stem Cell Res Ther. 2021;12(1):521.
Rokicki W, et al. The role and importance of club cells (Clara cells) in the pathogenesis of some respiratory diseases. Kardiochir Torakochirurgia Pol. 2016;13(1):26.
Barkauskas CE, et al. Type 2 alveolar cells are stem cells in adult lung. J Clin Invest. 2013;123(7):3025–36.
Yang J, et al. Exosome mediated delivery of miR-124 promotes neurogenesis after ischemia. Mol Ther Nucleic Acids. 2017;7:278–87.
Lee S-T, et al. Exosome-based delivery of miR-124 in a Huntington’s disease model. J Mov Disord. 2017;10(1):45.
Lang FM, et al. Mesenchymal stem cells as natural biofactories for exosomes carrying miR-124a in the treatment of gliomas. Neuro Oncol. 2018;20(3):380–90.
Naseri Z, et al. Exosome-mediated delivery of functionally active miRNA-142-3p inhibitor reduces tumorigenicity of breast cancer in vitro and in vivo. Int J Nanomedicine. 2018;13:7727.
Jia Y, et al. Mesenchymal stem cells-derived exosomal microRNA-139-5p restrains tumorigenesis in bladder cancer by targeting PRC1. Oncogene. 2021;40(2):246–61.
Yao S, et al. Exosome-mediated delivery of miR-204-5p inhibits tumor growth and chemoresistance. Cancer Med. 2020;9(16):5989–98.
Xiao G-Y, et al. Exosomal miR-10a derived from amniotic fluid stem cells preserves ovarian follicles after chemotherapy. Sci Rep. 2016;6(1):1–12.
Huang P, et al. Combinatorial treatment of acute myocardial infarction using stem cells and their derived exosomes resulted in improved heart performance. Stem Cell Res Ther. 2019;10(1):1–12.
Guo S, et al. Intranasal delivery of mesenchymal stem cell derived exosomes loaded with phosphatase and tensin homolog siRNA repairs complete spinal cord injury. ACS Nano. 2019;13(9):10015–28.
Zhang C, et al. Mesenchymal stem cells-derived and siRNAs-encapsulated exosomes inhibit osteonecrosis of the femoral head. J Cell Mol Med. 2020;24(17):9605–12.
Ju Z, et al. Exosomes from iPSCs delivering siRNA attenuate intracellular adhesion molecule-1 expression and neutrophils adhesion in pulmonary microvascular endothelial cells. Inflammation. 2017;40(2):486–96.
Xu C, et al. Exosomes derived from three-dimensional cultured human umbilical cord mesenchymal stem cells ameliorate pulmonary fibrosis in a mouse silicosis model. Stem Cell Res Ther. 2020;11(1):1–12.
Wang B, et al. Mesenchymal stem cells deliver exogenous microRNA-let7c via exosomes to attenuate renal fibrosis. Mol Ther. 2016;24(7):1290–301.
Rong X, et al. Human bone marrow mesenchymal stem cells-derived exosomes alleviate liver fibrosis through the Wnt/β-catenin pathway. Stem Cell Res Ther. 2019;10(1):1–11.
Ji C, et al. Exosomes derived from hucMSC attenuate renal fibrosis through CK1δ/β-TRCP-mediated YAP degradation. Cell Death Dis. 2020;11(5):1–10.
Zulueta A, et al. Lung mesenchymal stem cells-derived extracellular vesicles attenuate the inflammatory profile of cystic fibrosis epithelial cells. Cell Signal. 2018;51:110–8.
Villamizar O, et al. Mesenchymal Stem Cell exosome delivered Zinc Finger Protein activation of cystic fibrosis transmembrane conductance regulator. J Extracell Vesicles. 2021;10(3): e12053.
Li Y, et al. Exosomes derived from human adipose mesenchymal stem cells attenuate hypertrophic scar fibrosis by miR-192-5p/IL-17RA/Smad axis. Stem Cell Res Ther. 2021;12(1):1–16.
All authors would thank the Koç University Translational Medicine Research Center (KUTTAM) and Stem Cell Research Center staff for guidance and help.
This study was supported by a grant from Koç University Translational Medicine Research Center (KUTTAM).
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Rajabi, H., Konyalilar, N., Erkan, S. et al. Emerging role of exosomes in the pathology of chronic obstructive pulmonary diseases; destructive and therapeutic properties. Stem Cell Res Ther 13, 144 (2022). https://doi.org/10.1186/s13287-022-02820-4
- Immune cells
- Pathological remodeling
- Tissue regeneration