The therapeutic effect of mesenchymal stem cells on pulmonary myeloid cells following neonatal hyperoxic lung injury in mice

The fix is not yet in: recommendation for fixation of lungs within physiological/pathophysiological volume range in preclinical pulmonary structure-function studies

Quantitative characterization of lung structures by morphometrical or stereological analysis of histological sections is a powerful means of elucidating pulmonary structure-function relations. The overwhelming majority of studies, however, fix lungs for histology at pressures outside the physiological/pathophysiological respiratory volume range. Thus, valuable information is being lost. In this perspective article, we argue that investigators performing pulmonary histological studies should consider whether the aims of their studies would benefit from fixation at functional transpulmonary pressures, particularly those of end-inspiration and end-expiration. We survey the pressures at which lungs are typically fixed in preclinical structure-function studies, provide examples of conditions that would benefit from histological evaluation at functional lung volumes, summarize available fixation methods, discuss alternative imaging modalities, and discuss challenges to implementing the suggested approach and means of addressing those challenges. We aim to persuade investigators that modifying or complementing the traditional histological approach by fixing lungs at minimal and maximal functional volumes could enable new understanding of pulmonary structure-function relations.

MSCs alleviate LPS-induced acute lung injury by inhibiting the proinflammatory function of macrophages in mouse lung organoid-macrophage model

Acute lung injury (ALI) is an inflammatory disease associated with alveolar injury, subsequent macrophage activation, inflammatory cell infiltration, and cytokine production. Mesenchymal stem cells (MSCs) are beneficial for application in the treatment of inflammatory diseases due to their immunomodulatory effects. However, the mechanisms of regulatory effects by MSCs on macrophages in ALI need more in-depth study. Lung tissues were collected from mice for mouse lung organoid construction. Alveolar macrophages (AMs) derived from bronchoalveolar lavage and interstitial macrophages (IMs) derived from lung tissue were co-cultured, with novel matrigel-spreading lung organoids to construct an in vitro model of lung organoids-immune cells. Mouse compact bone-derived MSCs were co-cultured with organoids-macrophages to confirm their therapeutic effect on acute lung injury. Changes in transcriptome expression profile were analyzed by RNA sequencing. Well-established lung organoids expressed various lung cell type-specific markers. Lung organoids grown on spreading matrigel had the property of functional cells growing outside the lumen. Lipopolysaccharide (LPS)-induced injury promoted macrophage chemotaxis toward lung organoids and enhanced the expression of inflammation-associated genes in inflammation-injured lung organoids-macrophages compared with controls. Treatment with MSCs inhibited the injury progress and reduced the levels of inflammatory components. Furthermore, through the nuclear factor-κB pathway, MSC treatment inhibited inflammatory and phenotypic transformation of AMs and modulated the antigen-presenting function of IMs, thereby affecting the inflammatory phenotype of lung organoids. Lung organoids grown by spreading matrigel facilitate the reception of external stimuli and the construction of in vitro models containing immune cells, which is a potential novel model for disease research. MSCs exert protective effects against lung injury by regulating different functions of AMs and IMs in the lung, indicating a potential mechanism for therapeutic intervention.

Research hotspots and emerging trends in mesenchymal stem/stromal cells in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a prevalent lung disease in neonates that is associated with numerous complications and high mortality. The promising approach to treat BPD is the use of mesenchymal stem cells (MSCs), However, the current treatment of MSCs presents safety concerns, including occlusion of blood vessels and tumorigenicity. In this study, relevant publications from the Web of Science Core Collection were downloaded in January 2023. The acquired data were analyzed and predicted for trends and hotspots in this field using CiteSpace software. Results revealed that in recent years, the focus of co-cited references has been primarily on the clinical studies of MSCs and the application of MSCs derivatives for treating BPD models. The keywords that have gained attention are extracellular vesicles and exosomes. The United States has emerged as the most influential co-authoring country in this field. Among the co-cited journals, the American Journal of Respiratory and Critical Care Medicine holds the highest influence. Thus, this study provides trends in publications, collaboration, research interests, and hotspots, and provides clues for novel ideas and strategies in to further MSCs treatments for BPD.

Therapeutic strategies targeting pro-fibrotic macrophages in interstitial lung disease

Idiopathic pulmonary fibrosis (IPF) is the representative phenotype of interstitial lung disease where severe scarring develops in the lung interstitium. Although antifibrotic treatments are available and have been shown to slow the progression of IPF, improved therapeutic options are still needed. Recent data indicate that macrophages play essential pro-fibrotic roles in the pathogenesis of pulmonary fibrosis. Historically, macrophages have been classified into two functional subtypes, "M1" and "M2," and it is well described that "M2" or "alternatively activated" macrophages contribute to fibrosis via the production of fibrotic mediators, such as TGF-β, CTGF, and CCL18. However, highly plastic macrophages may possess distinct functions and phenotypes in the fibrotic lung environment. Thus, M2-like macrophages in vitro and pro-fibrotic macrophages in vivo are not completely identical cell populations. Recent developments in transcriptome analysis, including single-cell RNA sequencing, have attempted to depict more detailed phenotypic characteristics of pro-fibrotic macrophages. This review will outline the role and characterization of pro-fibrotic macrophages in fibrotic lung diseases and discuss the possibility of treating lung fibrosis by preventing or reprogramming the polarity of macrophages. We also utilized a systematic approach to review the literature and identify novel and promising therapeutic agents that follow this treatment strategy.

Mesenchymal Stem Cells Attenuate Acute Lung Injury in Mice Partly by Suppressing Alveolar Macrophage Activation in a PGE2-Dependent Manner

Mesenchymal stem cells (MSCs) have been demonstrated to attenuate acute lung injury (ALI). We also found that they can suppress the activation of alveolar macrophages (AMs), which can partly account for their therapeutic effects. MSCs do not inherently own immunosuppressive effects, when co-cultured with inflammatory immune cells, MSCs can be activated by inflammatory cytokines and meanwhile exert immunosuppressive effects. In order to further research, RNA sequencing (RNA-seq) of MSCs cultured before and after co-culturing with activated macrophages was performed. The data suggested a total of 5268 differentially expressed genes (DEGs) along the process. We used the data of 2754 upregulated DEGs to develop a signaling network of genes and the transcription factors targeting them in order to predict the altered functions of MSCs after exposure to inflammatory stimuli. This constructed network revealed some critical target genes and potential roles of MSCs under inflammatory conditions. According to the network, Ptgs2 was assumed to be an important gene participating in the immunosuppressive effects of MSCs. We also identified significant increases in the expression of COX2 protein and the secretion of PGE2 from MSCs. The use of the COX2 inhibitor NS-398 restrained the secretion of PGE2 and reversed the suppression of macrophage activation by MSCs in vitro. In addition, a selective antagonist of PGE2 binding receptor (EP4 receptor), GW627368X, also reversed the inhibitory effects of MSCs on AMs and the protective effects in ALI mouse. In summary, the therapeutic effects of MSCs on ALI partly occur through suppressing AM activation via PGE2 binding to EP4 receptor.

Insights into the mechanisms of alveolarization - Implications for lung regeneration and cell therapies

Although the lung has extensive regenerative capacity, some diseases affecting the distal lung result in irreversible loss of pulmonary alveoli. Hitherto, treatments are supportive and do not specifically target tissue repair. Regenerative medicine offers prospects to promote lung repair and regeneration. The neonatal lung may be particularly receptive, because of its growth potential, compared to the adult lung. Based on our current understanding of neonatal lung injury, the ideal therapeutic approach includes mitigation of inflammation and fibrosis, and induction of regenerative signals. Cell-based therapies have shown potential to prevent and reverse impaired lung development. Their mechanisms of action suggest effects on both, mitigating the pathophysiological processes and promoting lung growth. Here, we review our current understanding of normal and impaired alveolarization, provide some rationale for the use of cell-based therapies and summarize current evidence for the therapeutic potential of cell-based therapies for pulmonary regeneration in preterm infants.

Recent research on the mechanism of mesenchymal stem cells in the treatment of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease due to impaired pulmonary development and is one of the main causes of respiratory failure in preterm infants. Preterm infants with BPD have significantly higher complication and mortality rates than those without BPD. At present, comprehensive management is the main intervention method for BPD, including reasonable respiratory and circulatory support, appropriate enteral nutrition and parenteral nutrition, application of caffeine/glucocorticoids/surfactants, and out-of-hospital management after discharge. The continuous advances in stem cell medicine in recent years provide new ideas for the treatment of BPD. Various pre-clinical trials have confirmed that stem cell therapy can effectively prevent lung injury and promote lung growth and damage repair. This article performs a comprehensive analysis of the mechanism of mesenchymal stem cells in the treatment of BPD, so as to provide a basis for clinical applications.

Extracellular Vesicles Protect the Neonatal Lung from Hyperoxic Injury through the Epigenetic and Transcriptomic Reprogramming of Myeloid Cells

Rationale: Mesenchymal stem/stromal cell (MSC)-small extracellular vesicle (MEx) treatment has shown promise in experimental models of neonatal lung injury. The molecular mechanisms by which MEx afford beneficial effects remain incompletely understood. Objectives: To investigate the therapeutic mechanism of action through assessment of MEx biodistribution and impact on immune cell phenotypic heterogeneity. Methods: MEx were isolated from the conditioned medium of human umbilical cord Wharton's jelly-derived MSCs. Newborn mice were exposed to hyperoxia (HYRX, 75% O2) from birth and returned to room air at Postnatal Day 14 (PN14). Mice received either a bolus intravenous MEx dose at PN4 or bone marrow-derived myeloid cells (BMDMy) pretreated with MEx. Animals were killed at PN4, PN7, PN14, or PN28 to characterize MEx biodistribution or for assessment of pulmonary parameters. The therapeutic role of MEx-educated BMDMy was determined in vitro and in vivo. Measurements and Main Results: MEx therapy ameliorated core histological features of HYRX-induced neonatal lung injury. Biodistribution and mass cytometry studies demonstrated that MEx localize in the lung and interact with myeloid cells. MEx restored the apportion of alveolar macrophages in the HYRX-injured lung and concomitantly suppressed inflammatory cytokine production. In vitro and ex vivo studies revealed that MEx promoted an immunosuppressive BMDMy phenotype. Functional assays demonstrated that the immunosuppressive actions of BMDMy are driven by phenotypically and epigenetically reprogrammed monocytes. Adoptive transfer of MEx-educated BMDMy, but not naive BMDMy, restored alveolar architecture, blunted fibrosis and pulmonary vascular remodeling, and improved exercise capacity. Conclusions: MEx ameliorate hyperoxia-induced neonatal lung injury though epigenetic and phenotypic reprogramming of myeloid cells.

PM2.5-induced lung injury is attenuated in macrophage-specific NLRP3 deficient mice

Fine particulate matter (PM2.5) is one of the most important components of environmental pollutants and is associated with lung injury. Pyroptosis, a form of programmed cell death mainly mediated by the NLRP3 inflammasome, has been reported to be involved in sepsis-induced or ischemia/reperfusion-induced lung injury. However, the specific mechanisms of pyroptosis in PM2.5-induced lung injury are not yet clear. We constructed macrophage-specific NLRP3 knockout mice to explore the mechanism of PM2.5-induced lung injury in terms of inflammatory response, oxidative stress, and apoptosis levels, including the relationship between these effects and pyroptosis. The results disclosed that PM2.5 exposure increased the infiltration of macrophages and leukocytes and the secretion of inflammatory cytokines, including TNF-α and IL-6, in lung tissue. The activity of antioxidant enzymes, including SOD, GSH-PX, and CAT, significantly decreased, while MDA, the end product of lipid oxidation, remarkably increased. The level of apoptosis in lung tissue, measured by the TUNEL assay and apoptosis-related proteins (BAX and BCL-2), was significantly increased. Macrophage-specific NLRP3 knockout could offset these effects. We further observed that PM2.5 treatment activated the NLRP3 inflammasome and subsequently induced pyroptosis, as evidenced by the increased production of IL-1β and IL-18 and the increase of the protein levels of NLRP3, ASC, caspase-1, and GSDMD, which were inhibited when NLRP3 was knocked out in macrophages. Taken together, these results revealed that NLRP3-mediated macrophage pyroptosis promoted PM2.5-induced lung injury through aggravating inflammation, oxidative stress, and apoptosis. Targeting the inhibition of NLRP3-mediated macrophage pyroptosis provides a new way to study lung injury induced by the exposure to PM2.5.

Enhancing Cystic Fibrosis Immune Regulation

In cystic fibrosis (CF), sustained infection and exuberant inflammation results in debilitating and often fatal lung disease. Advancement in CF therapeutics has provided successful treatment regimens for a variety of clinical consequences in CF; however effective means to treat the pulmonary infection and inflammation continues to be problematic. Even with the successful development of small molecule cystic fibrosis transmembrane conductance regulator (CFTR) correctors and potentiators, there is only a modest effect on established infection and inflammation in CF patients. In the pursuit of therapeutics to treat inflammation, the conundrum to address is how to overcome the inflammatory response without jeopardizing the required immunity to manage pathogens and prevent infection. The key therapeutic would have the capacity to dull the inflammatory response, while sustaining the ability to manage infections. Advances in cell-based therapy have opened up the avenue for dynamic and versatile immune interventions that may support this requirement. Cell based therapy has the capacity to augment the patient’s own ability to manage their inflammatory status while at the same time sustaining anti-pathogen immunity. The studies highlighted in this manuscript outline the potential use of cell-based therapy for CF. The data demonstrate that 1) total bone marrow aspirates containing Cftr sufficient hematopoietic and mesenchymal stem cells (hMSCs) provide Cftr deficient mice >50% improvement in survival and improved management of infection and inflammation; 2) myeloid cells can provide sufficient Cftr to provide pre-clinical anti-inflammatory and antimicrobial benefit; 3) hMSCs provide significant improvement in survival and management of infection and inflammation in CF; 4) the combined interaction between macrophages and hMSCs can potentially enhance anti-inflammatory and antimicrobial support through manipulating PPARγ. These data support the development of optimized cell-based therapeutics to enhance CF patient’s own immune repertoire and capacity to maintain the balance between inflammation and pathogen management.

Characterization of the innate immune response in a novel murine model mimicking bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD), the most common complication of prematurity, arises from various factors that compromise lung development, including oxygen and inflammation. Hyperoxia has been used to mimic the disease in newborn rodents. The use of a second hit to induce systemic inflammation has been suggested as an added strategy to better mimic the inflammatory aspect of BPD. Here we report a novel 2 hit (2HIT) BPD model with in-depth characterization of the innate immune response, enabling mechanistic studies of therapies with an immunomodulatory component.

METHODS

C57BL/6N mice were exposed to 85% O₂ from postnatal day (P)1 to P7, and received postnatally (P3) Escherichia coli LPS. At various timepoints, immune activation in the lung and at the systemic level was analyzed by fluorescence-activated cell sorting (FACS), and gene and protein expressions.

RESULTS

2HIT mice showed fewer alveoli, increased lung compliance, and right ventricular hypertrophy. A transient proinflammatory cytokine response was observed locally and systemically. Type 2 anti-inflammatory cytokine expression was decreased in the lung together with the number of mature alveolar macrophages. Simultaneously, a Siglec-F intermediate macrophage population emerged.

CONCLUSION

This study provides long-term analysis of the 2HIT model, suggesting impairment of type 2 cytokine environment and altered alveolar macrophage profile in the lung.

IMPACT

We have developed a novel 2HIT mouse BPD model with postnatal LPS and hyperoxia exposure, which enables mechanistic studies of potential therapeutic strategies with an immunomodulatory component. This is the first report of in-depth characterization of the lung injury and recovery describing the evolution of the innate immune response in a standardized mouse model for experimental BPD with postnatal LPS and hyperoxia exposure. The 2HIT model has the potential to help understand the link between inflammation and impaired lung development, and will enable testing of new therapies in a short and more robust manner.

Sustained release buprenorphine effectively attenuates postoperative hypersensitivity in an incisional pain model in neonatal rats (Rattus norvegicus)

Despite the need for safe and effective postoperative analgesia in neonates, research regarding pain management in neonatal rodents is relatively limited. Here, we investigate whether sustained release buprenorphine (Bup SR) effectively attenuates thermal hypersensitivity in a neonatal rat model of incisional pain. Male and female postnatal day 3 Sprague Dawley rat pups (n = 34) were randomly assigned to one of four treatment groups: 1) saline (control), 0.1 mL, once subcutaneously (SC); 2) buprenorphine HCl (Bup HCl), 0.05 mg/kg, once SC; 3) low dose Bup SR (low-SR), 0.5 mg/kg, once SC; 4) high dose Bup SR (high-SR), 1 mg/kg, once SC. Pups were anesthetized with sevoflurane and a 0.5-cm long skin incision was made over the left lateral thigh. The underlying muscle was dissected and closed using surgical glue. Thermal hypersensitivity testing was performed at 24 h prior to surgery and subsequently at 1, 4, 8, 24, and 48 h post-surgery using an infrared diode laser. Thermal hypersensitivity was attenuated at 1 h post-surgery in the Bup HCl group, while it was attenuated through the entire postoperative period in both low-SR and high-SR groups. This data suggests that a single dose of low-SR (0.5 mg/kg) or high-SR (1 mg/kg) effectively attenuates thermal hypersensitivity for at least 8 h in neonatal rat pups.

Intratracheal administration of mesenchymal stem cell-derived extracellular vesicles reduces lung injuries in a chronic rat model of bronchopulmonary dysplasia

Early therapeutic effect of intratracheally (IT)-administered extracellular vesicles secreted by mesenchymal stem cells (MSC-EVs) has been demonstrated in a rat model of bronchopulmonary dysplasia (BPD) involving hyperoxia exposure in the first 2 postnatal weeks. The aim of this study was to evaluate the protective effects of IT-administered MSC-EVs in the long term. EVs were produced from MSCs following GMP standards. At birth, rats were distributed in three groups: (a) animals raised in ambient air for 6 weeks (n = 10); and animals exposed to 60% hyperoxia for 2 weeks and to room air for additional 4 weeks and treated with (b) IT-administered saline solution (n = 10), or (c) MSC-EVs (n = 10) on postnatal days 3, 7, 10, and 21. Hyperoxia exposure produced significant decreases in total number of alveoli, total surface area of alveolar air spaces, and proliferation index, together with increases in mean alveolar volume, mean linear intercept and fibrosis percentage; all these morphometric changes were prevented by MSC-EVs treatment. The medial thickness index for <100 µm vessels was higher for hyperoxia-exposed/sham-treated than for normoxia-exposed rats; MSC-EV treatment significantly reduced this index. There were no significant differences in interstitial/alveolar and perivascular F4/8-positive and CD86-positive macrophages. Conversely, hyperoxia exposure reduced CD163-positive macrophages both in interstitial/alveolar and perivascular populations and MSC-EV prevented these hyperoxia-induced reductions. These findings further support that IT-administered EVs could be an effective approach to prevent/treat BPD, ameliorating the impaired alveolarization and pulmonary artery remodeling also in a long-term model. M2 macrophage polarization could play a role through anti-inflammatory and proliferative mechanisms.

MSC Based Therapies to Prevent or Treat BPD-A Narrative Review on Advances and Ongoing Challenges

Bronchopulmonary dysplasia (BPD) remains one of the most devastating consequences of preterm birth resulting in life-long restrictions in lung function. Distorted lung development is caused by its inflammatory response which is mainly provoked by mechanical ventilation, oxygen toxicity and bacterial infections. Dysfunction of resident lung mesenchymal stem cells (MSC) represents one key hallmark that drives BPD pathology. Despite all progress in the understanding of pathomechanisms, therapeutics to prevent or treat BPD are to date restricted to a few drugs. The limited therapeutic efficacy of established drugs can be explained by the fact that they fail to concurrently tackle the broad spectrum of disease driving mechanisms and by the huge overlap between distorted signal pathways of lung development and inflammation. The great enthusiasm about MSC based therapies as novel therapeutic for BPD arises from the capacity to inhibit inflammation while simultaneously promoting lung development and repair. Preclinical studies, mainly performed in rodents, raise hopes that there will be finally a broadly acting, efficient therapy at hand to prevent or treat BPD. Our narrative review gives a comprehensive overview on preclinical achievements, results from first early phase clinical studies and challenges to a successful translation into the clinical setting.

Stem-cell therapy for bronchopulmonary dysplasia

PURPOSE OF REVIEW

Clinical trials of mesenchymal stem/stromal cell (MSC) therapy for bronchopulmonary dysplasia (BPD) are underway. A thorough understanding of the preclinical work that underpins these trials is critical for neonatal practitioners to properly evaluate them.

RECENT FINDINGS

Significant progress has been made in understanding that MSCs have anti-inflammatory and proangiogenic effects, and that these can be mediated by the noncellular exosome fraction of MSCs.

SUMMARY

In rodent hyperoxia models of BPD, MSCs have a proangiogenic effect mediated largely by vascular endothelial growth factor and shift the balance of endogenous lung cells from a proinflammatory to a prohealing phenotype. MSC-derived exosomes can recapitulate these effects.

Characterization of pulmonary immune responses to hyperoxia by high-dimensional mass cytometry analyses

Prolonged exposure to hyperoxia has deleterious effects on the lung, provoking both inflammation and alveolar injury. The elements of hyperoxic injury, which result in high rates of lethality in experimental models, are thought to include multicellular immune responses. To characterize these alterations in immune cell populations, we performed time-of-flight mass cytometry (CyTOF) analysis of CD45-expressing immune cells in whole lung parenchyma and the bronchoalveolar space of mice, exposed to 48 hours of hyperoxia together with normoxic controls. At the tested time point, hyperoxia exposure resulted in decreased abundance of immunoregulatory populations (regulatory B cells, myeloid regulatory cells) in lung parenchyma and markedly decreased proliferation rates of myeloid regulatory cells, monocytes and alveolar macrophages. Additionally, hyperoxia caused a shift in the phenotype of alveolar macrophages, increasing proportion of cells with elevated CD68, CD44, CD11c, PD-L1, and CD205 expression levels. These changes occurred in the absence of histologically evident alveolar damage and abundance of neutrophils in the parenchyma or alveolar space did not change at these time points. Collectively, these findings demonstrate that pulmonary response to hyperoxia involves marked changes in specific subsets of myeloid and lymphoid populations. These findings have important implications for therapeutic targeting in acute lung injury.

MSC Based Therapies-New Perspectives for the Injured Lung

Chronic lung diseases pose a tremendous global burden. At least one in four people suffer from severe pulmonary sequelae over the course of a lifetime. Despite substantial improvements in therapeutic interventions, persistent alleviation of clinical symptoms cannot be offered to most patients affected to date. Despite broad discrepancies in origins and pathomechanisms, the important disease entities all have in common the pulmonary inflammatory response which is central to lung injury and structural abnormalities. Mesenchymal stem cells (MSC) attract particular attention due to their broadly acting anti-inflammatory and regenerative properties. Plenty of preclinical studies provided congruent and convincing evidence that MSC have the therapeutic potential to alleviate lung injuries across ages. These include the disease entities bronchopulmonary dysplasia, asthma and the different forms of acute lung injury and chronic pulmonary diseases in adulthood. While clinical trials are so far restricted to pioneering trials on safety and feasibility, preclinical results point out possibilities to boost the therapeutic efficacy of MSC application and to take advantage of the MSC secretome. The presented review summarizes the most recent advances and highlights joint mechanisms of MSC action across disease entities which provide the basis to timely tackle this global disease burden.

The immunomodulatory effects of mesenchymal stem cells on long term pulmonary complications in an animal model exposed to a sulfur mustard analog

INTRODUCTION

Sulfur Mustard (SM) is one of the most lethal chemicals with major complications manifested in the lungs. Although the pathogenesis behind SM-induced lung injury still remains poorly understood, prolonged activation and the imbalance of two major macrophage populations (M1 and M2) have been suggested to be involved. Here, we tried to investigate the effectiveness of adipose-derived mesenchymal stem cells (AD-MSC) on long-term lesions induced by CEES, an SM analog. The modulation of pulmonary immune cells and alveolar macrophage phenotype alteration was studied in the animal model used.

METHODS

Histopathological changes were investigated in the lungs and analysis of surface markers of alveolar macrophages as well as their cytokine expression in the BAL fluid was carried out by flow cytometry and ELISA, respectively.

RESULTS

Treatment of mice with AD-MSC after intraperitoneal administration of CEES (10 mg/kg) reduces progressive histopathologic changes in the lung. Flow cytometric analysis of isolated alveolar macrophages in the bronchoalveolar lavage showed that the accumulation of both M1 and M2 macrophages in response to CEES was reduced by MSC administration. AD-MSCs caused a marked reduction in the CD86- and CD206-expressing macrophages compared to the untreated groups. The modulating effect of AD-MSCs in the M1-subset was much more significant compared to M2. These findings suggest that AD-MSCs understand their environment and restore the balance in disorders associated with Th1 or Th2 imbalance. Our results indicate that MSCs may represent an effective approach to repair lung injury induced by mustards.

Maternal Tn Immunization Attenuates Hyperoxia-Induced Lung Injury in Neonatal Rats Through Suppression of Oxidative Stress and Inflammation

Hyperoxia therapy is often required to treat newborns with respiratory disorders. Prolonged hyperoxia exposure increases oxidative stress and arrests alveolar development in newborn rats. Tn antigen is N-acetylgalactosamine residue that is one of the most remarkable tumor-associated carbohydrate antigens. Tn immunization increases the serum anti-Tn antibody titers and attenuates hyperoxia-induced lung injury in adult mice. We hypothesized that maternal Tn immunizations would attenuate hyperoxia-induced lung injury through the suppression of oxidative stress in neonatal rats. Female Sprague-Dawley rats (6 weeks old) were intraperitoneally immunized five times with Tn (50 μg/dose) or carrier protein at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the day of delivery. The pups were reared in room air (RA) or 2 weeks of 85% O₂, creating the four study groups: carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. The lungs were excised for oxidative stress, cytokine, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) expression, and histological analysis on postnatal day 14. Blood was withdrawn from dams and rat pups to check anti-Tn antibody using western blot. We observed that neonatal hyperoxia exposure reduced the body weight, increased 8-hydroxy-2-deoxyguanosine (8-OHdG) expression and lung cytokine (interleukin-4), increased mean linear intercept (MLI) values, and decreased vascular density and VEGF and PDGF-B expressions. By contrast, Tn immunization increased maternal and neonatal serum anti-Tn antibody titers on postnatal day 14, reduced MLI, and increased vascular density and VEGF and PDGF-B expressions to normoxic levels. Furthermore, the alleviation of lung injury was accompanied by a reduction in lung cytokine and 8-OHdG expression. Therefore, we propose that maternal Tn immunization attenuates hyperoxia-induced lung injury in neonatal rats through the suppression of oxidative stress and inflammation.