We previously found that human mesenchymal stem cells (MSC) or its conditioned medium restored lung protein permeability and reduced alveolar inflammation following E.coli endotoxin-induced acute lung injury (ALI) in an ex vivo perfused human lung in part through the secretion of soluble factors such as keratinocyte growth factor (KGF). Recently, MSC were found to release microvesicles (MV) that were biologically active because of the presence of mRNA or miRNA with reparative properties. MVs are circular fragments of membrane released from the endosomal compartment as exosomes or shed from the surface membranes. The current studies were designed to determine if MVs released by human bone marrow derived MSCs would be effective in restoring lung protein permeability and reducing inflammation in E.coli endotoxin-induced ALI in C57BL/6 mice. The intra-tracheal instillation of MVs improved several indices of ALI at 48 h. Compared to endotoxin-injured mice, MVs reduced extravascular lung water by 43% and reduced total protein levels in the bronchoalveolar lavage (BAL) fluid by 35%, demonstrating a reduction in pulmonary edema and lung protein permeability. MVs also reduced the influx of neutrophils and macrophage inflammatory protein-2 levels in the BAL fluid by 73% and 49% respectively, demonstrating a reduction in inflammation. KGF siRNA-pretreatment of MSC partially eliminated the therapeutic effects of MVs released by MSCs, suggesting that KGF protein expression was important for the underlying mechanism. In summary, human MSC derived microvesicles were therapeutically effective following E.coli endotoxin-induced ALI in mice in part through the expression of KGF mRNA in the injured alveolus.

Rationale: Microvesicles (MVs) are anuclear fragments of cells released from the endosomal compartment or shed from surface membranes. We and other investigators demonstrated that MVs released by mesenchymal stem cells (MSCs) were as effective as the cells themselves in inflammatory injuries, such as after endotoxininduced acute lung injury. However, the therapeutic effects of MVs in an infectious model of acute lung injury remain unknown.Objectives: We investigated the effects of human MSC MVs on lung inflammation, protein permeability, bacterial clearance, and survival after severe bacterial pneumonia.Methods: We tested the effects of MVs derived from human MSCs on Escherichia coli pneumonia in mice. We also studied the interactions between MVs and human monocytes and human alveolar epithelial type 2 cells.Measurements and Main Results: Administration of MVs derived from human MSCs improved survival in part through keratinocyte growth factor secretion and decreased the influx of inflammatory cells, cytokines, protein, and bacteria in mice injured with bacterial pneumonia. In primary cultures of human monocytes or alveolar type 2 cells, the uptake of MVs was mediated by CD44 receptors, which were essential for the therapeutic effects. MVs enhanced monocyte phagocytosis of bacteria while decreasing inflammatory cytokine secretion and increased intracellular ATP levels in injured alveolar epithelial type 2 cells. Prestimulation of MSCs with a toll-like receptor 3 agonist further enhanced the therapeutic effects of the released MVs.Conclusions: MVs derived from human MSCs were as effective as the parent stem cells in severe bacterial pneumonia.

The functional role of respiratory microbiota has attracted an accumulating attention recently. However, the role of respiratory microbiome in lung carcinogenesis is mostly unknown. Our study aimed to characterize and compare bilateral lower airway microbiome of lung cancer patients with unilateral lobar masses and control subjects. Protected bronchial specimen brushing samples were collected from 24 lung cancer patients with unilateral lobar masses (paired samples from cancerous site and the contralateral noncancerous site) and 18 healthy controls undergoing bronchoscopies and further analyzed by 16S rRNA amplicon sequencing. As results, significant decreases in microbial diversity were observed in patients with lung cancer in comparison to the controls, alpha diversity steadily declined from healthy site to noncancerous to cancerous site. Genus Streptococcus was significantly more abundant in cancer cases than the controls, while Staphylococcus was more abundant in the controls. The area under the curve of genus Streptococcus used to predict lung cancer was 0.693 (sensitivity = 87.5%, specificity = 55.6%). The abundance of genus Streptococcus and Neisseria displayed an increasing trend whereas Staphylococcus and Dialister gradually declined from healthy to noncancerous to cancerous site. Collectively, lung cancer-associated microbiota profile is distinct from that found in healthy controls, and the altered cancer-associated microbiota is not restricted to tumor tissue. The genus Streptococcus was abundant in lung cancer patients and exhibited moderate classification potential. The gradual microbiota profile shift from healthy site to noncancerous to paired cancerous site suggested a change of the microenvironment associated with the development of lung cancer.

Introduction Acute respiratory distress syndrome is a major cause of respiratory failure in critically ill patients. Despite extensive research into its pathophysiology, mortality remains high. No effective pharmacotherapy exists. Based largely on numerous preclinical studies, administration of mesenchymal stem or stromal cell (MSC) as a therapeutic for acute lung injury holds great promise, and clinical trials are currently underway. However, concern for the use of stem cells, specifically the risk of iatrogenic tumor formation, remains unresolved. Accumulating evidence now suggest that novel cell-free therapies including MSC-derived conditioned medium and extracellular vesicles released from MSCs might constitute compelling alternatives. Areas covered The current review summarizes the preclinical studies testing MSC conditioned medium and/or MSC extracellular vesicles as treatment for acute lung injury and other inflammatory lung diseases. Expert opinion While certain logistical obstacles limit the clinical applications of MSC conditioned medium such as the volume required for treatment, the therapeutic application of MSC extracellular vesicles remains promising, primarily due to ability of extracellular vesicles to maintain the functional phenotype of the parent cell. However, utilization of MSC extracellular vesicles will require large-scale production and standardization concerning identification, characterization and quantification.

Pneumocystis jirovecii pneumonia (PCP) can affect various types of immunocompromised patients. We sought to evaluate the diagnostic accuracy of (1→3)-β-D-glucan (BDG) for the diagnosis of PCP. We carried out a meta-analysis of relevant studies, identified through PubMed and Scopus. Eligible studies were those that reported BDG diagnostic data in cases with documented PCP and controls with other conditions. Cases of invasive fungal infections and healthy controls were excluded. We performed a bivariate meta-analysis of sensitivity and specificity and constructed a hierarchical summary receiver operating characteristics (HSROC) curve. Fourteen studies were included in the meta-analysis. BDG data were analysed for 357 PCP cases and 1723 controls. The average (95% confidence interval) sensitivity and specificity of BDG were 94.8% (90.8-97.1%) and 86.3% (81.7-89.9%), respectively. The positive and negative likelihood ratios were 6.9 (5.1-9.3) and 0.06 (0.03-0.11), respectively. The area under the HSROC curve was 0.965 (0.945-0.978). Serum BDG shows excellent sensitivity and very good specificity in the diagnosis of PCP. Still, in clinical practice the test results should be interpreted in the context of the underlying clinical characteristics of the individual patient.

Microvesicles (MVs) derived from human mesenchymal stem cells (MSC MVs) were demonstrated to ameliorate inflammation in lungs. We have found their content of mRNA for keratinocyte growth factor was partly involved in their therapeutic effects. As MSC MVs also contained a substantial quantity of angiopoietin-1 (Ang-1) mRNA, which plays an essential role in vascular stabilization and resolving inflammation, we hypothesized that Ang-1 mRNA might similarly account for a part of their therapeutic effects. We downregulated Ang-1 mRNA expression in MVs, using a lentivirus vector carrying Ang-1 short hairpin RNA to transfect MSCs. A mouse model of lipopolysaccharide induced acute lung injury (ALI) was used in vivo. We also studied in vitro interactions between Ang-1 mRNA deficient MVs on macrophages and human lung microvascular endothelial cells. Compared with negative control, Ang-1 mRNA deficient MVs increased the influx of neutrophils and macrophage inflammatory protein-2 levels in bronchoalveolar lavage fluid by 136% and 105%, respectively, suggesting a deteriorative lung inflammation and a failure to restore pulmonary capillary permeability assessed by Evan's blue dye and bronchoalveolar lavage albumin level. In vitro, the addition of Ang-1 mRNA deficient MVs failed to maintain the integrity of endotoxin-stimulated microvascular endothelial cells and abrogated the decrease in tumor necrosis factor-α level and the increase in interleukin-10 level mediated by negative control in RAW 264.7 cells. In summary, the therapeutic effects of MVs in ALI, and their immunomodulatory properties on macrophages were partly mediated through their content of Ang-1 mRNA. Stem Cells 2017;35:1849-1859.

Critically ill patients often suffer from multiple organ failures involving lung, kidney, liver or brain. Genomic, proteomic and metabolomic approaches highlight common injury mechanisms leading to acute organ failure. This underlines the need to focus on therapeutic strategies affecting multiple injury pathways. The use of adult stem cells such as mesenchymal stem or stromal cells (MSC) may represent a promising new therapeutic approach as increasing evidence shows that MSC can exert protective effects following injury through the release of pro-mitotic, anti-apoptotic, anti-inflammatory and immunomodulatory soluble factors. Furthermore, they can mitigate metabolomic and oxidative stress imbalance. In this work, we review the biological capabilities of MSC and the results of clinical trials using MSC as therapy in acute organ injuries. Although preliminary results are encouraging, more studies concerning safety and efficacy of MSC therapy are needed to determine their optimal clinical use.

Background Postoperative cognitive decline can be reproduced in animal models. In a well-validated rat model of the Metabolic Syndrome, we sought to investigate whether surgery induced a more severe and persistent form of cognitive decline similar to that noted in preliminary clinical studies. Methods In rats that had been selectively bred for low and high exercise endurance, the low capacity runners (LCR) exhibited features of Metabolic Syndrome (obesity, dyslipidemia, insulin resistance, and hypertension). Tibial fracture surgery was performed under isoflurane anesthesia in LCR and high capacity runner (HCR) rats and cognitive function was assessed postoperatively in a trace-fear conditioning paradigm and Morris Water Maze; non-operated rats were exposed to anesthesia and analgesia (sham). Group sizes were n = 6. Results On postoperative D7, LCR rats had shorter freezing times than postoperative HCR rats. Five months postoperatively, LCR rats had a flatter learning trajectory and took longer to locate the submerged platform than postoperative HCR rats; dwell-time in the target quadrant in a probe trial was shorter in the postoperative LCR compared to HCR rats. LCR and HCR sham rats did not differ in any test. Conclusion Postoperatively, LCR rats diverged from HCR rats exhibiting a greater decline in memory, acutely, with persistent learning and memory decline, remotely; this could not be attributed to changes in locomotor or swimming performance. This Metabolic Syndrome animal model of surgery-induced cognitive decline corroborates, with high fidelity, preliminary findings of postoperative cognitive dysfunction in Metabolic Syndrome patients.