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Background Sepsis is characterized by a complex immune response. This meta-analysis evaluated the clinical effectiveness of intravenous IgM-enriched immunoglobulin (IVIgGM) in patients with sepsis and septic shock. Methods Four databases, PubMed, the Cochrane Library, the ISI Web of Knowledge, and Embase, were systematically searched from inception to June 2018 to update the 2013 edition of the Cochrane review by two investigators, who independently selected studies, extracted relevant data, and evaluated study quality. Data were subjected to a meta-analysis and trial sequential analysis (TSA) for the primary and secondary outcomes. Level of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scale. Results Nineteen studies comprising 1530 patients were included in this meta-analysis. Pooled analyses showed that the use of IVIgGM reduced the mortality risk of septic patients (relative risk 0.60; 95% confidence interval [CI] 0.52–0.69, I 2 = 0%). TSA showed that IVIgGM had a significant effect on mortality. Additionally, the meta-analysis suggested that use of IVIgGM shortened length of mechanical ventilation (mean difference − 3.16 days; 95% CI − 5.71 to − 0.61 days) and did not shorten length of stay in the intensive care unit (mean difference − 0.38 days; 95% CI − 3.55 to 2.80 days). The GRADE scale showed that the certainty of the body of evidence was low for both benefits and IVIgGM. Conclusion Administration of IVIgGM to adult septic patients may be associated with reduced mortality. Treatment effects tended to be smaller or less consistent when including only those studies deemed adequate for each indicator. The available evidence is not clearly sufficient to support the widespread use of IVIgGM in the treatment of sepsis. Trial registration PROSPERO registration number: CRD42018084120. Registered on 11 February 2018. Electronic supplementary material The online version of this article (10.1186/s13613-019-0501-3) contains supplementary material, which is available to authorized users.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are the severe lung damage and respiratory failure without effective therapy. However, there was a lack of understanding of the mechanism by which exosomes regulate autophagy during ALI/ARDS. Here, we found lipopolysaccharide (LPS) significantly increased inflammatory factors, administration of exosomes released by human umbilical cord mesenchymal stem cells (hucMSCs) successfully improved lung morphometry. Further studies showed that miR-377-3p in the exosomes played a pivotal role in regulating autophagy, leading to protect LPS induced ALI. Compared to exosomes released by human fetal lung fibroblast cells (HFL-1), hucMSCs-exosomes overexpressing miR-377-3p more effectively suppressed the bronchoalveolar lavage (BALF) and inflammatory factors and induced autophagy, causing recoveration of ALI. Administration of miR-377-3p expressing hucMSCs-exosomes or its target regulatory-associated protein of mTOR (RPTOR) knockdown significantly reduced ALI. In summary, miR-377-3p released by hucMSCs-exosomes ameliorated Lipopolysaccharide-induced acute lung injury by targeting RPTOR to induce autophagy in vivo and in vitro.

Background: Acute lung injury (ALI) is a devastating syndrome with no effective pharmacological therapies in the clinic. Mesenchymal stromal cells (MSCs) have been demonstrated to promote inflammation resolution and tissue repair in ALI. However, the specific mechanisms of this have not been clearly elucidated. Stanniocalcin-2 (STC2) is a stress-responsive protein that has anti-oxidative properties. Our previous study found that STC2 is a highly expressed stanniocalcin in MSCs, which may be involved in immunomodulatory activities. However, the role of STC2 in MSCs to resolve ALI has never been elucidated. Methods: Specific shRNA was used to downregulate STC2 in MSCs. We detected ROS, cell apoptosis, and paracrine factors changes in MSCs. STC2-associated antioxidant genes were also investigated by Coimmunoprecipitation (Co-IP) and immunofluorescence. Macrophage (THP1 cells) phenotype transitions were measured by flow cytometry after coculturing with MSCs in vitro. Then, we used MSCs to treat LPSinduced ALI in mice, and assessed injury scores inflammation, and antioxidant activities in the lungs of the mice. Alveolar macrophage (AM) phenotypes and CFSE-labeled MSC apoptosis in collected bronchoalveolar fluids (BALF) were also analyzed by flow cytometry. Results: After the STC2 knockdown, MSCs increased ROS generation and cell apoptosis after PX12 pretreatment. The antioxidant protein Nrf2 was colocalized with STC2 in the nucleus. A lack of STC2 expression in MSCs produced less interleukin 10 (IL10) and blunted macrophage polarization in THP1 cells.Furthermore, in the murine LPS-induced ALI model, the STC2 knockdown counteracted the inflammatory resolution and antioxidative effect of MSCs in the lungs. MSC shSTC2 -treated mice had a higher lung injury score than the controls, which may be attributed to diminished AM polarization and increased apoptosis of MSCs in vivo.Conclusions: Collectively, these results suggested that STC2 is essential to the anti-oxidative and antiinflammation properties of MSCs and could prove to be crucial for stem cell therapies for ALI.

Objectives Acute lung injury (ALI) remains a common cause of morbidity and mortality worldwide, and to date, there is no effective treatment for ALI. Previous studies have revealed that topical administration of mesenchymal stem cells (MSCs) can attenuate the pathological changes in experimental acute lung injury. Heat shock (HS) pretreatment has been identified as a method to enhance the survival and function of cells. The present study aimed to assess whether HS-pretreated MSCs could enhance immunomodulation and recovery from ALI. Materials and methods HS pretreatment was performed at 42 °C for 1 h, and changes in biological characteristics and secretion functions were detected. In an in vivo mouse model of ALI, we intranasally administered pretreated umbilical cord-derived MSCs (UC-MSCs), confirmed their therapeutic effects, and detected the phenotypes of the macrophages in bronchoalveolar lavage fluid (BALF). To elucidate the underlying mechanisms, we cocultured pretreated UC-MSCs with macrophages in vitro, and the expression levels of inflammasome-related proteins in the macrophages were assessed. Results The data showed that UC-MSCs did not exhibit significant changes in viability or biological characteristics after HS pretreatment. The administration of HS-pretreated UC-MSCs to the ALI model improved the pathological changes and lung damage-related indexes, reduced the proinflammatory cytokine levels, and modulated the M1/M2 macrophage balance. Mechanistically, both the in vivo and in vitro studies demonstrated that HS pretreatment enhanced the protein level of HSP70 in UC-MSCs, which negatively modulated NLR family pyrin domain containing 3 (NLRP3) inflammasome activation in alveolar macrophages. These effects were partially reversed by knocking down HSP70 expression. Conclusion HS pretreatment can enhance the beneficial effects of UC-MSCs in inhibiting NLRP3 inflammasome activation in macrophages during ALI. The mechanism may be related to the upregulated expression of HSP70. Graphical abstract

The aim of the present study was topreliminarily visualize the distribution of humanumbilical cord-derived-mesenchymal stem cells (hUC-MSCs) in treating acute lung injury (ALI) using a targeted fluorescent technique. Anovel fluorescent molecule probe was first synthesized via the specific binding of antigen and antibody in vitro to label the hUC-MSCs. Two groups of mice, comprising a normal saline (NS)+MSC group and lipopolysaccharide (LPS)+MSC group, were subjected to optical imaging. At 4 h following ALI mouse model construction, the labeled hUC-MSCs were transplanted into the mice in the NS+MSC group and LPS+MSC group by tail vein injection. The mice were sacrificed 30 min, 1 day, 3 days and 7 days following injection of the labeled hUC-MSCs, and the lungs, heart, spleen, kidneys and liver were removed. The excised lungs, heart, spleen, kidneys and liver were then detected on asmall animal fluorescent imager. The fluorescent results showed that the signal intensity in the lungs of the LPS+MSC group was significantly higher, compared with that of the NS+MSC group at 30 min (3.53±0.06×10−4, vs. 1.95±0.05×10−4 scaled counts/sec), 1 day (36.20±0.77×10−4, vs. 23.45±0.43×10−4 scaled counts/sec), 3 days (11.83±0.26×10−4, vs. 5.39±0.10×10−4 scaled counts/sec), and 7 days (3.14±0.04×10−4, vs. 0.00±0.00×10−4 scaled counts/sec; all P<0.05). The fluorescence intensity in the liver of the LPS+MSC group, vs. NS+MSC group was measured at 30 min (0.00±0.00×10−4, vs. 0.00±0.00×10−4 scaled counts/sec); 1 day (5.53±0.08×10−4, vs. 5.44±0.16×10−4 scaled counts/sec); 3 days (0.00±0.00×10−4, vs. 8.67±0.05×10−4 scaled counts/sec); 7 days (0.00±0.00×10−4, vs. 0.00±0.00×10−4 scaled counts/sec). The signal intensity of the heart, spleen and kidneys was minimal. In conclusion, the novel targeted fluorescence molecular probe was suitable for tracking the distribution processes of hUC-MSCs in treating ALI.

Background and Purpose: Both NLRP3 inflammasome and chemokines are involved in the initiation and development of acute lung inflammation, but the underlying mechanism is still elusive. The present study investigated the role of chemokines and NLRP3 in recruiting neutrophils in the early phase of acute lung injury. Methods: In an endotoxin (lipopolysaccharide [LPS])-induced acute lung injury model, we measured the lung injury severity, myeloperoxidase (MPO) activity and chemokine profiles in wild-type (WT) and NLRP3 knockout (NLRP3-/-) mice, and then identified the key chemokines by specific antibody blockage. Results: The results showed that NLRP3 deficiency was associated with alleviating lung damage, by reducing alveolar epithelial cell apoptosis and decreasing neutrophil accumulation. Furthermore, compared with WT mice, IL-1β, CCL2, CXCL1, CXCL5 and CXCL12 levels from the serum of NLRP3-/mice were much lower after exposure to LPS. However, in lung tissue, only lower CXCL12 levels were observed from the NLRP3-/-ALI mice, and higher levels of CXCR4 were expressed in NLRP3-/neutrophils. Blockage of CXCL12 dramatically relieved the severity of ALI and reduced neutrophil accumulation in the lung. Conclusion: NLRP3 alters CXCL12 expression in acute lung injury. CXCL12 is crucial for neutrophil recruitment in NLRP3-mediated neutrophilic lung injury.

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