Project description:Peripheral blood neutrophils were isolated from septic patients and treated in vitro with LPS or HMGB1 Experiment Overall Design: 8 patients, each contributing a control, LPS-treated, and HMGB1-treated neutrophil sample.
Project description:Extracellular cold-inducible RNA-binding protein (eCIRP) is a key mediator of severity and mortality in sepsis. We found that stimulation of mouse bone marrow–derived neutrophils (BMDNs) with eCIRP generated a distinct neutrophil subpopulation, characterized by cell surface markers of both antigen-presenting cells and aged neutrophils as well as expression of IL-12, which we named antigen-presenting aged neutrophils (APANs). The frequency of APANs was significantly increased in the blood, spleen, and lungs of WT mice subjected to cecal ligation and puncture–induced sepsis but not in CIRP–/– mice. Patients with sepsis had a significant increase in circulating APAN counts compared with healthy individuals. Compared with non–APAN-transferred mice, APAN-transferred septic mice had increased serum levels of injury and inflammatory markers, exacerbated acute lung injury (ALI), and worsened survival. APANs and CD4+ T cells colocalized in the spleen, suggesting an immune interaction between these cells. APANs cocultured with CD4+ T cells significantly induced the release of IFN-γ via IL-12. BMDNs stimulated with eCIRP and IFN-γ underwent hyper-NETosis. Stimulating human peripheral blood neutrophils with eCIRP also induced APANs, and stimulating human neutrophils with eCIRP and IFN-γ caused hyper-NETosis. Thus, eCIRP released during sepsis induced APANs to aggravate ALI and worsen the survival of septic animals via CD4+ T cell activation, Th1 polarization, and IFN-γ–mediated hyper-NETosis.
Project description:Acute Lung Injury (ALI) can cause Acute Respiratory Distress Syndrome (ARDS), a lethal condition with limited treatment options and currently a common global cause of death due to COVID-19-induced ALI. ARDS secondary to Transfusion-Related Acute Lung Injury (TRALI) has been recapitulated pre-clinically by anti-MHC-I antibody administration to LPS-primed mice. In this model, we demonstrated that inhibitors of PTP1B, a protein tyrosine phosphatase that regulates signaling pathways of fundamental importance to homeostasis and inflammation, prevented lung injury and increased survival. Treatment with PTP1B inhibitors attenuated the aberrant neutrophil function that drives ALI, and was associated with release of myeloperoxidase, suppression of Neutrophil Extracellular Trap (NET) formation, and inhibition of neutrophil migration. Mechanistically, reduced signaling through the CXCR4 chemokine receptor, particularly to the activation of mTOR, was essential for these effects, linking PTP1B in hibition to promoting an aged neutrophil phenotype. Considering dysregulated activation of neutrophils is implicated in sepsis and can cause collateral tissue damage, we demonstrated also that PTP1B inhibitors improved survival and ameliorated lung injury in the LPS-induced sepsis model. Our data highlight PTP1B inhibition for prevention of TRALI and ARDS from multiple etiologies.
Project description:This project aimed to define the proteome of inflammatory lung neutrophils and determine how his is regulated by exposure to in vivo hypoxia. An acute lung injury was induced using nebulised LPS. Following LPS administration mice were housed in either normal room air or in a hypoxic chamber set at an inspired oxygen concentration of 10%. Highly pure bronchoalveolar lavage (BAL) neutrophils were isolated from the lungs of C57Bl6 mice 24 hours after being treated with LPS.
Project description:Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is an inflammatory process of the lungs characterized by increased permeability of the alveolar-capillary membrane with subsequent interstitial/alveolar edema and diffuse alveolar damage. ALI/ARDS can be the results of either direct or indirect lung injury, with pneumonia being the most common direct pulmonary insult and sepsis the most common extra-pulmonary cause. In this study, we employed the murine lipopolysaccharide (LPS)-induced direct and indirect lung injury model to explore the pathogenic mechanisms of pulmonary and extra-pulmonary ARDS, using an unbiased, discovery and quantitative proteomic approach. A total of 1,017 proteins were both identified and quantified in bronchoalveolar lavage fluid (BALF) from control, intratracheal LPS (I.T. LPS, 0.1 mg/kg) and intraperitoneal LPS (I.P. LPS, 5 mg/kg) treated mice. The two LPS groups shared 13 up-regulated and 22 down-regulated proteins compared to the control group. Among them, molecules related to bronchial and type II alveolar epithelial cell functions including cell adhesion molecule 1 and surfactant protein B were reduced, whereas lactotransferrin and resistin like alpha involved in lung innate immunity were upregulated in both LPS groups. Proteomic profiling also identified significant differences in BALF proteins between I.T. and I.P. LPS groups. Ingenuity pathway analysis revealed that acute-phase response signaling was activated by both I.T. and I.P. LPS, however, the magnitude of activation is much greater in I.T. LPS group compared to I.P. LPS group. Intriguingly, two canonical signaling pathways, liver X receptor/retinoid X receptor activation and the production of nitric oxide and reactive oxygen species in macrophages, were activated by I.T. LPS but suppressed by I.P. LPS. In addition, CXCL15 (also known as lungkine) was also up-regulated by I.T LPS but down-regulated by I.P. LPS. In conclusion, our quantitative discovery-based proteomic approach identified commonalities as well as significant differences in BALF protein expression profiles in LPS-induced direct and indirect lung injury, and importantly, LPS-induced indirect lung injury results in suppression of select components of lung innate immunity, which could contribute to the so-called “immunoparalysis” in sepsis patients.
Project description:To investigate the role of recipient neutrophil intracellular HMGB1 in early allograft injury after liver transplant. Using a mouse orthotopic liver transplant model, as well as LPS injection, we found that neutrophils significantly infiltrate the liver after liver transplant and LPS challenge. Deficiency of neutrophil HMGB1 enhances their activation, boosts their pro-oxidant and pro-inflammatory phenotype, and hinders biosynthesis and metabolism of inositol polyphosphates. Overall, these events exacerbate early allograft injury after liver transplant.
Project description:Polymorphonuclear cells (neutrophils) play an important role in the systemic inflammatory response syndrome and the development of sepsis. These cells are essential for the defense against microorganisms, but may also cause tissue damage. Therefore, neutrophil numbers and activity are considered to be tightly regulated. Previous studies have investigated gene transcription during experimental endotoxemia in whole blood and peripheral blood mononuclear cells. However, the gene transcription response of the circulating pool of neutrophils to systemic inflammatory stimulation in vivo is currently unclear. We examined neutrophil gene transcription kinetics in healthy human subjects (n=4) administered a single dose of endotoxin (LPS, 2 ng/kg iv). In addition, freshly isolated neutrophils were stimulated ex vivo with LPS, TNFM-NM-1, G-CSF and GM-CSF to identify stimulus-specific gene transcription responses. Whole transcriptome microarray analysis of circulating neutrophils at 2, 4 and 6 hours after LPS infusion revealed activation of inflammatory networks which are involved in signaling of TNFM-NM-1 and IL-1M-NM-1 and IL-1M-NM-2. The transcriptome profile of inflammatory activated neutrophils in vivo reflects extended survival and regulation of inflammatory responses. We show that these changes in neutrophil transcriptome are most likely due to a combination of early activation of circulating neutrophils by TNFM-NM-1 and G-CSF and a mobilization of young neutrophils from the bone marrow. After LPS infusion blood was taken at t=0, t=2, t=4 and t=6 hours. Neutrophils were isolated and gene expression of these cells was assessed. T=2, t=4 and t=6 were related to t=0 as control condition
Project description:Although the accumulation of neutrophils in the lungs and airways is common to many inflammatory lung diseases, including acute lung injury, the alterations that neutrophils undergo as they leave the peripheral circulation and migrate into the lungs have not been well characterized. Human volunteers were exposed to endotoxin by bronchoscopic instillation. The resulting air space neutrophil accumulation and peripheral blood neutrophils were isolated 16 h later, compared with circulating neutrophils isolated before or after to the pulmonary endotoxin exposure, and compared with circulating neutrophils exposed to endotoxin in vitro. Microarray analysis was performed on air space, circulatory, and in vitro endotoxin-stimulated neutrophils. Functional analysis included the determination of neutrophil apoptosis, chemotaxis, release of cytokines and growth factors, and superoxide anion release. Dramatic gene expression differences were apparent between air space and circulating neutrophils: approximately 15% of expressed genes have altered expression levels, including broad increases in inflammatory- and chemotaxis-related genes, as well as antiapoptotic and IKK-activating pathways. Functional analysis of air space compared with circulating neutrophils showed increased superoxide release, diminished apoptosis, decreased IL-8-induced chemotaxis, and a pattern of IL-8, macrophage inflammatory protein-1beta, monocyte chemoattractant protein-1, and tumor necrosis factor-alpha release different from either unstimulated or LPS-stimulated circulating neutrophils. Many of these changes are not elicited by in vitro treatment with endotoxin. Limited differences were detected between circulating neutrophils isolated before and 16 h after pulmonary endotoxin instillation. These results suggest that neutrophils sequestered in the lung become fundamentally different from those resident in the circulation, and this difference is distinct from in vitro activation with endotoxin.
Project description:Lactoferrin (LF) is an iron-binding multifunctional cationic glycoprotein secreted by exocrine glands and neutrophils in mammals. In this study, we created a mouse model of lipopolysaccharide (LPS)-induced acute lung injury and explored the anti-inflammatory effect and mechanism of bovine lactoferrin (bLF) in acute lung injury using the RNA sequencing (RNA-seq) technology and transcriptome analysis.