Osteopontin mediates murine transfusion-related acute lung injury via stimulation of pulmonary neutrophil accumulation

Quercetin regulates pulmonary vascular remodeling in pulmonary hypertension by downregulating TGF-β1-Smad2/3 pathway

BACKGROUND

Pulmonary arterial hypertension (PAH) is a worldwide challenging disease characterized by progressive elevation of pulmonary artery pressure. The proliferation, migration and phenotypic transformation of pulmonary smooth muscle cells are the key steps of pulmonary vascular remodeling. Quercetin (3,3', 4', 5, 6-pentahydroxyflavone, Que) is a natural flavonol compound that has antioxidant, anti-inflammatory, anti-tumor and other biological activities. Studies have shown that Que has therapeutic effects on PAH. However, the effect of quercetin on pulmonary vascular remodeling in PAH and its mechanism remain unclear.

METHODS AND RESULTS

In vivo, PAH rats were constructed by intraperitoneal injection of monocrotaline (MCT) at 60 mg/kg. Human pulmonary artery smooth muscle cells (HPASMCs) were treated with platelet-derived growth factor BB (PDGF-BB) 20 ng/mL to construct PAH cell model in vitro. The results showed that in vivo studies, MCT could induce right ventricular wall hyperplasia, narrow the small and medium pulmonary artery cavity, up-regulate the expression of proliferating and migration-related proteins proliferating cell nuclear antigen (PCNA) and osteopontin (OPN), and down-regulate the expression of alpha-smooth muscle actin (α-SMA). Que reversed the MCT-induced results. This process works by down-regulating the transforming growth factor-β1 (TGF-β1)/ Smad2/3 signaling pathway. In vitro studies, Que had the same effect on PDGF-BB-induced proliferation and migration cell models.

CONCLUSIONS

Que inhibits the proliferation, migration and phenotypic transformation of HPASMCs by down-regulating TGF-β1/Smad2/Smad3 pathway, thereby reducing right ventricular hyperplasia (RVH) and pulmonary vascular remodeling, providing potential pharmacological and molecular explanations for the treatment of PAH.

Targeting mast cell activation alleviates anti-MHC I antibody and LPS-induced TRALI in mice by pharmacologically blocking the TLR3 and MAPK pathway

Transfusion-related lung injury (TRALI) poses a significant risk following blood transfusion and remains the primary cause of transfusion-related morbidity and mortality, primarily driven by the activation of immune cells through anti-major histocompatibility complex class I (anti-MHC I) antibody. However, it remains to be defined how immune microenvironmental cue contributes to TRALI. Here, we uncover that activated mast cells within the immune microenvironment promote lung inflammation and injury in antibody-mediated TRALI, both in vitro and in vivo. This was demonstrated by co-culturing lipopolysaccharide (LPS)-pretreated mast cell line with anti-MHC I antibody and establishing a "two-hit" TRALI mouse model through intratracheal injection of LPS followed by tail-vein injection of anti-MHC I antibody. Importantly, mast cell-deficient KitW-sh/W-sh mice exhibited markedly reduced lung inflammation and injury responses in antibody-mediated TRALI compared with wild-type mice. Mechanistically, activation of toll-like receptor 3 (TLR3)/mitogen-activated protein kinase (MAPK) signaling pathway in mast cells contributes to the enhanced production of proinflammatory factors. These excessive proinflammatory factors produced by activated mast cells contribute to lung inflammation and injury in antibody-mediated TRALI. Pharmacologically targeting the TLR3/MAPK pathway to inhibit mast cell activation normalizes the proinflammatory microenvironment and alleviates lung inflammation and injury in the preclinical TRALI mouse model. Overall, we find that activation of mast cells via the TLR3/MAPK pathway contributes to lung inflammation and injury in antibody-mediated TRALI, providing novel insights into its underlying mechanisms. Furthermore, targeting activated mast cells and the associated pathway offers potential therapeutic strategies for antibody-mediated TRALI.

Developments in Transfusion Medicine: Pulmonary Transfusion Reactions and Novel Blood Cell Labeling Techniques

Staying updated on advancements in transfusion medicine is crucial, especially in critical care and perioperative setting, where timely and accurate transfusions can be lifesaving therapeutic interventions. This narrative review explores the landscape of transfusion-related adverse events, focusing on pulmonary transfusion reactions such as transfusion-associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI). TACO and TRALI are the leading causes of transfusion-related morbidity and mortality; however, specific treatments are lacking. Understanding the current incidence, diagnostic criteria, pathogenesis, treatment, and prevention strategies can equip clinicians to help reduce the incidence of these life-threatening complications. The review discusses emerging pathogenic mechanisms, including the possible role of inflammation in TACO and the mechanisms of reverse TRALI and therapeutic targets for TACO and TRALI, emphasizing the need for further research to uncover preventive and treatment modalities. Despite advancements, significant gaps remain in our understanding of what occurs during transfusions, highlighting the necessity for improved monitoring methods. To address this, the review also presents novel blood cell labeling techniques in transfusion medicine used for improving monitoring, quality assessment, and as a consequence, potentially reducing transfusion-related complications. This article aims to provide an update for anesthesiologists, critical care specialists, and transfusion medicine professionals regarding recent advancements and developments in the field of transfusion medicine.

Targeted Macrophage CRISPR-Cas13 mRNA Editing in Immunotherapy for Tendon Injury

CRISPR-Cas13 holds substantial promise for tissue repair through its RNA editing capabilities and swift catabolism. However, conventional delivery methods fall short in addressing the heightened inflammatory response orchestrated by macrophages during the acute stages of tendon injury. In this investigation, macrophage-targeting cationic polymers are systematically screened to facilitate the entry of Cas13 ribonucleic-protein complex (Cas13 RNP) into macrophages. Notably, SPP1 (OPN encoding)-producing macrophages are recognized as a profibrotic subtype that emerges during the inflammatory stage. By employing ROS-responsive release mechanisms tailored for macrophage-targeted Cas13 RNP editing systems, the overactivation of SPP1 is curbed in the face of an acute immune microenvironment. Upon encapsulating this composite membrane around the tendon injury site, the macrophage-targeted Cas13 RNP effectively curtails the emergence of injury-induced SPP1-producing macrophages in the acute phase, leading to diminished fibroblast activation and mitigated peritendinous adhesion. Consequently, this study furnishes a swift RNA editing strategy for macrophages in the inflammatory phase triggered by ROS in tendon injury, along with a pioneering macrophage-targeted carrier proficient in delivering Cas13 into macrophages efficiently.

The role of macrophage polarization in tendon healing and therapeutic strategies: Insights from animal models

Tendon injuries, a common musculoskeletal issue, usually result in adhesions to the surrounding tissue, that will impact functional recovery. Macrophages, particularly through their M1 and M2 polarizations, play a pivotal role in the inflammatory and healing phases of tendon repair. In this review, we explore the role of macrophage polarization in tendon healing, focusing on insights from animal models. The review delves into the complex interplay of macrophages in tendon pathology, detailing how various macrophage phenotypes contribute to both healing and adhesion formation. It also explores the potential of modulating macrophage activity to enhance tendon repair and minimize adhesions. With advancements in understanding macrophage behavior and the development of innovative biomaterials, this review highlights promising therapeutic strategies for tendon injuries.

Xuebijing improves inflammation and pyroptosis of acute lung injury by up-regulating miR-181d-5p-mediated SPP1 inactivation

BACKGROUND

Xuebijing (XBJ) is widely applied in the treatment of Acute Lung Injury (ALI). This study focused on the potential mechanism of XBJ in Lipopolysaccharide (LPS)-induced ALI.

METHODS

The rat ALI model was established by injection of LPS (10 mg/kg) and pretreated with XBJ (4 mL/kg) three days before LPS injection. BEAS-2B cell line was stimulated with LPS (1 μg/mL) and ATP (5 mM) to induce pyroptosis, and XBJ (2 g/L) was pretreated 24h before induction. The improvement effects of XBJ on pulmonary edema, morphological changes, and apoptosis in ALI lung tissue were evaluated by lung wet/dry weight ratio, HE-staining, and TUNEL staining. Inflammatory cytokines in lung tissue and cell supernatant were determined by ELISA. pyroptosis was detected by flow cytometry. Meanwhile, the expressions of miR-181d-5p, SPP1, p-p65, NLRP3, ASC, caspase-1, p20, and GSDMD-N in tissues and cells were assessed by RT-qPCR and immunoblotting. The relationship between miR-181d-5p and SPP1 in experimental inflammation was reported by dual luciferase assay.

RESULTS

XBJ could improve inflammation and pyroptosis of ALI by inhibiting contents of inflammatory cytokines, and levels of inflammation- and pyroptosis-related proteins. Mechanistically, XBJ could up-regulate miR-181d-5p and inhibit SPP1 in ALI. miR-181d-5p can target the regulation of SPP1. Depressing miR-181d-5p compensated for the ameliorative effect of XBJ on ALI, and overexpressing SPP1 suppressed the attenuating effect of XBJ on LPS-induced inflammation and pyroptosis.

CONCLUSION

XBJ can regulate the miR-181d-5p/SPP1 axis to improve inflammatory response and pyroptosis in ALI.

Osteopontin: A Novel Therapeutic Target for Respiratory Diseases

Osteopontin (OPN) is a multifunctional phosphorylated protein that is involved in physiological and pathological events. Emerging evidence suggests that OPN also plays a critical role in the pathogenesis of respiratory diseases. OPN can be produced and secreted by various cell types in lungs and overexpression of OPN has been found in acute lung injury/acute respiratory distress syndrome (ALI/ARDS), pulmonary hypertension (PH), pulmonary fibrosis diseases, lung cancer, lung infection, chronic obstructive pulmonary disease (COPD), and asthma. OPN exerts diverse effects on the inflammatory response, immune cell activation, fibrosis and tissue remodeling, and tumorigenesis of these respiratory diseases, and genetic and pharmacological moudulation of OPN exerts therapeutic effects in the treatment of respiratory diseases. In this review, we summarize the recent evidence of multifaceted roles and underlying mechanisms of OPN in these respiratory diseases, and targeting OPN appears to be a potential therapeutic intervention for these diseases.

Complement activation drives antibody-mediated transfusion-related acute lung injury via macrophage trafficking and formation of NETs

ABSTRACT

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-related fatalities and, to date, is without available therapies. Here, we investigated the role of the complement system in TRALI. Murine anti-major histocompatibility complex class I antibodies were used in TRALI mouse models, in combination with analyses of plasma samples from patients with TRALI. We found that in vitro complement activation was related to in vivo antibody-mediated TRALI induction, which was correlated with increased macrophage trafficking from the lungs to the blood in a fragment crystallizable region (Fc)-dependent manner and that this was dependent on C5. Human immunoglobulin G 1 variants of the murine TRALI-inducing antibody 34-1-2S, either unable to activate complement and/or bind to Fcγ receptors (FcγRs), revealed an essential role for the complement system, but not for FcγRs, in the onset of 34-1-2S-mediated TRALI in mice. In addition, we found high levels of complement activation in the plasma of patients with TRALI (n = 53), which correlated with elevated neutrophil extracellular trap (NET) markers. In vitro we found that NETs could be formed in a murine, 2-hit model, mimicking TRALI with lipopolysaccharide and C5a stimulation. Collectively, this reveals a critical role of Fc-mediated complement activation in TRALI, with a direct relation to macrophage trafficking from the lungs to the blood and an association with NET formation, suggesting that targeting the complement system may be an attractive therapeutic approach for combating TRALI.

Crosstalk between neutrophil extracellular traps and immune regulation: insights into pathobiology and therapeutic implications of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death, occurring during or within 6 hours after transfusion. Reports indicate that TRALI can be categorized as having or lacking acute respiratory distress syndrome (ARDS) risk factors. There are two types of TRALI in terms of its pathogenesis: antibody-mediated and non-antibody-mediated. The key initiation steps involve the priming and activation of neutrophils, with neutrophil extracellular traps (NETs) being established as effector molecules formed by activated neutrophils in response to various stimuli. These NETs contribute to the production and release of reactive oxygen species (ROS) and participate in the destruction of pulmonary vascular endothelial cells. The significant role of NETs in TRALI is well recognized, offering a potential pathway for TRALI treatment. Moreover, platelets, macrophages, endothelial cells, and complements have been identified as promoters of NET formation. Concurrently, studies have demonstrated that the storage of platelets and concentrated red blood cells (RBC) can induce TRALI through bioactive lipids. In this article, recent clinical and pre-clinical studies on the pathophysiology and pathogenesis of TRALI are reviewed to further illuminate the mechanism through which NETs induce TRALI. This review aims to propose new therapeutic strategies for TRALI, with the hope of effectively improving its poor prognosis.

Functionalized Decellularized Bone Matrix Promotes Bone Regeneration by Releasing Osteogenic Peptides

The decellularized bone matrix (DCB) provides a promising bone substitute for the treatment of bone defects because of its similar biochemical, biophysical, and mechanical properties to normal bone tissue. However, the decellularized procedure also greatly reduced its osteogenic induction activity. In this study, peptides derived from the knuckle epitope of bone morphogenetic protein-2 were incorporated into the thermo-sensitive hydrogel poloxamer 407, and the peptide-loaded hydrogel was then filled into the pores of DCB to construct a functionalized scaffold with enhanced osteogenesis. In vitro studies have shown that the functionalized DCB scaffold possessed appropriate mechanical properties and biocompatibility and exhibited a sustained release profile of osteogenic peptide. These performances critically facilitated cell proliferation and cell spreading of bone marrow mesenchymal stem cells and upregulated the expression of osteogenic-related genes by activating the Smad/Runx2 signaling pathway, thereby promoting osteogenic differentiation and extracellular matrix mineralization. Further in vivo studies demonstrated that the functionalized DCB scaffold accelerated the repair of critical radial defects in rabbits without inducing excessive graft-related inflammatory responses. These results suggest a clinically meaningful strategy for the treatment of large segmental bone defects, and the prepared osteogenic peptide modified composite DCB scaffold has great application potential for bone regeneration.

Mesenchymal stem cells shift the pro-inflammatory phenotype of neutrophils to ameliorate acute lung injury

BACKGROUND

Mesenchymal stem cell (MSC) treatment plays a major role in the management of acute lung injury (ALI), and neutrophils are the initial line of defense against ALI. However, the effect of MSCs on neutrophils in ALI remains mostly unknown.

METHODS

We investigated the characteristics of neutrophils in lung tissue of ALI mice induced by lipopolysaccharide after treatment with MSCs using single-cell RNA sequencing. Neutrophils separated from lung tissue in ALI were co-cultured with MSCs, and then samples were collected for reverse transcription-polymerase chain reaction and flow cytometry.

RESULTS

During inflammation, six clusters of neutrophils were identified, annotated as activated, aged, and circulatory neutrophils. Activated neutrophils had higher chemotaxis, reactive oxygen species (ROS) production, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase scores than aged neutrophils. Circulatory neutrophils occurred mainly in healthy tissue and were characterized by higher expression of Cxcr2 and Sell. Activated neutrophils tended to exhibit higher expression of Cxcl10 and Cd47, and lower expression of Cd24a, while aged neutrophils expressed a lower level of Cd47 and higher level of Cd24a. MSC treatment shifted activated neutrophils toward an aged neutrophil phenotype by upregulating the expression of CD24, thereby inhibiting inflammation by reducing chemotaxis, ROS production, and NADPH oxidase.

CONCLUSION

We identified the immunosuppressive effects of MSCs on the subtype distribution of neutrophils and provided new insight into the therapeutic mechanism of MSC treatment in ALI.

Update on transfusion-related acute lung injury: an overview of its pathogenesis and management

Transfusion-related acute lung injury (TRALI) is a severe adverse event and a leading cause of transfusion-associated death. Its poor associated prognosis is due, in large part, to the current dearth of effective therapeutic strategies. Hence, an urgent need exists for effective management strategies for the prevention and treatment of associated lung edema. Recently, various preclinical and clinical studies have advanced the current knowledge regarding TRALI pathogenesis. In fact, the application of this knowledge to patient management has successfully decreased TRALI-associated morbidity. This article reviews the most relevant data and recent progress related to TRALI pathogenesis. Based on the existing two-hit theory, a novel three-step pathogenesis model composed of a priming step, pulmonary reaction, and effector phase is postulated to explain the process of TRALI. TRALI pathogenesis stage-specific management strategies based on clinical studies and preclinical models are summarized with an explication of their models of prevention and experimental drugs. The primary aim of this review is to provide useful insights regarding the underlying pathogenesis of TRALI to inform the development of preventive or therapeutic alternatives.

Mechanism and intervention of murine transfusion-related acute lung injury caused by anti-CD36 antibodies

Anti-CD36 Abs have been suggested to induce transfusion-related acute lung injury (TRALI) upon blood transfusion, particularly in Asian populations. However, little is known about the pathological mechanism of anti-CD36 Ab-mediated TRALI, and potential therapies have not yet been identified. Here, we developed a murine model of anti-CD36 Ab-mediated TRALI to address these questions. Administration of mouse mAb against CD36 (mAb GZ1) or human anti-CD36 IgG, but not GZ1 F(ab')2 fragments, induced severe TRALI in Cd36+/+ male mice. Predepletion of recipient monocytes or complement, but not neutrophils or platelets, prevented the development of murine TRALI. Moreover, plasma C5a levels after TRALI induction by anti-CD36 Abs increased more than 3-fold, implying a critical role of complement C5 activation in the mechanism of Fc-dependent anti-CD36-mediated TRALI. Administration of GZ1 F(ab')2, antioxidant (N-acetyl cysteine, NAC), or C5 blocker (mAb BB5.1) before TRALI induction completely protected mice from anti-CD36-mediated TRALI. Although no significant amelioration in TRALI was observed when mice were injected with GZ1 F(ab')2 after TRALI induction, significant improvement was achieved when mice were treated postinduction with NAC or anti-C5. Importantly, anti-C5 treatment completely rescued mice from TRALI, suggesting the potential role of existing anti-C5 drugs in the treatment of patients with TRALI caused by anti-CD36.

Tartrate resistant acid phosphatase 5 (TRAP5) mediates immune cell recruitment in a murine model of pulmonary bacterial infection

Introduction

During airway infection, upregulation of proinflammatory cytokines and subsequent immune cell recruitment is essential to mitigate bacterial infection. Conversely, during prolonged and non-resolving airway inflammation, neutrophils contribute to tissue damage and remodeling. This occurs during diseases including cystic fibrosis (CF) and COPD where bacterial pathogens, not least Pseudomonas aeruginosa, contribute to disease progression through long-lasting infections. Tartrate-resistant acid phosphatase (TRAP) 5 is a metalloenzyme expressed by alveolar macrophages and one of its target substrates is the phosphoglycoprotein osteopontin (OPN).

Methods

We used a knockout mouse strain (Trap5-/-) and BALB/c-Tg (Rela-luc)31Xen mice paired with siRNA administration or functional protein add-back to elucidate the role of Trap5 during bacterial infection. In a series of experiments, Trap5-/- and wild-type control mice received intratracheal administration of P.aerugniosa (Xen41) or LPS, with mice monitored using intravital imaging (IVIS). In addition, multiplex cytokine immunoassays, flow cytometry, multispectral analyses, histological staining were performed.

Results

In this study, we found that Trap5-/- mice had impaired clearance of P. aeruginosa airway infection and reduced recruitment of immune cells (i.e. neutrophils and inflammatory macrophages). Trap5 knockdown using siRNA resulted in a decreased activation of the proinflammatory transcription factor NF-κB in reporter mice and a subsequent decrease of proinflammatory gene expression. Add-back experiments of enzymatically active TRAP5 to Trap5-/- mice restored immune cell recruitment and bacterial killing. In human CF lung tissue, TRAP5 of alveolar macrophages was detected in proximity to OPN to a higher degree than in normal lung tissue, indicating possible interactions.

Discussion

Taken together, the findings of this study suggest a key role for TRAP5 in modulating airway inflammation. This could have bearing in diseases such as CF and COPD where excessive neutrophilic inflammation could be targeted by pharmacological inhibitors of TRAP5.

A pulmonary endothelial amplification loop aggravates ex-vivo transfusion-related acute lung injury via increased toll-like receptor 4 and intra-cellular adhesion molecule-1 expression

BACKGROUND

Transfusion-Related Acute Lung Injury (TRALI) is a life-threatening complication of blood transfusions characterized by pulmonary endothelial cell damage and edema, with a high incidence in critically ill patients. The pathophysiology of TRALI is unresolved, but can generally be hypothesized to follow a 2-hit model in which the first hit is elicited by the underlying clinical condition of the patient (e.g., inflammation, which can be reflected by LPS in experimental models), and the second hit is delivered by the blood transfusion product (e.g., HLA class I antibodies). Here, we report a synergistic role for LPS and HLA class I antibody binding to pulmonary endothelium resulting in enhanced inflammatory responses.

MATERIALS AND METHODS

Pulmonary endothelial cells were treated with PBS or low-dose LPS, exclusively or in combination with anti-HLA class I. Endothelial surface expression of HLA class I, TLR4, and inflammatory marker ICAM-1 were measured, and trans-endothelial migration (TEM) of neutrophils was investigated.

RESULTS

LPS treatment of pulmonary endothelium enhanced HLA class I antibody binding, and combined LPS and HLA class I antibody binding enhanced TLR4 (LPS receptor) and ICAM-1 expression on the endothelial cell surface. Low-dose LPS and HLA antibody together also increased neutrophil TEM under physiological flow by on average 5-fold.

CONCLUSION

We conclude that LPS and anti-HLA class I antibody have the ability to activate the pulmonary endothelium into a spiral of increasing inflammation, opening the opportunity to potentially block TLR4 to prevent or reduce the severity of TRALI in vivo.

Endothelial cells of pulmonary origin display unique sensitivity to the bacterial endotoxin lipopolysaccharide

Acute respiratory distress syndrome (ARDS) is a major clinical problem without available therapies. Known risks for ARDS include severe sepsis, SARS-CoV-2, gram-negative bacteria, trauma, pancreatitis, and blood transfusion. During ARDS, blood fluids and inflammatory cells enter the alveoli, preventing oxygen exchange from air into blood vessels. Reduced pulmonary endothelial barrier function, resulting in leakage of plasma from blood vessels, is one of the major determinants in ARDS. It is, however, unknown why systemic inflammation particularly targets the pulmonary endothelium, as endothelial cells (ECs) line all vessels in the vascular system of the body. In this study, we examined ECs of pulmonary, umbilical, renal, pancreatic, and cardiac origin for upregulation of adhesion molecules, ability to facilitate neutrophil (PMN) trans-endothelial migration (TEM) and for endothelial barrier function, in response to the gram-negative bacterial endotoxin LPS. Interestingly, we found that upon LPS stimulation, pulmonary ECs showed increased levels of adhesion molecules, facilitated more PMN-TEM and significantly perturbed the endothelial barrier, compared to other types of ECs. These observations could partly be explained by a higher expression of the adhesion molecule ICAM-1 on the pulmonary endothelial surface compared to other ECs. Moreover, we identified an increased expression of Cadherin-13 in pulmonary ECs, for which we demonstrated that it aids PMN-TEM in pulmonary ECs stimulated with LPS. We conclude that pulmonary ECs are uniquely sensitive to LPS, and intrinsically different, compared to ECs from other vascular beds. This may add to our understanding of the development of ARDS upon systemic inflammation.

Rhubarb Alleviates Acute Lung Injury by Modulating Gut Microbiota Dysbiosis in Mice

Intestinal microbiota disorders can aggravate pulmonary inflammation during acute lung injury (ALI). As a traditional Chinese herb, Rhubarb can regulated the gut microbiota. Therefore, this study was conducted to test the hypothesis that rhubarb alleviates gut microbiota dysbiosis and inflammation. Feces were collected from patients with ALI to detect the gut microbiota using 16S rDNA sequencing. Subsequently, a mouse model of ALI was established using lipopolysaccharide to investigate changes in the gut microbiota, the peripheral blood was attained for detecting the Th17/Treg cell ratio and the serum level of HDAC6 and HDAC9, and the effect of rhubarb treatment on the gut microbiota and Th17/Treg ratio were also evaluated. The results indicated that both the Firmicutes phylum decreased and the Bacteroidetes phylum increased were identified in patients with ALI, which induced the alternation of histone metabolites. The mice models also showed a similar imbalance in the Firmicutes/Bacteroidetes ratio at phylum of level. Rhubarb treatment alleviated the damaged lung tissue, accelerated Alistipes, Clostridium, and Lactobacillus proliferation at the level of genus, increased the level of HDAC6 in both the mice lung tissue and serum, and markedly reduced the Treg cells and increased the Th17 cells in the spleen tissue. The study suggested that both patients and mouse models with ALI presented gut microbiota dysbiosis, and lead to a Th17/Treg cell imbalance in ALI mouse. Rhubarb promoted Alistipes, Clostridium, and Lactobacillus proliferation, increased the HDAC6 concentration, restored the Th17/Treg cell balance, and protected against ALI.

Platelet FcγRIIA-induced serotonin release exacerbates the severity of transfusion-related acute lung injury in mice

Transfusion-related acute lung injury (TRALI) remains a major cause of transfusion-related fatalities. The mechanism of human antibody-mediated TRALI, especially the involvement of the Fcγ receptors, is not clearly established. Contrary to mice, human platelets are unique in their expression of the FcγRIIA/CD32A receptor, suggesting that our understanding of the pathogenesis of antibody-mediated TRALI is partial, as the current murine models incompletely recapitulate the human immunology. We evaluated the role of FcγRIIA/CD32A in TRALI using a humanized mouse model expressing the FcγRIIA/CD32A receptor. When challenged with a recombinant chimeric human immunoglobulin G1/mouse anti-major histocompatibility complex class I monoclonal antibody, these mice exhibited exacerbated alveolar edema and higher mortality compared with wild-type (WT) mice. Unlike in WT mice, monocytes/macrophages in CD32A+ mice were accessory for TRALI initiation, indicating the decisive contribution of another cell type. Platelet activation was dramatically increased in CD32A+ animals, resulting in their increased consumption and massive release of their granule contents. Platelet depletion prevented the exacerbation of TRALI in CD32A+ mice but did not affect TRALI in WT animals. By blocking platelet serotonin uptake with fluoxetine, we showed that the severity of TRALI in CD32A+ mice resulted from the serotonin released by the activated platelets. Furthermore, inhibition of 5-hydroxytryptamine 2A serotonin receptor with sarpogrelate, before or after the induction of TRALI, abolished the aggravation of lung edema in CD32A+ mice. Our findings show that platelet FcγRIIA/CD32A activation exacerbates antibody-mediated TRALI and provide a rationale for designing prophylactic and therapeutic strategies targeting the serotonin pathway to attenuate TRALI in patients.

Seabuckthorn Berries Extract Attenuates Pulmonary Vascular Hyperpermeability in Lipopolysaccharide-Induced Acute Lung Injury in Mice

Objective

To investigate the effect of seabuckthorn berries extract (SBE) on pulmonary vascular hyperpermeability in the mice model of acute lung injury (ALI) induced by lipopolysaccharide (LPS).

Methods

Sixty Kunming mice were allocated into 6 groups by a random number table, including control, LPS, dexamethasone (Dex, 1 mg/kg), and 120, 240 and 480 mg/kg SBE groups, 10 mice in each group. Except the control group, mice were pre-treated with Dex and SBE, respectively, for 7 days before LPS was intraperitoneally injected to induce ALI. Pulmonary vascular hyperpermeability was evaluated by histopathologic observation and transvascular leakage determination. Tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) levels in serum were measured using enzyme-linked immunosorbent assay. The expression of nuclear factor-kappa B (NF-κB) p65 in lung cells was determined by immunofluorescence analysis. The contents of cytoplasmic inhibitor of nuclear factor-κB kinase (IKK) and nuclear p65, as well as downstream proteins of E-selectin (CD62E) and intercellular adhesion molecule-1 (ICAM-1), were determined using Western blot analysis.

Results

Histopathological observation confirmed SBE treatment alleviated morphological lesion induced by LPS. Compared with the LPS group, 480 mg/kg SBE significantly decreased the water content of lung, Evans blue accumulation in lung tissue, and protein concentration and neutrophils count in bronchoalveolar lavage fluid (P<0.01); moreover, 480 mg/kg SBE significantly suppressed release of TNF-α and IL-6, and down-regulated expressions of IKK, nuclear p65, ICAM-1 and CD62E (P<0.01).

Conclusion

SBE maintained alveolar-capillary barrier integrity under endotoxin challenge in mice by suppressing the key factors in the pathogenesis of ALI.

Electronic Supplementary Material

Supplementary material (Appendix 1) is available in the online version of this article at 10.1007/s11655-021-3346-1.

Necroptosis: A Novel Pathway in Neuroinflammation

Neuroinflammation is a complex inflammatory process in the nervous system that is expected to play a significant role in neurological diseases. Necroptosis is a kind of necrosis that triggers innate immune responses by rupturing dead cells and releasing intracellular components; it can be caused by Toll-like receptor (TLR)-3 and TLR-4 agonists, tumor necrosis factor (TNF), certain microbial infections, and T cell receptors. Necroptosis signaling is modulated by receptor-interacting protein kinase (RIPK) 1 when the activity of caspase-8 becomes compromised. Activated death receptors (DRs) cause the activation of RIPK1 and the RIPK1 kinase activity-dependent formation of an RIPK1-RIPK3-mixed lineage kinase domain-like protein (MLKL), which is complex II. RIPK3 phosphorylates MLKL, ultimately leading to necrosis through plasma membrane disruption and cell lysis. Current studies suggest that necroptosis is associated with the pathogenesis of neuroinflammatory diseases, such as Alzheimer’s disease, Parkinson’s disease, and traumatic brain injury. Inhibitors of necroptosis, such as necrostatin-1 (Nec-1) and stable variant of Nec (Nec-1s), have been proven to be effective in many neurological diseases. The purpose of this article is to illuminate the mechanism underlying necroptosis and the important role that necroptosis plays in neuroinflammatory diseases. Overall, this article shows a potential therapeutic strategy in which targeting necroptotic factors may improve the pathological changes and clinical symptoms of neuroinflammatory disorders.

Heme induces significant neutrophil adhesion in vitro via an NFκB and reactive oxygen species-dependent pathway

Intravascular hemolysis, a major manifestation of sickle cell disease (SCD) and other diseases, incurs the release of hemoglobin and heme from red blood cells, in turn triggering inflammatory processes. This study investigated the in vitro effects of heme, a major inflammatory DAMP, on the adhesive properties of isolated human neutrophils. Heme (20 and 50 µM) significantly increased the adhesion of neutrophils to fibronectin and to recombinant ICAM-1, under static conditions, even more efficiently than the potent pro-inflammatory cytokine, tumor necrosis factor-α (TNF); a microfluidic assay confirmed that heme stimulated neutrophil adhesion under conditions of shear stress. Heme-induced neutrophil adhesion was associated with the increased activities, but not expressions, of the Mac-1 and LFA-1 integrin subunits, CD11b and CD11a, on the cell surface. Notably, heme (50 µM) significantly induced NFκB translocation in neutrophils, and inhibition of NFκB activity with the BAY11-7082 molecule abolished heme-induced cell adhesion to fibronectin and significantly decreased CD11a activity. Flow cytometric analysis demonstrated major reactive oxygen species (ROS) generation in neutrophils following heme stimulation that could be inhibited by the antioxidant, α-tocopherol, and by BAY11-7082. Furthermore, co-incubation with α-tocopherol abrogated both heme-stimulated neutrophil adhesion and CD11a/CD11b activation. Thus, our data indicate that heme, at clinically relevant concentrations, is a potent activator of neutrophil adhesion, increasing the ligand affinity of the β2 integrins via a mechanism that may be partially mediated by an NFkB-dependent pathway and the generation of ROS. Given the fundamental role that the adhesion of neutrophils to the vascular wall plays in SCD vaso-occlusion and other vascular inflammatory processes, our findings provide further evidence that cell-free heme is a major therapeutic target in the hemolytic diseases.

Pulmonary coagulation and fibrinolysis abnormalities that favor fibrin deposition in the lungs of mouse antibody-mediated transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is a life-threatening disease caused by blood transfusion. However, its pathogenesis is poorly understood and specific therapies are not available. Experimental and clinical studies have indicated that alveolar fibrin deposition serves a pathological role in acute lung injuries. The present study investigated whether pulmonary fibrin deposition occurs in a TRALI mouse model and the possible mechanisms underlying this deposition. The TRALI model was established by priming male Balb/c mice with lipopolysaccharide (LPS) 18 h prior to injection of an anti-major histocompatibility complex class I (MHC-I) antibody. Untreated mice and mice administered LPS plus isotype antibody served as controls. At 2 h after TRALI induction, blood and lung tissue were collected. Disease characteristics were assessed based on lung tissue histology, inflammatory responses and alterations in the alveolar-capillary barrier. Immunofluorescence staining was used to detect pulmonary fibrin deposition, platelets and fibrin-platelet interactions. Levels of plasminogen activator inhibitor-1 (PAI-1), thrombin-antithrombin complex (TATc), tissue factor pathway inhibitor (TFPI), coagulation factor activity and fibrin degradation product (FDP) in lung tissue homogenates were measured. Severe lung injury, increased inflammatory responses and a damaged alveolar-capillary barrier in the LPS-primed, anti-MHC-I antibody-administered mice indicated that the TRALI model was successfully established. Fibrin deposition, fibrin-platelet interactions and platelets accumulation in the lungs of mouse models were clearly promoted. Additionally, levels of TATc, coagulation factor V (FV), TFPI and PAI-1 were elevated, whereas FDP level was decreased in TRALI mice. In conclusion, both impaired fibrinolysis and enhanced coagulation, which might be induced by boosted FV activity, increased pulmonary platelets accumulation and enhanced fibrin-platelet interactions and contributed to pulmonary fibrin deposition in TRALI mice. The results provided a therapeutic rationale to target abnormalities in either coagulation or fibrinolysis pathways for antibody-mediated TRALI.

MiR-144-induced KLF2 inhibition and NF-kappaB/CXCR1 activation promote neutrophil extracellular trap-induced transfusion-related acute lung injury

Transfusion‐related acute lung injury (TRALI) is a clinical syndrome which is associated with the formation of neutrophil extracellular trap (NET). Recent studies have demonstrated the roles of microRNAs (miRNAs) in the pathophysiological process of TRALI. Here, the study focused on the role of miR‐144 and the molecular mechanisms in NET‐induced TRALI. Up‐regulated miR‐144 and under‐expressed KLF2 were determined in patients with TRALI. In the mouse model of a two‐event TRALI induced by intraperitoneal injections with lipopolysaccharide and anti‐H‐2Kd mAb, we determined expression patterns of miR‐144, Krüppel‐like factor 2 (KLF2), chemokine (C‐X‐C motif) receptor 1 (CXCR1) and nuclear factor kappa‐B (NF‐kappaB) p65. The results confirmed that miR‐144 was highly expressed, while KLF2 was poorly expressed in mice with TRALI. Dual‐luciferase reporter gene assay identified that miR‐144 could target KLF2. Using gain‐ and loss‐of‐function approaches, we analysed the effects of miR‐144 and its interaction with KLF2 on TRALI. Enforced expression of miR‐144 was found to aggravate NET‐induced TRALI by down‐regulating KLF2 and activating the NF‐kappaB/CXCR1 signalling pathway in TRALI mice. Collectively, miR‐144‐targeted inhibition of KLF2 and activation of NF‐kappaB/CXCR1 are possible mechanisms responsible for NET‐caused TRALI. These findings aid in the development of therapeutic modalities for the treatment of TRALI.

Update on the pathophysiology of transfusion-related acute lung injury

PURPOSE OF REVIEW

The aim of this study was to discuss recent advances regarding the pathogenesis of transfusion-related acute lung injury (TRALI), which highlight the pathogenic role of macrophages.

RECENT FINDINGS

TRALI remains a leading cause of transfusion-related fatalities, despite the success of the mitigation strategy, and therapeutic approaches are unavailable. Neutrophils (PMNs) are recognized pathogenic cells in TRALI. Macrophages have previously also been suggested to be pathogenic in mice via binding of C5a to their C5a-receptor, producing reactive oxygen species (ROS), which damages the pulmonary endothelium. Recent work has further highlighted the role of macrophages in the TRALI-pathogenesis. It has been shown that the protein osteopontin (OPN) released by macrophages is critical for pulmonary PMN recruitment in mice suffering from TRALI and that targeting OPN prevents the occurrence of TRALI. Another recent study demonstrated the importance of M1-polarized alveolar macrophages in murine TRALI induction by showing that α1-antitrypsin (AAT) overexpression prevented TRALI in mice through decreasing the polarization of alveolar macrophages towards the M1 phenotype.

SUMMARY

Apart from PMNs, macrophages also appear to be important in the pathogenesis of TRALI. Targeting the pathogenic functions of macrophages may be a promising therapeutic strategy to explore in TRALI.

Platelets orchestrate the resolution of pulmonary inflammation in mice by T reg cell repositioning and macrophage education

Beyond hemostasis, platelets actively participate in immune cell recruitment and host defense, yet their potential in the resolution of inflammatory processes remains unknown. Here, we demonstrate that platelets are recruited into the lung together with neutrophils during the onset of inflammation and alongside regulatory T (T reg) cells during the resolution phase. This partnering dichotomy is regulated by differential adhesion molecule expression during resolution. Mechanistically, intravascular platelets form aggregates with T reg cells, a prerequisite for their recruitment into the lung. This interaction relies on platelet activation by sCD40L and platelet P-selectin binding to PSGL-1 on T reg cells. Physical platelet–T reg cell interactions are necessary to modulate the transcriptome and instruct T reg cells to release the anti-inflammatory mediators IL-10 and TGFβ. Notably, the presence of platelet–T reg cell aggregates in the lung was also required for macrophage transcriptional reprogramming, polarization toward an anti-inflammatory phenotype, and effective resolution of pulmonary inflammation. Thus, platelets partner with successive immune cell subsets to orchestrate both the initiation and resolution of inflammation.

Biological and structural characterization of murine TRALI antibody reveals increased Fc-mediated complement activation

Transfusion-related acute lung injury (TRALI) remains a leading cause of transfusion-related deaths. In most cases, anti-leukocyte antibodies in the transfusion product trigger TRALI, but not all anti-leukocyte antibodies cause TRALI. It has been shown that the anti-major histocompatibility complex (MHC) class I antibody 34-1-2S (anti-H-2Kd) causes TRALI in BALB/c mice (MHC class I haplotype H-2Kd), whereas SF1.1.10 (anti-H-2Kd) does not. In C57BL/6 mice (MHC class I haplotype H-2Kb), TRALI only occurs when anti-MHC class I antibody AF6-88.5.5.3 (anti-H-2Kb) is administered together with a high dose of 34-1-2S. It remains unknown which specific antibody characteristics are responsible for eliciting TRALI. We therefore investigated several biological and structural features of 34-1-2S compared with other anti-MHC class I antibodies, which on their own do not cause TRALI: SF1.1.10 and AF6-88.5.5.3. No substantial differences were observed between the TRALI-causing 34-1-2S and the TRALI-resistant SF1.1.10 regarding binding affinity to H-2Kd. Regarding binding affinity to H-2Kb, only AF6-88.5.5.3 potently bound to H-2Kb, whereas 34-1-2S exhibited weak but significant cross-reactivity. Furthermore, the binding affinity to FcγRs as well as the Fc glycan composition seemed to be similar for all antibodies. Similar Fc glycosylation profiles were also observed for human TRALI-causing donor anti-HLA antibodies compared with human anti-HLA antibodies from control donors. 34-1-2S, however, displayed superior complement activation capacity, which was fully Fc dependent and not significantly dependent on Fc glycosylation. We conclude that TRALI induction is not correlated with Fab- and Fc-binding affinities for antigen and FcγRs, respectively, nor with the composition of Fc glycans; but increased Fc-mediated complement activation is correlated with TRALI induction.

Bioinformatics analysis of the potential biomarkers for acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is caused by uncontrolled inflammation, and the activation of alveolar macrophages (AM) is involved in pathophysiologic procedures. The present study aimed to identify key AM genes and pathways and try to provide potential targets for prognosis and early intervention in ARDS.

METHODS

The mRNA expression profile of GSE89953 was obtained from the Gene Expression Omnibus database. The LIMMA package in R software was used to identify differentially expressed genes (DEGs), and the clusterProfiler package was used for functional enrichment and pathway analyses. A protein-protein interaction network of DEGs was constructed to identify hub genes via the STRING database and Cytoscape software. Hub gene expression was validated using differentially expressed proteins (DEPs) obtained from the ProteomeXchange datasets to screen potential biomarkers.

RESULTS

A total of 166 DEGs (101 up-regulated and 65 down-regulated) were identified. The up-regulated DEGs were mainly enriched in regulation of the ERK1 and ERK2 cascade, response to interferon-gamma, cell chemotaxis, and migration in biological processes. In the KEGG pathway analysis, up-regulated DEGs were mainly involved in rheumatoid arthritis, cytokine-cytokine receptor interactions, phagosome, and the chemokine signaling pathway. The 12 hub genes identified included GZMA, MPO, PRF1, CXCL8, ELANE, GZMB, SELL, APOE, SPP1, JUN, CD247, and CCL2.

CONCLUSION

SPP1 was consistently differentially expressed in both DEGs and DEPs. SPP1 could be a potential biomarker for ARDS.

The Immune System in Transfusion-Related Acute Lung Injury Prevention and Therapy: Update and Perspective

As an initiator of respiratory distress, transfusion-related acute lung injury (TRALI) is regarded as one of the rare complications associated with transfusion medicine. However, to date, the pathogenesis of TRALI is still unclear, and specific therapies are unavailable. Understanding the mechanisms of TRALI may promote the design of preventive and therapeutic strategies. The immune system plays vital roles in reproduction, development and homeostasis. Sterile tissue damage, such as physical trauma, ischemia, or reperfusion injury, induces an inflammatory reaction that results in wound healing and regenerative mechanisms. In other words, in addition to protecting against pathogens, the immune response may be strongly associated with TRALI prevention and treatment through a variety of immunomodulatory strategies to inhibit excessive immune system activation. Immunotherapy based on immune cells or immunological targets may eradicate complications. For example, IL-10 therapy is a promising therapeutic strategy to explore further. This review will focus on ultramodern advances in our understanding of the potential role of the immune system in TRALI prevention and treatment.

The antiinflammatory effects of Xuefu Zhuyu decoction on C3H/HeJ mice with alopecia areata

BACKGROUND

As a traditional and typical prescription of prominently activating blood circulation to remove blood stasis, Xuefu Zhuyu decoction (XZD) consists of 15 kinds of herbal medicine. Clinical investigations have showed that XZD could significantly promote the new hair generation of alopecia areata (AA) patients characterized by Qi stagnation and blood stasis.

PURPOSE

The purpose of this study was executed to determine whether the mechanisms by which XZD stimulated newborn hair were related to its anti-inflammatory effects.

METHODS

Clinical AA individuals were recruited to confirm the efficies of XZD. High performance liquid chromatography (HPLC) analysis was performed to qualitatively and quantitatively determine the contents of 15 compounds in XZD. Schrodinger molecular docking and in vivo surface plasmon resonance (SPR) techniques were used to evaluate the potential binding properties of compounds to target proteins. C3H/HeJ mice were randomly assigned to groups control, AA, and the XZD administration (6.5, 13.0 and 26.0 g/kg/d). Except for mice in control group, all the mice in the other groups were treated with a 21-day chronic unpredictable mild stress (CUMS) induced AA. Hematoxylin-eosin (H&E) staining was performed to determine the degree of pathological damage to the skin. Enzyme-linked immunosorbent assay (ELISA) was performed to detect levels of interleukin-6 (IL-6), interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) and in serum and skin tissues. Western blot, immunohistochemistry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used to examine the expression levels of IL-6, IL-1β, TNF-α and osteopontin proteins and genes in skin tissues.

RESULTS

XZD could visibly promote hair regeneration of AA patients. The potential active ingredients in XZD prescription included at least amygdalin, hydroxysafflor yellow A, kaempferide, ferulic acid, catalpol, verbascoside, β-ecdysone, platycodin D, paeoniflorin, naringin, neohesperidin, liquiritin, glycyrrhizic acid, saikosaponin A and saikosaponin D. The results of molecular docking and SPR analysis showed that verbascoside, liquiritin, kaempferide and amygdalin showed the best potential binding properties with IL-6, IL-1β, TNF-α and osteopontin, respectively. Pathological evaluation showed that compared with the CUMS group, the administration of XZD significantly promoted hair regeneration, evidenced by increased number of skin hair follicles in C3H/HeJ AA mice. Compared with control group, ELISA data showed that the levels of IL-6, IL-1β and TNF-α in serum and skin tissues of CUMS induced AA mice were significantly increased, while XZD administration dramatically restrained the contents of the three pro-inflammatory factors. Western blot, immunohistochemistry, and qRT-PCR results further demonstrated that XZD administration notably down-regulated the protein and gene expression levels of osteopontin, IL-6, IL-1β and TNF-α in comparation with CUMS group.

CONCLUSION

XZD could dramatically ameliorate CUMS-induced AA damage in the skin of C3H/HeJ mice, possibly by suppressing the levels of IL-6, IL-1β, TNF-α and osteopontin.

Alveolar epithelial cell-derived Sonic hedgehog promotes pulmonary fibrosis through OPN-dependent alternative macrophage activation

The alternative activation of macrophages in the lungs has been considered as a major factor promoting pulmonary fibrogenesis; however, the mechanisms underlying this phenomenon are still elusive. In this study, we investigated the interaction between macrophages and fibrosis-associated alveolar epithelial cells using a bleomycin-induced mouse pulmonary fibrosis model and a coculture system. We demonstrated that fibrosis-promoting macrophages are spatially proximate to alveolar type II (ATII) cells, permissive for paracrine-induced macrophage polarization. Importantly, we revealed that fibrosis-associated ATII cells secrete Sonic hedgehog (Shh), a hedgehog pathway ligand, and that ATII cell-derived Shh promotes the development of pulmonary fibrosis by osteopontin (OPN)-mediated macrophage alternative activation. Mechanistically, Shh promotes the secretion of OPN in macrophages via Shh/Gli signaling cascade. The secreted OPN acts on the surrounding macrophages in an autocrine or paracrine manner and induces macrophage alternative activation through activating the JAK2/STAT3 signaling pathway. Tissue samples from idiopathic pulmonary fibrosis patients confirmed the increased expression of Shh and OPN in ATII cells and macrophages, respectively. Together, our study illustrated an alveolar epithelium-dependent mechanism for macrophage M2 polarization and pulmonary fibrogenesis and suggested that targeting Shh may offer a selective and efficient therapeutic strategy for the development and progression of pulmonary fibrosis.

Bronchoalveolar Tregs are associated with duration of mechanical ventilation in acute respiratory distress syndrome

Background

Foxp3⁺ regulatory T cells (Tregs) play essential roles in immune homeostasis and repair of damaged lung tissue. We hypothesized that patients whose lung injury resolves quickly, as measured by time to liberation from mechanical ventilation, have a higher percentage of Tregs amongst CD4⁺ T cells in either airway, bronchoalveolar lavage (BAL) or peripheral blood samples.

Methods

We prospectively enrolled patients with ARDS requiring mechanical ventilation and collected serial samples, the first within 72 h of ARDS diagnosis (day 0) and the second 48–96 h later (day 3). We analyzed immune cell populations and cytokines in BAL, tracheal aspirates and peripheral blood, as well as cytokines in plasma, obtained at the time of bronchoscopy. The study cohort was divided into fast resolvers (FR; n = 8) and slow resolvers (SR; n = 5), based on the median number of days until first extubation for all participants (n = 13). The primary measure was the percentage of CD4⁺ T cells that were Tregs.

Results

The BAL of FR contained more Tregs than SR. This finding did not extend to Tregs in tracheal aspirates or blood. BAL Tregs expressed more of the full-length FOXP3 than a splice variant missing exon 2 compared to Tregs in simultaneously obtained peripheral blood.

Conclusion

Tregs are present in the bronchoalveolar space during ARDS. A greater percentage of CD4⁺ cells were Tregs in the BAL of FR than SR. Tregs may play a role in the resolution of ARDS, and enhancing their numbers or functions may be a therapeutic target.

Recombinant osteopontin provides protection for cerebral infarction by inhibiting the NLRP3 inflammasome in microglia

Neuroinflammation is one of the most important secondary pathological events after cerebral infarction. Activation of NLRP3 inflammasome is a pivotal form of neuroinflammation. Osteopontin (OPN) is expressed during the subacute phase after cerebral infarction and has an important chemotactic effect on microglia. The aim of this study was to reveal the effect of recombinant OPN on brain injury after cerebral infarction and the regulation of NLRP3 inflammasome. We used the middle cerebral artery occlusion (MCAO) method-established focal cerebral ischemia model and LPS-induced inflammation model on neonate rat primary microglia. The effects of OPN on cerebral ischemic injury, neural function, microglia inflammation and NLRP3 inflammasome function were studied by immunofluorescence, staining, enzyme-linked immunosorbent assay and Western blot assay. We established MCAO cerebral ischemia and reperfusion injury model, and found that recombinant OPN reduced the volume of cerebral infarction and alleviated the ischemic injury degree of cerebral tissues, neurons, and neurological function. We found that OPN was also involved in the negative regulation of inflammasome and microglia activity in cerebral ischemic injury, and that OPN inhibited the activation of NLRP3 inflammasome and the function of microglia in a LPS-induced inflammatory model. Our findings show that recombinant OPN can reduce the ischemic infarct size and alleviate the cerebral ischemic injury of rats, which may be related to its efficient involvement in the inhibitory regulation of inflammasome and microglia inflammatory activation.

Evaluation of Platelet Responses in Transfusion-Related Acute Lung Injury (TRALI)

Platelets are versatile cells which are capable of eliciting nonhemostatic immune functions, especially under inflammatory conditions. Depending on the specific setting, platelets may be either protective or pathogenic in acute lung injury and acute respiratory distress syndrome (ARDS). Their role in transfusion-related acute lung injury (TRALI) is less well defined; however, it has been hypothesized that recipient platelets and transfused platelets both play a pathogenic role in TRALI. Overall, despite conflicting findings, it appears that recipient platelets may play a pathogenic role in antibody-mediated TRALI; however, their contribution appears to be limited. It is imperative to first validate the involvement of recipient platelets by standardizing the animal models, methods, reagents, and readouts for lung injury and taking the animal housing environment into consideration. For the involvement of transfused platelets in TRALI, it appears that predominantly lipids such as ceramide in stored platelets are able to induce TRALI in animal models. These studies will also need to be validated, and moreover, the platelet-derived lipid-mediated mechanisms leading to TRALI will need to be investigated.

Lipopolysaccharide-Induced Acute Lung Injury Is Associated with Increased Ran-Binding Protein in Microtubule-Organizing Center (RanBPM) Molecule Expression and Mitochondria-Mediated Apoptosis Signaling Pathway in a Mouse Model

Background

Acute lung injury (ALI) is a severe and life-threatening disorder treated in intensive care units. This study aimed to determine molecules or associated signaling pathways that are involved in lipopolysaccharide (LPS)-induced inflammation in an ALI model.

Material/Methods

An ALI mouse model was established by administering LPS (25 mg/kg via intratracheal instillation). Thirty-two ALI mice were divided into Model-4 h, Model-8 h, Model-12 h, and Model-24 h groups, while another 8 mice without LPS treatment were assigned as the Control group. Hematoxylin-eosin (HE) staining was used to evaluate inflammation of lung tissues. Wet weight/dry weight (W/D) ratio and myeloperoxidase (MPO) activity of lung tissue in ALI mice were evaluated. Expressions of Bcl-2, Bcl-XL, Bak, Bax, cleaved caspase-3 (C-caspase-3), and Ran-binding protein in microtubule-organizing center (RanBPM) were determined using Western blot analysis.

Results

LPS administration caused obvious inflammatory cell infiltration of lung tissues in ALI mice. The W/D ratio of ALI mouse lung tissues was significantly higher in Model groups than in the Control group (p<0.05). MPO activity of ALI mice was remarkably higher in Model groups compared to the Control group (p<0.05). LPS-induced ALI model mice exhibited significantly higher levels of C-caspase 3 lung tissues compared to the Control group (p<0.05). LPS-induced ALI model mice had significantly lower Bcl-XL/Bcl-2 and remarkably higher Bak/Bax expression compared with the Control group (p<0.05). LPS-induced ALI model mice displayed obviously higher RanBPM expression than in the Control group (p<0.05).

Conclusions

Lipopolysaccharide-induced acute lung injury is associated with increased RanBPM molecule expression and with mitochondria-mediated apoptosis signaling pathway in a mouse model.

rIL-35 prevents murine transfusion-related acute lung injury by inhibiting the activation of endothelial cells

BACKGROUND

Transfusion-related acute lung injury (TRALI) is an important cause of death associated with transfusion, and no specific clinical treatments are available. Endothelial cells are believed to play an important role in the development of TRALI. This study investigated whether IL-35, an endothelial stabilizing cytokine could regulate the severity of antibody-mediated TRALI in vivo.

STUDY DESIGN AND METHODS

Human microvascular endothelial cells (HMVECs) were cultured in vitro, rIL-35(2 μg/mL) was added before HMVECs activation, and HMVECs were fully activated by LPS (0.5 μg/mL). Then cells were collected for flow cytometry analysis. We used a previously established "two-event" mouse model of TRALI with naive and lipopolysaccharide (LPS)-injected mice as controls. rIL-35(100 μg/kg) was injected into the tail vein for 3 consecutive days before the induction of the TRALI model. Samples were collected 2 hours after TRALI induction and tested for lung tissue myeloperoxidase activity, total protein levels, lung tissue histology, endothelial cell activation assay, and cytokine assay.

RESULTS

In vitro culture of HMVECs with rIL-35 verified that rIL-35 inhibited endothelial cells. In a mouse model, prophylactic administration of rIL-35 prevented pulmonary edema, increased lung protein levels, and reduced polymorphonuclear neutrophil accumulation in the lung.

CONCLUSIONS

This work suggests that antibody-mediated murine TRALI can be prevented by rIL-35, and that rIL-35 appears to work by inhibiting the activation of lung endothelial cells.

Neutrophil Adaptations upon Recruitment to the Lung: New Concepts and Implications for Homeostasis and Disease

Neutrophils have a prominent role in all human immune responses against any type of pathogen or stimulus. The lungs are a major neutrophil reservoir and neutrophilic inflammation is a primary response to both infectious and non-infectious challenges. While neutrophils are well known for their essential role in clearance of bacteria, they are also equipped with specific mechanisms to counter viruses and fungi. When these defense mechanisms become aberrantly activated in the absence of infection, this commonly results in debilitating chronic lung inflammation. Clearance of bacteria by phagocytosis is the hallmark role of neutrophils and has been studied extensively. New studies on neutrophil biology have revealed that this leukocyte subset is highly adaptable and fulfills diverse roles. Of special interest is how these adaptations can impact the outcome of an immune response in the lungs due to their potent capacity for clearing infection and causing damage to host tissue. The adaptability of neutrophils and their propensity to influence the outcome of immune responses implicates them as a much-needed target of future immunomodulatory therapies. This review highlights the recent advances elucidating the mechanisms of neutrophilic inflammation, with a focus on the lung environment due to the immense and growing public health burden of chronic lung diseases such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD), and acute lung inflammatory diseases such as transfusion-related acute lung injury (TRALI).

Avβ3 single-stranded DNA aptamer attenuates vascular restenosis via Ras-PI3K/MAPK pathway in rats after percutaneous transluminal coronary angioplasty

Our aim was to investigate the effect of avβ3 single-stranded DNA aptamer (avβ3 ssDNA) on vascular restenosis in rats after percutaneous transluminal coronary angioplasty (PTCA) via the Ras-PI3K/MAPK pathway. Sixty Sprague-Dawley rats were randomly divided into six groups: sham-operated, PTCA, PTCA+cilengitide (18 mg/kg, n = 8), and avβ3 ssDNA treatment at 50, 100, and 200 μg/kg. Hematoxylin-eosin staining was performed to evaluate the successful establishment of the PTCA model and to assess the degree of intimal hyperplasia. Immunofluorescence and in situ hybridization were carried out to observe the level of avβ3. Immunohistochemistry was used to detect the expression of E-cadherin, N-cadherin, α-smooth muscle actin (α-SMA), angiotensin 1 (ANG1), and ANG2. The expression of osteopontin (OPN), focal adhesion kinase (FAK), Ras, mitogen-activated protein kinase (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), signal transducer and activator of transcription 1 (STAT1), and GTPase was observed by the western blot and quantitative reverse transcription polymerase chain reaction. Compared with rats subjected to PTCA only, those treated with avβ3 ssDNA showed significantly decreased vascular occlusion rate (P < .05). The protein expression of avβ3, OPN, p-FAK, ANG2, and E-cadherin was significantly increased by avβ3 ssDNA (P < .05), while the levels of ANG1, α-SMA, N-cadherin Ras, MAPK, PI3K, STAT1, and GTPase were significantly decreased (P < .05). Avβ3 ssDNA reduced the proliferation, migration, epithelial-mesenchymal transition, and vascular remodeling of vascular smooth muscle cells, and the mechanism may be related to the Ras-PI3K/MAPK pathway.

Avβ3 Single-Stranded DNA Aptamer Attenuates Vascular Smooth Muscle Cell Proliferation and Migration via Ras-PI3K/MAPK Pathway

OBJECTIVES

To observe the effect of avβ3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism.

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) is currently the preferred method for the treatment of coronary heart disease. However, vascular restenosis still occurs after PTCA treatment, severely affecting the clinical efficacy of PTCA. Integrin avβ3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism.

METHODS

In this experiment, we used systematic evolution of ligands by exponential enrichment (SELEX) to screen out avβ3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism. β3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism. β3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism. β3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism.

RESULTS

In the present study, we found that avβ3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism. P < 0.05). Avβ3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism. P < 0.05). AvP < 0.05). Av.

CONCLUSIONS

The findings suggest that avβ3 ssDNA inhibited the proliferation and migration of VSMCs by suppressing the activation of Ras-PI3K/MAPK signaling.β3 single-stranded (ss) DNA on proliferation and migration of vascular smooth muscle cells (VSMCs) and its potential mechanism.

The Role of Complement in Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is a life-threatening complication of acute respiratory distress occurring within 6 hours of blood transfusion. TRALI is one of the leading causes of transfusion-related fatalities and specific therapies are unavailable. Neutrophils are recognized as the major pathogenic cells, whereas T regulatory cells and dendritic cells appear to be important for protection against TRALI. The pathogenesis, however, is complex and incompletely understood. It is frequently postulated that the complement system plays an important role in the TRALI pathogenesis. In this article, we assess the evidence regarding the involvement of complement in TRALI from both human and animal studies. We hypothesize about the potential connection between the complement system and neutrophils in TRALI. Additionally, we draw parallels between TRALI and other acute pulmonary disorders of acute lung injury and acute respiratory distress syndrome regarding the involvement of complement. We conclude that, even though a role for complement in the TRALI pathogenesis seems plausible, studies investigating the role of complement in TRALI are remarkably limited in number and also present conflicting findings. Different types of TRALI animal models, diverse experimental conditions, and the composition of the gastrointestinal microbiota may perhaps all be factors which contribute to these discrepancies. More systematic studies are warranted to shed light on the contribution of the complement cascade in TRALI. The underlying clinical condition of the patient, which influences the susceptibility to TRALI, as well as the transfusion factor (antibody-mediated vs non–antibody-mediated), will be important to take into consideration when researching the contribution of complement. This should significantly increase our understanding of the role of complement in TRALI and may potentially result in promising new treatment strategies.

•

Studies investigating complement and TRALI are limited in number and present conflicting findings.

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Systematic investigation is needed to better understand the contribution of the complement cascade in TRALI.

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Future studies in this area should consider both the clinical susceptibility of the patient as well as the effect of transfusion factors.