One-hit wonder: Late after burn injury,granulocytes can clear one bacterial infection but cannot control a subsequent infection

ObjectiveBurn injury induces an acute hyperactive immune response followed by a chronic immune dysregulation that leaves those afflicted susceptible to multiple secondary infections. Many murine models are able to recapitulate the acute immune response to burn injury, yet few models are able to recapitulate long-term immune suppression and thus chronic susceptibility to bacterial infections seen in burn patients. This has hindered the field, making evaluation of the mechanisms responsible for these susceptibilities difficult to study. Herein we describe a novel mouse model of burn injury that promotes chronic immune suppression allowing for susceptibility to primary and secondary infections and thus allows for the evaluation of associated mechanisms.MethodsC57Bl/6 mice receiving a full-thickness contact burn were infected with Pseudomonas aeruginosa 14 days (primary infection) and/or 17 days (secondary infection) after burn or sham injury. The survival, pulmonary and systemic bacterial load as well as frequency and function of innate immune cells (neutrophils and macrophages) were evaluated.ResultsFollowing secondary infection, burn mice were less effective in clearance of bacteria compared to sham injured or burn mice following a primary infection. Following secondary infection both neutrophils and macrophages recruited to the airways exhibited reduced production of anti-bacterial reactive oxygen and nitrogen species and the pro-inflammatory cytokineIL-12 while macrophages demonstrated increased expression of the anti-inflammatory cytokine interleukin-10 compared to those from sham burned mice and/or burn mice receiving a primary infection. In addition the BALF from these mice contained significantly higher level so of the anti-inflammatory cytokine IL-4 compared to those from sham burned mice and/or burn mice receiving a primary infection.ConclusionsBurn-mediated protection from infection is transient, with a secondary infection inducing immune protection to collapse. Repeated infection leads to increased neutrophil and macrophage numbers in the lungs late after burn injury, with diminished innate immune cell function and an increased anti-inflammatory cytokine environment.     

调衡方对Lewis肺癌荷瘤体巨噬细胞吞噬功能的影响＊

目的 研究调衡方对Lewis肺癌荷瘤小鼠巨噬细胞形态、 数量及活性的影响，探讨调衡方对荷瘤体巨噬细胞作用的免疫调节机制。方法 将传代培养的Lewis肺癌细胞接种于小鼠右腋皮下建转移肺癌模型；灌胃给药8 d后，从小鼠腹腔分离抽取巨噬细胞并培养；调衡方各组巨噬细胞培养48 h后，在显微镜下观察活细胞的形态，墨汁吞噬试验以及金葡菌吞噬试验观察巨噬细胞的吞噬能力，细胞酶化学染色观察巨噬细胞胞内酸性磷酸酶的变化，用酶联免疫吸附法（ELISA）检测各培养组M?上清中IL-1、IL-6、TNF-α表达水平。结果 调衡方小、中、大剂量各组巨噬细胞培养48 h后，与对照组比较，巨噬细胞体积显著增大，对墨汁和金葡菌的吞噬能力均显著提升，酸性磷酸酶的活性也明显增强，且能抑制炎性因子IL-1、IL-6、TNF-α分泌，这均与给药浓度呈正相关。结论 调衡方能增强巨噬细胞的吞噬功能，进而提高胞内酸性磷酸酶等的活性，通过抑制巨噬细胞分泌炎性因子（IL-1、IL-6、TNF-α）有控制巨噬细胞向M2型极化的可能，并减轻肿瘤浸润程度，降低肿瘤发展及转移，而发挥抗肿瘤免疫调节的作用。     

Anti-atherosclerotic action of GW9508 – Free fatty acid receptors activator – In apoE-knockout mice

BackgroundIn the past two decades, enhanced understanding of the biology of G-protein-coupled receptors (GPRs) has led to the identification of several such receptors as novel targets for free fatty acids (FFAs). Two GPRs, FFAR1 and FFAR4, have received special attention in the context of chronic inflammatory diseases, thanks to their anti-inflammatory activities.MethodsThe present study investigates the influence of prolonged treatment with GW9508 – agonist of FFAR1 and FFAR4 – on the development of atherosclerosis plaque in apoE-knockout mice, using morphometric and molecular methods.ResultsGW9508 administration has led to the reduction of atheroscletoric plaque size in an apoE-knockout mice model. Moreover, a FFAR1/FFAR4 agonist reduced the content of macrophages by almost 20%, attributed by immunohistochemical phenotyping to the pro-inflammatory M1-like activation state macrophages.ConclusionsProlonged administration of GW9508 resulted in significant amelioration of atherogenesis, providing evidence that the strategy based on macrophage phenotype switching toward an M2-like activation state via stimulation of FFAR1/FFAR4 receptors holds promise for a new approach to the prevention or treatment of atherosclerosis.     

Sequential delivery of immunomodulatory cytokines to facilitate the M1-to-M2 transition of macrophages and enhance vascularization of bone scaffolds

In normal tissue repair, macrophages exhibit a pro-inflammatory phenotype (M1) at early stages and a pro-healing phenotype (M2) at later stages. We have previously shown that M1 macrophages initiate angiogenesis while M2 macrophages promote vessel maturation. Therefore, we reasoned that scaffolds that promote sequential M1 and M2 polarization of infiltrating macrophages should result in enhanced angiogenesis and healing. To this end, we first analyzed the in vitro kinetics of macrophage phenotype switch using flow cytometry, gene expression, and cytokine secretion analysis. Then, we designed scaffolds for bone regeneration based on modifications of decellularized bone for a short release of interferon-gamma (IFNg) to promote the M1 phenotype, followed by a more sustained release of interleukin-4 (IL4) to promote the M2 phenotype. To achieve this sequential release profile, IFNg was physically adsorbed onto the scaffolds, while IL4 was attached via biotin-streptavidin binding. Interestingly, despite the strong interactions between biotin and streptavidin, release studies showed that biotinylated IL4 was released over 6 days. These scaffolds promoted sequential M1 and M2 polarization of primary human macrophages as measured by gene expression of ten M1 and M2 markers and secretion of four cytokines, although the overlapping phases of IFNg and IL4 release tempered polarization to some extent. Murine subcutaneous implantation model showed increased vascularization in scaffolds releasing IFNg compared to controls. This study demonstrates that scaffolds for tissue engineering can be designed to harness the angiogenic behavior of host macrophages towards scaffold vascularization.     

Simvastatin Reduces Lipopolysaccharides-Accelerated Cerebral Ischemic Injury via Inhibition of Nuclear Factor-kappa B Activity

Preceding infection or inflammation such as bacterial meningitis has been associated with poor outcomes after stroke. Previously, we reported that intracorpus callosum microinjection of lipopolysaccharides (LPS) strongly accelerated the ischemia/reperfusion-evoked brain tissue damage via recruiting inflammatory cells into the ischemic lesion. Simvastatin, 3-hydroxy-3-methylgultaryl (HMG)-CoA reductase inhibitor, has been shown to reduce inflammatory responses in vascular diseases. Thus, we investigated whether simvastatin could reduce the LPS-accelerated ischemic injury. Simvastatin (20 mg/kg) was orally administered to rats prior to cerebral ischemic insults (4 times at 72, 48, 25, and 1-h pre-ischemia). LPS was microinjected into rat corpus callosum 1 day before the ischemic injury. Treatment of simvastatin reduced the LPS-accelerated infarct size by 73%, and decreased the ischemia/reperfusion-induced expressions of pro-inflammatory mediators such as iNOS, COX-2 and IL-1β in LPS-injected rat brains. However, simvastatin did not reduce the infiltration of microglial/macrophageal cells into the LPS-pretreated brain lesion. In vitro migration assay also showed that simvastatin did not inhibit the monocyte chemoattractant protein-1-evoked migration of microglial/macrophageal cells. Instead, simvastatin inhibited the nuclear translocation of NF-κB, a key signaling event in expressions of various proinflammatory mediators, by decreasing the degradation of IκB. The present results indicate that simvastatin may be beneficial particularly to the accelerated cerebral ischemic injury under inflammatory or infectious conditions.     

Natural products that target macrophages in treating non-alcoholic steatohepatitis

Nonalcoholic steatohepatitis(NASH) is the progressive subtype of non-alcoholic fatty liver disease and potentiates risks for both hepatic and metabolic diseases.Although the pathophysiology of NASH is not completely understood, recent studies have revealed that macrophage activation is a major contributing factor for the disease progression. Macrophages integrate the immune response and metabolic process and have become promising targets for NASH therapy.Natural products are potential candidates for NASH treatment and have multifactorial underlying mechanisms. Macrophage involvement in the development of steatosis and inflammation in NASH has been widely investigated. In this review, we assess the evidence for natural products or their active ingredients in the modulation of macrophage activation, recruitment, and polarization, as well as the metabolic status of macrophages. Our work may highlight the possible natural products that target macrophages as potential treatment options for NASH.     

CSF-1R inhibition attenuates ischemia-induced renal injury and fibrosis by reducing Ly6C+ M2-like macrophage infiltration

Acute kidney injury (AKI) to chronic kidney disease (CKD) progression has become a life-threatening disease. However, an effective therapeutic strategy is still needed. The pathophysiology of AKI-to-CKD progression involves chronic inflammation and renal fibrosis driven by macrophage activation, which is physiologically dependent on colony-stimulating factor-1 receptor (CSF-1R) signaling. In this study, we modulated macrophage infiltration through oral administration of the CSF-1R inhibitor GW2580 in an ischemia–reperfusion (I/R)-induced AKI model to evaluate its therapeutic effects on preventing the progression of AKI to CKD. We found that GW2580 induced a significant reduction in the number of macrophages in I/R-injured kidneys and attenuated I/R-induced renal injury and subsequent interstitial fibrosis. By flow cytometry, we observed that the reduced macrophages were primarily Ly6C⁺ inflammatory macrophages in the GW2580-treated kidneys, while there was no significant difference in the number and percentage of Ly6C⁻CX3CR1⁺ macrophages. We further found that these reduced macrophages also demonstrated some characteristics of M2-like macrophages, which have been generally regarded as profibrotic subtypes in chronic inflammation. These results indicate the existence of phenotypic and functional crossover between Ly6C⁺ and M2-like macrophages in I/R kidneys, which induces AKI worsening to CKD. In conclusion, therapeutic GW2580 treatment alleviates acute renal injury and subsequent fibrosis by reducing Ly6C⁺ M2-like macrophage infiltration in ischemia-induced AKI.     

Functions of macrophage colony-stimulating factor (CSF1) in development,homeostasis, and tissue repair

Macrophage colony-stimulating factor (CSF1) is the primary growth factor required for the control of monocyte and macrophage differentiation, survival, proliferation and renewal. Although the cDNAs encoding multiple isoforms of human CSF1 were cloned in the 1980s, and recombinant proteins were available for testing in humans, CSF1 has not yet found substantial clinical application. Here we present an overview of CSF1 biology, including evolution, regulation and functions of cell surface and secreted isoforms. CSF1 is widely-expressed, primarily by cells of mesenchymal lineages, in all mouse tissues. Cell-specific deletion of a floxed Csf1 allele in mice indicates that local CSF1 production contributes to the maintenance of tissue-specific macrophage populations but is not saturating. CSF1 in the circulation is controlled primarily by receptor-mediated clearance by macrophages in liver and spleen. Administration of recombinant CSF1 to humans or animals leads to monocytosis and expansion of tissue macrophage populations and growth of the liver and spleen. In a wide variety of tissue injury models, CSF1 administration promotes monocyte infiltration, clearance of damaged cells and repair. We suggest that CSF1 has therapeutic potential in regenerative medicine.     

High frequency of macrophages expressing elevated level of CD80, PD-Ls and TLR1 in nasal polyps of CRS patients

Identification of the association between tissue biomarkers, their surrogates in blood and clinical features, could provide new diagnostic tools and facilitate adequate choices of therapeutic interventions for selected patients suffering from CRS. The aim of present study was the assessment of macrophages in the polyp tissue and monocytes in the peripheral blood in the course of CRSwNP, and their functional immunophenotype. We analyzed 31 patients with CRSwNP. Nasal mucosa tissue was obtained via functional endoscopic sinus surgery (FESS). The control group included 10 patients with deviated nasal septum (DNS). Fluorochrome stained cells were proceed to acquisition using FACS Canto flow cytometer, and the results were analyzed using the software FACS Diva. In our study, we observed a significantly higher level of CD80, CD274, CD273 and TLR1 in nasal polyps compared to blood samples from patients with CRSwNP. This finding may suggest the importance of the PD-1 pathway as a therapeutic target in CRS and an important role for TLR1 in nasal polyp formation and maintenance. Our results may provide some insight into potential future targets of recurrent nasal polyp treatment and contribute to a better understanding of the inflammatory process in Chronic Rhinosinusitis.