Mechanism of action of macrophage efferocytosis in acute and chronic liver diseases and related targeted therapy / 临床肝胆病杂志

Efferocytosis refers to the process by which apoptotic cells are engulfed and cleared by phagocytes， including professional phagocytes， such as macrophages and dendritic cells， and non-professional phagocytes， such as epithelial cells. Liver macrophages are the main cells with the function of efferocytosis in the liver. In recent years， an increasing number of studies have shown that various acute and chronic liver diseases are associated with the efferocytosis function of liver macrophages， including acute liver injury， alcoholic liver disease， nonalcoholic fatty liver disease， autoimmune liver disease， liver fibrosis， and liver cancer. This article elaborates on the expression of molecules associated with the efferocytosis function of macrophages， the process of efferocytosis， and the role of efferocytosis function in different liver diseases， so as to provide new ideas for the treatment of liver diseases.

Icariin Ameliorates Efferocytosis Dysfunction of Alveolar Macrophages Stimulated by Cigarette Smoke Extract via PPARγ Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the mechanism of icariin in ameliorating efferocytosis dysfunction and inflammatory response of alveolar macrophages induced by cigarette smoke extract via the peroxisome proliferator-activated receptor gamma （PPARγ） signaling pathway. MethodThe untreated rat alveolar macrophages （NR8383） were taken as the blank group. The NR8383 cells treated with 10% cigarette smoke extract were divided into model， low-， medium-， and high-dose （10， 20， 40 μmol·L-1） icariin， PPARγ inhibitor， and PPARγ inhibitor + low-， medium-， and high-dose icariin groups. Alamar blue colorimetry was employed to examine the proliferation and toxicity of icariin on NR8383 cells. The efferocytosis rate of NR8383 cells was detected by flow cytometry. Enzyme-linked immunosorbent assay was employed to measure the levels of tumor necrosis factor-alpha （TNF-α）， transforming growth factor-β1 （TGF-β1）， and milk fat globule-epidermal growth factor 8 （MFG-E8）. Western blot and Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） were employed to determine the protein and mRNA levels， respectively， of PPARγ， CD36， and RAS-related C3 botulinum toxin substrate 1 （Rac1）. ResultThe efferocytosis dysfunction model of NR8383 was established with the cigarette smoke extract. Compared with the blank control group， the model group showed decreased efferocytosis rate （P<0.05）， elevated TNF-α level （P<0.05）， lowered TGF-β1 and MFG-E8 levels （P<0.01）， and down-regulated mRNA and protein levels of PPARγ， CD36， and Rac1 （P<0.05， P<0.01）. Compared with the model group， the treatment with icariin increased the efferocytosis rate （P<0.05， P<0.01）， lowered the TNF-α level （P<0.01）， elevated TGF-β1 and MFG-E8 levels （P<0.05）， and up-regulated the protein and mRNA levels of PPARγ， CD36， and Rac1 （P<0.05， P<0.01）. Compared with icariin alone， PPARγ inhibitor + icariin decreased the efferocytosis rate （P<0.05） and down-regulated the protein and mRNA levels of PPARγ （P<0.05， P<0.01）. In addition， PPARγ inhibitor + low-dose icariin down-regulated the protein level of CD36 （P<0.01） and PPARγ inhibitor + low-/medium-dose icariin up-regulated the protein level of Rac1 （P<0.05）. ConclusionIcariin ameliorates the cigarette smoke extract-induced efferocytosis dysfunction of alveolar macrophage by regulating the PPARγ signaling pathway and cytoskeletal structure rearrangement.

Research progress of sepsis associated encephalopathy influenced by gut microbiota via efferocytosis / 中华危重病急救医学

Sepsis associated encephalopathy (SAE) is a severe disease secondary to sepsis, which is associated with increased mortality and causes long-term cognitive deficits in survivors. Recently, an increasing body of evidence has shown that gut microbiota is closely related to the central nervous system, and could influence brain function via microbiota-gut-brain axis. Therefore, in the occurrence and development of SAE, cholinergic anti-inflammatory pathway is one of the mechanisms by which gut microbiota could improve cognitive function. Efferocytosis, a process of eliminating apoptotic cells in the body, has anti-inflammatory effects and provides organ protection in sepsis. On the other hand, it could be enhanced by some metabolites of gut microbiota, making it another potential mechanism for gut microbiota regulating SAE. This review summarizes the mutual regulation of gut microbiota, efferocytosis and SAE, to explore potential mechanisms and therapeutic targets of SAE.

Efferocytosis impacts ocular surface inflammation in high-iron environment by regulating macrophage polarization / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To explore whether efferocytosis impacts ocular surface inflammation in high-iron environment by regulating macrophage polarization. METHODS: A total of 50 healthy C57BL/6 male mice aged 6-8wk were randomly divided into normal control group, iron group, inhibitor group, enhancer group and solvent control group, with 10 mice in each group. The normal control group was injected intraperitoneally with 0.2mL of normal saline, and the other groups were injected intraperitoneally with 50mg/mL iron dextran of 0.2mL, once every 3d. From the 14d, the inhibitor group, the enhancer group and the solvent control group were injected intraperitoneally with the same volume(0.2mL)50mg/kg XMD8-92, 10mg/kg simvastatin and 50% DMSO solvent once a day, respectively. The anterior segment of the eyes was observed under slit lamp microscope on the 7, 14, 28d after intraperitoneal injection, and the ocular surface inflammation index and corneal fluorescein staining score were evaluated. The cornea, conjunctiva and lacrimal gland tissues were taken at 28d for the HE staining and immunofluorescence staining, and RT-PCR were used to detect the expression of macrophage polarization related indexes(CD86, CD206, iNOS, Arg-1); Western blot were used to detect the expression of efferocytosis related signal factors(Gas6, MerTK); ELISA was used to detect the expression of inflammatory factors(IL-1β, TNF-α, MMP-9).RESULTS: After injection for 28d, compared with the normal control group, the ocular surface inflammatory index and corneal fluorescein staining score were increased in the iron group and the solvent control group. HE staining showed incomplete corneal epithelium, reduced conjunctival goblet cells, unclear lacrimal gland structure and relatively disordered arrangement of cells. In all tissues, the expressions of polarization related indexes of M1 macrophages such as CD86 and iNOS were up-regulated, while those of M2 macrophages such as CD206 and Arg-1 were down-regulated, and the expressions of inflammatory factors such as IL-1β, TNF-α and MMP-9 were up-regulated(all P&#x003C;0.05). Compared with the iron group and the solvent control group, the ocular surface inflammation index and corneal fluorescein staining score of the inhibitor group were further increased. HE staining showed obvious exfoliation of corneal epithelium, further decrease or even disappearance of conjunctival goblet cells, disorder of lacrimal gland structure and irregular arrangement of cells. In all tissues, the expression of signal factors related to efferocytosis such as Gas6 and MerTK was down-regulated(all P&#x003C;0.05), the expression of polarization related indexes of M1 macrophages such as CD86 and iNOS and the expression of inflammatory factors such as IL-1β, TNF-α and MMP-9 were further up-regulated(all P&#x003C;0.05). But the ocular surface inflammation index and corneal fluorescein staining score decreased in the enhancer group. HE staining showed the integrity of corneal epithelial, the increase of conjunctival goblet cells and the improvement of lacrimal gland structure and morphology. In all tissues, the expression of signal factors related to efferocytosis such as Gas6 and MerTK was up-regulated(all P&#x003C;0.05), and the expression of polarization related indexes of M2 macrophages such as CD206 and Arg-1 was up-regulated, while the expression of inflammatory factors such as IL-1β, TNF-α and MMP-9 was down-regulated(all P&#x003C;0.05). CONCLUSION: High-iron environment induces macrophages polarize to M1, which aggravates ocular surface inflammation and tissue damage. Efferocytosis by regulating the polarization of macrophages impact the occurrence of ocular surface inflammation in high-iron environment.

Relationship between MFG-E8-mediated efferocytosis and sepsis-associated encephalopathy in mice / 中华麻醉学杂志

Objective:To evaluate the relationship between milk fat globular epidermal growth factor Ⅷ (MFG-E8)-mediated efferocytosis and sepsis-associated encephalopathy (SAE) in mice.Methods:Forty clean-grade healthy male C57BL/6 mice, aged 2-3 months, weighing 18-22 g, were divided into 4 groups ( n=10 each) using a random number table method: sham operation group (group Sham), cecal ligation and perforation (CLP) group (group CLP), sham operation+ phosphate buffer solution (PBS) group (group Sham+ PBS) and CLP+ recombinant mouse MFG-E8 group (group CLP+ rmMFG-E8). SAE was induced by CLP in anesthetized mice.PBS 1 μl and rmMFG-E8 1 μg were injected into the lateral cerebral ventricle in Sham+ PBS and CLP+ rmMFG-E8 groups after operation for 5 consecutive days.Novel object recognition test was performed at 6 days after operation, and the contextual fear conditioning test was performed at 7 and 8 days after operation.The percentage of time spent exploring a novel object, discrimination index and percentage of freezing time induced by condition were calculated.The animals were sacrificed after the end of behavioral tests, and the hippocampus was extracted for determination of the expression of MFG-E8 and GTP-Rac1 (by Western blot), the mRNA expression levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β (using real-time reverse transcription-polymerase chain reaction) and the apoptosis rate in hippocampus (by TUNEL). Results:Compared with group Sham, the percentage of time spent exploring a novel object, discrimination index and percentage of freezing time were significantly decreased, hippocamcal MFG-E8 expression was down-regulated, GTP-Rac1 expression was up-regulated, mRNA expression of IL-6, TNF-α and IL-1β was up-regulated, and apoptosis rate was increased in group CLP ( P<0.05). Compared with group CLP, the percentage of time spent exploring a novel object and discrimination index were significantly increased, freezing time was prolonged, hippocamcal MFG-E8 and GTP-Rac1 expression was up-regulated, mRNA expression of IL-6, TNF-α and IL-1β was down-regulated, and apoptosis rate was decreased in group CLP+ rmMFG-E8 ( P<0.05). Conclusion:The reduction of hippocampal MFG-E8-mediated efferocytosis may be involved in the pathophysiological mechanism of SAE in mice.

Advances in research on the role of alveolar macrophage burial function in chronic obstructive pulmonary disease / 中华危重病急救医学

As one of the top three causes of death in the world, chronic obstructive pulmonary disease (COPD) is a serious hazard to human health. Macrophages play an important role in COPD, and their efferocytosis function is essential for ending chronic inflammation of COPD. Efferocytosis damage of alveolar macrophages (AM) in patients with COPD causes the rising of bacterial infection and airway bacterial colonization risk in lungs, which is the main reason for the acute exacerbation and the rising of incidence rate and mortality rate in COPD. In recent years, the regulation of macrophage efferocytosis function in COPD has becoming a research hotspot. Progress on the role of macrophage efferocytosis function on COPD, and the breakthrough points of improving AM efferocytosis dysfunction by traditional Chinese medicine is reviewed, so as to provide new ideas for the prevention and treatment of COPD.

Apoptosis and efferocytosis in atherosclerosis plaques / 基础医学与临床

Apoptosis is an important feature of atherosclerotic plaques, and it has both beneficial and detrimental effects depending on the cell type and plaque stage.Since apoptotic cells in advanced plaques launch proatherogenic inflammatory responses,efferocytosis is available to withstand atherosclerosis progression. Several efferocytosis sys-tems,composed of different phagocytic receptors,apoptotic ligands,and bridging molecules,can be identified.Im-paired efferocytosis pathway causes an overdue clearance of apoptotic cells and promotes secondary necrosis and the formation of necrotic core which leads to the instability and even rupture of plaques.

Advances in macrophage function and its anti-inflammatory and proresolving activity and role in periodontitis development / 华西口腔医学杂志

Macrophage plays an important role in human innate immune system. It has powerful functions, such as recognition, phagocytosis, and bacteria and foreign body removal. Periodontitis, which is a chronic infectious disease characterized by gum inflammation and bone loss, is a major cause of tooth loss in adults. Several studies demonstrated that periodontal tissue destruction is caused by the host immune response defending against infections. As an important part of host immune response, macrophage is also involved in periodontitis pathogenesis. Recently, anti-inflammatory and proresolving activities of macrophage was discovered. Thus, the complex function of macrophage in the occurrence, development, and resolution of inflammation and its potential role in periodontitis were reviewed.