MFG-E8 induces epithelial-mesenchymal transition and anoikis resistance to promote the metastasis of pancreatic cancer cells

Pancreatic cancer is an extremely malignant tumor, and only a few clinical treatment options exist. MFG-E8 and kindlin-2 all play an important role in cancer progression. However, the specific mechanism occurring between MFG-E8, kindlin-2 and the migration and invasion of pancreatic cancer cells remains unelucidated. To unravel the specific mechanism, this study assessed the potential association between MFG-E8 and kindlin-2 as well as the involvement of MFG-E8 in pancreatic cancer using two pancreatic cancer cell lines (MiaPaCa-2 and PANC-1). Pancreatic cancer cells were treated with 0, 250, and 500 ng/ml MFG-E8, and the effects of MFG-E8 on the migration, invasion, and anoikis of pancreatic cancer cells were observed. To investigate the role of kindlin-2 in pancreatic cancer, kindlin-2-shRNAi was transfected to knock down its expression level in the two pancreatic cancer cell lines. Furthermore, cilengitide, a receptor blocker of MFG-E8, was used to explore the relationship between MFG-E8, kindlin-2, and pancreatic cancer progression. Our findings demonstrated that MFG-E8 promotes the migration and invasion of pancreatic cancer cells and induces cell anoikis resistance in a dose-dependent manner, which was effectively counteracted by cilengitide, a receptor blocker. Additionally, the knockdown of kindlin-2 expression nullified the effect of MFG-E8 on the migration and invasion of pancreatic cancer cells. Consequently, this study provides insights into the specific mechanism underlying the interplay between MFG-E8 and kindlin-2 in the progression of pancreatic cancer cells.

MFG-E8 Alleviates Cognitive Impairments Induced by Chronic Cerebral Hypoperfusion by Phagocytosing Myelin Debris and Promoting Remyelination

Chronic cerebral hypoperfusion is one of the pathophysiological mechanisms contributing to cognitive decline by causing white matter injury. Microglia phagocytosing myelin debris in a timely manner can promote remyelination and contribute to the repair of white matter. However, milk fat globule-epidermal growth factor-factor 8 (MFG-E8), a microglial phagocytosis-related protein, has not been well studied in hypoperfusion-related cognitive dysfunction. We found that the expression of MFG-E8 was significantly decreased in the brain of mice after bilateral carotid artery stenosis (BCAS). MFG-E8 knockout mice demonstrated more severe BCAS-induced cognitive impairments in the behavioral tests. In addition, we discovered that the deletion of MFG-E8 aggravated white matter damage and the destruction of myelin microstructure through fluorescent staining and electron microscopy. Meanwhile, MFG-E8 overexpression by AAV improved white matter injury and increased the number of mature oligodendrocytes after BCAS. Moreover, in vitro and in vivo experiments showed that MFG-E8 could enhance the phagocytic function of microglia via the αVβ3/αVβ5/Rac1 pathway and IGF-1 production to promote the differentiation of oligodendrocyte progenitor cells into mature oligodendrocytes. Interestingly, we found that MFG-E8 was mainly derived from astrocytes, not microglia. Our findings suggest that MFG-E8 is a potential therapeutic target for cognitive impairments following cerebral hypoperfusion.

The Novel MFG-E8-derived Oligopeptide, MOP3, Improves Outcomes in a Preclinical Murine Model of Neonatal Sepsis

INTRODUCTION

Neonatal sepsis is a devastating inflammatory condition that remains a leading cause of morbidity and mortality. Milk fat globule-EGF-factor VIII (MFG-E8) is a glycoprotein that reduces inflammation, whereas extracellular cold-inducible RNA binding protein (eCIRP) worsens inflammation. This study aimed to determine the therapeutic potential of a novel MFG-E8-derived oligopeptide 3 (MOP3) designed to clear eCIRP and protect against inflammation, organ injury, and mortality in neonatal sepsis.

METHODS

C57BL6 mouse pups were injected intraperitoneally with cecal slurry (CS) and treated with MOP3 (20 μg/g) or vehicle. 10 h after injection, blood, lungs, and intestines were collected for analyses, and in a 7-day experiment, pups were monitored for differences in mortality.

RESULTS

MOP3 treatment protected septic pups from inflammation by reducing eCIRP, IL-6, TNFα, and LDH. MOP3 reduced lung and intestinal inflammation and injury as assessed by reductions in tissue mRNA levels of inflammatory markers, histopathologic injury, and apoptosis in lung and intestines. MOP3 also significantly improved 7-day overall survival for CS-septic mouse pups compared to vehicle (75% vs. 46%, respectively).

CONCLUSION

Deriving from MFG-E8 and designed to clear eCIRP, MOP3 protects against sepsis-induced inflammation, organ injury, and mortality in a preclinical model of neonatal sepsis, implicating it as an exciting potential new therapeutic.

LEVEL OF EVIDENCE

Level 1.

Eugenol Inhibits Ox-LDL-Induced Proliferation and Migration of Human Vascular Smooth Muscle Cells by Inhibiting the Ang II/MFG-E8/MCP-1 Signaling Cascade

Objective

In this study, we investigated the effect and mechanism of action of eugenol on oxidized low-density lipoprotein (ox-LDL)-induced abnormal proliferation and migration of human vascular smooth muscle cells (HVSMCs).

Methods

HVSMCs were treated with 100 ug/mL ox-LDL for 24 hours to establish a cell model. After 1-hour pretreatment, eugenol at concentrations of 5, 25, and 50 uM was added. Cell viability was assessed using an MTT assay, PCNA expression was detected using Western blot, cell cycle distribution was analyzed using flow cytometry, and cell migration ability was evaluated using wound healing and Transwell migration assays. To investigate the mechanisms, Ang II receptors were inhibited by 1000 nM valsartan, MFG-E8 was knocked down by shRNA, MCP-1 was inhibited by siRNA, and MFG-E8 was overexpressed using plasmids.

Results

The findings from this study elucidated the stimulatory impact of ox-LDL on the proliferation and functionality of HVSMCs. Different concentrations of eugenol effectively mitigated the enhanced activity of HVSMCs induced by ox-LDL, with 50 uM eugenol exhibiting the most pronounced inhibitory effect. Flow cytometry and Western blot results showed ox-LDL reduced G1 phase cells and increased PCNA expression, while 50 uM eugenol inhibited ox-LDL-induced HVSMC proliferation. In wound healing and Transwell migration experiments, the ox-LDL group showed larger cell scratch filling and migration than the control group, both of which were inhibited by 50 uM eugenol. Inhibiting the Ang II/MFG-E8/MCP-1 signaling cascade mimicked eugenol's effects, while MFG-E8 overexpression reversed eugenol's inhibitory effect.

Conclusion

Eugenol can inhibit the proliferation and migration of ox-LDL-induced HVSMCs by inhibiting Ang II/MFG-E8/MCP-1 signaling cascade, making it a potential therapeutic drug for atherosclerosis.

A novel opsonic eCIRP inhibitor for lethal sepsis

Sepsis is a life-threatening inflammatory condition partly orchestrated by the release of various damage-associated molecular patterns such as extracellular cold-inducible RNA-binding protein (eCIRP). Despite advances in understanding the pathogenic role of eCIRP in inflammatory diseases, novel therapeutic strategies to prevent its excessive inflammatory response are lacking. Milk fat globule-epidermal growth factor-VIII (MFG-E8) is critical for the opsonic clearance of apoptotic cells, but its potential involvement in the removal of eCIRP was previously unknown. Here, we report that MFG-E8 can strongly bind eCIRP to facilitate αvβ3-integrin-dependent internalization and lysosome-dependent degradation of MFG-E8/eCIRP complexes, thereby attenuating excessive inflammation. Genetic disruption of MFG-E8 expression exaggerated sepsis-induced systemic accumulation of eCIRP and other cytokines, and consequently exacerbated sepsis-associated acute lung injury. In contrast, MFG-E8-derived oligopeptide recapitulated its eCIRP binding properties, and significantly attenuated eCIRP-induced inflammation to confer protection against sepsis. Our findings suggest a novel therapeutic approach to attenuate eCIRP-induced inflammation to improve outcomes of lethal sepsis.

MFG-E8 promotes M2 polarization of macrophages and is associated with poor prognosis in patients with gastric cancer

Background

Milk Fat Globule-Epidermal Growth Factor 8 (MFG-E8) has been reported to play an oncogenic role in a variety of tumors. However, its involvement in gastric cancer (GC) development has not been described.

Methods

The cancer genome atlas (TCGA) and the gene expression omnibus database (GEO) databases were used to analyze the expression of MFG-E8 in GC. These findings were further validated using immunohistochemistry (IHC) and western blotting assay (WB). Kaplan-Meier method, univariate logistic regression, and Christopher Cox regression were used to study the relationship between MFG-E8 and clinical pathology. In addition, the potential signaling pathways involved in MFG-E8 and its potential correlation with levels of immune cell infiltration were investigated. Finally, the biological function of MFG-E8 in GC cells was revealed.

Results

MFG-E8 was highly expressed in GC patients and cells, and the high level of MFG-E8 was associated with poor overall survival (OS). KEGG analysis indicated that MFG-E8 may play an important role in the cAMP signaling pathway. The expression of MFG-E8 was positively correlated with the infiltration of M2 macrophages. The patients with high MFG-E8 were easy to develop chemotherapy resistance. Furthermore, the knockdown of MFG-E8 significantly inhibited the proliferation and invasion of GC cells.

Conclusion

MFG-E8 in GC may serve as a prognostic marker and a potential immunotherapy target for GC.

Synergistic effects of MFG-E8 and whey protein on mitigating d-galactose-induced sarcopenia through PI3K/AKT/PGC-1α and MAPK/ERK signaling pathways

Milk fat globule epidermal growth factor 8 (MFG-E8) and whey protein have emerged as promising bionutrient supplements for enhancing skeletal muscle mass and function. In the present study, aging-related sarcopenia rat model was employed to elucidate the effects of the combined administration of MFG-E8 and whey protein on the catabolism and anabolism of gastrocnemius protein. Combined intervention led to notable enhancements in the antioxidative stress status and mitochondrial biogenesis capacity of gastrocnemius muscle fibers in the aging rats, concomitant with a significant inhibition of lipid accumulation. Moreover, the synergistic effect of MFG-E8 and whey protein was found to exert modulatory effects on key signaling pathways, including PI3K/Akt/PGC-1α pathway and MAPK/ERK signaling pathways in the gastrocnemius muscle of the aging rats. Specifically, this combined intervention was observed to promote mitochondrial biogenesis and regulate the expression of protein anabolism and catabolism-related regulators, thereby facilitating the alleviation of mitochondrial oxidative stress and enhancing biogenesis in gastrocnemius tissues. The findings of our study provide compelling evidence for the potential of MFG-E8 as a promising dietary supplement with antisarcopenic properties to ameliorate muscle protein metabolism disorders and mitigate mitochondrial-mediated myoblast apoptosis induced by oxidative stress.

Effects of MFG-E8 expression on the biological characteristics of ovarian cancer cells via the AKT/mTOR/S6K signalling pathway

In this study, we assessed the effects of MFG-E8 on the biological characteristics of ovarian cancer cells and explored the underlying mechanisms. Human ovarian cancer SKOV3 cells were transfected with MFG-E8 siRNA or NC siRNA. CCK-8, cell adhesion, scratch-wound, and Transwell assays were used to detect changes in cell metastatic processes. Effects of MFG-E8 silencing on the proteins involved in AKT/mTOR/S6K signalling pathway were assessed using qRT-PCR and Western blotting. Transient silencing of MFG-E8 in SKOV3 cells decreased cell proliferation and downregulated the expression of CDK4, cyclin D1, and caspase-3 proteins. Cell adhesion, migration, and invasion were also suppressed. p-AKT, p-mTORC1, and p-p70S6K levels decreased following MFG-E8 knockdown. Hence, MFG-E8 enhances carcinogenesis and affects the AKT/mTOR/S6K signalling pathway in ovarian cancer cells. In conclusion, our results suggested that MFG-E8 could promote ovarian cancer via AKT/mTOR/S6K signalling pathway which improved our understanding of the molecular mechanisms involved in ovarian cancer.IMPACT STATEMENTWhat is already known on this subject? Milk fat globule-epidermal growth factor 8 (MFG-E8) is expressed in several types of cancers such as oesophageal, breast, and liver. However, the mechanism of MFG-E8 involving in EOC remains unknown. We previously found that MFG-E8 expression was related to pathological staging, tissue differentiation, platinum sensitivity, ascites state, and other clinicopathological characteristics.What the results of this study add? Due to a series of in vitro studies, we confirmed that MFG-E8 is involved in the process of proliferation, invasion and metastasis. Our results show that silencing MFG-E8 can significantly inhibit the expression of cyclin D1 and CDK4 in EOC SKOV3 cells. MFG-E8 enhances carcinogenesis and affects the AKT/mTOR/S6K signaling pathway in ovarian cancer.What the implications are of these findings for clinical practice and/or further research? Taken together, our findings suggest that MFG-E8 may be an oncogene in EOC and provide new insights into the mechanism of MFG-E8 in the progression of EOC.

The m6A reader YTHDF1 attenuates fulminant hepatitis via MFG-E8 translation in an m6A dependent manner

Background and Aims: N6-methyladenosine (m6A) is the most common post-transcriptional modification of RNA in eukaryotes, which has been demonstrated to play important roles in various biological processes. However, its roles in fulminant hepatitis remain largely unknown. In the current study, YTHDF1 expression was found to be significantly downregulated in the livers among patients, as well as murine models with fulminant hepatitis versus normal controls. Thus, we hypothesized that YTHDF1 protects against fulminant hepatitis and investigated the underlying molecular mechanisms. Methods: Fulminant hepatitis was induced by D-GalN/LPS in conventional YTHDF1 knockout (YTHDF1-/-) mice, hepatocyte-specific YTHDF1 overexpression (AAV8- YTHDF1) mice, and corresponding control mice. Primary hepatocytes were cultured and subjected to LPS insult in vitro. Hepatic histology, cell death, oxidative stress and mitochondrial function were examined to assess liver damage. The molecular mechanisms of YTHDF1 function were explored using multi-omics analysis. Results: Ablation of YTHDF1 exacerbated hepatic apoptosis and reactive oxygen species (ROS) production and increased the number of aberrant mitochondria, while YTHDF1 overexpression resulted in the opposite effects. Multiomics analysis identified MFG-E8 as the direct target of YTHDF1. YTHDF1 augmented the translation of MFG-E8 in an m6A-dependent manner without effect on its mRNA expression, thereby restoring mitochondrial function. Additionally, administration of MFG-E8 almost completely reversed the YTHDF1 deficiency-mediated exacerbation of liver injury. Conclusions: The current study suggested that the m6A reader YTHDF1 alleviates cell death, enhances antioxidant capacity and restores mitochondrial function in fulminant hepatitis by promoting MFG-E8 protein translation in an m6A-dependent manner.

Genetically encoded phosphatidylserine biosensor for in vitro, ex vivo and in vivo labelling

BACKGROUND

The dynamics of phosphatidylserine in the plasma membrane is a tightly regulated feature of eukaryotic cells. Phosphatidylserine (PS) is found preferentially in the inner leaflet of the plasma membrane. Disruption of this asymmetry leads to the exposure of phosphatidylserine on the cell surface and is associated with cell death, synaptic pruning, blood clotting and other cellular processes. Due to the role of phosphatidylserine in widespread cellular functions, an efficient phosphatidylserine probe is needed to study them. Currently, a few different phosphatidylserine labelling tools are available; however, these labels have unfavourable signal-to-noise ratios and are difficult to use in tissues due to limited permeability. Their application in living tissue requires injection procedures that damage the tissue and release damage-associated molecular patterns, which in turn stimulates phosphatidylserine exposure.

METHODS

For this reason, we developed a novel genetically encoded phosphatidylserine probe based on the C2 domain of the lactadherin (MFG-E8) protein, suitable for labelling exposed phosphatidylserine in various research models. We tested the C2 probe specificity to phosphatidylserine on hybrid bilayer lipid membranes by observing surface plasmon resonance angle shift. Then, we analysed purified fused C2 proteins on different cell culture lines or engineered AAVs encoding C2 probes on tissue cultures after apoptosis induction. For in vivo experiments, neurotropic AAVs were intravenously injected into perinatal mice, and after 2 weeks, brain slices were collected to observe C2-SNAP expression.

RESULTS

The biophysical analysis revealed the high specificity of the C2 probe for phosphatidylserine. The fused recombinant C2 proteins were suitable for labelling phosphatidylserine on the surface of apoptotic cells in various cell lines. We engineered AAVs and validated them in organotypic brain tissue cultures for non-invasive delivery of the genetically encoded C2 probe and showed that these probes were expressed in the brain in vivo after intravenous AAV delivery to mice.

CONCLUSIONS

We have demonstrated that the developed genetically encoded PS biosensor can be utilised in a variety of assays as a two-component system of C2 and C2m2 fusion proteins. This system allows for precise quantification and PS visualisation at directly specified threshold levels, enabling the evaluation of PS exposure in both physiological and cell death processes.

MFG-E8 promotes osteogenic differentiation of human bone marrow mesenchymal stem cells through GSK3β/β-catenin signaling pathway

Fracture nonunion and bone defects are challenging for orthopedic surgeons. Milk fat globule-epidermal growth factor 8 (MFG-E8), a glycoprotein possibly secreted by macrophages in a fracture hematoma, participates in bone development. However, the role of MFG-E8 in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is unclear. We investigated the osteogenic effect of MFG-E8 in vitro and in vivo. The CCK-8 assay was used to assess the effect of recombinant human MFG-E8 (rhMFG-E8) on the viability of hBMSCs. Osteogenesis was investigated using RT-PCR, Western blotting, and immunofluorescence. Alkaline phosphatase (ALP) and Alizarin red staining were used to evaluate ALP activity and mineralization, respectively. An enzyme-linked immunosorbent assay was conducted to evaluate the secretory MFG-E8 concentration. Knockdown and overexpression of MFG-E8 in hBMSCs were established via siRNA and lentivirus vector transfection, respectively. Exogenous rhMFG-E8 was used to verify the in vivo therapeutic effect in a tibia bone defect model based on radiographic analysis and histological evaluation. Endogenous and secretory MFG-E8 levels increased significantly during the early osteogenic differentiation of hBMSCs. Knockdown of MFG-E8 inhibited the osteogenic differentiation of hBMSCs. Overexpression of MFG-E8 and rhMFG-E8 protein increased the expression of osteogenesis-related genes and proteins and enhanced calcium deposition. The active β-catenin to total β-catenin ratio and the p-GSK3β protein level were increased by MFG-E8. The MFG-E8-induced enhanced osteogenic differentiation of hBMSCs was partially attenuated by a GSK3β/β-catenin signaling inhibitor. Recombinant MFG-E8 accelerated bone healing in a rat tibial-defect model. In conclusion, MFG-E8 promotes the osteogenic differentiation of hBMSCs by regulating the GSK3β/β-catenin signaling pathway and so, is a potential therapeutic target.

Could maternal serum MFG-E8 level predict adverse first trimester pregnancy outcome? A preliminary study

BACKGROUND

Milk fat globule-epidermal growth factor 8 (MFG-E8) is expressed in the endometrial epithelium and its expression increases during the implantation process. Due to this knowledge, we aimed to investigate the maternal serum MFG-E8 levels on both healthy pregnant women in the first trimester and pregnant women complicated with missed abortion and threatened abortion in the first trimester.

METHODS

This prospective, cross-sectional study was conducted in a tertiary referral hospital, department of obstetrics between July 2020 and February 2021 after ethical committee approval. The study population was consisted of 30 healthy pregnant women (HP) in the first trimester, 30 pregnant women suffering from threatened abortion (TA) in the first trimester and 30 pregnant women suffering from missed abortion (MA) in the first trimester. Maternal serum MFG-E8 levels were analyzed with enzyme linked immunosorbent assay. Delivery and neonatal outcomes of the study population was evaluated. The continuous variables were compared among three groups with variance analysis with post hoc tests. The categorical variables were compared with chi-square and Fisher's exact tests where applicable.

RESULTS

The mean age of the study population was 29.36 ± 5.31 years. There was no significant difference among three groups for parameters of age, body mass index, parity number, and gestational week. Despite being within normal ranges, the mean neutrophil and international normalized ratio values of the three groups showed statistically significant difference (p < 0.05). The mean maternal serum MFG-E8 levels of MA, TA, and HP groups were 270 ± 152.3, 414.7 ± 236.7, and 474 ± 222.5 ng/mL, respectively (p = 0.001). It was found that mean of MFG-E8 of the MA group was statistically significantly lower than those of the other two groups (p < 0.05).

DISCUSSION

Although maternal serum MFG-E8 level seems to be a parameter that differ between live and nonlive pregnancies, studies with large number of cases are needed to discuss our results and to determine a cut-off value for prediction.

Corrigendum: MFG-E8 maintains cellular homeostasis by suppressing endoplasmic reticulum stress in pancreatic exocrine acinar cells

[This corrects the article DOI: 10.3389/fcell.2021.803876.].

Involvement of phosphatidylserine receptors in the skeletal muscle regeneration: therapeutic implications

Sarcopenia is a progressive loss of muscle mass and strength with a risk of adverse outcomes such as disability, poor quality of life, and death. Increasing evidence indicates that diminished ability of the muscle to activate satellite cell-dependent regeneration is one of the factors that might contribute to its development. Skeletal muscle regeneration following myogenic cell death results from the proliferation and differentiation of myogenic stem cells, called satellite cells, located beneath the basal lamina of the muscle fibres. Satellite cell differentiation is not a satellite cell-autonomous process but depends on signals provided by the surrounding cells. Infiltrating macrophages play a key role in the process partly by clearing the necrotic cell debris, partly by producing cytokines and growth factors that guide myogenesis. At the beginning of the muscle regeneration process, macrophages are pro-inflammatory, and the cytokines produced by them trigger the proliferation and differentiation of satellite cells. Following the uptake of dead cells, however, a transcriptionally regulated phenotypic change (macrophage polarization) is induced in them resulting in their transformation into healing macrophages that guide resolution of inflammation, completion of myoblast differentiation, myoblast fusion and growth, and return to homeostasis. Impaired efferocytosis results in delayed cell death clearance, delayed macrophage polarization, prolonged inflammation, and impaired muscle regeneration. Thus, proper efferocytosis by macrophages is a determining factor during muscle repair. Here we review that both efferocytosis and myogenesis are dependent on the cell surface phosphatidylserine (PS), and surprisingly, these two processes share a number of common PS receptors and signalling pathways. Based on these findings, we propose that stimulating the function of PS receptors for facilitating muscle repair following injury could be a successful approach, as it would enhance efferocytosis and myogenesis simultaneously. Because increasing evidence indicates a pathophysiological role of impaired efferocytosis in the development of chronic inflammatory conditions, as well as in impaired muscle regeneration both contributing to the development of sarcopenia, improving efferocytosis should be considered also in its management. Again applying or combining those treatments that target PS receptors would be expected to be the most effective, because they would also promote myogenesis. A potential PS receptor-triggering candidate molecule is milk fat globule-EGF-factor 8 (MFG-E8), which not only stimulates PS-dependent efferocytosis and myoblast fusion but also promotes extracellular signal-regulated kinase (ERK) and Akt activation-mediated cell proliferation and cell cycle progression in myoblasts.

Sphingosine 1-phosphate receptor 2 promotes erythrocyte clearance by vascular smooth muscle cells in intraplaque hemorrhage through MFG-E8 production

Intraplaque hemorrhage (IPH) accelerates atherosclerosis progression. To scavenge excessive red blood cells (RBCs), vascular smooth muscle cells (VSMCs) with great plasticity may function as phagocytes. Here, we investigated the erythrophagocytosis function of VSMCs and possible regulations involved. Based on transcriptional microarray analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that genes up-regulated in human carotid atheroma with IPH were enriched in functions of phagocytic activities, while those down-regulated were enriched in VSMCs contraction function. Transcriptional expression of Milk fat globule-epidermal growth factor 8 (MFG-E8) was also down-regulated in atheroma with IPH. In high-fat diet-fed apolipoprotein E-deficient mice, erythrocytes were present in cells expressing VSMC markers αSMA in the brachiocephalic artery, suggesting VSMCs play a role in erythrophagocytosis. Using immunofluorescence and flow cytometry, we also found that eryptotic RBCs were bound to and internalized by VSMCs in a phosphatidylserine/MFG-E8/integrin α_Vβ₃ dependent manner in vitro. Inhibiting S1PR2 signaling with specific inhibitor JTE-013 or siRNA decreased Mfge8 expression and impaired the erythrophagocytosis of VSMCs in vitro. Partial ligation was performed in the left common carotid artery (LCA) followed by intra-intimal injection of isolated erythrocytes to observe their clearance in vivo. Interfering S1PR2 expression in VSMCs with Adeno-associated virus 9 inhibited MFG-E8 expression inside LCA plaques receiving RBCs injection and attenuated erythrocytes clearance. Erythrophagocytosis by VSMCs increased vascular endothelial growth factor-a secretion and promoted angiogenesis. The present study revealed that VSMCs act as phagocytes for RBC clearance through S1PR2 activation induced MFG-E8 release.

MFG-E8 Reduces Aortic Intimal Proliferation in a Murine Model of Transplant Vasculopathy

Transplant vasculopathy is characterized by endothelial apoptosis, which modulates the local microenvironment. Milk fat globule epidermal growth factor 8 (MFG-E8), which is released by apoptotic endothelial cells, limits tissue damage and inflammation by promoting anti-inflammatory macrophages. We aimed to study its role in transplant vasculopathy using the murine aortic allotransplantation model. BALB/c mice were transplanted with fully mismatched aortic transplants from MFG-E8 knockout (KO) or wild type (WT) C57BL/6J mice. Thereafter, mice received MFG-E8 (or vehicle) injections for 9 weeks prior to histopathological analysis of allografts for intimal proliferation (hematoxylin and eosin staining) and leukocyte infiltration assessment (immunofluorescence). Phenotypes of blood leukocytes and humoral responses were also evaluated (flow cytometry and ELISA). Mice receiving MFG-E8 KO aortas without MFG-E8 injections had the most severe intimal proliferation (p < 0.001). Administration of MFG-E8 decreased intimal proliferation, especially in mice receiving MFG-E8 KO aortas. Administration of MFG-E8 also increased the proportion of anti-inflammatory macrophages among graft-infiltrating macrophages (p = 0.003) and decreased systemic CD4+ and CD8+ T-cell activation (p < 0.001). An increase in regulatory T cells occurred in both groups of mice receiving WT aortas (p < 0.01). Thus, the analarmin MFG-E8 appears to be an important protein for reducing intimal proliferation in this murine model of transplant vasculopathy. MFG-E8 effects are associated with intra-allograft macrophage reprogramming and systemic T-cell activation dampening.

MFG-E8 Maintains Cellular Homeostasis by Suppressing Endoplasmic Reticulum Stress in Pancreatic Exocrine Acinar Cells

Excessive endoplasmic reticulum (ER) stress contributes significantly to the pathogenesis of exocrine acinar damage in acute pancreatitis. Our previous study found that milk fat globule EGF factor 8 (MFG-E8), a lipophilic glycoprotein, alleviates acinar cell damage during AP via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining cellular homeostasis. However, MFG-E8's role in ER stress in pancreatic exocrine acinar cells has not been evaluated. To study this, thapsigargin, brefeldin A, tunicamycin and cerulein + LPS were used to induce ER stress in rat pancreatic acinar cells in vitro. L-arginine- and cerulein + LPS-induced acute pancreatitis in mice were used to study ER stress in vivo. The results showed that MFG-E8 dose-dependently inhibited ER stress under both in vitro and in vivo conditions. MFG-E8 knockout mice suffered more severe ER stress and greater inflammatory response after L-arginine administration. Mechanistically, MFG-E8 increased phosphorylation of FAK and STAT3 in cerulein + LPS-treated pancreatic acinar cells. The presence of specific inhibitors of αvβ3/5 integrin, FAK or STAT3 abolished MFG-E8's effect on cerulein + LPS-induced ER stress in pancreatic acinar cells. In conclusion, MFG-E8 maintains cellular homeostasis by alleviating ER stress in pancreatic exocrine acinar cells.

Increased MFG-E8 at neuromuscular junctions is an exacerbating factor for sarcopenia-associated denervation

Sarcopenia is an important health problem associated with adverse outcomes. Although the etiology of sarcopenia remains poorly understood, factors apart from muscle fibers, including humoral factors, might be involved. Here, we used cytokine antibody arrays to identify humoral factors involved in sarcopenia and found a significant increase in levels of milk fat globule epidermal growth factor 8 (MFG‐E8) in skeletal muscle of aged mice, compared with young mice. We found that the increase in MFG‐E8 protein at arterial walls and neuromuscular junctions (NMJs) in muscles of aged mice. High levels of MFG‐E8 at NMJs and an age‐related increase in arterial MFG‐E8 have also been identified in human skeletal muscle. In NMJs, MFG‐E8 is localized on the surface of terminal Schwann cells, which are important accessory cells for the maintenance of NMJs. We found that increased MFG‐E8 at NMJs precedes age‐related denervation and is more prominent in sarcopenia‐susceptible fast‐twitch than in sarcopenia‐resistant slow‐twitch muscle. Comparison between fast and slow muscles further revealed that arterial MFG‐E8 can be uncoupled from sarcopenic phenotype. A genetic deficiency in MFG‐E8 attenuated age‐related denervation of NMJs and muscle weakness, providing evidence of a pathogenic role of increased MFG‐E8. Thus, our study revealed a mechanism by which increased MFG‐E8 at NMJs leads to age‐related NMJ degeneration and suggests that targeting MFG‐E8 could be a promising therapeutic approach to prevent sarcopenia.

Extracellular Vesicles from Human Teeth Stem Cells Trigger ATP Release and Promote Migration of Human Microglia through P2X4 Receptor/MFG-E8-Dependent Mechanisms

Extracellular vesicles (EVs) effectively suppress neuroinflammation and induce neuroprotective effects in different disease models. However, the mechanisms by which EVs regulate the neuroinflammatory response of microglia remains largely unexplored. Here, we addressed this issue by testing the action of EVs derived from human exfoliated deciduous teeth stem cells (SHEDs) on immortalized human microglial cells. We found that EVs induced a rapid increase in intracellular Ca²⁺ and promoted significant ATP release in microglial cells after 20 min of treatment. Boyden chamber assays revealed that EVs promoted microglial migration by 20%. Pharmacological inhibition of different subtypes of purinergic receptors demonstrated that EVs activated microglial migration preferentially through the P2X4 receptor (P2X4R) pathway. Proximity ligation and co-immunoprecipitation assays revealed that EVs promote association between milk fat globule-epidermal growth factor-factor VIII (MFG-E8) and P2X4R proteins. Furthermore, pharmacological inhibition of αVβ3/αVβ5 integrin suppressed EV-induced cell migration and formation of lipid rafts in microglia. These results demonstrate that EVs promote microglial motility through P2X4R/MFG-E8-dependent mechanisms. Our findings provide novel insights into the molecular mechanisms through which EVs target human microglia that may be exploited for the development of new therapeutic strategies targeting disease-associated neuroinflammation.

MFG-E8 (LACTADHERIN): a novel marker associated with cerebral amyloid angiopathy

Brain accumulation of amyloid-beta (Aβ) is a crucial feature in Alzheimer´s disease (AD) and cerebral amyloid angiopathy (CAA), although the pathophysiological relationship between these diseases remains unclear. Numerous proteins are associated with Aβ deposited in parenchymal plaques and/or cerebral vessels. We hypothesized that the study of these proteins would increase our understanding of the overlap and biological differences between these two pathologies and may yield new diagnostic tools and specific therapeutic targets. We used a laser capture microdissection approach combined with mass spectrometry in the APP23 transgenic mouse model of cerebral-β-amyloidosis to specifically identify vascular Aβ-associated proteins. We focused on one of the main proteins detected in the Aβ-affected cerebrovasculature: MFG-E8 (milk fat globule-EGF factor 8), also known as lactadherin. We first validated the presence of MFG-E8 in mouse and human brains. Immunofluorescence and immunoblotting studies revealed that MFG-E8 brain levels were higher in APP23 mice than in WT mice. Furthermore, MFG-E8 was strongly detected in Aβ-positive vessels in human postmortem CAA brains, whereas MFG-E8 was not present in parenchymal Aβ deposits. Levels of MFG-E8 were additionally analysed in serum and cerebrospinal fluid (CSF) from patients diagnosed with CAA, patients with AD and control subjects. Whereas no differences were found in MFG-E8 serum levels between groups, MFG-E8 concentration was significantly lower in the CSF of CAA patients compared to controls and AD patients. Finally, in human vascular smooth muscle cells MFG-E8 was protective against the toxic effects of the treatment with the Aβ40 peptide containing the Dutch mutation. In summary, our study shows that MFG-E8 is highly associated with CAA pathology and highlights MFG-E8 as a new CSF biomarker that could potentially be used to differentiate cerebrovascular Aβ pathology from parenchymal Aβ deposition.

Milk Fat Globule-EGF Factor 8 Alleviates Pancreatic Fibrosis by Inhibiting ER Stress-Induced Chaperone-Mediated Autophagy in Mice

Pancreatic fibrosis is an important pathophysiological feature of chronic pancreatitis (CP). Our recent study has shown that milk fat globule-EGF factor 8 (MFG-E8) is beneficial in acute pancreatitis. However, its role in CP remained unknown. To study this, CP was induced in male adult Mfge8-knockout (Mfge8-KO) mice and wild type (WT) mice by six intraperitoneal injections of cerulein (50 μg/kg/body weight) twice a week for 10 weeks. The results showed that knockout of mfge8 gene aggravated pancreatic fibrosis after repeated cerulein injection. In WT mice, pancreatic levels of MFG-E8 were reduced after induction of CP and administration of recombinant MFG-E8 alleviated cerulein-induced pancreatic fibrosis. The protective effect of MFG-E8 in CP was associated with reduced autophagy and oxidative stress. In human pancreatic stellate cells (PSCs), MFG-E8 inhibited TGF-β1-induced ER stress and autophagy. MFG-E8 downregulated the expression of lysosomal associated membrane protein 2A (LAMP2A), a key factor in ER stress-induced chaperone-mediated autophagy (CMA). QX77, an activator of CMA, eliminated the effects of MFG-E8 on TGF-β1-induced PSC activation. In conclusion, MFG-E8 appears to mitigate pancreatic fibrosis via inhibiting ER stress-induced chaperone-mediated autophagy. Recombinant MFG-E8 may be developed as a novel treatment for pancreatic fibrosis in CP.

MFG-E8 Plays an Important Role in Attenuating Cerulein-Induced Acute Pancreatitis in Mice

Milk fat globule-EGF factor 8 (MFG-E8) is a secreted glycoprotein that regulates tissue homeostasis, possesses potent anti-inflammatory properties, and protects against tissue injury. The human pancreas expresses MFG-E8; however, the role of MFG-E8 in the pancreas remains unclear. We examined the expression of MFG-E8 in the pancreas at baseline and during cerulein-induced acute pancreatitis in mice and determined whether MFG-E8 attenuates the progression of pancreatitis, a serious inflammatory condition that can be life-threatening. We administered cerulein to wild-type (WT) and Mfge8 knockout (KO) mice to induce pancreatitis. Immunoblot analysis showed that MFG-E8 is constitutively expressed in the murine pancreas and is increased in mice with cerulein-induced acute pancreatitis. In situ hybridization revealed that ductal epithelial cells in the mouse pancreas express Mfge8 transcripts at baseline. During pancreatitis, Mfge8 transcripts were abundantly expressed in acinar cells and endothelial cells in addition to ductal epithelial cells. Knocking out Mfge8 in mice exacerbated the severity of cerulein-induced acute pancreatitis and delayed its resolution. In contrast, administration of recombinant MFG-E8 attenuated cerulein-induced acute pancreatitis and promoted repair of pancreatic injury in Mfge8 KO mice. Taken together, our study suggests that MFG-E8 protects the pancreas against inflammatory injury and promotes pancreatic tissue repair. MFG-E8 may represent a novel therapeutic target in acute pancreatitis.

Insight into the role of phosphatidylserine in complement-mediated synapse loss in Alzheimer's disease

The innate immune system plays an integral role in the brain. Synaptic pruning, a fundamental process in developmental circuit refinement, is partially mediated by neuroimmune signalling at the synapse. In particular, microglia, the major tissue-resident macrophages of the brain, and the classical complement cascade, an innate immune pathway that aids in the clearance of unwanted material, have been implicated in mediating synapse elimination. Emerging data suggest that improper signalling of the innate immune pathway at the synapse leads to pathological synapse loss in age-related neurodegenerative diseases, including Alzheimer's disease. Now the key questions are whether synapses are targeted by complement and, if so, which synapses are vulnerable to elimination. Here, we review recent work implicating C1q, the initiator of the classical complement cascade, and surrounding glia as mediators of synapse loss. We examine how synapses could undergo apoptosis-like pathways in the Alzheimer brain, which may lead to the externalisation of phosphatidylserine on synapses. Finally, we discuss potential roles for microglia and astrocytes in this 'synaptic apoptosis'. Critical insight into neuroimmune regulatory pathways on synapses will be key to developing effective targets against pathological synapse loss in dementia.

Clinical significance of CD8+ and FoxP3+ tumor-infiltrating lymphocytes and MFG-E8 expression in lower rectal cancer with preoperative chemoradiotherapy

Preoperative chemoradiotherapy (CRT) for rectal cancer contributes to tumor down-staging and decreases locoregional recurrence. However, each patient shows a significantly different response to CRT. Therefore, the identification of predictive factors to CRT response would be beneficial to avoid unnecessary treatment. Cancer immunity in patients has been suggested to play an important role in the eradication of the tumor by CRT. In the present study, the utility of CD8⁺ and forkhead box P3 (FoxP3)⁺ tumor-infiltrating lymphocytes (TILs) and the expression of a novel immuno-regulatory factor, lactadherin (MFG-E8), in predicting CRT effectiveness in patients with rectal cancer was examined. A total of 61 patients with rectal cancer, who underwent curative resection following CRT were included in the study. The numbers of CD8⁺ and FoxP3⁺ TILs in a biopsy taken before CRT and MFG-E8 expression level in the specimens obtained at the time of the surgery after CRT were examined using immunohistochemical staining, and their association with clinicopathological characteristics, including patient survival, was determined. The tumors with more CD8⁺ TILs in the biopsy samples before CRT showed a significantly more favorable CRT response. The patients with tumors and a higher number of CD8⁺ TILs before CRT also exhibited significantly longer disease-free and overall survival times. Higher MFG-E8 expression level in post-CRT specimens was significantly associated with favorable CRT response; however, no significant association was found with any other clinicopathological characteristics, including survival time. The number of CD8⁺ TILs before CRT was a valuable predictor for CRT response and was associated with favorable prognosis in patients with lower rectal cancer and who were treated with CRT. High MFG-E8 expression level after CRT was also associated with a favorable CRT response.

Milk fat globule EGF factor 8 restores mitochondrial function via integrin-medicated activation of the FAK-STAT3 signaling pathway in acute pancreatitis

Acute pancreatitis (AP) remains a significant clinical challenge. Mitochondrial dysfunction contributes significantly to the pathogenesis of AP. Milk fat globule EGF factor 8 (MFG-E8) is an opsonizing protein, which has many biological functions via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining a normal mitochondrial function. However, MFG-E8's role in AP has not been evaluated.

METHODS

Blood samples were acquired from 69 healthy controls and 134 AP patients. Serum MFG-E8 levels were measured by ELISA. The relationship between serum concentrations of MFG-E8 and disease severity were analyzed. The role of MFG-E8 was evaluated in experimental models of AP.

RESULTS

Serum concentrations of MFG-E8 were lower in AP patients than healthy controls. And serum MFG-E8 concentrations were negatively correlated with disease severity in AP patients. In mice, MFG-E8 administration decreased L-arginine-induced pancreatic injury and mortality. MFG-E8's protective effects in experimental AP were associated with improvement in mitochondrial function and reduction in oxidative stress. MFG-E8 knockout mice suffered more severe pancreatic injury and greater mitochondrial damage after l-arginine administration. Mechanistically, MFG-E8 activated the FAK-STAT3 pathway in AP mice. Cilengitide, a specific αvβ3/5 integrin inhibitor, abolished MFG-E8's beneficial effects in AP. PF00562271, a specific FAK inhibitor, blocked MFG-E8-induced STAT3 phosphorylation. APTSTAT3-9R, a specific STAT3 antagonist, also eliminated MFG-E8's beneficial effects under such a condition.

CONCLUSIONS

MFG-E8 acts as an endogenous protective mediator in the pathogenesis of AP. MFG-E8 administration protects against AP possibly by restoring mitochondrial function via activation of the integrin-FAK-STAT3 signaling pathway. Targeting the action of MFG-E8 may present a potential therapeutic option for AP.

Propofol suppresses microglial phagocytosis through the downregulation of MFG-E8

BACKGROUND

Microglia are highly motile phagocytic cells in the healthy brain with surveillance and clearance functions. Although microglia have been shown to engulf cellular debris following brain insult, less is known about their phagocytic function in the absence of injury. Propofol can inhibit microglial activity, including phagocytosis. Milk fat globule epidermal growth factor 8 (MFG-E8), as a regulator of microglia, plays an essential role in the phagocytic process. However, whether MFG-E8 affects the alteration of phagocytosis by propofol remains unknown.

METHODS

Microglial BV2 cells were treated with propofol, with or without MFG-E8. Phagocytosis of latex beads was evaluated by flow cytometry and immunofluorescence. MFG-E8, p-AMPK, AMPK, p-Src, and Src levels were assessed by western blot analysis. Compound C (AMPK inhibitor) and dasatinib (Src inhibitor) were applied to determine the roles of AMPK and Src in microglial phagocytosis under propofol treatment.

RESULTS

The phagocytic ability of microglia was significantly decreased after propofol treatment for 4 h (P < 0.05). MFG-E8 production was inhibited by propofol in a concentration- and time-dependent manner (P < 0.05). Preadministration of MFG-E8 dose-dependently (from 10 to 100 ng/ml) reversed the suppression of phagocytosis by propofol (P < 0.05). Furthermore, the decline in p-AMPK and p-Src levels induced by propofol intervention was reversed by MFG-E8 activation (P < 0.05). Administration of compound C (AMPK inhibitor) and dasatinib (Src inhibitor) to microglia blocked the trend of enhanced phagocytosis induced by MFG-E8 (P < 0.05).

CONCLUSIONS

These findings reveal the intermediate role of MFG-E8 between propofol and microglial phagocytic activity. Moreover, MFG-E8 may reverse the suppression of phagocytosis induced by propofol through the regulation of the AMPK and Src signaling pathways.

MFG-E8-derived peptide attenuates inflammation and injury after renal ischemia-reperfusion in mice

Background

Renal ischemia-reperfusion (renal I/R) injury may lead to acute kidney injury (AKI). After renal I/R, proinflammatory mediators cause immune cell infiltration and further injury. Milk fat globule-epidermal growth factor-factor 8 (MFG-E8) is a protein involved in cell-cell and cell-matrix interactions. MSP68 is an MFG-E8-derived peptide that inhibits neutrophil adhesion and migration. Here, we evaluated whether MSP68 attenuates renal I/R injury.

Materials and methods

Adult C57BL/6 mice were subjected to bilateral renal ischemia for 30 min followed by reperfusion and intraperitoneal administration of saline (vehicle) or MSP68 (5 mg/kg). Sham animals underwent laparotomy without renal I/R. The blood collected and studied for BUN, creatinine, and LDH by colorimetry. The kidneys were analyzed for IL-6 and TNFα by qPCR, ELISA, histological injury, and apoptosis by TUNEL.

Results

At 24 h after surgery, serum levels of BUN, creatinine, and LDH were markedly higher in vehicle-treated renal I/R mice than in sham mice, but significantly lower in MSP68-treated renal I/R mice. Similarly, compared to sham, renal levels of IL-6 mRNA and protein and TNFα protein were markedly higher in vehicle-treated renal I/R mice, but significantly lower in MSP68-treated renal I/R mice. Vehicle-treated renal I/R mice also had severe renal tubular histological injury, which was significantly lower in MSP68-treated renal I/R mice. Additionally, the kidneys of vehicle-treated renal I/R mice had a 93-fold increase in TUNEL-positive cells, which were reduced by 35% in mice treated with MSP68.

Conclusion

MSP68 has the potential to be developed as novel therapeutic agent for patients with AKI.

Roles and mechanisms of MFG-E8 in vascular aging-related diseases

The aging of the vasculature plays a crucial role in the pathological progression of various vascular aging-related diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are essential parts in the inner and medial layers of vessel wall, respectively, the structural and functional alterations of ECs and VSMCs are the major causes of vascular aging. Milk fat globule-epidermal growth factor 8 (MFG-E8) is a multifunctional glycoprotein which exerts a regulatory role in the intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that MFG-E8 is a novel and outstanding modulator for vascular aging via targeting at ECs and VSMCs. In this review, we will summarise the cumulative roles and mechanisms of MFG-E8 in vascular aging and vascular aging-related diseases with special emphasis on the functions of ECs and VSMCs. In addition, we also aim to focus on the promising diagnostic function as a biomarker and the potential therapeutic application of MFG-E8 in vascular aging and the clinical evaluation of vascular aging-related diseases.

Autoantigen-specific immune tolerance in pathological and physiological cell death: Nanotechnology comes into view

Apoptotic cells are tolerogenic and can present self-antigens in the absence of inflammation, to antigen-presenting cells by the process of efferocytosis, resulting in anergy and depletion of immune effector cells. This tolerance is essential to maintain immune homeostasis and prevent systemic autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Consequently, effective efferocytosis can result in the induction of immune tolerance mediated via triggering modulatory lymphocytes and anti-inflammatory responses. Furthermore, several distinct soluble factors, receptors and pathways have been found to be involved in the efferocytosis, which are able to regulate immune tolerance by lessening antigen presentation, inhibition of T-cell proliferation and induction of regulatory T-cells. Some newly developed nanotechnology-based approaches can induce antigen-specific immunological tolerance without any systemic immunosuppression. These strategies have been explored to reverse autoimmune responses induced against various protein antigens in different diseases. In this review, we describe some nanotechnology-based approaches for the maintenance of self-tolerance using the apoptotic cell clearance process (efferocytosis) that may be able to induce immune tolerance and treat autoimmune diseases.

Medin aggregation causes cerebrovascular dysfunction in aging wild-type mice

Medin is the most common amyloid known in humans, as it can be found in blood vessels of the upper body in virtually everybody over 50 years of age. However, it remains unknown whether deposition of Medin plays a causal role in age-related vascular dysfunction. We now report that aggregates of Medin also develop in the aorta and brain vasculature of wild-type mice in an age-dependent manner. Strikingly, genetic deficiency of the Medin precursor protein, MFG-E8, eliminates not only vascular aggregates but also prevents age-associated decline of cerebrovascular function in mice. Given the prevalence of Medin aggregates in the general population and its role in vascular dysfunction with aging, targeting Medin may become a novel approach to sustain healthy aging.

The expression levels and clinical significance of MFG-E8 and CD133 in epithelial ovarian cancer

The aim of our study was to test whether there is an association between high expression of milk fat globule EGF factor 8 (MFG-E8) and CD133 presence or clinical outcomes of patients with epithelial ovarian cancer (EOC). MFG-E8 and CD133 expression levels were analyzed by immunohistochemistry in 88 EOC tumor specimens. High expression of MFG-E8 directly and significantly correlated with the presence of CD133 immunostaining (R = 0.353, p=.001), whereas immunostaining of MFG-E8 and CD133 significantly correlated with FIGO stage, tumor grade, debulking status, the dualistic model, ascites status, and nonresponse to chemotherapy (p<.05). It was also found that high expression of MFG-E8 and CD133 presence is a potent predictor of poor clinical outcomes among patients with EOC. Our study is the first to show that high expression of MFG-E8 in EOCs positively correlates with CD133 presence. Further research on MFG-E8 in EOC is needed to determine whether MFG-E8 is a new tumor marker of ovarian cancer and a new target for anticancer therapy as well as whether it can interact with cancer stem cell inhibitors for the treatment of refractory tumors.

The structure and properties of MFG-E8 and the In vitro assessment of its toxic effects on myoblast cells

Four high-molecular-weight protein fractions of milk fat globule membrane (MFGM) were isolated from bovine milk. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), MALDI-TOF/TOF™ and Liquid chromatography electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) were used to measure the molecular sizes of the MFGM. Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) were performed to determine the conformations of the MFGM. The results showed that the main protein (98.33%) in MFGM protein fraction 2 was Milk fat globule epidermal growth factor-VIII (MFG-E8), with a molecular weight of 47.82 kDa. The secondary structural component measurements showed that the MFG-E8 consisted of 5% helix, 70% sheet and 25% random coil, and the results matched well with the prediction by SSPro 5.1 bioinformatic analysis. The thermograms analysis revealed that Td and△H of MFG-E8 were 60.50°Cand 132.29 kJ/mol. The in vitro digestibility of MFG-E8 showed that it can be enzymatically hydrolyzed in the stomach and relatively stable in the intestinal fluid. The in vitro C₂C₁₂ and Caco2 cell activity tests indicated that MFG-E8 promoted the proliferation of C₂C₁₂ myoblast cells without cytotoxicity. The biological functional properties of MFG-E8 may be related to the fact that MFG-E8 possesses a high level of β-sheet structure. Our results suggested that MFG-E8 possesses broad prospects not only for use in functional food products but also as a source of natural anti-sarcopenia drugs.

Absence of the MFG-E8 gene prevents hypoxia-induced pulmonary hypertension in mice

Pulmonary hypertension (PH) is a chronic vascular disease characterized by elevated pulmonary arterial resistance and vascular remodeling, and chronic hypoxia plays an important role in PH. Milk fat globule‐EGF factor 8 (MFG‐E8) is a glycoprotein that regulates cell proliferation and apoptosis, but its role in hypoxia‐induced PH is unknown. The current study aimed to determine the function and fundamental mechanisms of MFG‐E8 in hypoxia‐induced PH. Herein, we exposed mice to hypoxia for 5 weeks, and MFG‐E8 was found to be elevated in mouse lung tissues, arteries, and plasma. Compared with wild‐type littermates, mice lacking MFG‐E8 showed a significant increase in the ratio of pulmonary artery acceleration time to ejection time (PAT/PET), while they showed decreases in right ventricular systolic pressure, the Fulton's Index, percent medial wall thickness (%WT), and vascular muscularization in pulmonary arteries. In addition, MFG‐E8 protein levels were also increased in the serum of patients with chronic PH. Similarly, we observed a higher expression of MFG‐E8 in human pulmonary artery smooth muscle cells (PASMCs) in the presence of hypoxic stimulation than MFG‐E8 in cells in normoxic conditions. Furthermore, MFG‐E8 silencing resulted in partial inhibition of proliferation, migration and cell cycle progression in human PASMCs, and the possible mechanisms might involve the interaction between MFG‐E8 and the p‐Akt/cyclin D1 pathway. Collectively, our study suggests that the absence of MFG‐E8 can attenuate the development of hypoxia‐induced PH and vascular remodeling. MFG‐E8 can be a potential therapeutic target or a biomarker for PH.

Extracellular vesicles produced by bone marrow mesenchymal stem cells attenuate renal fibrosis, in part by inhibiting the RhoA/ROCK pathway, in a UUO rat model

Background

Extracellular vesicles produced by bone marrow mesenchymal stem cells (BMSC-EVs) can play important roles in the repair of injured tissues. Though numerous studies have reported the effect of EVs on renal fibrosis, the underlying mechanisms remain unclear. We hypothesized that BMSC-EVs containing milk fat globule–epidermal growth factor–factor 8 (MFG-E8) could attenuate renal fibrosis by inhibiting the RhoA/ROCK pathway.

Methods

We investigated whether BMSC-EVs have anti-fibrotic effects in a rat model of renal fibrosis, in which rats were subjected to unilateral ureteral obstruction (UUO), as well as in cultured HK2 cells. Extracellular vesicles from BMSCs were collected and co-cultured with HK2 cells during transforming growth factor-β1 (TGF-β1) treatment. HK2 cells co-cultured with TGF-β1 were also treated with the ROCK inhibitor, Y-27632.

Results

Compared with the Sham group, UUO rats displayed fibrotic abnormalities, accompanied by an increased expression of α-smooth muscle actin and Fibronectin and reduced expression of E-cadherin. These molecular and pathological changes suggested increased inflammation in damaged kidneys. Oxidative stress, as evidenced by an increased level of MDA and decreased levels of SOD1 and Catalase, was also observed in UUO kidneys. Additionally, activation of cleaved caspase-3 and PARP1 and increased apoptosis in the proximal tubules confirmed tubular cell apoptosis in the UUO group. All of these phenotypes exhibited by UUO rats were suppressed by treatment with BMSC-EVs. However, the protective effect of BMSC-EVs was completely abolished by the inhibition of MFG-E8. Consistent with the in vivo results, treatment with BMSC-EVs reduced inflammation, oxidative stress, apoptosis, and fibrosis in HK-2 cells stimulated with TGF-β1 in vitro. Interestingly, treatment with Y-27632 protected HK-2 cells against inflammation and fibrosis, although oxidative stress and apoptosis were unchanged.

Conclusions

Our results show that BMSC-EVs containing MFG-E8 attenuate renal fibrosis in a rat model of renal fibrosis, partly through RhoA/ROCK pathway inhibition.

Cerebrospinal fluid MFG-E8 as a promising biomarker of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disease resulting in the dysfunction of upper and lower motor neurons. Biomarkers in fluid have been used to monitor the disease and its progression. Milk fat globule-EGF factor 8 (MFG-E8) is an inflammation modulator, which is involved in the pathogenesis of neurodegenerative diseases. We here took this study to evaluate the predictive value of MFG-E8 in ALS.

METHODS

This study consisted of 19 patients with ALS and 15 healthy controls. Cerebrospinal fluid (CSF) were collected from all participants and tested for the levels of MFG-E8, neurofilament light (NFL), and heavy chain (NFH). The correlations between MFG-E8 and NFL, NFH, ALS severity, cognitive status, and forced vital capacity (FVC) were analyzed.

RESULTS

We found that MFG-E8 performs well in distinguishing ALS from controls, with relatively higher level of MFG-E8 in ALS subjects, than controls. Moreover, MFG-E8 negatively correlated with the revised ALS function rating scale (ALS-FRS), but not with the levels of NFL and NFH, disease duration, progression rate, mini-mental state examination (MMSE), and FVC.

CONCLUSIONS

The study proved that CSF MFG-E8 helps distinguish ALS from controls. However, the protein in CSF negatively predicted disease severity.

Knockdown of milk-fat globule EGF factor-8 suppresses glioma progression in GL261 glioma cells by repressing microglial M2 polarization

Tumor-associated microglial cells promote glioma growth, invasion, and chemoresistance by releasing inflammatory factors. Milk fat globule EGF factor 8 protein (MFG-E8), a secreted glycoprotein, is closely related to tissue homeostasis and anti-inflammation. In the present study, we investigated the role of MFG-E8 in microglial polarization and glioma progression in vitro and in vivo. We found that glioma cells secrete comparable amounts of MFG-E8 in culture media to astrocytes. Recombinant MFG-E8 triggered microglia to express the M2 polarization markers, such as arginase-1 (ARG-1), macrophage galactose-type C-type lectin-2 (MGL-2), and macrophage mannose receptor (CD206). Forced expression of MFG-E8 in BV-2 microglia cells not only promoted IL-4-induced M2 polarization but also inhibited lipopolysaccharide (LPS)-induced M1 microglial polarization. Mechanistic studies demonstrated that recombinant MFG-E8 markedly induced signal transducer and activator of transcription 3 (STAT3) phosphorylation, and the STAT3 inhibitor stattic significantly blocked MFG-E8-induced ARG-1 expression. Administration of antibody against MFG-E8 and knockdown of its receptor, integrin β3, significantly attenuated MFG-E8-induced ARG-1 expression. Similarly, knockdown of MFG-E8 also markedly reduced IL-4-induced M2 marker expression and increased LPS-induced M1 marker expression in microglia cells. Moreover, the knockdown of MFG-E8 in GL261 glioma cells inhibited cell proliferation and enhanced chemosensitivity to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), which was likely associated with the downregulation of FAK/AKT activation and STAT3/cyclin D1 signaling. The murine GL261 glioma experimental model demonstrated that knockdown of MFG-E8 significantly reduced tumor size and extended survival times. Additionally, attenuated CD11b⁺ cell infiltration and reduced CD206⁺ expression in CD11b⁺ cells were also observed in an MFG-E8 knockdown GL261 murine glioma model. These results suggested that inhibition of MFG-E8 might hamper the immunosuppressive microenvironment in gliomas and therefore ameliorate tumor progression.

Milk Fat Globule-Epidermal Growth Factor VIII Ameliorates Brain Injury in the Subacute Phase of Cerebral Ischemia in an Animal Model

Objective

Milk fat globule-epidermal growth factor VIII (MFG-E8) may play a key role in inflammatory responses and has the potential to function as a neuroprotective agent for ameliorating brain injury in cerebral infarction. This study aimed to determine the role of MFG-E8 in brain injury in the subacute phase of cerebral ischemia in a rat model.

Methods

Focal cerebral ischemia was induced in rats by occluding the middle cerebral artery with the modified intraluminal filament technique. Twenty-four hours after ischemia induction, rats were randomly assigned to two groups and treated with either recombinant human MFG-E8 or saline. Functional outcomes were assessed using the modified Neurological Severity Score (mNSS), and infarct volumes were evaluated using histology. Anti-inflammation, angiogenesis, and neurogenesis were assessed using immunohistochemistry with antibodies against ionized calcium-binding adapter molecule 1 (Iba-1), rat endothelial cell antigen-1 (RECA-1), and bromodeoxyuridine (BrdU)/doublecortin (DCX), respectively.

Results

Our results showed that intravenous MFG-E8 treatment did not reduce the infarct volume; however, the mNSS test revealed that neurobehavioral deficits were significantly improved in the MFG-E8-treated group than in the vehicle group. Immunofluorescence staining revealed a significantly lower number of Iba-1-positive cells and higher number of RECA-1 in the peri-infarcted brain region, and significantly higher numbers of BrdU- and DCX-positive cells in the subventricular zone in the MFG-E8-treated group than in the vehicle group.

Conclusion

Our findings suggest that MFG-E8 improves neurological function by suppressing inflammation and enhancing angiogenesis and neuronal proliferation in the subacute phase of cerebral infarction.

MFG-E8 alleviates oxygen-glucose deprivation-induced neuronal cell apoptosis by STAT3 regulating the selective polarization of microglia

Background: Ischemic stroke is a complex pathological process, involving inflammatory reaction, energy metabolism disorder, free radical injury, cell apoptosis and other aspects. Accumulating evidences have revealed that MFG-E8 had a protective effect on multiple organ injuries. However, the comprehensive function and mechanism of MFG-E8 in ischemic brain remain largely unclear.Methods: BV-2 cells were treated with recombinant murine MFG-E8 (rmMFG-E8) or/and Colivelin TFA after exposing for 4 h with oxygen glucose deprivation (OGD). Cell viability and apoptosis were assessed by MTT assay and Flow cytometry. RT-qPCR and Western blot assays were applied to examine the expression levels of MFG-E8, apoptosis-related proteins and M1/M2 polarization markers.Results: Our results demonstrated that OGD significantly inhibited microglial viability and facilitated apoptosis. In addition, we found that OGD downregulated MFG-E8 expression, and MFG-E8 inhibited OGD-induced microglial apoptosis and promoted microglial M2 polarization. In terms of mechanism, we proved that MFG-E8 regulated OGD-induced microglial M1/M2 polarization by inhibiting p-STAT3 and SOCS3 expressions, which was reversed by STAT3 activator (Colivelin TFA). Finally, we verified MFG-E8 alleviated OGD-induced neuronal cell apoptosis by M2 polarization of BV-2 cells.Conclusions: We demonstrated that MFG-E8 reduced neuronal cell apoptosis by enhancing activation of microglia via STAT3 signaling. Therefore, we suggested that MFG-E8 might provide a novel mechanism for ischemic stroke.

Bridging molecules are secreted from the skeletal muscle and potentially regulate muscle differentiation

Muscle myogenesis is an essential step for muscle development and recovery. During muscle fusion, multiple molecules are thought to be necessary for the formation of normal myotubes. Milk fat globule-EGF factor 8 (MFG-E8) and Gas6 are phosphatidylserine-recognizing bridging molecules that are secreted mainly from immune cells. In this study, we confirmed that these molecules are expressed and secreted from C2C12 cells. Mouse muscle and satellite cells also expressed these molecules. MFG-E8 was highly expressed and secreted in both undifferentiated and differentiated C2C12 cells. We observed that MFG-E8 and Gas6 were bound to the surface of differentiated C2C12 cells more compared with undifferentiated cells. Additionally, the treatment of recombinant MFG-E8 upregulated expression of myogenic genes and suppressed apoptosis during myogenesis in C2C12 cells. In this paper, we discuss the presence of novel functional molecules expressed and secreted in the skeletal muscle. The results of this study suggest that bridging molecules are one of the determinants of myogenesis or other muscle responses.

Retinol Saturase Knock-Out Mice are Characterized by Impaired Clearance of Apoptotic Cells and Develop Mild Autoimmunity

Apoptosis and the proper clearance of apoptotic cells play a central role in maintaining tissue homeostasis. Previous work in our laboratory has shown that when a high number of cells enters apoptosis in a tissue, the macrophages that engulf them produce retinoids to enhance their own phagocytic capacity by upregulating several phagocytic genes. Our data indicated that these retinoids might be dihydroretinoids, which are products of the retinol saturase (RetSat) pathway. In the present study, the efferocytosis of RetSat-null mice was investigated. We show that among the retinoid-sensitive phagocytic genes, only transglutaminase 2 responded in macrophages and in differentiating monocytes to dihydroretinol. Administration of dihydroretinol did not affect the expression of the tested genes differently between differentiating wild type and RetSat-null monocytes, despite the fact that the expression of RetSat was induced. However, in the absence of RetSat, the expression of numerous differentiation-related genes was altered. Among these, impaired production of MFG-E8, a protein that bridges apoptotic cells to the α_vβ₃/β₅ integrin receptors of macrophages, resulted in impaired efferocytosis, very likely causing the development of mild autoimmunity in aged female mice. Our data indicate that RetSat affects monocyte/macrophage differentiation independently of its capability to produce dihydroretinol at this stage.

MFG-E8 mediates arterial aging by promoting the proinflammatory phenotype of vascular smooth muscle cells

BACKGROUND

Among older adults, arterial aging is the major factor contributing to increased risk for cardiovascular disease-related morbidity and mortality. The chronic vascular inflammation that accompanies aging causes diffuse intimal-medial thickening of the arterial wall, thus increasing the vulnerability of aged vessels to vascular insults. Milk fat globule-epidermal growth factor 8 (MFG-E8) is a biomarker for aging arteries. This integrin-binding glycoprotein, induced by angiotensin II, facilitates vascular smooth muscle cell (VSMC) proliferation and invasion in aging vasculatures. This study investigated whether MFG-E8 directly mediates the initial inflammatory responses in aged arteries or VSMCs.

METHODS

A model of neointimal hyperplasia was induced in the common carotid artery (CCA) of aged mice to exacerbate age-associated vascular remodeling. Recombinant MFG-E8 (rMFG-E8) was administered to the injured artery using Pluronic gel to accentuate the effect on age-related vascular pathophysiology. The MFG-E8 level, leukocyte infiltration, and proinflammatory cell adhesion molecule (CAM) expression in the arterial wall were evaluated through immunohistochemistry. By using immunofluorescence and immunoblotting, the activation of the critical proinflammatory transcription factor nuclear factor (NF)-κB in the injured CCAs was analyzed. Immunofluorescence, immunoblotting, and quantitative real-time polymerase chain reaction were conducted using VSMCs isolated from the aortas of young and aged mice to assess NF-κB nuclear translocation, NF-κB-dependent gene expression, and cell proliferation. The extent of intimal-medial thickening in the injured vessels was analyzed morphometrically. Finally, Transwell migration assay was used to examine VSMC migration.

RESULTS

Endogenous MFG-E8 expression in aged CCAs was significantly induced by ligation injury. Aged CCAs treated with rMFG-E8 exhibited increased leukocyte extravasation, CAM expression, and considerably increased NF-κB activation induced by rMFG-E8 in the ligated vessels. Exposure of early passage VSMCs from aged aortas to rMFG-E8 substantially increased NF-κB activation, proinflammatory gene expression, and cell proliferation. However, rMFG-E8 attenuated VSMC migration.

CONCLUSIONS

MFG-E8 promoted the proinflammatory phenotypic shift of aged VSMCs and arteries, rendering the vasculature prone to vascular diseases. MFG-E8 may constitute a novel therapeutic target for retarding the aging processes in such vessels.

The significance of tumor cells-derived MFG-E8 in tumor growth of angiosarcoma

BACKGROUND

Previous studies have indicated that MFG-E8 enhances tumor cell survival, invasion and angiogenesis. However, the role of MFG-E8 in angiosarcoma (AS) has not been clarified.

OBJECTIVE

Objective was to elucidate the mechanism of the regulation by MFG-E8 in AS and the association between MFG-E8 and clinicopathological features of AS.

METHODS

The effects of the depletion of MFG-E8 by siRNA on tube formation, migration and proliferation in murine AS cells were examined. The effect of administration of anti-MFG-E8 antibody (Ab) on tumor growth of AS in mice was examined. The associations of MFG-E8 expression and clinicopathological features of human AS were assessed.

RESULTS

The expressions of MFG-E8 in murine and human AS cells were significantly higher than those in melanoma cells, macrophages and endothelial cells. Depletion of MFG-E8 in murine AS cells by siRNA significantly inhibited the formation of capillary-like structures and migration, but not proliferation. Administration of anti-MFG-E8 Ab significantly inhibited tumor growth and decreased the number of tumor-associated macrophages (TAMs) in AS tumors. Tumor size and the number of TAMs in human AS with high expression of MFG-E8 were significantly increased compared to those of AS with low expression of MFG-E8. Progression-free survival and overall survival time of the patients of AS with high expression of MFG-E8 were significantly shorter than those of AS with low expression of MFG-E8.

CONCLUSIONS

AS-derived MFG-E8 might enhance tumor growth via angiogenesis and the induction of TAMs in autocrine/paracrine manner, and administration of anti-MFG-E8 Ab could be a therapeutic potential for AS.

Neurogenesis in Neurodegenerative Diseases: Role of MFG-E8

Neurodegenerative diseases are devastating medical conditions with no effective treatments. Restoration of impaired neurogenesis represents a promising therapeutic strategy for neurodegenerative diseases. Milk fat globule-epidermal growth factor-factor VIII (MFG-E8) is a secretory glycoprotein that plays a wide range of cellular functions including phagocytosis of apoptotic cells, anti-inflammation, tissue regeneration, and homeostasis. The beneficial role of MFG-E8 has been shown in cerebral ischemia (stroke), neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, and traumatic brain injury. In stroke, MFG-E8 promotes neural stem cell proliferation and their migration toward the ischemic brain tissues. These novel functions of MFG-E8 are primarily mediated through its receptor α_vβ₃-integrin. Here, we focus on the pivotal role of MFG-E8 in protecting against neuronal diseases by promoting neurogenesis. We also discuss the mechanisms of MFG-E8-mediated neural stem/progenitor cell (NSPC) proliferation and migration, and the potential of MFG-E8 for neural stem cell niche maintenance via angiogenesis. We propose further investigation of the molecular pathways for MFG-E8 signaling in NSPC and effective strategies for MFG-E8 delivery across the blood–brain barrier, which will help develop MFG-E8 as a future drug candidate for the bedside management of neurodegenerative diseases.

Evaluation of milk fat globule-epidermal growth factor-factor VIII and IL-1β levels in gingival crevicular fluid and saliva in periodontal disease and health

The aim of this study is to determine the levels of MFG-E8 and interleukin (IL)-1β in saliva and gingival crevicular fluid (GCF) associated with periodontal health and disease. Whole saliva and GCF samples were obtained from systemically healthy participants who were either periodontally healthy (n = 24) or suffered from gingivitis (n = 25) or chronic periodontitis (n = 25). Full-mouth clinical periodontal measurements, including bleeding on probing, probing depth, gingival index, plaque index, and clinical attachment level were also recorded. Enzyme-linked immunosorbent assay was used to estimate MFG-E8 and IL-1β levels in the samples. Analysis of variance, Kruskal-Wallis tests, and Pearson correlation tests were used to analyse the data statistically. The total level of MFG-E8 in GCF was significantly higher in the healthy group than in the other two groups (P = 0.01). Salivary MFG-E8 levels did not differ significantly among the groups. There were negative correlations between the level of MFG-E8 in GCF and probing depth (P = 0.03), bleeding on probing (P = 0.001), plaque index (P = 0.003), and gingival index (P = 0.003). The total level of IL-1β in GCF was significantly lower in the healthy group than in the groups with gingivitis and chronic periodontitis (P < 0.001). Salivary IL-1β levels showed significant differences across all three groups (P < 0.001). The level of MFG-E8 in GCF was higher in the healthy group than in the periodontal disease groups. Furthermore, there was no difference between gingivitis and periodontitis groups. The relationship between MFG-E8 and periodontal status should be further investigated.

MFG-E8 overexpression is associated with poor prognosis in breast cancer patients

BACKGROUND

MFG-E8(Milk fat globule-EGF factor 8), a secreted glycoprotein, plays an exceptional role in various diseases. MFG-E8 overexpression is found in a variety of cancers. However, it remains unclear whether MFG-E8 overexpression is associated with the clinicopathological characteristics and prognosis of human breast cancer.

MATERIALS AND METHODS

In this study, we detected the expression and localization of MFG-E8 protein in breast cancer and cancer-adjacent tissues using immunohistochemical staining, Western blot analysis and immunofluorescence. We analyzed the association between MFG-E8 expression and clinical characteristics and outcomes of breast cancer patients with different HR and HER2 statuses.

RESULTS

Our results confirmed that MFG-E8 expression increased significantly in breast cancer compared with cancer-adjacent tissues by immunohistochemical staining (P <  0.001). Similarly, the Western blot results further confirmed the increased expression of MFG-E8 in breast cancer compared with cancer-adjacent tissues (P =  0.001). Immunofluorescence staining showed that MFG-E8 was mainly localized in the cytoplasm and membrane of tumor cells, consistent with the immunohistochemical staining results. The high expression levels of MFG-E8 showed a greater association with lymph node metastasis, TNM stage and histological grade (P < 0.001). Moreover, high MFG-E8 expression was related to a shortened overall survival (OS) (P <  0.001) and disease-free survival (DFS) (P <  0.001). Bioinformatics analysis with a Kaplan-Meier plotter also demonstrated a strong association of MFG-E8 mRNA overexpression with a short OS and DFS compared with low MFG-E8 expression (P =  0.040, P =  0.005).

CONCLUSIONS

Our findings indicate that MFG-E8 may be a potential marker for poor prognosis and survival in breast cancer.

MFG-E8 reverses microglial-induced neurotoxic astrocyte (A1) via NF-κB and PI3K-Akt pathways

Recent evidence have suggested that neuroinflammation and ischemia induce the activation of two different types of reactive astrocytes, termed A1 and A2. Additionally, A1 astrocytes contribute to the death of neurons and oligodendrocytes in neurodegenerative diseases, such as Alzheimer's disease (AD). In the current study, we constructed an Aβ42-activated microglia-conditioned medium to induce A1 astrocytic activation via secretion of interleukin 1α, tumor necrosis factor, and complement component 1q in vitro, and indicated the regulatory role of milk fat globule epidermal growth factor 8 (MFG-E8) on A1/A2 astrocytic alteration through the downregulation of nuclear factor-κB and the upregulation of PI3K-Akt. This study showed that MFG-E8 suppressed A1 astrocytes and holds great potential for the treatment of AD.

Alterations in expression of endometrial milk fat globule-EGF factor 8 (MFG-E8) and leukemia inhibitory factor (LIF) in patients with infertility and endometriosis

OBJECTIVE

The aim of this study was to compare the endometrial expression of milk fat globule-EGF factor 8 (MFG-E8), its receptor integrin αvβ3, and leukemia inhibitory factor (LIF) in patients with endometriosis and infertility and in healthy fertile patients during the window of implantation.

METHODS

Five patients with peritoneal endometriosis and infertility (case group) and four healthy fertile patients (control group) were recruited. All patients were either diagnosed with or ruled out for endometriosis by laparoscopic surgery; the case group underwent surgery for infertility investigation and the control group for tubal ligation. Endometrial biopsies were performed in all patients during the window of implantation (LH+8 to LH+10), and then the samples were analyzed by immunochemistry for MFG-E8, integrin αvβ3, and LIF.

RESULTS

In patients with endometriosis and infertility, expression of MFG-E8 was significantly increased in the glandular epithelium when compared to healthy fertile patients (p<0.001). Moreover, LIF expression was lower in patients with endometriosis and infertility (p<0.05). Nevertheless, we found no difference in integrin αvβ3 expression between the groups (p=0.084).

CONCLUSION

This study showed for the first time that MFG-E8 expression is impaired in the endometrium of patients with endometriosis and infertility during the window of implantation. Moreover, LIF is also diminished in the endometrium of these patients as shown before.

Lactadherin: An unappreciated haemostasis regulator and potential therapeutic agent

Lactadherin is a small (53-66kDa) multifunctional glycoprotein belonging to the secreted extracellular matrix protein family. It has a multi-domain structure and is involved in many biological and physiological processes, including phagocytosis, angiogenesis, atherosclerosis, tissue remodeling, and haemostasis regulation. Lactadherin binds phosphatidylserine (PS)-enriched cell surfaces in a receptor-independent manner. Interaction between lactadherin and PS is crucial for regulation of blood coagulation processes. This review summarizes recent knowledge on the possible role of lactadherin in haemostasis control, emphasizing the great significance of the interaction between lactadherin and PS expressed on activated platelets and extracellular vesicles. The possible role of lactadherin as a therapeutic target and biomarker is also discussed.

Prognostic Correlation Between MFG-E8 Expression Level and Colorectal Cancer

BACKGROUND AND AIMS

Colorectal cancer (CRC) is one of the leading causes of cancer-related death all over the world. Milk fat globule-epidermal growth factor (EGF)-factor VIII (MFG-E8) was found to be highly expressed in a variety of cancers. However its role in CRC is unclear. This study investigates the expression of MFG-E8 in CRC tissues and the correlation with clinicopathological features and prognosis in CRC patients.

METHODS

The expression of MFG-E8 proteins was detected by immunohistochemical staining in 90 samples of CRC. The localization of MFG-E8 in colorectal tumor was examined by immunofluorescence staining. The correlation between MFG-E8 protein expression and the clinical pathological features of CRC were evaluated by χ² test and Fisher's exact test. The survival rates were analyzed by the Kaplan-Meier method, and the relationship between prognostic factors and patient survival was analyzed by the Cox proportional hazard models.

RESULTS

Our results showed that MFG-E8 expression increased significantly in colorectal cancer compared with normal mucosa tissues (p <0.001). We further validated MFG-E8 overexpression in 6 pairs of fresh tumor and adjacent normal mucosa tissues from colorectal cancer patients by Western blot (p <0.05). Immunofluorescence staining showed that MFG-E8 accumulated in close proximity to endothelial cells in human colorectal tumor tissue. In addition, high MFG-E8 protein expression was correlated with lymph node metastasis and some pathological classifications (p <0.05). Furthermore, patients with high protein level of MFG-E8 showed shortened overall survivals (p <0.05).

CONCLUSION

Our results showed that MFG-E8 could be a potential novel prognostic marker for CRC and overexpression of MFG-E8 might be involved in lymph node metastasis and angiogenesis of CRC.

Deficiency in milk fat globule-epidermal growth factor-factor 8 exacerbates organ injury and mortality in neonatal sepsis

INTRODUCTION

Neonatal sepsis is a systemic inflammation occurring in neonates because of a proven infection within the first 28days of birth. It is the third leading cause of morbidity and mortality in the newborns. The mechanism(s) underlying the systemic inflammation in neonatal sepsis has not been completely understood. We hypothesize that the deficiency of milk fat globule-epidermal growth factor-factor 8 (MFG-E8), a protein commonly found in human milk, could be responsible for the increased inflammatory response leading to morbidity and mortality in neonatal sepsis.

METHODS

Male and female newborn mice aged 5-7days were injected intraperitoneally with 0.9mg/g body weight cecal slurry (CS). At 10h after CS injection, they were euthanized, and blood, lungs and gut tissues were obtained for further analyses. Control newborn mice underwent similar procedures with the exception of the CS injection. In duplicate newborn mice after CS injection, they were returned to their respective cages with their mothers and were closely monitored for 7days and survival rate recorded.

RESULTS

At 10h after CS injection, serum LDH in the MFG-E8 knockout (KO) newborn mice was significantly increased by 58% and serum IL-6, IL-1β and TNF-α in the MFG-E8KO newborn mice were also significantly increased by 56%, 65%, and 105%, respectively, from wild type (WT) newborn mice. There were no significant difference between WT control and MFG-E8 control newborn mice. The lung architecture was severely damaged and a significant 162% increase in injury score was observed in the CS MFG-E8KO newborn mice. The MPO, TUNEL staining, and cytokine levels in the lungs and the intestine in CS MFG-E8KO newborn mice were significantly increased from CS WT newborn mice. Similarly, intestinal integrity was also compromised in the CS MFG-E8KO newborn mice. In a survival study, while the mortality rate within 7days was only 29% in the CS WT newborn mice, 80% of the CS MFG-E8KO newborn mice died during the same time period with the majority of mortality occurring within 48h.

CONCLUSION

The deficiency in MFG-E8 caused increases in inflammation, tissue injury, neutrophil infiltration and apoptosis, which led to morbidity and mortality in murine neonatal sepsis. These studies suggest that MFG-E8 has a protective role in fighting against neonatal sepsis.