Milk Fat Globule-epidermal Growth Factor Research Articles

Milk fat globule-epidermal growth factor 8 (MFGE8) prevents intestinal fibrosis

ObjectiveIntestinal fibrosis is considered an inevitable consequence of chronic IBD, leading to stricture formation and need for surgery. During the process of fibrogenesis, extracellular matrix (ECM) components critically regulate the...

MFG-E8 facilitates heart repair through M1/M2 polarization after myocardial infarction by inhibiting CaMKII

BackgroundM1/M2 macrophage polarization affects patient outcomes after myocardial infarction (MI). The relationship between milk fat globule-epidermal growth factor 8 (MFG-E8) and Ca2+/calmodulin-dependent protein kinase II (CaMKII) on macrophage polarization after MI is unknown. To investigate the functional role of MFG-E8 in modulating cardiac M1/M2 macrophage polarization after MI, especially its influence on CaMKII signaling. MethodsHuman ventricular tissue and blood were obtained from patients with MI and controls. MFG-E8-KO mice were constructed (C57BL/6). The mice were randomized to WT-sham, sham-MFG-E8-KO, WT-PBS, rmMFG-E8 (WT injected with rmMFG-E8 10 min after MI), and MFG-E8-KO. The mouse macrophage cell line RAW264.7 was obtained. CaMKII, p-CaMKII, Akt, and NF-κB p65 were determined by qRT-PCR, western blot, and immunofluorescence. ResultsThe MFG-E8 levels were significantly enhanced after MI in the hearts and plasma of patients with MI compared with controls. The MFG-E8 levels were significantly increased in the hearts and plasma of mice after MI. MFG-E8 was derived from cardiac fibroblasts. The administration of rmMFG-E8 improved ventricular remodeling and cardiac function after MI. rmMFG-E8 did not suppress infiltrating monocyte/macrophages into the peri-infarct area. rmMFG-E8 suppressed the polarization of macrophages to the M1 phenotype and promoted the polarization of macrophages to the M2 phenotype. rmMFG-E8 suppressed CaMKII-dependent signaling in macrophages. ConclusionsMFG-E8 and CaMKII appear to collaboratively regulate myocardial remodeling and M1/M2 macrophage polarization after MI. These observations suggest new roles for MFG-E8 in inhibiting M1 but promoting M2 macrophage polarization.

Expression and clinical association of MFG-E8 and TAM receptors in diabetic patients with different stages of microvascular complication: An experimental study.

Diabetic nephropathy (DN) is a major microvascular complication of diabetes mellitus that leads to end-stage renal disease. Hyperglycemia triggers apoptosis and kidney damage. Milk fat globule-epidermal growth factor 8 (MFG-E8) and TAM receptor tyrosine kinases, Tyro3, Axl, and Mer, are phagocytic receptors that mediate the clearance of apoptotic cells. This study aimed to identify the role of MFG-E8 and TAM receptors in the development of DN. A total of 146 patients with type 2 diabetes mellitus (T2DM), early stage DN, clinical DN and 48 healthy controls were employed to analyze the serum levels of MFG-E8, soluble Tyro3, Axl, Mer, and RAGE by enzyme-linked immunosorbent assay. The serum levels of CREA, hsCRP, CysC, and β2-microglobulin were measured by spectrophotometric analysis using a biochemical analyzer (AU5800). Our results showed that the serum levels of MFG-E8 were elevated in patients with T2DM compared with healthy controls; however, it decreased gradually in patients with DN with the severity of kidney injury, especially in the clinical DN group. Moreover, the levels of sTyro3, sAxl, and sMer were reduced in patients with T2DM and DN compared to healthy controls, particularly in patients with DN. The levels of MFG-E8, sTyro3, sAxl, and sMer were negatively correlated with UAER at 24 hours, CREA, hsCRP, CysC, β2-microglobulin, and RAGE, respectively. In addition, TAM receptors had significantly higher predictive and diagnostic values for early stage DN from T2DM than hsCRP, β2-microglobulin, and CysC, which are also predictive biomarkers of early stage DN from clinical DN. Decreased MFG-E8 and TAM receptor expression is associated with an increased risk of microvascular complications in patients with T2DM, which plays a critical role in the diagnosis of diabetic patients with microvascular complications, especially early stage DN, and in monitoring the development of DN.

Correlation of Serum and Gingival Crevicular Fluid Levels of Caspase-3 and Milk Fat Globule-Epidermal Growth Factor 8 on Gingival Health.

This study aimed to estimate and correlate the serum and gingival crevicular fluid (GCF) levels of caspase-3 and milk fat globule-epidermal growth factor 8 (MFG-E8) in healthy, gingivitis and generalised chronic periodontitis subjects. A total of 24 subjects were selected and divided into three groups. After recording the periodontal parameters (plaque index (PI), modified gingival index (MGI), probing depth (PD) and clinical attachment level (CAL)), the serum and GCF samples were collected and the levels of caspase-3 and MFG-E8 were estimated using enzyme-linked immunoassay (ELISA). The mean values of PI, MGI, PD and CALs were significantly higher in group III when compared to group II and group I. The mean value of serum and GCF caspase-3 increased with increasing disease severity, whereas the mean serum and GCF values of MFG-E8 decreased with increasing severity of disease. Spearman's correlation showed a strong positive correlation between the serum and GCF levels of caspase-3 and periodontal parameters, whereas serum and GCF levels of MFG-E8 showed a strong negative correlation with the periodontal parameters. The findings of this study are suggestive that the serum and GCF levels of caspase-3 and MFG-E8 could serve as a potential biomarker for the role of apoptosis in periodontal disease. However, further studies are required to explore the mechanism and understand the relationship between these apoptotic markers and periodontitis.

Gene expression levels of inflammatory mediators in diabetic foot ulcer patients

Background: Diabetic foot ulcer (DFU) is a common serious complication of diabetes. Nowadays there is a suggestion that referred to the fact
 the chronicity of DFU is a result of the positive feedback of proinflammatory cytokines production. Objective: This study aimed to display the negative effects of persistent expression of proinflammatory cytokines of (IL-1β and IL-18) under hyperglycemic condition on the DFU microenvironment and clarify the role of growth factor Milk fat globule-epidermal growth factor- 8( MFG-) in the DFU healing process. Approach: Clinical data of a total of 49 type 2 diabetic patients have chronic diabetic foot ulcer grade 2 and 3 (infected DFU n= 29 and non-infected n=21) in addition to the control group (n=25) were participated in the study since June 2021 to April 2022 , venous blood samples were collected for the measurement of the gene expression levels of (IL-1β ; IL-18 and MFG-E8) by Real-Time PCR technique . Results: There was no significant difference in age and sex when compared with the control group at p= 0.798, p =0.514 respectively. High levels of gene expression of (IL-1β ; IL-18 and MFG-E8) were shown in the patients group in comparison to the healthy control.
 Conclusions: Current data confirmed that the inflammatory mediators’ (IL-1β ; IL-18 and MFG-E8) have a strong association with the pathogenesis of DFU healing process.
 
 

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.

Progranulin deficiency suppresses allergic asthma and enhances efferocytosis via PPAR-γ/MFG-E8 regulation in macrophages.

Efferocytosis can resolve airway inflammation and enhance airway tolerance in allergic asthma. While previous work has reported that progranulin (PGRN) regulated macrophage efferocytosis, but it is unclear whether PGRN-mediated efferocytosis is associated with asthma. Here, we found that in an ovalbumin (OVA)-induced allergic asthma model, the airway inflammation was suppressed and the apoptosis in lung tissues was ameliorated in PGRN-deficient mice. In contrast, PGRN knockdown in human bronchial epithelial cellsincreased apoptosis in vitro. Furthermore, PGRN-deficient macrophages had significantly stronger efferocytosis ability than wild type (WT) macrophages both in vitro and in vivo. PGRN-deficient peritoneal macrophages (PMs) exhibited increased expression of genes associated with efferocytosis including milk fat globule-epidermal growth factor 8 (MFG-E8), peroxisome proliferator-activated receptor gamma (PPAR-γ) and sirtuin1 (SIRT1) and increased capacity to produce the anti-inflammatory mediator interleukin (IL)-10 during efferocytosis. GW9662, the inhibitor of PPAR-γ, abolished increased efferocytosis and MFG-E8 expression in PGRN-deficient PMs suggesting that PGRN deficiency enhanced MFG-E8-mediated efferocytosis through PPAR-γ. Correspondingly, efferocytosis genes were increased in the lungs of OVA-induced PGRN-deficient mice. GW9662 treatment reduced MFG-E8 expression but did not significantly affect airway inflammation. Our results demonstrated that PGRN deficiency enhanced efferocytosis via the PPAR-γ/MFG-E8 pathway and this may be one of the reasons PGRN deficiency results in inhibition of airway inflammation in allergic asthma.

DOP32 Crohn’s disease stricture matrisome analysis reveals the anti-fibrotic activity of milk-fat globule-epidermal growth factor 8 (MFGE8)

Abstract Background Intestinal fibrosis is considered an inevitable consequence of chronic inflammatory bowel disease (IBD), leading to stricture formation and need for surgery. During the process of fibrogenesis, extracellular matrix (ECM) components critically regulate the function of mesenchymal cells. We characterized the composition and function of the ECM in fibrostenosing Crohn’s disease (CD) and control tissues. Methods Decellularized full thickness intestinal tissue platforms were tested using three different protocols and ECM composition in different tissue phenotypes was explored by proteomics and validated by quantitative polymerase chain reaction (qPCR) and immunohistochemistry. Primary human intestinal myofibroblasts (HIMF) treated with Milk Fat Globule-Epidermal growth factor 8 (MFGE8) were evaluated regarding mechanism of their anti-fibrotic response, and the action of MFGE8 was tested in experimental intestinal fibrosis. Results We established and validated an optimal decellularization protocol for intestinal IBD tissues. Matrisome analysis revealed elevated MFGE8 expression in CD strictured tissue (CDs), which was confirmed at the mRNA and protein levels. Treatment with MFGE8 inhibited ECM production in normal control (NL) HIMF but not CDs HIMF. Next generation sequencing (NGS) uncovered functionally relevant integrin-mediated signaling pathways, and blockade of integrin αvβ5 and focal adhesion kinase rendered HIMF non-responsive to MFGE8. MFGE8 prevented and reversed experimental intestinal fibrosis in vitro and in vivo. Conclusion MFGE8 displays anti-fibrotic effects, and its administration may represent a future therapeutic approach for prevention of IBD-induced intestinal strictures.

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

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. 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. 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). 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.

Association between serum MFG-E8 levels and coronary severity index in patients with acute coronary syndrome

Aim: MFG-E8 (milk fat globule-epidermal growth factor 8, also known as lactaderin) plays an important role in many adverse clinical conditions such as atherosclerosis, angiogenesis, ischemia/reperfusion injury and cancers. The present study aims to investigate the association of serum MFG-E8 levels at admission with the severity of coronary artery disease (CAD) in patients with acute coronary syndrome (ACS). &#x0D; Material and Methods: A total of 88 patients were enrolled into the study. Patients were divided into two groups according to SYNTAX score as low SYNTAX score 0.05). However, there was a moderate and negative correlation between MFG-E8 levels and Thrombolysis In Myocardial Infarction (TIMI) risk score (r = -0.365, p = 0.001). A slightly negative association between serum uric acid level and MFG-E8 was also determined ( r = -0.232, p = 0.03). In addition, diabetes mellitus (p = 0.031), monocyte to HDL ratio (p = 0.049), TIMI risk score (p = 0.004) and SYNTAX II (p = 0.012) score were significantly higher in the high SYNTAX group with a significantly lower LVEF (p = 0.014). &#x0D; Conclusion: The serum levels of MFG-E8 were not found to be correlated with the SYNTAX score, an indicator of worsening clinical cardiovascular event risk and the severity of coronary artery stenosis. However, MFG-E8 levels were found to be correlated with TIMI risk score, which is one of the most commonly used risk stratification model for patients presenting with non-ST segment elevation miyocardial infarction (NSTEMI).

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 STATEMENT What 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.

Inflammatory Role of Milk Fat Globule-Epidermal Growth Factor VIII in Age-Associated Arterial Remodeling.

BackgroundAge‐associated aortic remodeling includes a marked increase in intimal medial thickness (IMT), associated with signs of inflammation. Although aortic wall milk fat globule–epidermal growth factor VIII (MFG‐E8) increases with age, and is associated with aortic inflammation, it is not known whether MFG‐E8 is required for the age‐associated increase in aortic IMT. Here, we tested whether MFG‐E8 is required for the age‐associated increase in aortic IMT.Methods and ResultsTo determine the role of MFG‐E8 in the age‐associated increase of IMT, we compared aortic remodeling in adult (20‐week) and aged (96‐week) MFG‐E8 (−/−) knockout and age matched wild‐type (WT) littermate mice. The average aortic IMT increased with age in the WT from 50±10 to 70±20 μm (P<0.0001) but did not significantly increase with age in MFG‐E8 knockout mice. Because angiotensin II signaling is implicated as a driver of age‐associated increase in IMT, we infused 30‐week‐old MFG‐E8 knockout and age‐matched littermate WT mice with angiotensin II or saline via osmotic mini‐pumps to determine whether MFG‐E8 is required for angiotensin II–induced aortic remodeling. (1) In WT mice, angiotensin II infusion substantially increased IMT, elastic lamina degradation, collagen deposition, and the proliferation of vascular smooth muscle cells; in contrast, these effects were significantly reduced in MFG‐E8 KO mice; (2) On a molecular level, angiotensin II treatment significantly increased the activation and expression of matrix metalloproteinase type 2, transforming growth factor beta 1, and its downstream signaling molecule phosphorylated mother against decapentaplegic homolog 2, and collagen type I production in WT mice; however, in the MFG‐E8 knockout mice, these molecular effects were significantly reduced; and (3) in WT mice, angiotensin II increased levels of aortic inflammatory markers phosphorylated nuclear factor‐kappa beta p65, monocyte chemoattractant protein 1, tumor necrosis factor alpha, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 molecular expression, while in contrast, these inflammatory markers did not change in knockout mice.ConclusionsThus, MFG‐E8 is required for both age‐associated proinflammatory aortic remodeling and also for the angiotensin II–dependent induction in younger mice of an aortic inflammatory phenotype observed in advanced age. Targeting MFG‐E8 would be a novel molecular approach to curb adverse arterial remodeling.

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 αVβ3 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.

P-366 Tumor necrosis factor-alpha and milk fat globule-epidermal growth factor 8: novel biomarkers to predict implantation failure and pregnancy loss

Abstract Study question Can implantation failure (IF) and pregnancy loss be predicted in serum prior to in vitro fertilization (IVF)? Summary answer Tumor necrosis factor (TNFα) and milk fat globule-epidermal growth factor 8 (MFG-E8) levels may serve as serum markers to predict IF and pregnancy loss. What is known already In a normal pregnancy, mediators such as TNFα are released creating a physiological inflammatory response. However, an exaggerated release of TNFα has been associated with IF and recurrent pregnancy loss (RPL). Recent studies demonstrated that TNFα up-regulates the expression of inflammatory factors such as MFG-E8. MFG-E8 is known to modulate implantation by acting at various levels of the trophoblast and endometrial compartments. Hence an overexpression of this protein may result in apoptosis, endometrial damage, and impaired implantation. Study design, size, duration This multicentric prospective controlled pilot clinical study was conducted from January 2016 to January 2020 and included 30 women in their natural cycle in which serum MFG-E8, TNFα, estradiol (E2), and progesterone (P4) levels were quantified in the early proliferative (cycle day 2) and secretory phases (urinary LH + 7 days). Additionally, an endometrial biopsy was obtained on urinary LH + 7 days for MFG-E8 and TNF α protein and gene expression analysis. Participants/materials, setting, methods Women ages 21-35y were recruited from 3 groups: fertile controls (C), unexplained IF (following 3 failed good quality embryo transfers), and RPL (at least 2 unexplained first trimester miscarriages). Patients with history of uterine surgery, abnormal uterine cavity (fibroids, endometrial polyps, adhesions, adenomyosis, and congenital uterine abnormalities), hydrosalpinx, diminished ovarian reserve, harboring chromosomal rearrangements, thrombophilia, or autoimmune diseases were excluded. Main results and the role of chance Ten women were included in each group. No statistical differences were found in age, BMI, AMH, baseline FSH, and baseline antral follicle count among cohorts. Mean serum E2 and P4 levels were similar among all groups in both the proliferative and secretory phases: E2 proliferative (C 69.19±26.64 pg/ml, IF 64.19±32.56 pg/ml, RPL proliferative 57.44±38.51; p = 0.55), E2 secretory (C 164.10±52.57 pg/ml, IF 172.57±121, RPL 173.81±.97.35; p = 0.25), P4 proliferative (C 0.45±0.15 ng/ml, IF 0.45±0.19 ng/ml, RPL 0.53±0.18 ng/ml; p = 0.85), P4 secretory (C 7.42±4.06 ng/ml, IF 7.8±4.56 ng/ml, RPL 8.05±4.38 ng/ml; p = 0.74). Mean serum TNFα levels were significantly higher in both, the proliferative and secretory phases for the RPL group (proliferative RPL 9.98±4.47 pg/ml, IF 4.73±2.56 pg/ml, C 3.42±1.01 pg/ml; p = 0.001 vs secretory RPL 8.67±4.45 pg/ml, C 3.35±0.94 pg/ml, IF 3.85±1.01 pg/ml; p = 0.03). Mean serum MFG-E8 levels were significantly higher in the IF group during the proliferative phase (IF 373±201 pg/ml, RPL 201±115 pg/ml, C 225.58±109.73pg/ml; p = 0.03), but not in the secretory phase (IF 237±101 pg/ml, RPL 189±116 pg/ml, C 199.41±112.43 pg/ml; p = 0.15). Endometrial MFG-E8 mRNA levels were significantly lower in the IF and RPL group compared to C (p = 0.03). TNFα mRNA levels were not statistically significant among groups (p = 0.12). Limitations, reasons for caution This is a pilot study to assess feasibility. Due to the small sample size, the effects of more subtle covariates would not have been detected. Future larger studies are warranted. Wider implications of the findings These novels differentially expressed serum and endometrial markers may provide information on the physiology of implantation and could generate the basis for non-invasive diagnostic tools and therapeutic use of MFG-E8/TNFα antagonists in women with IF and RPL. Trial registration number IIT-2014-100366

Chondroprotective Effects of Periodontal Ligament-Derived Stem Cells Conditioned Medium on Articular Cartilage After Impact Injury.

Paracrine factors secreted in the conditioned media (CMs) of periodontal ligament-derived stem cells (PDLSCs) have been shown to downregulate inflammatory effects of interleukin (IL)-1β on chondrocytes wherein milk fat globule-epidermal growth factor 8 (MFG-E8) is one of the PDLSCs' highly secretory proteins. Therefore, the objective of this study was to investigate the ability of PDLSC CMs and MFG-E8 to reduce the inflammatory effects of impact injury on porcine talar articular cartilage (AC) and IL-1β on chondrocytes, respectively. Stem cells were isolated from human periodontal ligaments. The MFG-E8 content in CM collected at 5% and 20% oxygen was measured by ELISA assay and compared across subcultures and donors. AC samples were divided into three groups: control, impact, and impact+CM. Chondrocytes were isolated from pig knees and were divided into three groups: control, IL-1β, and IL-1β+MFG-E8. Gene expression data were analyzed by reverse transcription-polymerase chain reaction. It was found that impact load and IL-1β treatment upregulated IL-1β, TNF-α, ADAMTS-4, and ADAMTS-5 gene expression in AC and chondrocytes, respectively. PDLSCs-CM prevented the upregulation of all four genes due to impact, whereas MFG-E8 prevented upregulation of IL-1β, ADAMTS-4, and ADAMTS-5 in chondrocytes, but it did not prevent TNF-α upregulation. There were no significant differences in MFG-E8 content in CM among oxygen levels, passage numbers, or donors. The findings suggested that MFG-E8 is an effective anti-inflammatory agent contributing to the chondroprotective effects of PDLSCs-CM on acutely injured AC. Thus, introducing PDLSCs-CM to sites of acute traumatic AC injury could prevent the development of post-traumatic osteoarthritis.

αvβ3-targeted sEVs for efficient intracellular delivery of proteins using MFG-E8

BackgroundSmall extracellular vesicles (sEVs) are nanometer-sized membranous particles shed by many types of cells and can transfer a multitude of cargos between cells. Recent studies of sEVs have been focusing on their potential to be novel drug carriers due to natural composition and other promising characteristics. However, there are challenges in sEVs-based drug delivery, one of which is the inefficient loading of drugs into sEVs, especially for large biomolecules.ResultsIn this study, we proposed a membrane-associated protein, milk fat globule–epidermal growth factor 8 protein (MFG-E8), to produce αvβ3-targeted sEVs with high delivery efficiency of interested protein. MFG-E8 is a secreted protein with NH2-terminal epidermal growth factor (EGF)–like domains, containing an Arg-Gly-Asp(RGD) sequence that binds αvβ3 and αvβ5 integrins, and COOH terminal domains C1 and C2, which can bind to lipid membrane with strong affinity. Firstly, we transiently expressed MFG-E8 in HEK293F cells and found that this protein could be secreted and adhere to the cell membrane. The recombinant MFG-E8 is also found to locate at the outer membrane of sEVs. Then we generated engineered sEVs by expressing high levels of the EGFP fused to MFG-E8 in HEK293F cells and showed that MFG-E8 could increase the delivery efficiency of EGFP into sEVs. Further delivery of Gaussia luciferase (GL) by fusion expression with MFG-E8 in donor cells demonstrated that target proteins fused with MFG-E8 still kept their activity. Finally, we identified the sEVs’ target to integrin αvβ3 by comparing the transfection efficiency with MFG-E8 loaded sEVs (MFG-E8-sEVs) in αvβ3 positive cells and αvβ3 negative cells. Analysis showed higher target protein could transfect into αvβ3 positive cells with MFG-E8-sEVs than with EGFP loaded sEVs (EGFP-sEVs), meaning the engineered sEVs with MFG-E8 not only could increase the delivery of target protein into sEVs, but also could target the αvβ3 positive cells.ConclusionThis study suggests that recombinant MFG-E8 is an ideal protein to increasingly deliver the drug into sEVs and give sEVs the ability to target the αvβ3 positive cells.

Milk fat-globule epidermal growth factor 8: A potential Regulator of Cutaneous Wound Healing.

Destroying the integrity of the skin may causes disability and even death from injury or illness. Wound healing is a core mechanism to maintain skin barrier function. Milk fat-globule epidermal growth factor 8 (MFG-E8) is a key factor in wound healing and is involved in regulating blood coagulation, mediating macrophage uptake of apoptotic cells, shifting macrophages from an inflammatory to an anti-inflammatory phenotype, promoting angiogenesis, enhancing vascular endothelial growth factor (VEGF) signaling, and assisting wound tissue perfusion. However, these abilities are dysregulated in pathological conditions, such as glucose disorders and ischemic injury. Restricted application of exogenous MFG-E8 can restore function and play a beneficial role in cutaneous wound healing.

MFG-E8 promotes osteogenic transdifferentiation of smooth muscle cells and vascular calcification by regulating TGF-\u03b21 signaling

Vascular calcification occurs in arterial aging, atherosclerosis, diabetes mellitus, and chronic kidney disease. Transforming growth factor-β1 (TGF-β1) is a key modulator driving the osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs), leading to vascular calcification. We hypothesize that milk fat globule–epidermal growth factor 8 (MFG-E8), a glycoprotein expressed in VSMCs, promotes the osteogenic transdifferentiation of VSMCs through the activation of TGF-β1-mediated signaling. We observe that the genetic deletion of MFG-E8 prevents calcium chloride-induced vascular calcification in common carotid arteries (CCAs). The exogenous application of MFG-E8 to aged CCAs promotes arterial wall calcification. MFG-E8-deficient cultured VSMCs exhibit decreased biomineralization and phenotypic transformation to osteoblast-like cells in response to osteogenic medium. MFG-E8 promotes β1 integrin–dependent MMP2 expression, causing TGF-β1 activation and subsequent VSMC osteogenic transdifferentiation and biomineralization. Thus, the established molecular link between MFG-E8 and vascular calcification suggests that MFG-E8 can be therapeutically targeted to mitigate vascular calcification.

TGF-β Increases MFGE8 Production in Myeloid-Derived Suppressor Cells to Promote B16F10 Melanoma Metastasis.

There is growing evidence that myeloid-derived suppressor cells (MDSCs) are directly involved in all stages leading to metastasis. Many mechanisms for this effect have been proposed, but mechanisms of coregulation between tumor cells and MDSCs remain poorly understood. In this study, we demonstrate that MDSCs are a source of milk fat globule-epidermal growth factor (EGF) factor 8 (MFGE8), which is known to be involved in tumor metastasis. Interestingly, TGF-β, an abundant cytokine in the tumor microenvironment (TME), increased MFGE8 production by MDSCs. In addition, co-culturing MDSCs with B16F10 melanoma cells increased B16F10 cell migration, while MFGE8 neutralization decreased their migration. Taken together, these findings suggest that MFGE8 is an important effector molecule through which MDSCs promote tumor metastasis, and the TME positively regulates MFGE8 production by MDSCs through TGF-β.

MFG-E8 regulated by miR-99b-5p protects against osteoarthritis by targeting chondrocyte senescence and macrophage reprogramming via the NF-\u03baB pathway

Milk fat globule-epidermal growth factor (EGF) factor 8 (MFG-E8), as a necessary bridging molecule between apoptotic cells and phagocytic cells, has been widely studied in various organs and diseases, while the effect of MFG-E8 in osteoarthritis (OA) remains unclear. Here, we identified MFG-E8 as a key factor mediating chondrocyte senescence and macrophage polarization and revealed its role in the pathology of OA. We found that MFG-E8 expression was downregulated both locally and systemically as OA advanced in patients with OA and in mice after destabilization of the medial meniscus surgery (DMM) to induce OA. MFG-E8 loss caused striking progressive articular cartilage damage, synovial hyperplasia, and massive osteophyte formation in OA mice, which was relieved by intra-articular administration of recombinant mouse MFG-E8 (rmMFG-E8). Moreover, MFG-E8 restored chondrocyte homeostasis, deferred chondrocyte senescence and reprogrammed macrophages to the M2 subtype to alleviate OA. Further studies showed that MFG-E8 was inhibited by miR-99b-5p, expression of which was significantly upregulated in OA cartilage, leading to exacerbation of experimental OA partially through activation of NF-κB signaling in chondrocytes. Our findings established an essential role of MFG-E8 in chondrocyte senescence and macrophage reprogramming during OA, and identified intra-articular injection of MFG-E8 as a potential therapeutic target for OA prevention and treatment.