Truncated Milk Fat Globule-EGF-like Factor 8 Ameliorates Liver Fibrosis via Inhibition of Integrin-TGFβ Receptor Interaction.
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SUBMITTER: An GH
PROVIDER: S-EPMC8615163 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundHepatic ischemia-reperfusion (I/R) injury is a serious clinical complication that may compromise liver function because of extensive hepatocyte loss. Therefore, the development of novel and effective therapies for hepatic I/R is critical for the improvement of patient outcome. It has been previously shown that administration of milk fat globule-EGF factor VIII (MFG-E8), a membrane-associated secretory glycoprotein, exerts significant beneficial effects under acute inflammatory conditions through multiple physiological processes associated with tissue remodeling.MethodsTo determine whether administration of recombinant human (rh) MFG-E8 attenuates liver injury in an animal model of hepatic I/R, male adult rats were subjected to 70% hepatic ischemia for 90 min, followed by reperfusion. At the beginning of reperfusion, rats were treated intravenously with normal saline (vehicle) or rhMFG-E8 (160 ?g/kg) over a period of 30 min. MFG-E8 levels and various measurements were assessed 4 h after reperfusion. In addition, survival study was conducted in MFG-E8(-/-) and rhMFG-E8-treated wild-type (WT) mice using a total hepatic ischemia model.ResultsLiver and plasma MFG-E8 protein levels were significantly decreased after hepatic I/R. Administration of rhMFG-E8 significantly improved liver injury, suppressed apoptosis, attenuated inflammation and oxidative stress, and downregulated NF-?B pathway. We also noticed that rhMFG-E8 treatment restored the downregulated PPAR-? expression after hepatic I/R. MFG-E8(-/-) mice showed deterioration on survival and, in contrast, rhMFG-E8-treated WT mice showed a significant improvement of survival compared with vehicle-treated WT mice.ConclusionsMFG-E8-mediated multiple physiological events may represent an effective therapeutic option in tissue injury following an episode of hepatic I/R.
| S-EPMC3401639 | biostudies-literature
Project description:Milk fat globule-EGF factor 8 (MFG-E8) is an anti-inflammatory glycoprotein that mediates a wide spectrum of pathophysiological processes. MFG-E8 has been studied as a key regulator of cancer cell invasion, migration, and proliferation in different tissues and organs. However, potential roles of MFG-E8 in the growth and progression of liver cancer have not been investigated to date. Here, we analyzed 33 human hepatocellular carcinoma (HCC) samples and found that levels of MFG-E8 expression were significantly higher in HCC cells than in normal liver tissues. In addition, our in vitro gain-of-function study in three different HCC cell lines revealed that overexpression of MFG-E8 promoted the proliferation and migration of HCC cells, as determined by RT-qPCR, MTT assays, and wound healing analyses. Conversely, an MFG-E8 loss-of function study showed that proliferation capacity was significantly reduced by MFG-E8 knockdown in HCC cells. Additionally, MFG-E8 activity-neutralizing antibodies profoundly inhibited both migration and proliferation of HCC cells, attenuating their tumorigenic properties. These reductions in migration and proliferation were rescued by treatment of HCC cells with recombinant MFG-E8 protein. Furthermore, an in vivo HCC xenograft study showed that the number of proliferating HCC cells and tumor volume/weight were all significantly increased by MFG-E8 overexpression, compared to control mice. These results clearly show that MFG-E8 plays an important role in HCC progression and may provide a basis for future mechanistic studies and new strategies for the treatment of liver cancer.
| S-EPMC7072366 | biostudies-literature
Project description: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.
| S-EPMC8375434 | biostudies-literature
Project description: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.MethodsBlood 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.ResultsSerum 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.ConclusionsMFG-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.
| S-EPMC7828261 | biostudies-literature
Project description:Accumulating evidence suggests neuronal apoptosis has the potential to lead to more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that milk fat globule-EGF factor-8 (MFG-E8) provides neuroprotection through modulation of inflammation, oxidative stress, and especially apoptosis in cerebral ischemia and neurodegenerative disease. However, the effects of MFG-E8 on neuronal apoptosis in TBI have not yet been investigated. Therefore, we explored the role of MFG-E8 on anti-apoptosis and its potential mechanism following TBI. In the first set of experiments, adult male Sprague-Dawley (SD) rats were randomly divided into Sham and TBI groups that were each further divided into five groups representing different time points (6?h, 24?h, 72?h, and 7 days) (n?=?9 each). Western blotting, quantitative real-time PCR, and immunofluorescence staining were performed to identify the expression and cellular localization of MFG-E8. In the second set of experiments, four groups were randomly assigned: Sham group, TBI?+?Vehicle group, and TBI?+?rhMFG-E8 (1 and 3?µg) (n?=?15). Recombinant human MFGE8 (rhMFG-E8) was administrated as two concentrations through intracerebroventricular (i.c.v.) injection at 1?h after TBI induction. Brain water content, neurological severity score, western blotting, and immunofluorescence staining were measured at 24 and 72?h following TBI. In the final set of experiments, MFG-E8 siRNA (500?pmol/3?µl), integrin ?3 siRNA (500?pmol/3?µl), and PI3K inhibitor LY294002 (5 and 20?µM) were injected i.c.v. and thereafter rats exposed to TBI. Western blotting, immunofluorescence staining, brain water content, neurological severity score, and Fluoro-Jade C (FJC) staining were used to investigate the effect of the integrin-?3/FAK/PI3K/AKT signaling pathway on MFG-E8-mediated anti-apoptosis after TBI. The expression of MFG-E8 was mainly located in microglial cells and increased to peak at 24?h after TBI. Treatment with rhMFG-E8 (3?µg) markedly decreased brain water content, improved neurological deficits, and reduced neuronal apoptosis at 24 and 72?h after TBI. rhMFG-E8 significantly enhanced the expression of integrin-?3/FAK/PI3K/AKT pathway-related components. Administration of integrin-?3 siRNA and LY294002 (5 and 20?µM) abolished the effect of rhMFG-E8 on anti-apoptosis and neuroprotection after TBI. This study demonstrated for the first time that rhMFG-E8 inhibits neuronal apoptosis and offers neuroprotection. This is suggested to occur through the modulation of the integrin-?3/FAK/PI3K/AKT signaling pathway, highlighting rhMFG-E8 as a potentially promising therapeutic strategy for TBI patients.
| S-EPMC6113274 | biostudies-literature
Project description:The phagocytic clearance of apoptotic cells is essential to prevent chronic inflammation and autoimmunity. The phosphatidylserine-binding protein milk fat globule-EGF factor 8 (MFG-E8) is a major opsonin for apoptotic cells, and MFG-E8(-/-) mice spontaneously develop a lupus-like disease. Similar to human systemic lupus erythematosus (SLE), the murine disease is associated with an impaired clearance of apoptotic cells. SLE is routinely treated with glucocorticoids (GCs), whose anti-inflammatory effects are consentaneously attributed to the transrepression of pro-inflammatory cytokines. Here, we show that the GC-mediated transactivation of MFG-E8 expression and the concomitantly enhanced elimination of apoptotic cells constitute a novel aspect in this context. Patients with chronic inflammation receiving high-dose prednisone therapy displayed substantially increased MFG-E8 mRNA levels in circulating monocytes. MFG-E8 induction was dependent on the GC receptor and several GC response elements within the MFG-E8 promoter. Most intriguingly, the inhibition of MFG-E8 induction by RNA interference or genetic knockout strongly reduced or completely abolished the phagocytosis-enhancing effect of GCs in vitro and in vivo. Thus, MFG-E8-dependent promotion of apoptotic cell clearance is a novel anti-inflammatory facet of GC treatment and renders MFG-E8 a prospective target for future therapeutic interventions in SLE.
| S-EPMC3741508 | biostudies-literature
Project description:Background/aimsUseful biomarkers for metabolic syndrome have been insufficient. We investigated the performance of serum milk fat globule-EGF factor-8 (MFG-E8), the key mediator of inflammatory pathway, in diagnosis of metabolic syndrome.MethodsSubjects aged between 30 and 64 years were prospectively enrolled in the Seoul Metabolic Syndrome cohort. Serum MFG-E8 levels were measured at baseline.ResultsA total of 556 subjects were included, comprising 279 women (50.2%) and 277 men (49.8%). Metabolic syndrome was diagnosed in 236 subjects (42.4%), and the mean MFG-E8 level of subjects with metabolic syndrome was significantly higher than that of subjects without metabolic syndrome (P<0.001). MFG-E8 level was significantly correlated with all metabolic syndrome components and pulse wave velocity (all P<0.05). Subjects were categorized into two groups according to the best MFG-E8 cut-off value as follows: group 1, MFG-E8 level <4,745.1 pg/mL (n=401, 72.1%); and group 2, MFG-E8 level ≥4,745.1 (n=155, 27.9%). At baseline, metabolic syndrome in group 2 was significantly more prevalent than in group 1 (63.9% vs. 34.2%, P<0.001). During median follow-up of 17 months, metabolic syndrome developed in 122 (38.1%) subjects among 320 subjects without it at baseline. The incidence of metabolic syndrome in group 2 was significantly higher than that in group 1 (55.4% vs. 34.5%, P=0.003). On multivariate analysis, MFG-E8 level ≥4,745.1 pg/mL was an independent predictor for diagnosis and development of metabolic syndrome after adjusting other factors (all P<0.05).ConclusionSerum MFG-E8 level is a potent biomarker for the screening and prediction of metabolic syndrome.
| S-EPMC8273636 | biostudies-literature
Project description:During the involution of mammary glands, epithelial cells undergo apoptosis and are cleared for the next cycle of lactation. The clearance of apoptotic epithelial cells is mediated by neighboring epithelial cells and by macrophages that migrate into the mammary glands. Here, we report that milk fat globule EGF factor 8 (MFG-E8), a secreted glycoprotein that binds to apoptotic cells by recognizing phosphatidylserine, was expressed by epithelial cells and macrophages in mammary glands and was involved in engulfment of apoptotic cells. A deficiency of MFG-E8 caused the accumulation of a large number of milk fat globules (MFGs) in the mammary ducts during involution, indicating that the excess MFGs were cleared by an MFG-E8-dependent mechanism. The MFG-E8(-/-) mice developed mammary duct ectasia with periductal mastitis, and the redevelopment of the mammary gland for their second litter was impaired. These results demonstrate that MFG-E8-mediated phagocytosis of apoptotic epithelial cells and MFGs is important for efficient involution of mammary glands.
| S-EPMC1277971 | biostudies-literature
Project description:The molecular mechanism underlying milk fat globule secretion in mammary epithelial cells ostensibly involves the formation of complexes between plasma membrane butyrophilin and cytosolic xanthine oxidoreductase. These complexes bind adipophilin in the phospholipid monolayer of milk secretory granules, the precursors of milk fat globules, enveloping the nascent fat globules in a layer of plasma membrane and pinching them off the cell. However, using freeze-fracture immunocytochemistry, we find these proteins in locations other than those previously inferred. Significantly, butyrophilin in the residual plasma membrane of the fat globule envelope is concentrated in a network of ridges that are tightly apposed to the monolayer derived from the secretory granule, and the ridges coincide with butyrophilin labeling in the globule monolayer. Therefore, we propose that milk fat globule secretion is controlled by interactions between plasma membrane butyrophilin and butyrophilin in the secretory granule phospholipid monolayer rather than binding of butyrophilin-xanthine oxidoreductase complexes to secretory granule adipophilin.
| S-EPMC1502467 | biostudies-literature
Project description:Background and purposeMilk fat globule-EGF factor-8 (MFGE8) has been reported to be neuroprotective in ischemic stroke. However, the effects of MFGE8 in early brain injury after subarachnoid hemorrhage (SAH) have not been investigated. We investigated the role of MFGE8 in early brain injury and the potential mechanisms in antioxidation after SAH.MethodsTwo dosages (1 μg and 3.3 μg) of recombinant human MFGE8 were injected intracerebroventricularly at 1.5 hours after SAH. SAH grades, neurological scores, and brain water content were measured at 24 and 72 hours. For mechanistic study, MFGE8 siRNA, integrin β3 siRNA, and heme oxygenase (HO) inhibitor SnPP IX were used for intervention. The oxidative stress and expression of MFGE8, integrin β3, HO-1, extracellular signal-regulated kinase, and nuclear factor erythroid 2-related factor 2 were measured by Western blots 24 hours after SAH.ResultsThe expression of MFGE8 and HO-1 increased and peaked 24 hours after SAH. Administration of recombinant human MFGE8 decreased brain water content and improved neurological functions both at 24 hours and at 72 hours after SAH. Recombinant human MFGE8 reduced oxidative stress and enhanced the expression of extracellular signal-regulated kinase, nuclear factor erythroid 2-related factor 2, and HO-1; and the effects were abolished by integrin β3 siRNA and HO inhibitor SnPP IX.ConclusionsRecombinant MFGE8 attenuated oxidative stress that may be mediated by integrin β3/nuclear factor erythroid 2-related factor 2/HO pathway after SAH. Recombinant MFGE8 may serve as an alternative treatment to ameliorate early brain injury for SAH patients.
| S-EPMC4245320 | biostudies-literature