Overexpressed pigment epithelium-derived factor alleviates pulmonary hypertension in two rat models induced by monocrotaline and SU5416/hypoxia

BACKGROUND

Pulmonary hypertension (PH) is a progressive and fatal cardiopulmonary disease characterized by vascular remodeling and is associated with endothelial-to-mesenchymal transition (EndoMT). The pigment epithelium-derived factor (PEDF), a secretory protein widely distributed in multiple organs, has been shown to demonstrate anti-EndoMT activity in cardiovascular diseases. In the present study, the role of PEDF in PH was investigated.

METHODS

For PEDF overexpression, Sprague Dawley rats were infected with an adeno-associated virus through injection via the internal jugular vein. To establish PH models, the animals were subjected to monocrotaline or Sugen/hypoxia. Four weeks later, pulmonary artery angiography was performed, and hemodynamic parameters, right ventricular function, and vascular remodeling were evaluated. EndoMT and cell proliferation in the pulmonary arteries were assessed via immunofluorescence staining. Moreover, pulmonary artery endothelial cells (PAECs) isolated from experimental PH rats were cultured to investigate the underlying molecular mechanisms involved.

RESULTS

PEDF expression was significantly downregulated in PAECs from PH patients and PH model rats. Overexpressed PEDF alleviated the development of PH by improving pulmonary artery morphology and perfusion, reducing pulmonary artery pressure, improving right ventricular function, and alleviating vascular remodeling. PEDF inhibits EndoMT and reduces excessive PAEC proliferation. Moreover, PEDF overexpression reduced EndoMT in cultured PAECs by competitively inhibiting the binding of wnt to LRP6 and downregulating phosphorylation at the 1490 site of LRP6.

CONCLUSIONS

Our findings suggest that PEDF may be a potential therapeutic target for PH. We also found that PEDF can inhibit EndoMT in PAECs and may exert these effects by inhibiting the Wnt/LRP6/β-catenin pathway.

A new R,R-RvD6 isomer with protective actions following corneal nerve injury

The transparent cornea is the most densely innervated tissue in the body, primarily by sensory nerves originating from the trigeminal ganglia (TG). Damage to corneal nerves reduces sensitivity and tear secretion and results in dry eye. Consequently, ocular pain, for which no satisfactory therapies exist, arises in many cases. Treatment of injured corneas with pigment epithelium-derived factor (PEDF) combined with docosahexaenoic acid (DHA) stimulates nerve regeneration in models of refractive surgery, which damages nerves. The mechanism involves the synthesis of a stereoisomer of resolvin D6 (R,R-RvD6) formed after incorporating DHA into membrane lipids. Activation of a PEDF receptor (PEDF-R) with phospholipase activity releases DHA to synthesize the new resolvin isomer, which is secreted via tears. Topical treatment of mice corneas with R,R-RvD6 shows higher bioactivity in regenerating nerves and increasing sensitivity compared to PEDF+DHA. It also stimulates a transcriptome in the TG that modulates genes involved in ocular pain. Our studies suggest an important therapeutic role for R,R-RvD6 in regenerating corneal nerves and decreasing pain resulting from dry eye.

Enhanced therapeutic effect of PEDF-loaded mesenchymal stem cell-derived small extracellular vesicles against oxygen-induced retinopathy through increased stability and penetrability of PEDF

BACKGROUND

Several common retinal diseases that cause blindness are characterised by pathological neovascularisation accompanied by inflammation and neurodegeneration, including retinopathy of prematurity (ROP), diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinal vein occlusion (RVO). The current treatment strategies for these diseases have limited benefits. Thus, safer and more effective alternative approaches are required. In this study, we loaded small extracellular vesicles (sEVs) derived from mesenchymal stem cell (MSC) with pigment epithelium-derived factor (PEDF), and tested the therapeutic effect of PEDF-loaded sEVs (PEDF-sEVs) using an oxygen induced retinopathy (OIR) mouse model, aiming to establish a new therapy strategy for the treatment of retinal pathological angiogenesis.

RESULTS

We formulated PEDF-loaded sEVs (PEDF-sEVs) containing high concentrations of PEDF and evaluated their effects through in vivo and in vitro experiments. In OIR mice, PEDF-sEVs showed significantly better effects on retinal avascular areas, inflammation, and neuronal degeneration compared with the anti-vascular endothelial growth factor (VEGF) drug, which may indicate a possible advantage of PEDF-sEVs over anti-VEGF drugs in the treatment of pathological neovascularisation. In vitro, PEDF-sEVs greatly inhibited endothelial cell (EC) proliferation, migration, and tube formation by suppressing the VEGF-induced phosphorylation of extracellular signal-regulated kinase (ERK) and AKT (also known as Protein Kinase B). All experiments and analyses were performed in triplicate. PEDF-sEVs were more effective than PEDF or sEVs alone, both in vitro and in vivo. Furthermore, to determine the distribution of PEDF-sEVs, we used DiD-labelled sEVs and FITC-labelled PEDF to track the sEVs and PEDF, respectively. We found that PEDF-sEVs effectively reduced the degradation of PEDF.

CONCLUSIONS

Loading PEDF on sEVs effectively enhanced the anti-angiogenic, anti-inflammatory, and neuroprotective effects of PEDF by increasing the stability and penetrability. These results suggest a potential role for PEDF-sEVs in retinal pathological neovascularisation.

Resveratrol alleviates preeclampsia-like symptoms in rats through a mechanism involving the miR-363-3p/PEDF/VEGF axis

Preeclampsia (PE) is a hypertension-associated disease, and resveratrol (RES) is a polyphenol recognized to present beneficial effects in cardiovascular disease including hypertension. Recently, attentions have come to the therapeutic effect of RES in PE, but the underlying molecular mechanisms remain largely unknown. This study sought to delineate the mechanistic basis regarding bioinformatically identified miR-363-3p/PEDF/VEGF axis for RES treatment in PE. PE-like symptoms were induced in vivo in Sprague-Dawley rats by intraperitoneal injection with Ng-nitro-L-arginine methyl ester (L-NAME), and hypoxia was induced in vitro in trophoblasts by CoCl₂. Accordingly, RES was found to enhance viability, migration, angiogenesis, and to repress the apoptosis of hypoxic trophoblasts in vitro. Furthermore, in vivo experiments noted that RES alleviated placental injury and promoted angiogenesis in rats with PE-like symptoms in vivo by increasing VEGF via promoting miR-363-3p-mediated PEDF suppression. Collectively, RES ameliorates PE by upregulating VEGF through miR-363-3p-mediated PEDF downregulation, the mechanism of which may be of promising significance to augment RES efficacy in PE treatment.

Pigment epithelium-derived factor downregulation in oestrogen receptor positive breast cancer bone metastases is associated with menopause

Pigment epithelium-derived factor (PEDF) has a critical role in bone development and anti-tumour function in breast cancer (BC). As the expression and role of PEDF in BC bone metastases is unknown, we aimed to characterise PEDF in primary and metastatic BC. Subcellular PEDF localisation was semi-quantitatively analysed via immunohistochemistry in patient-matched, archived formalin-fixed paraffin-embedded primary BC and liver, lung, and decalcified bone metastases specimens. PEDF localisation was evaluated in 23 metastatic BC patients diagnosed with ER+, human epidermal growth factor receptor-2 (HER2) negative BC or TNBC. Cytoplasmic (p = 0.019) and membrane (p = 0.048) PEDF was lower in bone metastases compared to primary ER+/HER2- BC. In contrast, nuclear PEDF scores were higher in metastases compared to primary TNBC (p = 0.027), and increased membrane PEDF in metastatic tissue had improved disease-free interval (p = 0.016). Nuclear PEDF was decreased in bone metastases compared to primary ER+//HER2- BC in post-menopausal patients (p = 0.029). These novel findings indicate PEDF plays a role in clinical BC metastasis. Significantly lower PEDF levels in the post-menopausal compared to pre-menopausal setting suggests future PEDF research may have greater clinical importance in the post-menopausal ER+/HER2- BC population.

Aryl hydrocarbon receptor deficiency augments dysregulated microangiogenesis and diabetic retinopathy

Diabetic retinopathy (DR) is a pathophysiologic vasculopathic process with obscure mechanisms and limited effective therapeutic strategies. Aryl hydrocarbon receptor (AhR) is an important regulator of xenobiotic metabolism and an environmental sensor. The aim of the present study was to investigate the role of AhR in the development of DR and elucidate the molecular mechanism of its downregulation. DR was evaluated in diabetes-induced retinal injury in wild type and AhR knockout (AhR-/-) mice. Retinal expression of AhR was determined in human donor and mice eyes by immunofluorescence since AhR activity was examined in diabetes. AhR knockout (AhRKO) mice were used to induce diabetes with streptozotocin, high-fat diet, or genetic double knockout with diabetes spontaneous mutation (Leprdb) (DKO; AhR-/-×Leprdb/db) for investigating structural, functional, and metabolic abnormalities in vascular and epithelial retina. Structural molecular docking simulation was used to survey the pharmacologic AhR agonists targeting phosphorylated AhR (Tyr245). Compared to diabetic control mice, diabetic AhRKO mice had aggravated alterations in retinal vasculature that amplified hallmark features of DR like vasopermeability, vascular leakage, inflammation, blood-retinal barrier breakdown, capillary degeneration, and neovascularization. AhR agonists effectively inhibited inflammasome formation and promoted AhR activity in human retinal microvascular endothelial cells and pigment epithelial cells. AhR activity and protein expression was downregulated, resulting in a decrease in DNA promoter binding site of pigment epithelium-derived factor (PEDF) by gene regulation in transcriptional cascade. This was reversed by AhR agonists. Our study identified a novel of DR model that target the protective AhR/PEDF axis can potentially maintain retinal vascular homeostasis, providing opportunities to delay the development of DR.

Pigment epithelium-derived factor modulates periodontal homeostasis in mice and induces osteogenic differentiation of human periodontal ligament fibroblasts

AIM

The aim of this study was to investigate the influence of pigment epithelium-derived factor (PEDF) on periodontal homeostasis in mice and the osteogenic differentiation of human periodontal ligament fibroblasts (PDLFs).

MATERIALS AND METHODS

Micro-computed tomography and histology were performed to compare the alveolar bone volume, density, and bone-related markers between PEDF-deficient (PEDF^-/-) and wild-type (WT) mice. Furthermore, after recombinant human PEDF treatment, the PDLF viability and osteogenic differentiation were examined using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, alkaline phosphatase (ALP) activity assay, Von Kossa staining, Alizarin red staining, real-time quantitative polymerase chain reaction (qRT-PCR), and immunoblotting.

RESULTS

The alveolar bone volume and density of PEDF^-/- mice were significantly lower than those of the WT mice. Higher receptor activator for nuclear factor-κB ligand (RANKL) expression and lower osteoprotegerin (OPG) expression levels were observed in the PEDF^-/- group. Moreover, PEDF treatment did not affect the PDLF proliferation. PEDF dose-dependently improved mineral deposition. Compared with the control group, 250 ng/mL PEDF promoted OPG mRNA expression in PDLFs on Day 3 but inhibited RANKL, Wnt5a, GSK3b mRNA, and non-phosphorylated β-catenin protein expression. However, 250 ng/mL PEDF had no significant effect on the expression of Wnt3a. On Day 7, after culture with 250 ng/mL PEDF in osteogenic medium, the ALP and RUNX2 protein levels were upregulated. VEGF protein expression was reduced in a dose-dependent manner after PEDF stimulation. The PEDF protein expression increased as the osteogenic induction time increased.

CONCLUSION

PEDF gene knockout suppresses periodontal homeostasis in mice, and PEDF treatment induces PDLF osteogenic differentiation in vitro.

Pigment epithelium-derived factor maintains tight junction stability after myocardial infarction in rats through inhibition of the Wnt/β-catenin signaling pathway

PURPOSE

The impairment of the coronary microcirculatory barrier caused by acute myocardial infarction (AMI) is closely related to poor prognosis. Recently, pigment epithelial-derived factor (PEDF) has been proven to be a promising cardiovascular protective drug. In this study, we demonstrated the protective role of PEDF in endothelial tight junctions (TJs) and the vascular barrier in AMI.

MATERIALS AND METHODS

2, 3, 5-triphenyltetrazolium chloride (TTC), echocardiography and immunofluorescence staining were used to observe the size of infarcted myocardium area and cardiac function in myocardial tissue, and the distribution of tight junction proteins in human coronary endothelial cells (HCAEC). Dextran leakage assay and Transwell were used to assess the extent of vascular and HCAEC leakage. PCR and Western blot were used to detect tight junction-related mRNA and protein, and signaling pathway protein expression.

RESULTS

PEDF effectively reduced the infarction area and improved cardiac function in AMI rats, and lowered the leakage in AMI rats' angiocarpy and oxygen-glucose deprivation (OGD)-treated HCAEC. Furthermore, PEDF upregulated the expression of TJ mRNA and proteins in vivo and vitro. Mechanistically, PEDF inhibited the expression of phosphorylated low-density lipoprotein receptor-related protein 6 (p-LRP6) and active β-catenin under OGD, thus suppressing the activation of the classical Wnt pathway.

CONCLUSIONS

These novel findings demonstrated that PEDF maintained the expression of TJ proteins and endothelial barrier integrity by inhibiting the classical Wnt pathway during AMI.

Pigment epithelium-derived factor engineered to increase glycosaminoglycan affinity while maintaining bioactivity

Pigment epithelium-derived factor (PEDF) is a secreted protein that is essential in tissue homeostasis and is involved in multiple functions in the eye, such as antiangiogenesis and neuroprotection. However, short retention in the retinal microenvironment can limit its therapeutic effects. In this study, we modified the amino acid sequence of PEDF to increase its affinity for heparin and hyaluronic acid (HA), which are negatively charged extracellular matrix (ECM) molecules. HA is the major component of the vitreous humor. We selectively converted neutral or anionic residues into cationic residues to obtain engineered PEDF (ePEDF). Using in vitro binding assays, we demonstrate that ePEDF had higher affinity for heparin and HA than wild-type PEDF (wtPEDF). ePEDF exhibited antiangiogenic and retinal survival bioactivities. It inhibited endothelial cell proliferation and tube formation in vitro. In an ex vivo model mimicking retinal degeneration, ePEDF protected photoreceptors from cell death. The findings suggest that protein engineering is an approach to develop active PEDF with higher ECM affinity to potentially improve its retention in the retina microenvironment and in turn make it a more efficient therapeutic drug for retinal diseases.

[Effects of Pigment Epithelium-derived Factor and Its Peptides on Proliferation, Apoptosis and Migration of Non-small Cell Lung Cancer]

BACKGROUND

The anti-tumor effect of pigment epithelium-derived factor (PEDF) has been widely confirmed. However, the anti-tumor effect of its peptides is rarely reported. This study aims to investigate the effects of PEDF and its peptides on the apoptosis and migration of non-small cell lung cancer (NSCLC).

METHODS

In this study, A549 cells and H1299 cells were selected as the research object, and the cells were divided into normal group, PEDF treatment group, 34 peptide treatment group, 44 peptide treatment group and 34+44 peptide treatment group by administering different drugs at the same concentration to the cells. The proliferation activity of cells in each group was detected by CCK-8 method; the migration ability of cells was detected by scratch test; the expression levels of apoptosis related proteins such as protein kinase 3 (RIP3) and cleaved-caspase-3 were detected by Western blot; the expression levels of epithelial mesenchymal transition (EMT) markers in each group, such as cadherin (E-cadherin) and α-smooth muscle actin (α-SMA) were detected by Western blot; the apoptosis rate of each group was detected by flow cytometry.

RESULTS

The results of CCK-8 showed that PEDF and its peptides could inhibit cell proliferation, and the inhibitory effect of 34+44 peptide was the strongest (P<0.05); Observation under the microscope found that PEDF and its peptides can inhibit the proliferation and mesenchymal transformation of A549 cells and H1299 cells, and the inhibitory effect of the 34+44 peptide group is the most obvious; Western blot indicated that compared with other groups, the expressions of cleaved-caspase-3 and RIP3 in 34+44 peptide group were significantly higher (P<0.05), and the expressions of EMT protein E-cadherin were higher, the expression of α-SMA decreased (P<0.05); The results of flow cytometry showed that the apoptosis rate of 34+44 peptide group was significantly higher than those of other groups (P<0.05); The scratch test showed that compared with all the other groups, the healing rate of 34+44 peptide group was the lowest (P<0.05).

CONCLUSIONS

34+44 combination peptide can better promote the apoptosis of NSCLC, inhibit the migration of NSCLC, and thereby inhibit the growth of NSCLC.

Exploration of novel anti-angiogenic PEDF-derived peptides with improved activitives by inhibiting proliferation, suppressing migration, and inducing 67LR internalization

Diabetic retinopathy (DR) remains high incidence and accounts for severe impact on vision in diabetics, but its mechanism is still poorly understood. Abnormal migration and proliferation of endothelial cells (ECs) drive neovascular retinopathies, which has an important role in promoting the occurrence and development of DR. In this study, we designed and synthesized a series of PEDF-derived peptides as angiogenesis inhibitors. Especially, compound G24 significantly inhibited the cell proliferation in VEGF-activated human umbilical vein endothelial cells (HUVECs) with IC₅₀ values of 2.88 ± 0.19 μM. Further biological evaluation demonstrated that compound G24 exhibited strong inducing-effects on cell apoptosis and internalization of 67LR, and advanced inhibitory potency in cell migration and angiogenesis formed by HUVECs in vitro. In summary, the optimal compound G24 as a novel angiogenesis inhibitor showed the potentiality in the further research for the treatment for DR.

Development of strategies to modulate gene expression of angiogenesis-related molecules in the retina

Intravitreal anti-vascular endothelial growth factor agents are the gold standard treatment of ocular neovascular diseases. However, their short-term efficacy implies frequent intravitreal injections. Gene therapy has the ability to provide longer duration of the therapeutic effect. We have previously described the effectiveness of the self-replicating episomal vector, pEPito, in long-term gene expression in mouse retina. In this study, we evaluated different constructs to overexpress pigment epithelium-derived factor (PEDF), an angiogenesis inhibitor, and simultaneously, to silence placental growth factor (PlGF), a key player in neovascularization. We employed the human cytomegalovirus promoter to drive the expression of PEDF and PlGF shRNA, in conjunction with cis-acting ribozymes, using pEPito as expressing vector. Our results demonstrated that the non-viral systems were able to efficiently promote a sustained increase of the PEDF: PlGF ratio in the mice retina, decreased in pathological conditions. This innovative approach could open avenues for the development of new therapeutic strategies.

The effect of methylethylpiridinol addition to the therapy on the level of pigment epithelium-derived factor and oxidative status in patients with diabetic nephropathy: randomized controlled open-label clinical study

Purpose

The diabetic nephropathy is associated with oxidative stress and increases in pigment epithelium-derived factor (PEDF) level in the patient's blood. For the first time, authors investigated the effect of methylethylpiridinol addition to the therapy on oxidative status and pigment epithelium-derived factor concentrations, and examined the relationship between these indicators and clinical markers of pathology development.

Methods

Study design: open label randomized controlled trial study. Authors assessed the effect of methylethylpiridinol addition to the therapy vs basic treatment on antioxidant and NADPH-generating enzymes activity, glutathione's concentration and free radical-induced oxidation's intensity using a spectrophotometric method and iron-induced biochemiluminescence. The pigment epithelium-derived factor concentration in the serum was measured by enzyme-linked immunosorbent assay.

Results

Patients receiving combination therapy with methylethylpiridinol showed a more substantial increase in activity of glutathione peroxidase (Δ = 0.04 ± 0.11, p = 0.002), glutathione transferase (Δ = 0.12 ± 0.08, p < 0.001) and the concentration of reduced glutathione (Δ = 0.30 ± 0.17, p = 0.039). In addition, there was a significant decrease in PEDF level (Δ = -6.4 ± 5.4, p = 0.004). Correlation analysis showed a negative link between Δ postprandial glucose and Δ NADP-isocitrate dehydrogenase (-0.39, p = 0.033), Δ reduced glutathione and Δ postprandial glucose (-0.372, p = 0.043), Δ glutathione transferase and Δ PEDF (-0.37, p = 0.044).

Conclusions

The methylethylpiridinol addition to the therapy had a more potent stimulating effect on the patients' oxidative status in comparison with standard treatment, and reliably decreased pigment epithelium-derived factor level in patients' serum. The observed differences seem to be associated with the antioxidant activity of methylethylpiridinol which contributing to the mitigation of oxidative stress reducing at diabetes mellitus.

The biological relevance of pigment epithelium-derived factor on the path from aging to age-related disease

Pigment epithelium-derived factor (PEDF) is an endogenously produced protein that contributes to cell growth arrest, and reduced levels of PEDF are associated with the progression of cellular senescence and the aging process. However, the mechanisms underlying PEDF regulation of these events are not completely clear. Increased PEDF activity may induce anti-aging processes, suggesting the potential therapeutic value of PEDF as an anti-aging and age-related disease. In this review, we recapitulate the molecular and cellular mechanisms of aging following the characteristics and specific roles of the PEDF in cell cycle arrest and its relevance to cellular senescence and aging pathways. In this context, the discovery and fluctuations of PEDF in age-related diseases are summarised. In light of the importance of PEDF in cellular senescence and aging processes, better comprehension of the mechanism(s) of PEDF in the regulation of cell cycle and the aging process can conceivably facilitate the development of therapeutic strategies for diseases that occur with aging.

Elevated pigment epithelium-derived factor induces diabetic erectile dysfunction via interruption of the Akt/Hsp90β/eNOS complex

AIMS/HYPOTHESIS

Diabetes mellitus erectile dysfunction (DMED) is a common complication of diabetes. The level of pigment epithelium-derived factor (PEDF) is significantly upregulated in the serum of individuals with obesity and diabetes. However, whether elevated PEDF levels contribute to DMED remains unknown. This study aimed to investigate the pathogenic role of PEDF and its related mechanism in DMED.

METHODS

We enrolled 65 men, of whom 20 were nondiabetic control participants, 21 participants with diabetes but without erectile dysfunction, and 24 with DMED. The International Index of Erectile Function (IIEF-5) questionnaire was administered to evaluate erectile function. Plasma PEDF in diabetic participants and streptozotocin (STZ)-induced diabetic animals was detected by ELISA. Erectile function was evaluated by measuring the intracavernous pressure (ICP) and the ICP/mean arterial pressure (MAP) ratio in STZ-induced diabetic rats treated with PEDF-neutralising antibody (PEDF-Ab), db/db mice treated with PEDF-Ab, and Pedf knockout mice with STZ-induced diabetes. The overexpression of PEDF was implemented by intraperitoneal injection of recombinant PEDF and intracavernous injection of PEDF-expressing adenovirus. A mechanistic study was performed by immunofluorescence staining, bimolecular fluorescence complementation (BiFC), immunoprecipitation and western blotting.

RESULTS

We found that the plasma level of PEDF was significantly higher in participants with DMED compared with diabetic counterparts without erectile dysfunction and nondiabetic controls. Interestingly, PEDF levels were negatively correlated with plasma nitrite/nitrate levels and erectile function in DMED patients and STZ-induced diabetic rats. Furthermore, overexpression of PEDF significantly suppressed ICP and endothelial nitric oxide synthase (eNOS) phosphorylation in control rats. In contrast, the PEDF-Ab and Pedf knockout ameliorated ICP and eNOS phosphorylation in diabetic rats and mice. Mechanistically, PEDF promoted the membrane translocation of Hsp90β and directly bound to the amino acid residues 341-724 of Hsp90β on the endothelial cell surface, subsequently blocking intracellular Hsp90β/Akt/eNOS complex formation and downregulating eNOS phosphorylation.

CONCLUSIONS/INTERPRETATION

These results indicate that elevated PEDF levels contribute to impaired erectile function by suppressing Hsp90β-mediated eNOS phosphorylation and that PEDF may represent a novel therapeutic target for diabetic erectile dysfunction. Graphical abstract.

PEDF deficiency increases the susceptibility of rd10 mice to retinal degeneration

The SERPINF1 gene encodes pigment epithelium-derived factor (PEDF), a member of the serpin superfamily with neurotrophic and antiangiogenic properties in the retina. We hypothesized that absence of PEDF would lead to increased stress-associated retinal degeneration in Serpinf1 null mice. Accordingly, using a Serpinf1 null mouse model, we investigated the impact of PEDF absence on retinal morphology, and susceptibility to induced and inherited retinal degeneration. We studied the pattern of Serpinf1 expression in the mouse retina layers. PEDF protein was detected by western blotting. Transmission electron microscopy was performed on mouse retina. Serpinf1 null mice and wild type littermates were injected with NaIO₃ (30 mg/kg body weight) intraperitonially. At post-injection day 1, 3, 4, 6 and 8 mice were euthanized, and eyes were enucleated. Serpinf1 null and rd10 double mutant mice were generated and their eyes enucleated at different time points from post-natal day 15 to post-natal day 28. Enucleated eyes were processed for hematoxylin and eosin staining and histopathological evaluations. We found that Serpinf1 was expressed in the retinal pigment epithelium, in the inner nuclear layer and in the ganglion cell layer, but undetectable in the outer nuclear layer of wild type mice. Plasma PEDF protein levels were undetectable in Serpinf1 null animals. RPE atrophy and retinal thinning were observed in NaIO₃-treated wild type mice that progressed with time post-injection. NaIO₃-treated Serpinf1 null mice showed comparatively better retinal morphology than wild type mice at day 4 post-injection. However, the absence of PEDF in Serpinf1 null x rd10 mice increased the susceptibility to retinal degeneration relative to that of rd10 mice. We concluded that histopathological evaluation of retinas lacking PEDF showed that removal of the Serpinf1 gene may activate PEDF-independent compensatory mechanisms to protect the retina against oxidative stress, while it increases the susceptibility to degenerate the retina in inherited retinal degeneration models.

Roxadustat (FG-4592) accelerates pulmonary growth, development, and function in a compensatory lung growth model

Children with hypoplastic lung disease associated with congenital diaphragmatic hernia (CDH) continue to suffer significant morbidity and mortality secondary to progressive pulmonary disease. Current management of CDH is primarily supportive and mortality rates of the most severely affected children have remained unchanged in the last few decades. Previous work in our lab has demonstrated the importance of vascular endothelial growth factor (VEGF)-mediated angiogenesis in accelerating compensatory lung growth. In this study, we evaluated the potential for Roxadustat (FG-4592), a prolyl hydroxylase inhibitor known to increase endogenous VEGF, in accelerating compensatory lung growth. Treatment with Roxadustat increased lung volume, total lung capacity, alveolarization, and exercise tolerance compared to controls following left pneumonectomy. However, this effect was likely modulated not only by increased VEGF, but rather also by decreased pigment epithelium-derived factor (PEDF), an anti-angiogenic factor. Furthermore, this mechanism of action may be specific to Roxadustat. Vadadustat (AKB-6548), a structurally similar prolyl hydroxylase inhibitor, did not demonstrate accelerated compensatory lung growth or decreased PEDF expression following left pneumonectomy. Given that Roxadustat is already in Phase III clinical studies for the treatment of chronic kidney disease-associated anemia with minimal side effects, its use for the treatment of pulmonary hypoplasia could potentially proceed expeditiously.

Dysregulation of trophic factors contributes to diabetic retinopathy in the Ins2Akita mouse

Diabetic retinopathy (DR) is considered as a diabetes-related complication that can lead to severe visual impairments. By 2030, it is expected that 1 in 5 adults will suffer from the disease. Suitable animal models for chronic DR are essential for a better understanding of the pathophysiology and to further develop new treatments. The Ins2^Akita mouse is a type 1 diabetes model that shows signs of both early and late stages of DR, including pericyte loss, increased vascular permeability, increased acellular capillaries and neovascularization. To further characterize DR in the Ins2^Akita mouse model, we have evaluated the protein levels of the angiogenesis inducers vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) and the angiogenesis inhibitor pigment epithelium-derived factor (PEDF). Additionally, we have analyzed the protein expression profile of the glial markers ionized calcium binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) as well as of the chemokine monocyte chemoattractant protein 1 (MCP-1). In this study we demonstrate that, with disease progression, there is the development of an inflammatory response and an unbalanced expression of pro- and antiangiogenic factors in the neural retina and in the retinal pigment epithelium (RPE) of Ins2^Akita mice. Therefore, our data provide support for the diabetic retinopathy features detected in the Ins2^Akita retina, reflecting what is observed in the human pathology.

Expression of Neovascular Associated Factors PEDF and αB-crystallin in Human Lens Epithelial Cells

Objective: To investigate the expression of pigment epithelium-derived factor (PEDF) and αB-crystallin in human lens epithelial cells (LEC) and explore their relationships with diabetes. Methods: Lens anterior capsules attached with LEC were collected from cataract surgeries in patients with or without diabetes, and grouped as following: non-diabetes mellitus (NDM) group, no diabetic retinopathy (NDR) group, non-proliferative diabetic retinopathy (NPDR) group and proliferative diabetic retinopathy (PDR) group. The expression of PEDF and αB-crystallin in all groups was determined by Western blot and immunofluorescence assay. Results: PEDF and αB-crystallin protein were both detected in LEC. PEDF was mainly distributed in the cytoplasm, whereas αB-crystallin was present in both cytoplasm and nucleus. The levels of PEDF protein and αB-crystallin protein in LEC were significantly increased with the appearance and aggravation of diabetic retinopathy (DR) (p < .01). Conclusion: The expression of PEDF and αB-crystallin protein is both positively correlated with the progression of DR, which may contribute to the regulation of iris neovascularization.

Type I pig collagen enhances the efficacy of PEDF 34-mer peptide in a mouse model of laser-induced choroidal neovascularization

BACKGROUND

Pigment epithelium-derived factor (PEDF)-derived 34-mer peptide (PEDF34, Asp⁴⁴-Asn⁷⁷) has anti-angiogenic activity but has limitations in clinical application because of an inverted bell-shaped dose-effect relationship and a short half-life. In this study, we attempted to mitigate these problems by mixing PEDF34 with type I collagen.

METHODS

The anti-angiogenic activity of the PEDF34/atelocollagen mixture was evaluated by HUVEC tube formation assay and in a laser-induced choroidal neovascular (CNV) mouse model. PEDF34 and/or collagen were administrated using intravitreal injections or eye drops. CNV lesion size was quantified using FITC-dextran-perfused retinal whole mounts. Western blot analysis and inhibitor assays were used to define the action mechanisms of PEDF34 and the mixture.

RESULTS

Collagen broadened the effective dose range of PEDF34 in the tube formation assay by > 250 times (from 0.2 to 50 nM). In the CNV model, five intravitreal injections of PEDF34 were required for therapeutic effect, whereas the mixture had a significant therapeutic effect following a single injection. Eye drops of the mixture showed significantly stronger CNV-suppressive effects than drops of PEDF34 alone. The anti-angiogenic activity of PEDF34 might be mediated by inhibition of ERK and JNK activation by VEGF, and collagen potentiated these effects.

CONCLUSIONS

Collagen can serve as a carrier and reservoir of PEDF34. PEDF peptide/collagen mixture is easy to prepare than conventional methods for maintaining the therapeutic effect of PEDF peptide.

Pigment epithelium-derived factor in lipid metabolic disorders

Pigment epithelium-derived factor (PEDF) is a secreted glycoprotein that has anti-angiogenic, anti-proliferative, neurotrophic and immunomodulatory properties. PEDF has recently emerged as a critical metabolic regulatory protein since the discovery of its modulatory activities in the lipolytic pathway by binding to adipose triglyceride lipase (ATGL). Despite being beneficial in maintaining the homeostasis of hepatic lipid accumulation, PEDF has been uncovered an unfavorable role associated with insulin resistance. The molecular events that connect these two apparent distinct observations have been controversial and remained largely unknown. Therefore in this short review, we attempt to summarize the current findings of PEDF regarding its lipid metabolic functions and provide perspectives in identifying PEDF as a potential therapeutic target in lipid disorders.

Effects of concentration of amyloid β (Aβ) on viability of cultured retinal pigment epithelial cells

Background

Amyloid beta (Aβ) is a constituent of drusen that is a common sign of age-related macular degeneration (AMD). The purpose of this study was to investigate the effect of Aβ on human retinal pigment epithelial (RPE) cells in culture.

Methods

Cells from a human RPE cell line (ARPE-19) were exposed to 0 to 25 μM of Aβ 1–40 for 48 h, and the number of living cells was determined by WST-8 cleavage. Replicative DNA synthesis was measured by the incorporation of 5′-bromo-2′-deoxyuridine. The cell death pathway was investigated by the WST-8 cleavage assay after the addition of caspase-9 inhibitor, an anti-apoptotic factor. Real-time qRT-PCR was performed using Aβ-exposed cellular RNA to determine the level of vascular endothelial growth factor (VEGF)-A and pigment epithelium derived factor (PEDF). To determine the effect of receptor-for-advanced glycation end products (RAGE), the siRNA for RAGE was inserted into ARPE-19 treated with Aβ, and the levels of expression of VEGF-A and PEDF were determined.

Results

The number of living ARPE-19 cells was increased by exposure to 5 μM Aβ but was decreased by exposure to 25 μM of Aβ. Replicative DNA synthesis by ARPE-19 cells exposed to 25 μM of Aβ was significantly decreased indicating that 25 μM of Aβ inhibited cell proliferation. Real-time RT-PCR showed that the level of the mRNA of PEDF was increased by exposure to 5 μM Aβ, and the levels of the mRNAs of PEDF and VEGF-A were also increased by exposure to 25 μM Aβ. The addition of an inhibitor of caspase-9 blocked the decrease the number of ARPE-19 cells exposed to 25 μM Aβ. Exposure to si-RAGE attenuated the increase of VEGF-A and PEDF mRNA expression in ARPE-19 exposed to Aβ.

Conclusions

Exposure of ARPE-19 cells to low concentrations of Aβ increases the level of PEDF which then inhibits the apoptosis of ARPE-19 cells leading to RPE cell proliferation. Exposure to high concentrations of Aβ induces RPE cell death and enhances the expression of the mRNA of VEGF-A in RPE cells. The Aβ-RAGE pathway may lead to the expression VEGF-A and PEDF in RPE cells. These results suggest that Aβ is strongly related to the pathogenesis of choroidal neovascularization.

Pigment Epithelium-Derived Factor Affects Angiogenesis in Celiac Disease

OBJECTIVE

Recent studies have demonstrated that angiogenesis is impaired in patients with celiac disease (CD). In this study, we evaluated the levels of the novel antiangiogenic factor pigment epithelium-derived factor (PEDF) in CD patients.

METHODS

Eighty-four patients were included in the study; 71 patients with CD and 13 healthy controls. In the CD patient cohort, there were 21 newly diagnosed patients, 19 with adherence to a gluten-free diet and 31 practicing no adherence to this diet. The PEDF levels were measured using enzyme-linked immunosorbent assays.

RESULTS

The data revealed that celiac patients had higher levels of PEDF than did healthy controls. PEDF levels were not significantly different among the three CD groups. Additionally, the PEDF levels were not correlated with tissue transglutaminase IgA or IgG.

CONCLUSIONS

Our data indicate that PEDF levels are significantly higher in CD patients than those in the healthy controls. This result suggests that PEDF negatively affects angiogenesis in CD. Although we did not observe any differences of PEDF levels among celiac patients, additional studies including more patients could clarify this issue.

MicroRNA-93 promotes bladder cancer proliferation and invasion by targeting PEDF

OBJECTIVE

MicroRNA-93 (miR-93) is upregulated in the urine of patients with bladder cancer (BC). Here, we investigated the role of miR-93 in BC progression and explored the underlying mechanism.

METHODS

miR-93 expression in BC tissues and cells was detected by real time-polymerase chain reaction. The effects of miR-93 and pigment epithelium-derived factor (PEDF) on cell proliferation and invasion were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell assays. The binding of miR-93 to the 3'-untranslated region of PEDF was identified by the luciferase reporter assay.

RESULTS

miR-93 expression was higher in BC tissues than in normal controls, and its expression was associated with tumor stage and node stage. Inhibition of miR-93 suppressed the proliferation and invasion of BC cells. PEDF was identified as a target of miR-93 and shown to mediate the effect of miR-93 on cell proliferation and invasion.

CONCLUSIONS

The present data suggested that miR-93 promoted BC cell proliferation and invasion by targeting PEDF, providing new biomarkers and targets for BC diagnosis and treatment.

Pigment epithelium-derived factor inhibits lung cancer migration and invasion by upregulating exosomal thrombospondin 1

Exosomes are implicated in cancer cell development, migration and invasion. Pigment epithelium-derived factor (PEDF) is a secreted anticancer protein that can regulate lung cancer progression; however, the role of PEDF in non-small cell lung cancer (NSCLC), including metastasis and cancer cell-derived exosome secretion, is unclear. In this study, we analyzed the effects of PEDF on exosome-mediated migration, invasion, and tumorigenicity of cultured NSCLC cells. The results showed that PEDF overexpression significantly reduced NSCLC invasion and migration, while inducing cell aggregation, whereas PEDF knockdown had the opposite effects. Exosomes from NSCLC cells treated with recombinant PEDF had a significantly reduced ability to promote cancer cell motility, migration, and invasion compared to exosomes from untreated cells. Exosomes from PEDF-treated cells contained thrombospondin 1 (THBS1), which inhibited cytoskeletal remodeling and exosome-induced lung cancer cell motility, migration, and invasion. Furthermore, PEDF-overexpressing NSCLC cells formed smaller xenograft tumors with higher THBS1 expression compared to control tumors. Our findings indicate that PEDF decreases the metastatic potential of NSCLC cells through regulation of THBS1 release in cancer cell-derived exosomes, thus uncovering a new mechanism of lung cancer progression.

Loss of pigment epithelium-derived factor leads to ovarian oxidative damage accompanied by diminished ovarian reserve in mice

AIMS

This study aims to investigate the pathophysiological role and mechanism of pigment epithelium-derived factor (PEDF) deletion in ovarian damage.

METHODS

Female PEDF-knockout mice and their wild-type littermates were used in this study. Relevant tests were performed at 8-10 weeks or 32 weeks of age.

KEY FINDINGS

Compared to the wild-type mice, the PEDF-knockout mice showed diminished ovarian reserve (DOR), worse ovum quality after injection to induce controlled ovarian stimulation, increased serum follicle stimulating hormone (FSH) level and an follicle stimulating hormone/luteinizing hormone (FSH/LH) ratio. Moreover, severe ovarian oxidative damage was found in ovaries of PEDF-knockout mice that mainly manifested as an accumulation of reactive oxygen species (ROS), NF‑E2-related factor 2 (Nrf2) pathway activation, significantly upregulated expression of ROS-generating genes. Correspondingly, the PEDF-knockout mice exhibited lipid metabolism disorder and insulin resistance, which mainly manifested as obesity, abdominal fat accumulation, adipocyte enlargement, severe ectopic fat deposition, dyslipidemia, changes in adipokine levels, hyperglycemia, hyperinsulinemia, impaired glucose tolerance, impaired insulin tolerance and significantly declined protein kinase B (Akt) phosphorylation levels.

SIGNIFICANCE

Loss of PEDF leads to ovarian oxidative damage accompanied by DOR in mice, this is related to PEDF deficiency induced severe insulin resistance and lipid metabolism disorder. Therefore, PEDF may be a potential target for the treatment of diseases related to ovarian oxidative damage.

The effects of pigment epithelium-derived factor on atherosclerosis: putative mechanisms of the process

Cardiovascular disease (CVD) is a leading cause of death worldwide. Atherosclerosis is believed to be the major cause of CVD, characterized by atherosclerotic lesion formation and plaque disruption. Although remarkable advances in understanding the mechanisms of atherosclerosis have been made, the application of these theories is still limited in the prevention and treatment of atherosclerosis. Therefore, novel and effective strategies to treat high-risk patients with atherosclerosis require further development. Pigment epithelium-derived factor (PEDF), a glycoprotein with anti-inflammatory, anti-oxidant, anti-angiogenic, anti-thrombotic and anti-tumorigenic properties, is of considerable interest in the prevention of atherosclerosis. Accumulating research has suggested that PEDF exerts beneficial effects on atherosclerotic lesions and CVD patients. Our group, along with colleagues, has demonstrated that PEDF may be associated with acute coronary syndrome (ACS), and that the polymorphisms of rs8075977 of PEDF are correlated with coronary artery disease (CAD). Moreover, we have explored the anti-atherosclerosis mechanisms of PEDF, showing that oxidized-low density lipoprotein (ox-LDL) reduced PEDF concentrations through the upregulation of reactive oxygen species (ROS), and that D-4F can protect endothelial cells against ox-LDL-induced injury by preventing the downregulation of PEDF. Additionally, PEDF might alleviate endothelial injury by inhibiting the Wnt/β-catenin pathway. These data suggest that PEDF may be a novel therapeutic target for the treatment of atherosclerosis. In this review, we will summarize the role of PEDF in the development of atherosclerosis, focusing on endothelial dysfunction, inflammation, oxidative stress, angiogenesis and cell proliferation. We will also discuss its promising therapeutic implications for atherosclerosis.

Exosomes derived from PEDF modified adipose-derived mesenchymal stem cells ameliorate cerebral ischemia-reperfusion injury by regulation of autophagy and apoptosis

Increasing evidence suggest that exosomes from mesenchymal stem cells have therapeutic effects in cerebral ischemia-reperfusion (I/R) injury, but the underlying mechanisms are unclear. Pigment epithelium-derived factor (PEDF) is a multifunctional protein that exhibits anti-inflammatory, antioxidative, and neuroprotective properties. We investigated the involvement of PEDF in I/R, using adipose-derived mesenchymal stem cells (ADSCs) isolated from rat. PEDF-overexpressing ADSCs were constructed and exosomes from ADSCs were isolated. SY-5Y cells were employed to identify the protective effects of exosomes in oxygen-glucose deprivation (OGD) experiments. Exosome treatment suppressed OGD-induced apoptosis by inhibiting the two-step caspase dependent (caspase-9 and caspase-3) apoptotic pathway. Increasing the PEDF content of exosomes further promoted the protective effect against OGD-induced apoptosis by activating autophagy, while blocking autophagy reduced the effect of PEDF-containing exosomes. We constructed a middle cerebral artery occlusion-reperfusion (MCAO) model using male Sprague-Dawley rats to identify the role of PEDF in exosome-mediated neuroprotection. These in vivo experiments further confirmed that exosomes from PEDF-modified ADSCs ameliorated cerebral I/R injury by activating autophagy and suppressing neuronal apoptosis. These findings suggest that PEDF plays a role in exosome-mediated prevention of cerebral I/R injury by modulating apoptotic factors and promoting autophagy.

Lactation-related changes in tissue expression of PEDF in dairy cows

Pigment epithelium-derived factor (PEDF) is evolving as metabolic regulatory protein. Albeit mostly considered in only pathological conditions related to excess energy intake resulting in obesity and insulin resistance, PEDF is likely to be involved in other physiological processes such as the homeorhetic adaptation of metabolism to lactation. We aimed to characterize the expression of PEDF and its association to the concomitant mobilization of body reserves during lactation in nonobese subjects. This mobilization is particularly distinct in dairy cows, and we therefore assessed the mRNA expression of PEDF and its putative receptors in different tissues in 2 trials with dairy cows fed with or without conjugated linoleic acids (CLAs). Conjugated linoleic acids depress milk fat synthesis and may thus reduce the drain of energy via milk. In pluriparous cows, the serum PEDF concentrations and the mRNA abundance in subcutaneous adipose tissue (scAT), as well as the hepatic and scAT mRNA abundance of the putative receptors, adipose triglyceride lipase, and laminin receptor 1, changed over time of sampling (day -21 until day 252 relative to calving). Conjugated linoleic acid treatment was associated with reduced PEDF concentrations in serum and lower PEDF mRNA abundance in scAT on day 21 postpartum. Comparing different tissues from primiparous cows, PEDF mRNA was highest in the liver, followed by scAT, visceral adipose tissue (AT), and mammary gland, and lowest in the muscle. Significant changes in PEDF expression with time of sampling were limited to AT in primiparous and pluriparous cows. Our data support a regulatory role for PEDF. The similarities between the time course of the serum concentrations of PEDF and its mRNA abundance in scAT may point to a regulatory role for AT rather than the liver for PEDF in dairy cows.

Pigment Epithelium-Derived Factor Plays a Role in Alzheimer's Disease by Negatively Regulating Aβ42

Alzheimer's disease (AD) is the most common cause of dementia. Pigment epithelium-derived factor (PEDF), a unique neurotrophic protein, decreases with aging. Previous reports have conflicted regarding whether the PEDF concentration is altered in AD patients. In addition, the effect of PEDF on AD has not been documented. Here, we tested serum samples of 31 AD patients and 271 normal controls. We found that compared to PEDF levels in young and middle-aged control subjects, PEDF levels were reduced in old-aged controls and even more so in AD patients. Furthermore, we verified that PEDF expression was much lower and amyloid β-protein (Aβ)42 expression was much higher in senescence-accelerated mouse prone 8 (SAMP8) strain mice than in senescence-accelerated mouse resistant 1 (SAMR1) control strain mice. Accordingly, high levels of Aβ42 were also observed in PEDF knockout (KO) mice. PEDF notably reduced cognitive impairment in the Morris water maze (MWM) and significantly downregulated Aβ42 in SAMP8 mice. Mechanistically, PEDF downregulated presenilin-1 (PS1) expression by inhibiting the c-Jun N-terminal kinase (JNK) pathway. Taken together, our findings demonstrate for the first time that PEDF negatively regulates Aβ42 and that PEDF deficiency with aging might play a crucial role in the development of AD.

Long-term follow-up in osteogenesis imperfecta type VI

This retrospective study on long-term outcomes in osteogenesis imperfecta type VI found that patients who received intravenous bisphosphonate treatment had an increase in lumbar spine areal bone mineral density, a higher final height z-score, and some reshaping of vertebral bodies.

INTRODUCTION

Osteogenesis imperfecta (OI) type VI is an ultra-rare bone fragility disorder caused by recessive mutations in SERPINF1. Here, we describe long-term outcomes in OI type VI and compare the clinical phenotypes caused by different types of SERPINF1 mutations.

METHODS

This study includes a retrospective chart review of 13 individuals with OI type VI.

RESULTS

In the absence of therapy, lumbar spine areal bone mineral density (BMD) did not increase during childhood and longitudinal growth seemed to stall after the age of 6 to 8 years. The phenotype was similar between individuals with different types of SERPINF1 mutations. Intravenous bisphosphonate treatment was associated with an increase in lumbar spine areal BMD and some reshaping of compressed vertebral bodies. Patients who had started bisphosphonate treatment early (before the age of 6 years) were taller than patients who had received bisphosphonate treatment later during their growing years. Lower extremity fractures were frequent despite bisphosphonate treatment and scoliosis was present in all patients who had reached the final height. Most patients had restricted mobility. In four patients, intravenous bisphosphonate treatment was eventually substituted by subcutaneous injections of denosumab, without clear changes in the clinical picture.

CONCLUSIONS

Patients with OI type VI who received intravenous bisphosphonate treatment during growth had an increase in lumbar spine areal BMD, a higher final height z-score, and presented some reshaping of vertebral bodies. More effective treatment modalities are clearly required in OI type VI.

[Clinical pathological characteristics of resectable papillary thyroid microcarcinoma]

Objective: To investigate the difference of prognostic factors and recurrence rates between papillary thyroid microcarcinoma (PTMC) and lager papillary thyroid carcinoma (PTC) and analyze the clinical pathological characteristics of PTMC suitable for surgery. Methods: A retrospective analysis on the clinicopathological features, expression level of of v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E gene mutation and pigment epithelium-derived factor (PEDF), and postoperative follow-up results of the 251 PTC patients who underwent surgical treatment from October 2011 to October 2013, including 169 cases with PTMC and 82 with lager PTC (Tumor diameter>1 cm). Results: The BRAF V600E mutation rates of PTMC and lager PTC patients are 65.1%(110/169)and 78.0% (64/82) respectively, and the difference is statistically significant (P<0.05). The prevalence of extrathyroidal invasion (7.1%) and lymph nodes metastasis (27.2%) of the patients with PTMC were significantly lower than those of the patients with larger PTC (15.9% and 46.3%, respectively)(P<0.01). The follow-up durations for PTMC and lager PTC were (45.6±3.6) months and (45.0±3.4) months, respectively (P>0.05). There was no statistic significance for the difference in age, gender, coexistent hashimoto's thyroiditis, PEDF expression, and recurrence rate between the patients with PTMC and with larger PTC (P>0.05). The recurrence rate of the patients who have the high risk factors of PTMC was 1.6%(2/122)and that of larger PTC was 4.9% (4/82). Conclusions: Extrathyroid invasion, lymph node metastases and BRAF V600E gene mutation are the high risk factors of recurrent PTMC. The same treatment strategy should be considered for PTMC with coexistent high risk factors as that for larger PTC. For PTMC with BRAF V600E gene mutation, earlier surgical treatment is suggested. PTMC patients with BRAF V600E gene mutation and high cell subtype are suggested to undergo total thyroidectomy for the first operation in order to reduce the potential risk of recurrence.

Diabetic nephropathy: serum miR-9 confers a poor prognosis in and is associated with level changes of vascular endothelial growth factor and pigment epithelium-derived factor

OBJECTIVE

To investigate the relationship between the serum level of miR-9 and the progression of diabetic nephropathy (DN) and related molecular mechanisms.

RESULTS

Thirty-five healthy subjects and 140 DN patients were divided into five groups: control, DN I-II, DN III, DN IV and DN V. Serum level of miR-9 was measured by real-time qPCR. Serum levels of vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF) lipids, fasting glucose, insulin, hemoglobin A1c (HBA1c), creatinine, fibrinogen and insulin resistance (HOMA-IR) were also measured. The results show that the levels of miR-9, PEDF and VEGF are increased with DN progression (P < 0.05). miR-9, VEGF and PEDF are independent risk factors of DN (R² = 0.430). Spearman rank correlation analysis showed that miR-9 level is positively related to the levels of VEGF, PEDF, cholesterol, triglyceride, fasting glucose, fasting insulin, HBA1c, creatinine, fibrinogen and HOMA-IR (P < 0.05).

CONCLUSIONS

Serum miR-9 is a potential marker for conferring a poor prognosis in DN and associated with the levels of VEGF, PEDF and biochemical indices.

High serum soluble tumor necrosis factor receptor 1 predicts poor treatment response in acute-stage schizophrenia

Inflammation may be involved in the pathophysiology of schizophrenia. However, few cross-sectional or longitudinal studies have examined changes in biomarker expression to evaluate diagnostic and prognostic efficacy in acute-stage schizophrenia. We compared serum inflammatory biomarker concentrations in 87 patients with acute-stage schizophrenia on admission to 105 age-, sex-, and body mass index (BMI)-matched healthy controls. The measured biomarkers were soluble tumor necrosis factor receptor 1 (sTNFR1) and adiponectin, which are associated with inflammatory responses, and pigment epithelium-derived factor (PEDF), which has anti-inflammatory properties. We then investigated biomarker concentrations and associations with clinical factors in 213 patients (including 42 medication-free patients) and 110 unmatched healthy controls to model conditions typical of clinical practice. Clinical symptoms were assessed using the Brief Psychiatric Rating Scale and Global Assessment of Function. In 121 patients, biomarker levels and clinical status were evaluated at both admission and discharge. Serum sTNFR1 was significantly higher in patients with acute-stage schizophrenia compared to matched controls while no significant group differences were observed for the other markers. Serum sTNFR1 was also significantly higher in the 213 patients compared to unmatched controls. The 42 unmedicated patients had significantly lower PEDF levels compared to controls. Between admission and discharge, sTNFR1 levels decreased significantly; however, biomarker changes did not correlate with clinical symptoms. The discriminant accuracy of sTNFR1 was 93.2% between controls and patients, showing no symptom improvement during care. Inflammation and a low-level anti-inflammatory state may be involved in both schizophrenia pathogenesis and acute-stage onset. High serum sTNFR1 in the acute stage could be a useful prognostic biomarker for treatment response in clinical practice.

Pigment Epithelium-Derived Factor (PEDF) Prevents Hepatic Fat Storage, Inflammation, and Fibrosis in Dietary Steatohepatitis of Mice

BACKGROUND AND AIMS

Pigment epithelium-derived factor (PEDF) has been shown to be a potent inhibitor of inflammation through its anti-oxidative property. Since oxidative response is considered to play the pivotal role of the development and progression of nonalcoholic steatohepatitis (NASH), it is conceivable that PEDF may play a protective role against NASH. In this study, we examined whether administration of PEDF slowed the progression of NASH in mice models.

METHODS

Mice were fed methionine- and choline-deficient (MCD) diet with or without intramuscular administration of adenovirus-expressing PEDF (Ad-PEDF). Effects of PEDF administration on NASH were histologically and biochemically evaluated.

RESULTS

Administration of Ad-PEDF significantly decreased hepatic fat storage as well as serum levels of ALT in MCD diet-fed mice. Dihydroethidium staining showed that MCD diet-triggered oxidative stress was reduced in the liver of Ad-PEDF-administered mice compared to that of PBS- or Ad-LacZ-administered mice. Activation of Kupffer cells and hepatic fibrosis was also inhibited by Ad-PEDF administration. Quantitative real-time RT-PCR revealed that MCD diet up-regulated expressions of TNF-α, IL-1β, IL-6, TGF-β, collagen-1, and collagen-3 mRNA, which were also attenuated with Ad-PEDF administration, whereas MCD diet-induced down-regulation of expressions of PPAR-γ mRNA was restored with Ad-PEDF administration. Furthermore, immunoblotting analysis showed that MCD diet-induced up-regulation of NADPH oxidase components was significantly decreased in Ad-PEDF-administered mice.

CONCLUSIONS

The present results demonstrated for the first time that PEDF could slow the development and progression of steatohepatitis through the suppression of steatosis and inflammatory response in MCD diet-fed mice. Our study suggests that PEDF supplementation may be a novel therapeutic strategy for the treatment of NASH.

Identification of vitreous proteins in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a disorder of blood vessels in the retina developed in premature infants and the leading cause of the blindness in children. Proteomic analysis was performed to identify vitreous proteins specific to patients with ROP. Vitreous humor samples were obtained from three patients with ROP and two patients with congenital cataract, the latter included as a control group. The vitreous samples were separated by 2D-PAGE and the proteins running as definitive spots were identified by MALDI-TOF MS spectrometry. We identified 13 and 6 proteins in the vitreous from ROP and cataract patients, respectively. Albumin, transferrin, pigment epithelium-derived factor (PEDF) and transthyretin were found in both patient groups. In the samples from ROP patients, PEDF and transthyretin levels were lower than in those from cataract patients, and retinol binding protein 3 and prostaglandin D synthase were not detected. Of the 13 proteins, 9 proteins including α-2-macroglobulin, ceruloplasmin, α-fetoprotein, vitamin D-binding protein, α-1-antitrypsin, α-1-β-glycoprotein, hemopexin, apolipoprotein A-1 and A-lV were found in vitreous samples of only the ROP patients. PEDF has anti-angiogenic and neurotrophic functions. Whether PEDF is increased or decreased in diabetic retinopathy has been controversial but we observed lower PEDF in the ROP samples than in the controls. The proteins specific to or decreased in ROP, if confirmed in future studies, may provide clue to understanding its pathogenesis.

Pigment epithelium-derived factor alleviates endothelial injury by inhibiting Wnt/β-catenin pathway

Background

Oxidized low-density lipoprotein (ox-LDL) can induce endothelial injury and plays a vital role in the procession and development of atherosclerosis. Little is known regarding whether Wnt/β-catenin pathway is involved in ox-LDL-induced endothelial injury or whether it further promotes atherosclerosis via increased oxidative stress. This study aimed to investigate the role of Wnt/β-catenin pathway in ox-LDL-induced vascular endothelial injury and determine whether pigment epithelium-derived factor (PEDF) could alleviate ox-LDL-induced endothelial injury by inhibiting Wnt/β-catenin pathway.

Methods

Injury of human umbilical vein endothelial cells (HUVECs) was evaluated with an MTT assay, by monitoring lactate dehydrogenase (LDH) release and determining the apoptotic ratio. The expression of β-catenin (non-phosphorylated-β-catenin), disheveled-1 (Dvl-1) and Cyclin D1 was analyzed with western blotting and quantitative real-time PCR. Oxidative stress status was assessed by measuring the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO).

Results

Exposure of HUVECs to ox-LDL led to a decrease in cell viability and an increase in LDH release and apoptosis with concomitant enhancement of oxidative stress, as assessed by increased ROS and MDA generation, as well as decreased SOD activity and NO levels. Similar to lithium chloride (LiCl, a Wnt/β-catenin pathway activator), ox-LDL up-regulated the expression of β-catenin, Dvl-1 and Cyclin D1, markers of Wnt/β-catenin pathway activation. However, ox-LDL-induced activation of Wnt/β-catenin pathway, as well as ox-LDL-induced cell injury and oxidative stress, were synergistically promoted by LiCl and mitigated by Dickkopf 1 (DKK-1), an inhibitor of Wnt/β-catenin pathway. Additionally, ox-LDL-induced HUVEC injury and apoptosis, oxidative stress and activation of Wnt/β-catenin pathway were suppressed by PEDF, while they were further strengthened by a small interfering RNA of PEDF.

Conclusion

Wnt/β-catenin pathway may mediate ox-LDL-induced endothelial injury via oxidative stress, and PEDF ameliorates endothelial injury by suppressing Wnt/β-catenin pathway and subsequently reducing oxidative stress.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0407-8) contains supplementary material, which is available to authorized users.

Pigment Epithelium-Derived Factor (PEDF) mediates cartilage matrix loss in an age-dependent manner under inflammatory conditions

Background

Inflammation is a major cause of cartilage destruction and leads to the imbalance of metabolic activities in the arthritic joint. Pigment epithelium-derived factor (PEDF) has been reported to have both pro- and anti-inflammatory activities in various cell types and to be upregulated in the arthritic joint, but its role in joint destruction is unclear. Our aim was to investigate the role of PEDF in cartilage degeneration under inflammatory conditions.

Methods

PEDF was ectopically expressed in primary human articular chondrocytes, and catabolic gene expression and protein secretion in response to the pro-inflammatory cytokine interleukin 1 beta (IL-1β) were evaluated. Metatarsal bones from PEDF-deficient and wild type mice were cultured in the presence or absence of IL-1β. Cartilage matrix integrity and matrix metalloproteinases MMP-1, MMP-3, and MMP-13 were evaluated. PEDF-deficient and wild type mice were evaluated in the monosodium iodoacetate (MIA) inflammatory joint destruction animal model to determine the role of PEDF in inflammatory arthritis in vivo. Student’s t-tests and Mann–Whitney tests were employed where appropriate, for parametric and non-parametric data, respectively.

Results

We showed that PEDF protein levels were higher in human osteoarthritis samples compared to normal samples. We demonstrated that ectopic PEDF expression in primary human articular chondrocytes exacerbated catabolic gene expression in the presence of IL-1β. In whole bone organ cultures, IL-1β induced MMP-1, MMP-3 and MMP-13 protein production, and caused significant cartilage matrix loss. Interestingly, Toluidine Blue staining showed that PEDF-deficient bones from 29 week old animals, but not 10 week old animals, had reduced matrix loss in response to IL-1β compared to their wild type counterparts. In addition, PEDF-deficiency in 29 week old animals preserved matrix integrity and protected against cell loss in the MIA joint destruction model in vivo.

Conclusion

We conclude that PEDF exacerbates cartilage degeneration in an age-dependent manner under an inflammatory setting. This is the first study identifying a specific role for PEDF in joint inflammation and highlights the multi-faceted activities of PEDF.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1410-y) contains supplementary material, which is available to authorized users.

Circulating level of pigment epithelium-derived factor is associated with vascular function and structure: A cross-sectional study

BACKGROUND

Pigment epithelium-derived factor (PEDF) is a glycoprotein that belongs to the superfamily of serine protease inhibitors. It is thought that PEDF plays a protective role against atherosclerosis. Clinical studies have shown that serum levels of PEDF are increased in subjects with cardiovascular risk factors. The role of PEDF in cardiovascular disease is still controversial. The purpose of this study was to evaluate the associations between serum levels of PEDF and vascular function and structure.

METHODS

We measured serum levels of PEDF, assessed vascular function by measurements of flow-mediated vasodilation (FMD) and nitroglycerine-induced vasodilation in the brachial artery, and measured brachial artery intima-media thickness (IMT) in 150 subjects who underwent health examinations.

RESULTS AND CONCLUSIONS

Univariate regression analysis revealed that serum level of PEDF was significantly correlated with body mass index, high-density lipoprotein cholesterol, glucose, FMD, nitroglycerine-induced vasodilation, and brachial artery IMT. Multivariate analysis revealed that serum levels of PEDF remained an independent predictor of nitroglycerine-induced vasodilation (β=-0.20, P=0.02) and brachial artery IMT (β=0.14, P=0.03) after adjustment of cardiovascular risk factors, while serum level of PEDF was not associated with FMD (β=-0.02, P=0.79). These findings suggest that PEDF may be a factor directly associated with atherosclerosis. The serum level of PEDF may be a new biochemical marker of atherosclerosis.

Neural Stem Cell-based Intraocular Administration of Pigment Epithelium-derived Factor Promotes Retinal Ganglion Cell Survival and Axon Regeneration after Optic Nerve Crush Injury in Rat: An Experimental Study

BACKGROUND

Pigment epithelium-derived factor (PEDF) is regarded as a multifunctional protein possessing neurotrophic and neuroprotective properties. PEDF has a very short half-life, and it would require multiple injections to maintain a therapeutically relevant level without a delivery system. However, multiple injections are prone to cause local damage or infection. To overcome this, we chose a cell-based system that provided sustained delivery of PEDF and compared the effect of weekly injections of PEDF and neural stem cell (NSC)-based intraocular administration of PEDF on retinal ganglion cell (RGC) survival and axon regeneration after optic nerve injury.

METHODS

Seventy-two rats were randomly assigned to 3 groups: group with injections of phosphate buffered saline (PBS) (n=24), group with weekly injections of PEDF (n=24), and group with NSC-based administration of PEDF (n=24). Western blot was used to analyze the PEDF protein level 2 weeks after injection. Retinal flat mounts and immunohistochemistry were employed to analyze RGC survival and axon regeneration 2 weeks and 4 weeks after injection. The data were analyzed with one-way ANOVA in SPSS (version 19.0). A P<0.05 was considered significant.

RESULTS

The PEDF protein level in the group with NSC-based administration of PEDF increased compared with that in the groups with injections of PEDF and PBS (P<0.05). The PEDF-modified NSCs differentiated into GFAP-positive astrocytes andβ-tubulin-III-positive neurons. NSC-based administration of PEDF effectively increased RGC survival and improved the axon regeneration of the optic nerve compared with weekly injections of PEDF.

CONCLUSION

Subretinal space transplantation of PEDF-secreting NSCs sustained high concentrations of PEDF, differentiated into neurons and astrocytes, and significantly promoted RGC survival and axon regeneration after optic nerve injury.

Abnormal pigment epithelium-derived factor processing in progressive myopia

Pigment Epithelium-Derived Factor (PEDF) is a secreted glycoprotein belonging to the family of non-inhibitory serpins. It is known, that in cases of complicated myopia, the content of PEDF in aqueous humor of the anterior chamber is significantly reduced. Here we examined a bulk of Tenon's capsule samples obtained from various groups of myopes, to examine PEDF processing in progressive myopia. We have analyzed the distribution of full length PEDF50 and its truncated form PEDF45 in the soluble and insoluble fractions extracted from Tenon's capsule of myopic and control (non-myopic) patients using SDS-polyacrylamide gel electrophoresis, as well as monitored the proteolytic degradation of PEDF ex vivo by enzyme-linked immunosorbent assay. These results were complemented by PEDF mRNA analysis in correspondent tissues by using qPCR and immunohistochemistry analysis of PEDF distribution in normal and myopic specimens. We found that in the Tenon's capsule of patients suffering from a high myopia the level of "soluble" 45 kDa PEDF reduced by 2-fold, while the content of "insoluble" 50 kDa form of PEDF was increased by 4-fold compared to controls. Excessive amount of PEDF50 in myopic specimens have been shown to correlate with the abrogated PEDF processing rather than with an increase of its expression. Moreover, immunohistochemical staining of the myopic Tenon's capsule tissue sections revealed the halo of deposited PEDF50 in the fibroblast extracellular space. These findings suggest that in myopia limited proteolysis of PEDF is altered or abrogated. Accumulation of full-length PEDF insoluble aggregates in the fibroblast intercellular space may affect cell survival and consequently causes the destructive changes in the extracellular matrix of the eye connective tissues. As a result, the abrogation of full-length PEDF normal processing can be an important mechanism leading to biomechanical destabilization of the scleral capsule and myopia progression.

Pigment epithelium-derived factor (PEDF) regulates metabolism and insulin secretion from a clonal rat pancreatic beta cell line BRIN-BD11 and mouse islets

Pigment epithelium-derived factor (PEDF) is a multifunctional glycoprotein, associated with lipid catabolism and insulin resistance. In the present study, PEDF increased chronic and acute insulin secretion in a clonal rat β-cell line BRIN-BD11, without alteration of glucose consumption. PEDF also stimulated insulin secretion from primary mouse islets. Seahorse flux analysis demonstrated that PEDF did not change mitochondrial respiration and glycolytic function. The cytosolic presence of the putative PEDF receptor - adipose triglyceride lipase (ATGL) - was identified, and ATGL associated stimulation of glycerol release was robustly enhanced by PEDF, while intracellular ATP levels increased. Addition of palmitate or ex vivo stimulation with inflammatory mediators induced β-cell dysfunction, effects not altered by the addition of PEDF. In conclusion, PEDF increased insulin secretion in BRIN-BD11 and islet cells, but had no impact on glucose metabolism. Thus elevated lipolysis and enhanced fatty acid availability may impact insulin secretion following PEDF receptor (ATGL) stimulation.

Protective Effects of Human iPS-Derived Retinal Pigmented Epithelial Cells in Comparison with Human Mesenchymal Stromal Cells and Human Neural Stem Cells on the Degenerating Retina in rd1 mice

Retinitis pigmentosa (RP) is a group of visual impairments characterized by progressive rod photoreceptor cell loss due to a genetic background. Pigment epithelium-derived factor (PEDF) predominantly secreted by the retinal pigmented epithelium (RPE) has been reported to protect photoreceptors in retinal degeneration models, including rd1. In addition, clinical trials are currently underway outside Japan using human mesenchymal stromal cells and human neural stem cells to protect photoreceptors in RP and dry age-related macular degeneration, respectively. Thus, this study aimed to investigate the rescue effects of induced pluripotent stem (iPS)-RPE cells in comparison with those types of cells used in clinical trials on photoreceptor degeneration in rd1 mice. Cells were injected into the subretinal space of immune-suppressed 2-week-old rd1 mice. The results demonstrated that human iPS-RPE cells significantly attenuated photoreceptor degeneration on postoperative days (PODs) 14 and 21 and survived longer up to at least 12 weeks after operation than the other two types of graft cells with less immune responses and apoptosis. The mean PEDF concentration in the intraocular fluid in RPE-transplanted eyes was more than 1 µg/ml at PODs 14 and 21, and this may have contributed to the protective effect of RPE transplantation. Our findings suggest that iPS-RPE cells serve as a competent source to delay photoreceptor degeneration through stable survival in degenerating ocular environment and by releasing neuroprotective factors such as PEDF.

Proteomics of vitreous in neovascular age-related macular degeneration

Neovascular age-related macular degeneration (nAMD) has been described as a predominantly inflammatory and proangiogenic retino-choroidal disease. Vitreous humor (VH) is the adjacent and accessible compartment which, due to the vicinity to the retina, might best represent changes of protein-based mediators of nAMD. The aim of this clinical-experimental study was to analyze the nAMD associated VH proteome of previously untreated patients whilst taking different groups of nAMD into account, based on their clinical presentation (clinical diagnosis groups). Electrophoresis coupled online to mass spectrometry (CE-MS) as well as liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) were used to analyze VH of 108 nAMD patients and 24 controls with idiopathic floaters. A total of 101 different proteins with at least two unique peptides could be identified. Using a stringent statistical analysis with implementation of the closed test principle, we were able to identify four proteins that may be involved in the pathophysiology of nAMD: Clusterin, opticin, pigment epithelium-derived factor and prostaglandin-H2 d-isomerase. Using independent samples, ROC-Area under the curve was determined proving the validity of the results: Clusterin 0.747, opticin 0.656, pigment epithelium-derived factor 0.514, prostaglandin-H2 d-isomerase 0.712. In addition, validation through ELISA measurements was performed. The identified proteins may serve as potential biomarkers or even targets of therapy for nAMD.

Mechanism of PEDF promoting the proliferation of lens epithelial cells in human eyes

OBJECTIVE

To investigate the regulation effect of pigment epithelium-derived factor (PEDF) on the growth of human lens endothelial cells (LECs) and related mechanisms in vivo and in vitro.

METHODS

In the part of in vivo study, 82 eyes of 82 patients with age-related cataract were included to collect the central lens anterior capsule (diameter at 5.0-5.5 mm) with the informed consent of surgery for patients. The selected specimens were divided into the LECs low density group and high density group with 20 specimens for each group based on hematoxylin and eosin staining results. The relative expression level of PEDF mRNA in LECs was detected by reverse transcription PCR. In the part of in vitro study, LEC line (HLE-B3) was cultured and 50 ng/mL PEDF was added in media for 72 h in PEDF culture group, while normally cultured cells were used as the control group. The percentage of LECs at G0 and S phases and apoptotic rate of cells were assayed by using flow cytometry with annexin Ⅴ-FITC/7-AAD double staining method. Intracellular expression of vascular endothelial growth factor (VEGF) mRNA was detected by real-time fluorescence quantitative PCR.

RESULTS

The central anterior subcapsular LECs density and relative expression level of PEDF mRNA were lower than those of high density group. There were no significant differences between two groups (P = 0.168). The apoptotic rate in the PEDF culture group was significantly reduced in comparison with the control group (P < 0.001). In addition, the expression level of VEGF mRNA was lower in the PEDF culture group compared with the control group (P < 0.001).

CONCLUSIONS

In human eyes, PEDF may function as cytotropic factor to promote survival of LECs through anti-apoptosis and reducing-expression of VEGF. Decrease of PEDF content in LECs probably modulates the pathophysiological process of lens cells and further cataractogenesis.

Myo-inositol is a promising treatment for the prevention of ovarian hyperstimulation syndrome (OHSS): an animal study

PURPOSE

To evaluate the efficacy of myo-inositol (MI) pretreatment in OHSS.

METHODS

In this experimental OHSS rat model, 42 immature Wistar albino female rats were divided into 6 groups: (1) the control group, (2) the ovarian stimulation group, (3) the OHSS group, (4) the OHSS + Metformin group, (5) OHSS + MI group, (6) OHSS + Metformin + MI group. OHSS was established after treatment with metformin and myo-inositol for 14 days, in the meanwhile the treatment of metformin and myo-inositol was also continued. All animals were killed 48 h after hCG administration and were compared in terms of vascular permeability, ovarian weight and diameter, ovarian VEGF, COX-2 and PEDF expression (immunohistochemistry), serum PEDF and estradiol (E2) levels.

RESULTS

Vascular permeability, VEGF and COX-2 expressions were reduced in animals treated with MI and/or metformin. While PEDF expression was increased in the groups taking metformin, there was no difference in PEDF expression in the group taking MI and OHSS group. There was no significant difference in serum PEDF levels between groups. Blood E2 levels were decreased in groups treated with MI or metformin compared to the OHSS group.

CONCLUSIONS

Our data demonstrate that myo-inositol is effective in preventing OHSS, similar to metformin. Although the two drugs are thought to act through distinct mechanisms, there is no apparent benefit to co-treatment with both drugs in an animal model of OHSS. Administration of myo-inositol prior to IVF treatment may favor the control of ovulation induction. Further studies are necessary to elucidate the mechanism of action and further support our findings.

Pigment epithelium-derived factor as a new predictor of mortality among chronic kidney disease patients treated with hemodialysis

Pigment epithelium-derived factor (PEDF) plays a protective role against atherosclerosis. Although serum PEDF level is increased in patients undergoing regular hemodialysis (HD), the pathophysiological role of PEDF in HD patients is unknown. We measured serum PEDF levels in 74 HD patients, and the association between serum PEDF and adverse events such as all-cause death and cardiovascular accident was evaluated prospectively. During the follow up of 45.4 ± 25.1 months, 24 patients (32.4%) experienced cardiovascular accident and 18 (24.3%) died. Significantly higher incidences of all-cause mortality and cardiovascular accident were observed in the lower PEDF group than in the higher PEDF group. After adjusting for propensity score calculated from multiple confounding factors (age, gender, systolic blood pressure, history of previous cardiovascular disease, level of carbonyl content, albumin, hemoglobin, total cholesterol, creatinine, C-reactive protein, dialysis vintage, Kt/V-urea and history of diabetes), lower predialytic PEDF was a significant risk factor for all-cause mortality (relative hazard = 6.060, standard error = 0.68467, P = 0.0085). Lower levels of predialytic PEDF was associated with an increased risk of mortality.

Pigment epithelium-derived factor promotes Fas-induced cardiomyocyte apoptosis via its receptor phospholipase A2

AIMS

Cardiovascular diseases cause significant morbidity and mortality worldwide. Recently, our research team demonstrated that a multifunctional cytokine, pigment epithelium-derived factor (PEDF), plays a critical role in regulating myocardial infarction. However, few researchers have studied the molecular mechanisms by which PEDF and its receptors influence the pathophysiology of cardiovascular disease. We tested the hypothesis that PEDF affects cardiomyocyte apoptosis under hypoxic conditions and determined the role that its receptors phospholipase A2 (PLA2) and laminin receptor play in this process.

MAIN METHODS

Cardiomyocytes were isolated from neonatal mice and treated with PEDF under normoxic and hypoxic conditions; then, apoptosis was assessed using Annexin V/PI staining and flow cytometry. Western blotting and immunofluorescence staining were used to detect PEDF receptor expression, and siRNA knockdown of PEDF receptors was performed to determine which receptor was involved in mediating cardiomyocyte apoptosis.

KEY FINDINGS

Our results demonstrated that PEDF increased cardiomyocyte apoptosis during hypoxia via Fas and that PEDF receptors were expressed on cardiomyocyte cell membranes. Furthermore, siRNA experiments indicated that the PEDF receptor PLA2 was responsible for inducing cardiomyocyte apoptosis via the Fas pathway.

SIGNIFICANCE

PEDF promoted Fas-induced cardiomyocyte apoptosis via its receptor PLA2.

The expression of pigment epithelium-derived factor in bladder transitional cell carcinoma

Background

Pigment epithelium-derived factor (PEDF) is an anti-angiogenic factor. The purpose of this study is to examine the involvement of PEDF in the angiogenesis and biological behavior of bladder transitional cell carcinoma (TCC).

Methods

We examined the expression of PEDF in 99 bladder TCCs and ten non-neoplastic tissues, and evaluated microvessel density (MVD).

Results

The positive immunoreactivity for PEDF was seen in normal urothelium in 60% (6/10) and TCC in 13% (13/99). The PEDF expression had a significant correlation with MVD, i.e., a low MVD in 42% (5/12), a middle MVD in 11% (8/76) and a high MVD 0% (0/11) of tumors. The PEDF expression was not significantly correlated with the differentiation and invasion of TCC, but the degree of MVD was significantly higher in both high grade TCC and the pT2 tumors.

Conclusions

The degree of PEDF expression is significantly higher in normal bladder urothelium than bladder TCC; it is inversely correlated with the angiogenesis; and it is not related to the differentiation and progression of TCC. It can therefore be concluded that bladder TCC would initially occur if there is a lack of the PEDF expression.

Increased expression of pigment epithelium-derived factor in aged mesenchymal stem cells impairs their therapeutic efficacy for attenuating myocardial infarction injury

AIMS

Mesenchymal stem cells (MSCs) can ameliorate myocardial infarction (MI) injury. However, older-donor MSCs seem less efficacious than those from younger donors, and the contributing underlying mechanisms remain unknown. Here, we determine how age-related expression of pigment epithelium-derived factor (PEDF) affects MSC therapeutic efficacy for MI.

METHODS AND RESULTS

Reverse transcriptase-polymerized chain reaction  and enzyme-linked immunosorbent assay analyses revealed dramatically increased PEDF expression in MSCs from old mice compared to young mice. Morphological and functional experiments demonstrated significantly impaired old MSC therapeutic efficacy compared with young MSCs in treatment of mice subjected to MI. Immunofluorescent staining demonstrated that administration of old MSCs compared with young MSCs resulted in an infarct region containing fewer endothelial cells, vascular smooth muscle cells, and macrophages, but more fibroblasts. Pigment epithelium-derived factor overexpression in young MSCs impaired the beneficial effects against MI injury, and induced cellular profile changes in the infarct region similar to administration of old MSCs. Knocking down PEDF expression in old MSCs improved MSC therapeutic efficacy, and induced a cellular profile similar to young MSCs administration. Studies in vitro showed that PEDF secreted by MSCs regulated the proliferation and migration of cardiac fibroblasts.

CONCLUSIONS

This is the first evidence that paracrine factor PEDF plays critical role in the regulatory effects of MSCs against MI injury. Furthermore, the impaired therapeutic ability of aged MSCs is predominantly caused by increased PEDF secretion. These findings indicate PEDF as a promising novel genetic modification target for improving aged MSC therapeutic efficacy.