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/ß-catenin pathway.

Acute-Phase Plasma Pigment Epithelium-Derived Factor Predicting Outcomes after Aneurysmal Subarachnoid Hemorrhage in the Elderly.

Aneurysmal subarachnoid hemorrhage (SAH) has increased with the aging of the population, but the outcome for elderly SAH patients is very poor. Therefore, predicting the outcome is important for determining whether to pursue aggressive treatment. Pigment epithelium-derived factor (PEDF) is a matricellular protein that is induced in the brain, and the plasma levels could be used as a biomarker for the severity of metabolic diseases. This study investigated whether acute-phase plasma PEDF levels could predict outcomes after aneurysmal SAH in the elderly. Plasma samples and clinical variables were collected over 1-3 days, post-SAH, from 56 consecutive elderly SAH patients ≥75 years of age registered in nine regional stroke centers in Japan between September 2013 and December 2016. The samples and variables were analyzed in terms of 3-month outcomes. Acute-phase plasma PEDF levels were significantly elevated in patients with ultimately poor outcomes, and the cutoff value of 12.6 µg/mL differentiated 3-month outcomes with high sensitivity (75.6%) and specificity (80.0%). Acute-phase plasma PEDF levels of ≥12.6 µg/mL were an independent and possibly better predictor of poor outcome than previously reported clinical variables. Acute-phase plasma PEDF levels may serve as the first biomarker to predict 3-month outcomes and to select elderly SAH patients who should be actively treated.

Tissue-targeted and localized AAV5-DCN and AAV5-PEDF combination gene therapy abrogates corneal fibrosis and concurrent neovascularization in rabbit eyes in vivo.

PURPOSE: Corneal fibrosis and neovascularization (CNV) after ocular trauma impairs vision. This study tested therapeutic potential of tissue-targeted adeno-associated virus5 (AAV5) mediated decorin (DCN) and pigment epithelium-derived factor (PEDF) combination genes in vivo. METHODS: Corneal fibrosis and CNV were induced in New Zealand White rabbits via chemical trauma. Gene therapy in stroma was delivered 30-min after chemical-trauma via topical AAV5-DCN and AAV5-PEDF application using a cloning cylinder. Clinical eye examinations and multimodal imaging in live rabbits were performed periodically and corneal tissues were collected 9-day and 15-day post euthanasia. Histological, cellular, and molecular and apoptosis assays were used for efficacy, tolerability, and mechanistic studies. RESULTS: The AAV5-DCN and AAV5-PEDF combination gene therapy significantly reduced corneal fibrosis (p < 0.01 or p < 0.001) and CNV (p < 0.001) in therapy-given (chemical-trauma and AAV5-DCN + AAV5-PEDF) rabbit eyes compared to the no-therapy given eyes (chemical-trauma and AAV5-naked vector). Histopathological analyses demonstrated significantly reduced fibrotic α-smooth muscle actin and endothelial lectin expression in therapy-given corneas compared to no-therapy corneas on day-9 (p < 0.001) and day-15 (p < 0.001). Further, therapy-given corneas showed significantly increased Fas-ligand mRNA levels (p < 0.001) and apoptotic cell death in neovessels (p < 0.001) compared to no-therapy corneas. AAV5 delivered 2.69 × 107 copies of DCN and 2.31 × 107 copies of PEDF genes per µg of DNA. AAV5 vector and delivered DCN and PEDF genes found tolerable to the rabbit eyes and caused no significant toxicity to the cornea. CONCLUSION: The combination AAV5-DCN and AAV5-PEDF topical gene therapy effectively reduces corneal fibrosis and CNV with high tolerability in vivo in rabbits. Additional studies are warranted.

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.

Characterization of three adults and an adolescent with Osteogenesis Imperfecta type VI and a novel founder SERPINF1 variant.

Osteogenesis imperfecta (OI) type VI is an extremely rare form of OI caused by biallelic variants in the SERPINF1 gene, which codes for the pigment-epithelium derived factor (PEDF). We report on four patients (three adults and one adolescent) with a severe deforming form of OI. All patients presented no abnormalities at birth, frequent long bone and vertebrae fractures (mainly during childhood), marked short stature, severe bone deformities, chronic mild to moderate pain, and severe limitation of mobility, with three being completely wheelchair bound. Blue sclera and dentinogenesis imperfecta were absent, although some patients presented tooth, ophthalmological, and/or cardiac features. Radiographic findings included, among others, thin diaphysis and popcorn calcifications, both of which are non-specific to this type of OI. The novel homozygous variants c.816_819del (p.Met272Ilefs*8) and c.283+2T > G in SERPINF1 were identified in three and one patient, respectively. The three patients carrying the frameshift variant were born in nearby regions suggesting a founder effect. Describing the long-term outcomes of four patients with OI type VI, this cohort adds relevant data on the clinical features and prognosis of this type of OI.

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.

Tyrosine-Mutant AAV8 Vector Mediated Efficient and Safe Gene Transfer of Pigment Epithelium-Derived Factor to Mouse Lungs.

BACKGROUND/AIMS: Recombinant adeno-associated viruses (rAAV) are an important tool for lung targeted gene therapy. Substitution of tyrosine with phenylalanine residues (Y-F) in the capsid have been shown to protect the AAV vector from ubiquitin/proteasome degradation, increasing transduction efficiency. We tested the mutant Y733F-AAV8 vector for mucus diffusion, as well as the safety and efficacy of pigment epithelium-derived factor (PEDF) gene transfer to the lung. METHODS: For this purpose, Y733F-AAV8-PEDF (1010 viral genome) was administered intratracheally to C57BL/6 mice. Lung mechanics, morphometry, and inflammation were evaluated 7, 14, 21, and 28 days after injection. RESULTS: The tyrosine-mutant AAV8 vector was efficient at penetrating mucus in ex vivo assays and at transferring the gene to lung cells after in vivo instillation. Increased levels of transgene mRNA were observed 28 days after vector administration. Overexpression of PEDF did not affect in vivo lung parameters. CONCLUSION: These findings provide a basis for further development of Y733F-AAV8-based gene therapies for safe and effective delivery of PEDF, which has anti-angiogenic, anti-inflammatory and anti-fibrotic activities and might be a promising therapy for lung inflammatory disorders.

SERPINF1 gene variants causing late-onset progressive deforming osteogenesis imperfecta - A study of 18 patients from India.

SERPINF1 gene variants lead to a severe type of osteogenesis imperfecta (OI) attributed to defects in the matrix mineralization. We present 18 patients with SERPINF1 gene variants leading to severe progressive deforming OI, the largest series in the world to date. These patients were normal at birth and had the first fracture between 2 months to 9 years; progression of deformities was seen in 12 adolescents who became nonambulatory. Radiologically, compression fractures with kyphoscoliosis, protrusio acetabuli, and lytic lesions in the metaphysis and pelvis were seen in older children with classical popcorn appearance in the distal femoral metaphysis in three. By exome sequencing and targeted sequencing, we identified ten variants. One was unreported and novel; three other novel variants in this series were reported earlier. The recurrent deletion inframe mutation p.phe277del was found in 5 patients from three families. Alkaline phosphatase was elevated in all children on the first visit. Bone mineral density was low in all patients and showed improvement at two years in seven children on regular pamidronate therapy. For others, the 2 year BMD data were not available. The Z scores for four of the seven children showed worsening at the 2-year follow-up.

AATF inhibition exerts antiangiogenic effects against human hepatocellular carcinoma.

Background and aims: Angiogenesis is a key factor in the growth and metastasis of hepatic tumors and thus a potential therapeutic target in hepatocellular carcinoma (HCC). In this study, we aim to identify the key role of apoptosis antagonizing transcription factor (AATF) in tumor angiogenesis and its underlying mechanisms in HCC. Methods: HCC tissues were analyzed for AATF expression by qRT-PCR and immunohistochemistry. Stable clones of control and AATF knockdown (KD) were established in human HCC cells. The effect of AATF inhibition on the angiogenic processes was determined by proliferation, invasion, migration, chick chorioallantoic membrane (CAM) assay, zymography, and immunoblotting techniques. Results: We identified high levels of AATF in human HCC tissues compared to adjacent normal liver tissues, and the expression was found to be correlated with the stages and tumor grades of HCC. Inhibiting AATF in QGY-7703 cells resulted in higher levels of pigment epithelium-derived factor (PEDF) than controls due to decreased matric metalloproteinase activity. Conditioned media from AATF KD cells inhibited the proliferation, migration, and invasion of human umbilical vein endothelial cells as well as the vascularization of the chick chorioallantoic membrane. Furthermore, the VEGF-mediated downstream signaling pathway responsible for endothelial cell survival and vascular permeability, cell proliferation, and migration favoring angiogenesis was suppressed by AATF inhibition. Notably, PEDF inhibition effectively reversed the anti-angiogenic effect of AATF KD. Conclusion: Our study reports the first evidence that the therapeutic strategy based on the inhibition of AATF to disrupt tumor angiogenesis may serve as a promising approach for HCC treatment.

Receptors that bind to PEDF and their therapeutic roles in retinal diseases.

Retinal neovascular, neurodegenerative, and inflammatory diseases represented by diabetic retinopathy are the main types of blinding eye disorders that continually cause the increased burden worldwide. Pigment epithelium-derived factor (PEDF) is an endogenous factor with multiple effects including neurotrophic activity, anti-angiogenesis, anti-tumorigenesis, and anti-inflammatory activity. PEDF activity depends on the interaction with the proteins on the cell surface. At present, seven independent receptors, including adipose triglyceride lipase, laminin receptor, lipoprotein receptor-related protein, plexin domain-containing 1, plexin domain-containing 2, F1-ATP synthase, and vascular endothelial growth factor receptor 2, have been demonstrated and confirmed to be high affinity receptors for PEDF. Understanding the interactions between PEDF and PEDF receptors, their roles in normal cellular metabolism and the response the initiate in disease will be accommodating for elucidating the ways in which inflammation, angiogenesis, and neurodegeneration exacerbate disease pathology. In this review, we firstly introduce PEDF receptors comprehensively, focusing particularly on their expression pattern, ligands, related diseases, and signal transduction pathways, respectively. We also discuss the interactive ways of PEDF and receptors to expand the prospective understanding of PEDF receptors in the diagnosis and treatment of retinal diseases.

Potential therapeutic role for pigment epithelium-derived factor in post-menopausal breast cancer bone metastasis.

OBJECTIVES: This review discusses key oestrogens associated with the circulating pre- and post-menopausal milieu and how they may impact intratumoral oestrogen levels and breast cancer (BC) metastasis. It also identifies critical steps in BC metastasis to bone from the viewpoint of pigment epithelium-derived factor (PEDF) function, and discusses the role of several associated pro-metastatic biomarkers in BC bone metastasis. KEY FINDINGS: PEDF is regulated by oestrogen in a number of oestrogen-sensitive tissues. Changes in circulating oestrogen levels associated with menopause may enhance the growth of BC bone metastases, leading to the establishment of a pre-metastatic niche. The establishment of such a pre-metastatic niche is driven by several key mediators, with pro-osteoclastic and pro-metastatic function which are upregulated by BC cells. These mediators appear to be regulated by oestrogen, as well as differentially affected by menopausal status. PEDF interacts with several pro-metastatic, pro-osteoclastic biomarkers, including C-X-C motif chemokine receptor 4 (CXCR4) and nuclear factor kappa B (NFκB) in BC bone metastasis. CONCLUSION: Mediators such as CXCR4 and MT1-MMP underpin the ability of PEDF to function as an antimetastatic in other cancers such as osteosarcoma, highlighting the possibility that this serpin could be used as a therapeutic against BC metastasis in future.

Dual Pigment Epithelium-derived Factor and Hepatocyte Growth Factor Overexpression: A New Therapy for Pulmonary Hypertension.

Pulmonary hypertension (PH) is a disease characterized by advanced pulmonary vasculature remodeling that is thought to be curable only through lung transplantation. The application of angiogenic hepatocyte growth factor (HGF) is reported to be protective in PH through its anti-vascular remodeling effect, but excessive HGF-mediated immature neovascularization is not conducive to the restoration of pulmonary perfusion because of apparent vascular leakage. As a canonical antiangiogenic molecule, pigment epithelium-derived factor (PEDF) inhibits angiogenesis and reduces vascular permeability in a variety of diseases. However, the effect of PEDF on HGF-based PH treatment remains to be determined. In this study, monocrotaline-induced PH rats and endothelial cells isolated from rat and human PH lung tissues were used. We assessed PH progression, right cardiac function, and pulmonary perfusion in HGF- and/or PEDF-treated rats with PH. Additionally, the receptor and mechanism responsible for the role of PEDF in HGF-based PH therapy were investigated. In this study, we found that HGF and PEDF jointly prevent PH development and improve right cardiac function in rats with PH. Moreover, PEDF delivery increases the pulmonary perfusion in PH lungs and inhibits immature angiogenesis and vascular endothelial (VE)-cadherin junction disintegration induced by HGF without affecting the therapeutic inhibition of pulmonary vascular remodeling by HGF. Mechanistically, PEDF targets VE growth factor receptor 2 and suppresses its phosphorylation at Y951 and Y1175 but not Y1214. Finally, VE growth factor receptor 2/VE protein tyrosine phosphatase/VE-cadherin complex formation and Akt and Erk1/2 inactivation were observed in rat and human PH lung endothelial cells. Collectively, our data indicate that PEDF additively enhances the efficacy of HGF against PH, which may provide new insights into treatment strategies for clinical PH.

Circulating AFABP, FGF21, and PEDF Levels as Prognostic Biomarkers of Sight-threatening Diabetic Retinopathy.

CONTEXT: Adipocyte fatty acid-binding protein (AFABP), fibroblast growth factor 21 (FGF21), and pigment epithelium-derived factor (PEDF) are 3 diabetes-related biomarkers whose circulating levels had been shown to associate with nephropathy progression in Chinese patients with type 2 diabetes. OBJECTIVE: Here, we evaluated and compared their prospective associations with the development of sight-threatening DR (STDR), another important diabetic microvascular complication. METHODS: Baseline serum AFABP, PEDF, and FGF21 levels were measured in 4760 Chinese individuals with type 2 diabetes and without STDR at baseline. The associations of these biomarkers with incident STDR were analyzed using Cox regression analysis. RESULTS: Among these 4760 participants (mean diabetes duration of 11 years and ≥ 50% with nonproliferative DR at baseline), 172 participants developed STDR over a median follow-up of 8.8 years. Participants with incident STDR had comparable baseline serum FGF21 levels but significantly higher baseline serum AFABP and PEDF levels (both P < .001) than those without. However, in multivariable Cox regression analysis, only serum AFABP remained independently associated with incident STDR (hazard ratio 1.28; 95% CI, 1.05-1.55; P = .013). The addition of serum AFABP to a clinical model of conventional STDR risk factors including diabetes duration, glycemic control, albuminuria, and baseline DR status significantly improved the c statistics (P < .001), net reclassification index (P = .0027), and integrated discrimination index (P = .033) in predicting incident STDR among participants without DR or with mild DR at baseline. CONCLUSION: Among the 3 diabetes-related biomarkers, serum AFABP level appeared to be a more clinically useful biomarker for predicting incident STDR in type 2 diabetes.

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.

Computational assessment of pigment epithelium-derived factor as an anti-cancer protein during its interaction with the receptors.

Pigment epithelium-derived factor (PEDF) is a member of the serine proteinase inhibitor (serpin) with antiangiogenic, anti-tumorigenic, antioxidant, anti-atherosclerosis, antithrombotic, anti-inflammatory, and neuroprotective properties. The PEDF can bind to low-density lipoprotein receptor-related protein 6 (LRP6), laminin (LR), vascular endothelial growth factor receptor 1 (VEGFR1), vascular endothelial growth factor receptor 2 (VEGFR2), and ATP synthase ß-subunit receptors. In this study, we aimed to investigate the structural basis of the interaction between PEDF and its receptors using bioinformatics approaches to identify the critical amino acids for designing anticancer peptides. The human ATP synthase ß-subunit was predicted by homology modeling. The molecular docking, molecular dynamics (MD) simulation, and Molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) were used to study this protein-receptor complex. The molecular docking showed PEDF could bind to the Laminin and VEGFR2 much stronger than ATP synthase ß-subunit, VEGFR1, and LRP6. The PEDF could effectively interact with various receptors during the simulation. The N-terminal of PEDF has an important role in the interaction with the receptors. The MM/PBSA showed the electrostatic (ΔEElec) and van der Waals interactions (ΔEVdW) contributed positively to the binding process of the complexes. The critical amino acids in the binding interaction of PEDF to its receptors in the MD simulation were determined. The interaction mode of 34-mer PEDF to laminin, VEGFR2, and LRP6 were different from VEGFR1, ATP synthase ß-subunit. The 34-mer PEDF has an important role in the interaction with different receptors and these critical amino acids can be used for designing peptides for future therapeutic aims.Communicated by Ramaswamy H. Sarma.

Progress on the function and mechanism of pigment epithelium derived factor receptors in the occurrence and development of diabetic retinopathy / 中华眼底病杂志

Endogenous pigment epithelium derived factor (PEDF) shows great potential as a drug target for the treatment of diabetes retinopathy (DR) due to its anti-angiogenesis, anti-inflammatory, neuroprotective and neurotrophic effects. PEDF plays a biological role by combining with receptor proteins on cell membrane surface and regulating a variety of signaling pathways. Low density lipoprotein receptor related protein 6 plays a role in inhibiting oxidative stress reaction, inflammatory reaction, and neovascularization of DR. Adipose triglyceride lipase, laminin receptor, plexin domain containing 1 (PLXDC) 1, PLXDC2 and F 1-adenosine triphosphate synthase have the effect of promoting endothelial cell apoptosis, among which PLXDC1 also has neuroprotective effect. By clarifying the receptor that PEDF acts on, exploring the affinity between the receptor and PEDF, the difference in the expression level of each receptor in the process of disease, and the specific function that PEDF plays after binding with specific receptors, we can develop fusion protein drugs for the active domain of high affinity of receptors, have a clearer understanding of the pathogenesis of DR, and take PEDF or PEDF receptor as the target to consolidate the theoretical basis for the development of new therapeutic drugs and strategies for DR.

Potential application value of pigment epithelium-derived factor in sensorineural hearing loss.

The inner ear is a complex and precise auditory perception system responsible for receiving and converting sound signals into neural signals, enabling us to perceive and understand sound. However, the occurrence and development of inner ear diseases and auditory disorders, such as sensorineural hearing loss, remain a global problem. In recent years, there has been increasing research on the treatment of inner ear diseases and auditory regeneration. Among these treatments, pigment epithelium-derived factor (PEDF), as a multifunctional secretory protein, exhibits diverse biological activities and functions through various mechanisms, and has shown potential applications in the inner ear. This minireview comprehensively evaluates the performance of PEDF in sensorineural hearing loss in inner ear and its potential targets and therapeutic prospects.

Pigment epithelium-derived factor is an interleukin-6 antagonist in the RPE: Insight of structure-function relationships.

Retinal and choroidal inflammatory lesions increase the levels of the pro-inflammatory cytokine interleukin-6 (IL-6). Pigment epithelium-derived factor (PEDF) has anti-inflammatory properties, but it is not known if it can prevent the production of IL-6 by the retinal pigment epithelium. To investigate the anti-inflammatory effects of PEDF in the RPE, we used human ARPE-19 cells stimulated with human recombinant tumor necrosis factor-alpha (TNF-α) to induce overexpression of the IL6 gene. We found that the viability of ARPE-19 cells decreased by 22% with TNF-α at 10 ng/ml, being drastically decreased at ≥50 ng/ml. TNF-α at 5-100 ng/ml elevated the production and secretion of IL-6 protein, as measured by ELISA. To challenge the TNF-α-mediated stimulation of IL-6, we used recombinant human PEDF protein. PEDF at 100 nM recovered the TNF-α-mediated loss of cell viability and repressed IL-6 gene expression as determined by RT-PCR. PEDF at 10-100 nM attenuated the IL-6 protein secretion in a dose dependent fashion (IC50 = 65 nM), being abolished with 100 nM PEDF. To map the region that confers the IL-6 blocking effect to the PEDF polypeptide, we used chemically synthesized peptides designed from its biologically active domains, pro-death 34-mer, and pro-survival 44-mer and 17-mer (H105A), to challenge the IL-6 overproduction. The pro-survival peptides recovered the TNF-α-mediated cell viability loss, and inhibited IL-6 secretion, while the 34-mer did not have an effect, suggesting a role for the pro-survival domain in blocking TNF-α-mediated cell death and IL-6 stimulation. Our findings position PEDF as a novel antagonistic agent of IL-6 production in RPE cells, underscoring its use for the management of retinal disease-related inflammation.

NFκB-Mediated Mechanisms Drive PEDF Expression and Function in Pre- and Post-Menopausal Oestrogen Levels in Breast Cancer.

Pigment epithelium-derived factor (PEDF) protein regulates normal bone, with anti-tumour roles in bone and breast cancer (BC). Pre- and post-menopausal oestrogen levels may regulate PEDF expression and function in BC, though the mechanisms behind this remain unknown. In this study, in vitro models simulating pre- and post-menopausal bone microenvironments were used to evaluate if PEDF regulates pro-metastatic biomarker expression and downstream functional effects on BC cells. PEDF treatment reduced phosphorylated-nuclear factor-κB p65 subunit (p-NFκB-p65), tumour necrosis factor-α (TNFα), C-X-C chemokine receptor type-4 (CXCR4), and urokinase plasminogen activator receptor (uPAR) in oestrogen receptor (ER)+/human epidermal growth factor receptor-2 (HER2)- BC cells under post-menopausal oestrogen conditions. In triple negative BC (TNBC) cells, PEDF treatment reduced pNFκB-p65 and uPAR expression under pre-menopausal oestrogen conditions. A potential reciprocal regulatory axis between p-NFκB-65 and PEDF in BC was identified, which was BC subtype-specific and differentially regulated by menopausal oestrogen conditions. The effects of PEDF treatment and NFκB inhibition on BC cell function under menopausal conditions were also compared. PEDF treatment exhibited superior anti-viability effects, while combined PEDF and NFκB-p65 inhibitor treatment was superior in reducing BC cell colony formation in a subtype-specific manner. Lastly, immunohistochemical evaluation of p-NFκB-p65 and PEDF expression in human BC and bone metastases specimens revealed an inverse correlation between nuclear PEDF and NFκB expression in bone metastases. We propose that menopausal status is associated with a PEDF/NFκB reciprocal regulatory axis, which drives PEDF expression and anti-metastatic function in a subtype-specific manner. Altogether, our findings identify pre-menopausal TNBC and post-menopausal ER+/HER2- BC patients as target populations for future PEDF research.