title: Pigment epithelium-derived factor (PEDF) peptide eye drops reduce inflammation, cell death and vascular leakage in diabetic retinopathy in Ins2(Akita) mice.
abstract: Inflammation, neurodegeneration and microvascular irregularities are included in the spectrum of defects associated with diabetic retinopathy. Here, we evaluated intraocular deliverability features of two pigment epithelium-derived factor (PEDF) derivatives given as eye drops and their efficacy in modulating diabetes-induced retinal complications. The antiangiogenic PEDF60-77 (P60) and neuroprotective PEDF78-121 (P78) derivatives were applied to Ins2(Akita) mouse eyes once a week for 15 wks at the onset of hyperglycemia. Peptides, labeled with Alexa Fluor 488, were observed penetrating the cornea by 1-4 h and gained access to the ciliary body, retinal pigment epithelium (RPE)-choroid complex, retina microvasculature and vitreous. Peak vitreous levels were 0.2 μg/mL for P60 and 0.9 μg/mL for P78 after 0.5 and 4 h, respectively. Both peptides reduced vascular leakage by ~60% and increased zona occludens 1 (ZO1) and occludin expression in the microvasculature to nondiabetic levels. P60 induced pERK1/2 and P78 promoted pAKT in Muller glia, two signals that were dampened in diabetic conditions. Pharmacologically inhibiting AKT signaling in the retina blocked effects of the peptides on ZO1 and occludin expression. P78 reduced levels of 9/20 cytokines in diabetic vitreous including interferon (IFN)-γ, interleukin (IL)-6, IL-3 and tumor necrosis factor (TNF)-α. P60 lowered levels of 6/20 cytokines but was less effective than P78. Neuroprotective P78 prevented diabetes-induced microglia activation by ~60%, retinal ganglion cell (RGC) death by ~22% and inner plexiform layer thinning by ~13%. In summary, we provide evidence that PEDF bioactive derivatives gained access to the retina by topical delivery and validated their efficacy in reducing diabetic retinopathy complications. Our findings argue for glia regulation of microvascular leakage and an early root cause for RGC degeneration embedded in microglia activation.
authors.affiliation: Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, United States of America.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Liu
authors.forename: Lan Franco
authors.initials: LF
authors.lastname: Leo
authors.forename: Corban
authors.initials: C
authors.lastname: McGregor
authors.forename: Anzor
authors.initials: A
authors.lastname: Grivitishvili
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Barnstable
authors.forename: Joyce
authors.initials: J
authors.lastname: Tombran-Tink
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000473:pathology*; D004789:Enzyme Activation / Q000187:drug effects; D005136:Eye Proteins / Q000737:chemistry*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000188:drug therapy* / Q000473:pathology; D007328:Insulin / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D008301:Maleimides / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009414:Nerve Growth Factors / Q000737:chemistry*; D009457:Neuroglia / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D009883:Ophthalmic Solutions / Q000494:pharmacology / Q000627:therapeutic use*; D010455:Peptides / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D012171:Retinal Vessels / Q000187:drug effects / Q000473:pathology*; D015843:Serpins / Q000737:chemistry*; D062725:Tight Junction Proteins / Q000378:metabolism; D014018:Tissue Distribution / Q000187:drug effects; D014822:Vitreous Body / Q000187:drug effects / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D005136:Eye Proteins; D007328:Insulin; D008301:Maleimides; D009414:Nerve Growth Factors; D009883:Ophthalmic Solutions; D010455:Peptides; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D015843:Serpins; D062725:Tight Junction Proteins; D000099174:Pigment Epithelium-Derived Factor; C561967:Ins2 protein, mouse