Abnormal pigment epithelium-derived factor processing in progressive myopia

High Myopia and the Complement System: Factor H in Myopic Maculopathy

High myopia (HM) is both a medical problem and refractive error of the eye owing to excessive eyeball length, which progressively makes eye tissue atrophic, and is one of the main causes for diminishing visual acuity in developed countries. Despite its high prevalence and many genetic and proteomic studies, no molecular pattern exists that explain the degenerative process underlying HM, which predisposes patients to other diseases like glaucoma, cataracts, retinal detachment and chorioretinal atrophy that affect the macular area. To determine the relation between complement Factors H (CFH) and D (CFD) and the maculopathy of patients with degenerative myopia, we studied aqueous humor samples that were collected by aspiration from 122 patients during cataract surgery. Eyes were classified according to eyeball axial length as high myopia (axial length > 26 mm), low myopia (axial length 23.5–25.9 mm) and control (axial length ˂ 23.4 mm). The degree of maculopathy was classified according to fundus oculi findings following IMI’s classification. Subfoveal choroid thickness was measured by optical coherence tomography. CFH and CFD measurements were taken by ELISA. CFH levels were significantly high in the high myopia group vs. the low myopia and control groups (p ˂ 0.05). Significantly high CFH values were found in those eyes with choroid atrophy and neovascularization (p ˂ 0.05). In parallel, the CFH concentration correlated inversely with choroid thickness (R = −0.624). CFD levels did not correlate with maculopathy. All the obtained data seem to suggest that CFH plays a key role in myopic pathology.

Protein spectrum changes in exosomes after therapeutic plasma exchange in patients with neuromyelitis optica

INTRODUCTION

Neuromyelitis optica (NMO) is an autoimmune disease with a high rate of blindness and positive for the detection of aquaporin-4 antibody (AQP4) in most patients. NMO acute attacks are managed by high-doses of intravenous methylprednisolone followed by oral taper, and if symptoms fail to resolve, therapeutic plasma exchange (TPE) is added. TPE can remove pathological antibodies and inflammatory factors leading to clinical improvement.

METHODS

A total of 40 TPE fluid collections from the first to fifth TPE treatments were obtained from eight patients. Exosomes were isolated by ultracentrifugation. Mass spectrometry analyses were used to compare protein change in TPE fluid collection exosomes after the first to the fifth TPE treatments in these patients.

RESULTS

We detected 647 exosome proteins through data-independent acquisition analysis. It was found that some unknown functional antibody fragments and complement pathway proteins decreased after TPE treatment. The results revealed a significant involvement of the following two key pathways: the primary immunodeficiency and systemic lupus erythematosus that may be associated with NMO pathophysiology and TPE treatment efficacy (P < .05). A series of complement proteins may contribute to NMO; in addition, the following proteins increased with plasma exchange: complement factor H-related protein 5, bridging integrator 2, neuroplastin, pigment epithelium-derived factor, ficolin-1, extracellular matrix protein 1, and fatty acid-binding protein 5.

CONCLUSION

Our study may provide a new perspective on the pathogenesis and treatment efficacy of NMO.

Pigment Epithelium-Derived Factor as a Possible Treatment Agent for Choroidal Neovascularization

Choroidal neovascularization (CNV) is a sight-threatening disease and is characterized by the formation of pathological neovascularization in the choroid which extends into the subretinal space. Exudative age-related macular degeneration (AMD) is the formation of CNV in the macular area which leads to irreversible blindness. Continuous leakage and hemorrhage of the CNV lesion may eventually result in scarring or later fibrosis, which could result in photoreceptor cell atrophy. The current strategy for treating CNV is the use of antivascular endothelial growth factor (VEGF) agents. Many studies have demonstrated the efficacy of intravitreal anti-VEGF therapy. Other studies have also reported the side effects of single anti-VEGF treatment. And long-term inhibition of a single system may result in collateral damage to other visual elements. Pigment epithelium-derived factor (PEDF) is a 50 kDa protein that was first isolated from the conditioned medium of human RPE cells. PEDF has both antiangiogenesis and neuroprotective functions for photoreceptor cells. It may be a potential ocular antiangiogenic agent. This review outlines the distribution of PEDF in the eye, the mechanism of antiangiogenesis, the protective effect on the retina, and the relationship between PEDF and VEGF.

Correlation of axial length and myopic macular degeneration to levels of molecular factors in the aqueous

To elucidate the molecular processes associated with the development of myopic macular degeneration (MMD), we measured the intraocular concentrations of molecular factors in emmetropic and myopic eyes. This is a retrospective clinic-based case-control study that included eyes undergoing routine cataract surgery whereby aqueous humour samples were obtained. We measured the concentrations of pigment epithelium derived factor(PEDF), matrix metalloproteinase 2(MMP-2), tissue inhibitor of metalloproteinase(TIMP-2), vascular endothelial growth factor isoform A(VEGF-A), interleukin 8(IL-8), interleukin 6(IL-6), C-reactive protein(CRP), angiopoietin 2(Ang2), and amphiregulin. 38 eyes (axial length (AL): 22.4–32.4 mm), including 12 highly myopic (HM) eyes (AL ≥ 26.5 mm) without MMD and 12 HM eyes with MMD but without neovascularization were included. Eyes with MMD were found to have significantly lower VEGF-A levels (p = 0.007) and higher MMP-2 levels (p = 0.02) than control eyes after adjusting for age and gender. MMP-2 levels correlated positively (r = 0.58, p = 0.002), while VEGF-A levels correlated negatively with longer axial length (r = −0.75, p < 0.001). Both the concentrations of VEGF-A (P = 0.25) and MMP-2 (P = 0.69) were not significantly associated with MMD after adjusting for AL. These findings suggest that the predominant mechanism underlying the development of non-neovascular MMD may be axial elongation, driven in part by MMP-2 related mechanisms.