M. Setaccioli

Study of FTMT and ABCA4 genes in a patient affected by age-related macular degeneration: identification and analysis of new mutations

Abstract Background: Age-related macular degeneration (AMD) is a multifactorial disease for which an involvement of alterations in the retinal ABC transporter gene (ABCA4) is still debated. Oxidative stress in retinal pigment epithelial cells has been postulated to contribute to the pathogenesis of the disease. Mitochondrial ferritin (FtMt), an iron-sequestering protein, is expressed in cell types characterized by high metabolic activity and oxygen consumption, including human retina, suggesting a role in protecting mitochondria from iron-dependent oxidative damage. Based on these findings we wanted to investigate whether mutations in this gene could be found in AMD patients. Methods: Mutational scanning of the FTMTgene was performed in a cohort of 50 patients affected by age-related macular degeneration. The ABCA4 gene was also scanned in one patient carrying an FtMt mutation. In silico analyses were carried out on the identified variants. The recombinant form of FtMt variant was expressed in Escherichia coli and biochemically characterized. Results: One patient was found to be heterozygous for two previously unreported genetic changes: a complex FtMt mutation (c.437_450delinsCT: delAGGACATCAAGAAGinsCT) and a missense p.Leu973Phe (c.2919G>T) mutation in exon 20 of ABCA4. Computational analyses predicted a severe structural impairment for FtMt variant and a mild destabilizing effect for ABCA4. E. coli expression of recombinant FtMt variant yielded a highly insoluble protein that could not be renatured under in vitro conditions suitable for wild-type ferritins. Conclusions: Our findings suggest that the FtMt mutation may determine a condition similar to haploinsufficiency resulting in a reduced protection from iron-dependent oxidative stress in mitochondria.

Endothelial Progenitor Cells And Response To Ranibizumab In Age-related Macular Degeneration

Background: Choroidal neovascularization (CNV) is the main cause of vision loss in age-related macular degeneration (AMD). In experimental CNV, endothelial progenitor cells (EPCs) contribute to the formation of new vessels. The aim of this study was to investigate whether the behavior of EPCs in patients with AMD supports a role for EPCs in human CNV. Methods: The number of circulating EPCs that are considered pure endothelial precursors and EPCs with monocytic characteristics, and the plasma levels of regulatory cytokines were evaluated in 23 patients with AMD with active CNV and 20 matched controls. In the patients, this profile was re-evaluated after ranibizumab. Results: When compared with controls, the patients with AMD showed a lower number of both EPC types (P = 0.03) and higher plasma levels (P = 0.03) of stromal cell–derived factor 1. Three monthly injections of ranibizumab returned to control levels the number of circulating EPCs considered pure endothelial precursors and of stromal cell–derived factor 1, but not of monocytic EPCs. Conclusion: The observations indicate responsiveness of circulating EPCs to the CNV process in AMD. They suggest the hypothesis that increased stromal cell–derived factor 1 production at the CNV site (reflected in higher plasma levels) recruits EPCs from the circulation, and that antivascular endothelial growth factor therapy selectively decreases the recruitment of cells to be incorporated into new vessels.

Multimodal imaging and diagnosis of myopic choroidal neovascularization in Caucasians

Purpose To investigate myopic choroidal neovascularization (mCNV) by fluorescein angiography (FA), spectral-domain optical coherence tomography (SD-OCT), near-infrared (NIR) reflectance, and autofluorescence (AF). Methods This retrospective study included 65 eyes of 62 Caucasian patients with a mean age of 66.72 years (95% confidence interval [CI] 63–70 years) and a mean refraction of −9.72 diopters (95% CI −8.74 to −10.70 diopters). Results Most of the mCNV cases were foveal-juxtafoveal (60/65, 92.3%), with thickening of the corresponding retina (62/65, 95.3%) and leakage on FA (44/65, 67.6%). No retinal fluid was detectable in 32 (49.2%) eyes and there was no hemorrhage in 25 (38.4%) eyes. Papillary chorioretinal atrophy was evident in 58 (89.2%), a shadowing effect in 48 (73.8%), and an epiretinal membrane in 38 (58.4%) eyes. If an area of macular chorioretinal atrophy was present, mCNV frequently developed adjacent to it and was hyperfluorescent rather than with leakage (P⩽0.001). In eyes with edema or hemorrhage, hyper-reflective foci were more frequent (P⩽0.005). NIR and AF features were indeterminable in 19 (29.2%) and 27 (41.5%) eyes, respectively. The predominant feature was black or grayish on NIR (34/65, 52.3%) and patchy (hypo- and hyperfluorescence was observed) on AF (25/65, 38.4%). FA and SD-OCT correctly detected mCNV in 49 (75.3%) and 48 (73.8%) eyes, respectively, whereas NIR and AF exhibited limited diagnostic sensitivity. Doubtful diagnosis was associated with hyperfluorescent mCNV (P⩽0.001), absence of retinal fluid and epiretinal membrane (P⩽0.05), and presence of macular chorioretinal atrophy (P⩽0.01). Conclusion Tomographic, angiographic, AF, and NIR features of mCNV are described in this study. Combination of SD-OCT and FA is recommendable for diagnosis.