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Christine A Curcio

Publications and source records attributed to Christine A Curcio.

15 recordsLinked to original sources
PubMed2006

Distribution of complement anaphylatoxin receptors and membrane-bound regulators in normal human retina.

To characterize the distribution of membrane-bound components of the complement system in normal human retina, eyes from eight human donors with no history of ocular disease, ranging in age from 47 to 85 years were examined using immunohistochemistry to localize the C3a receptor (C3aR), C5a receptor (C5aR), CD46, CD55, and CD59 in cryosections prepared from donor posterior segments. The C3aR was identified in the nerve fiber layer in a sawtooth-patterned band. Vimentin, used as a Müller cell marker, produced a similar staining pattern. The C5aR was detected on specific rounded structures in the inner plexiform layer and occasionally in the nerve fiber layer. CD46 produced markedly specific staining of the basolateral surface of the retinal pigment epithelium. CD55 was localized to the nerve fiber layer. Staining for these proteins was consistent across all eyes studied. CD59 was expressed throughout the nerve fiber layer and labeled vessels that extended through the ganglion cell, inner plexiform, and inner nuclear layers, but this pattern was only confirmable in a single subject. Complement anaphylatoxin receptors and regulatory proteins are localized in different but internally consistent patterns in normal adult human retina, independent of the age of the donor. C3aR and C5aR localization only in the inner retina contrasts with previously reported findings in the central nervous system of wide spread diffuse staining. The complement regulators CD55 and CD59 were found primarily on the inner retina, while CD46 was present exclusively in a polarized fashion on the RPE.

Aged↗
PubMed2006

The iron carrier transferrin is upregulated in retinas from patients with age-related macular degeneration.

PURPOSE: Iron can cause oxidative stress, and elevated iron levels have been associated with several neurodegenerative diseases including age-related macular degeneration (AMD). Transferrin, an iron transport protein, is expressed at high levels in the retina. The purpose of this study was to assess transferrin involvement in AMD by determining the expression profile of transferrin in retinas with AMD compared with retinas without evidence of disease. METHODS: Postmortem retinas were obtained from AMD and non-AMD eyes. Expression of transferrin was assessed in a microarray dataset from 33 retinas of unaffected donors and 12 retinas of patients with AMD (six with neovascular AMD and six with non-neovascular AMD). Quantitative real-time RT-PCR (QPCR) was used to confirm the microarray results. Transferrin protein expression was assessed by semiquantitative Western blot analysis and immunohistochemistry. RESULTS: In comparison to unaffected retinas, mean transferrin mRNA levels, as measured by microarray analysis were elevated 3.5- and 2.1-fold in non-neovascular and neovascular AMD retinas, respectively. Semiquantitative Western blot analysis demonstrated a 2.1-fold increase in transferrin protein in AMD eyes. Immunohistochemistry showed more intense and widespread transferrin label in AMD maculas, particularly in large drusen, Müller cells, and photoreceptors. CONCLUSIONS: These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.

Adult↗
PubMed2006

Apolipoprotein localization in isolated drusen and retinal apolipoprotein gene expression.

PURPOSE: To evaluate apolipoprotein (Apo) gene expression in native human retinal pigment epithelium (RPE) and neurosensory retina and to detect apolipoproteins within age-related, extramacular drusen. METHOD: Drusen were isolated manually from 10 eyes of 10 donors (age range, 58-93 years) with grossly normal maculas that were preserved in 4% paraformaldehyde within 6 hours of death. In cryosections of druse-enriched pellets (6-57 drusen per eye), the Apos A-I, A-II, B, C-I, C-II, C-III, E, and J were detected by indirect immunofluorescence. Two graders assessed the prevalence and pattern of immunoreactivity. mRNA transcripts were detected by reverse-transcription polymerase chain reaction (RT-PCR), with human hepatoma HepG2 cells as the positive control. RESULTS: Extramacular drusen were classified in two groups on gross appearance: transparent with a reflective shell and cloudy. The proportion of the latter increased significantly with age. All Apos examined were detectable, in descending order of prevalence: ApoE (99.5%), J (99.5%), C-I (93.1%), B (80.4%), A-I (61.0%), A-II (59.2%), C-II (57.7%), and C-III (16.6%). Immunoreactivity was either diffusely distributed throughout the drusen (56.7%), confined to the druse rim (16.0%), or both (21.2%). Six percent displayed evidence of organized substructure reminiscent of active remodeling. The proportion of diffusely labeled drusen decreased significantly with age for ApoE (P=0.034) and ApoE/C-I combined (P=0.027). RT-PCR products for Apos C-I, C-II, E, and J were found in retina and RPE; for ApoA-II in the retina only. The ApoC-III message was undetectable. CONCLUSIONS: To an emerging model of an RPE-secreted large lipoprotein particle implied by previous work, this study adds ApoC-I and ApoC-II, major modulators of lipoprotein lipase activity, and confirms previously demonstrated Apos A-I, B-100, and E. It is possible that a neutral lipid-rich druse shell containing Apos will be visible in the living fundus.

Aged↗
PubMed2005

Imaging maculopathy in post-mortem human eyes.

Age-related maculopathy (ARM) remains a poorly understood degeneration. To discover new pathways using contemporary genomics, proteomics, and immunohistochemistry, validate emerging animal models, and validate new imaging modalities, human tissues obtained from donor eyes will be essential to ARM research for the foreseeable future. Because fundus appearance is the clinical diagnostic lingua franca, laboratory investigators adapted these standards to the distinctive appearance of post-mortem tissues in order to identify and stage ARM in donor eyes. Post-mortem tissues offer unique advantages and limitations relative to pre-mortem tissues for imaging studies. One fellow eye can be used for imaging and the other for correlative laboratory studies, if some degree of disease stage asymmetry between eyes is acceptable. Histological verification is a necessary, albeit challenging, step in validating a grading system.

Animals↗
PubMed2005

Esterified and unesterified cholesterol in drusen and basal deposits of eyes with age-related maculopathy.

To address the potential for an outer segment (OS) contribution to the sub-retinal pigment epithelium (RPE) lesions of age-related maculopathy (ARM), we quantified esterified and unesterified cholesterol (EC, UC) with the sterol-specific fluorescent probe filipin in cryosections of ARM eyes. Twenty six eyes from 20 donors were preserved <5 hr after death in 4% paraformaldehyde (n = 16) or 2.5% glutaraldehyde/1% paraformaldehyde (n = 10). Eyes had exudative late ARM (n = 6), geographic atrophy (n = 15), and drusen > or =125 microm (n = 11). Sections were stained with filipin for UC or were extracted and hydrolysed with cholesterol esterase before filipin staining for EC. Drusen varied in cholesterol content, with a rough correlation between EC and UC. Dome-shaped drusen contained distinctive, loosely packed UC-rich loops. In basal deposits, EC and UC were more prominent near Bruch's membrane than near the RPE. A UC-rich material was localized within the subretinal space (n = 4). Maximum filipin fluorescence due to UC was quantified in 47 lesions (19 drusen, 24 basal deposits, and 4 sub-retinal) from 12 ARM eyes and compared to OS and inner plexiform layer (IPL) of uninvolved retina in the same sections. Relative to IPL, UC fluorescence was higher in lesions (mean+/-s.d: 1.63+/-0.69) and lower in OS (0.64+/-0.18). If only the packing of membranes explained fluorescence intensity, then one would expect much higher intensities in membrane-rich OS than in lesions. Because the converse is true, the membranous material in lesions must be more highly enriched in cholesterol on a per unit area basis. UC in sub-RPE deposits cannot be derived directly from OS without considerable intracellular processing within RPE, additional cholesterol sources, or both.

Aged↗
PubMed2005

Retina expresses microsomal triglyceride transfer protein: implications for age-related maculopathy.

The principal extracellular lesions of age-related maculopathy (ARM), the leading cause of vision loss in the elderly, involve Bruch's membrane (BrM), a thin vascular intima between the retinal pigment epithelium (RPE) and its blood supply. With age, 80-100 nm solid particles containing esterified cholesterol (EC) accumulate in normal BrM, and apolipoprotein B (apoB) immunoreactivity is detectable in BrM- and ARM-associated lesions. Yet little evidence indicates that increased plasma cholesterol is a risk factor for ARM. To determine if RPE is capable of assembling its own apoB-containing lipoprotein, we examined RPE for the expression of microsomal triglyceride transfer protein (MTP), which is required for this process. Consistent with previous evidence for apoB expression, MTP is expressed in RPE, the ARPE-19 cell line, and, unexpectedly, retinal ganglion cells, which are neurons of the central nervous system. De novo synthesis and secretion of neutral lipid by ARPE-19 was supported by high levels of radiolabeled EC and triglyceride in medium after supplementation with oleate. Lipoprotein assembly and secretion is implicated as a constitutive retinal function and a plausible candidate mechanism involved in forming extracellular cholesterol-containing lesions in ARM. The pigmentary retinopathy and neuropathy of abetalipoproteinemia (Mendelian Inheritance of Man 200100; Bassen-Kornzwieg disease), which is caused by mutations in the MTP gene, may involve loss of function at the retina.

Adult↗
PubMed2005

Phosphatidylcholine-rich acceptors, but not native HDL or its apolipoproteins, mobilize cholesterol from cholesterol-rich insoluble components of human atherosclerotic plaques.

To examine the potential of high density lipoproteins (HDL) to ameliorate atherosclerotic plaques in vivo, we examined the ability of native HDL, lipid-free HDL apolipoproteins (apo HDL), cholesterol-free discoidal reconstituted HDL (R-HDL) comprised of apo HDL and phosphatidylcholine (PC) and PC liposomes to release cholesterol from cholesterol-rich insoluble components of plaques (ICP) isolated from atherosclerotic human aorta. Isolated ICP had a free cholesterol (FC) to phospholipid (PL) mass ratio (0.8-3.1) and a sphingomyelin (SPM) to PC mass ratio (1.2-4.2) that exceeded those of plasma membranes of cultured cells. Surprisingly, native HDL and its apolipoproteins were not able to release cholesterol from ICP. However, R-HDL and PC liposomes were effectively released cholesterol from ICP. The release of ICP cholesterol by R-HDL was dose-dependent and accompanied by the transfer of > 8 x more PC in the reverse direction (i.e., from R-HDL to ICP), resulting in a marked enrichment of ICP with PC. Compared to R-HDL, PC liposomes were significantly less effective in releasing cholesterol from ICP but were somewhat more effective in enriching ICP with PC. Native HDL was minimally effective in enriching ICP with PC, but became effective after prior in vitro enrichment of HDL with PC from multilamellar PC liposomes. The enrichment of ICP with PC resulted in the dissolution of cholesterol crystals on ICP and allowed the removal of ICP cholesterol by apo HDL and plasma. Our study revealed that the removal of cholesterol from ICP in vivo will be possible through a change in the level, composition, and physical state of ICP lipids mediated by PC-enriched HDL.

Aorta↗
PubMed2005

Basal deposits and drusen in eyes with age-related maculopathy: evidence for solid lipid particles.

Neutral lipid, including esterified cholesterol, and apolipoproteins B and E are abundant in basal deposits and drusen of aged and age-related maculopathy (ARM) eyes. The principal component of basal linear deposit (BlinD), a specific ARM lesion, is membranous debris, which if actually derived from membranes cannot account for extracellular neutral lipid. We therefore used a lipid-preserving ultrastructural method to obtain improved images of membranous debris. Maculas from 44 human donors (71-96 yr) were preserved <7.5 hr after death. Blocks were post-fixed in 2% osmium or osmium-tannic acid-paraphenylenediamine (OTAP) to preserve neutral lipid for thin-section transmission electron microscopic (TEM) examination. Solid particles identified by OTAP were considered closest to the in vivo state of extracellular lipids. Micrographs were examined for intermediate forms, with greatest weight given to comparable images from different preparations of same or fellow eyes. Twenty eyes of older adults (12 with ARM including fellows treated with photodynamic and radiation therapies) had adequately preserved extracellular lipid. The exterior surface of membranous debris was thicker and more electron-dense than basal infoldings of retinal pigment epithelium (RPE) cells. By OTAP, individual membranous debris profiles were solid (diameters, 80-200 nm) and formed tracks across or aggregations within basal laminar deposits. Solid particles and/or pools of neutral lipid were visible in BlinD and drusen. When processed to preserve lipid, membranous debris resembles neither membranes of surrounding cells nor vesicles possessing aqueous interiors but rather solid particles. These results are consistent with recent evidence implicating lipoprotein particles of intra-ocular origin as a potential source of neutral lipids, including esterified cholesterol, in the specific lesions of ARM.

Aged↗
PubMed2005

Lipoprotein-like particles and cholesteryl esters in human Bruch's membrane: initial characterization.

PURPOSE: To isolate and characterize cholesteryl ester-containing, lipoprotein-like particles (LLPs) from normal aged human Bruch's membrane (BrM)/choroid (Ch). METHODS: From BrM/Ch of 20 eyes of 10 donors aged >60 years, LLPs were released by high-salt buffer, fractionated by density gradient ultracentrifugation, and characterized by determining cholesterol, triglyceride, and phospholipid concentration (by enzymatic colorimetry and fluorometry); cholesteryl ester composition (by electrospray ionization mass spectrometry, ESI/MS); and particle morphology (by negative stain electron microscopy). Apolipoprotein (apo) gene expression was determined with RT-PCR, Western blot analysis, and immunofluorescence of retinal-choroidal cryosections. In paraformaldehyde-preserved eyes (20 eyes of 20 donors), cholesteryl ester composition of BrM/Ch, cornea, and sclera was determined by ESI/MS. RESULTS: A pooled fraction of LLP released from BrM/Ch (concentrated total LLP, density [d] < 1.24 g/mL fraction) was fractionated into two peaks. A large Peak 1 (with plasma LDL-HDL density range), containing predominantly phospholipid and unesterified cholesterol, was morphologically heterogeneous. A small Peak 2 (with plasma VLDL density range), enriched with esterified cholesterol, contained approximately 100 nm diameter round electron-lucent particles. Both peaks contained apoB and apoA-I, RPE and retina contained apoA-I mRNA transcripts, and BrM and drusen contained apoA-I immunoreactivity. Peaks 1 and 2, native RPE, and fresh BrM/Ch were cholesteryl linoleate enriched and contained little cholesteryl docosahexaenoate. Preserved BrM/Ch was cholesteryl oleate-enriched, unlike sclera and cornea. CONCLUSIONS: BrM/Ch LLP do not resemble plasma lipoproteins in density profile, cholesterol distribution, or morphology. Peak 2 contains EC-rich LLP resembling BrM particles in situ. BrM/Ch cholesteryl esters respond to long-term storage differently than esters of plasma lipoprotein origin accumulated in other ocular tissues. Evidence of intraocular apoB and apoA-I expression supports an emerging hypothesis that the RPE assembles and secretes a large, possibly novel, lipoprotein particle.

Apolipoprotein A-I↗
PubMed2003

Apolipoprotein B in cholesterol-containing drusen and basal deposits of human eyes with age-related maculopathy.

Lipids accumulate in Bruch's membrane (BrM), a specialized vascular intima of the eye, and in extracellular lesions associated with aging and age-related maculopathy (ARM). We tested the hypothesis that ARM and atherosclerotic cardiovascular disease share molecules and mechanisms pertaining to extracellular lipid accumulation by localizing cholesterol and apolipoprotein B (apo B) in BrM, basal deposits, and drusen. Human donor eyes were preserved <4 hours postmortem and cryosectioned. Sections were stained with traditional lipid stains and filipin for esterified and unesterified cholesterol or probed with antibodies to apo B, apo E, and apo C-III. Normal adult retinal pigment epithelium (RPE) was subjected to RT-PCR and Western blot analysis for apolipoprotein mRNA and protein. Esterified and unesterified cholesterol was present in all drusen and basal deposits of ARM and normal eyes. Both apo B and apo E but not apo C-III were found in BrM, drusen, and basal deposits. Fewer macular drusen were stained by traditional lipid stains and apolipoprotein antibodies than peripheral drusen. RPE contained apo B and apo E mRNA and protein. Finding cholesterol and apo B in sub-RPE deposits links ARM with important molecules and mechanisms in atherosclerosis initiation and progression. The combination of apo B mRNA and protein in RPE raises the possibility that intraocular assembly of apo B-containing lipoproteins is a pathway involved in forming cholesterol-enriched lesions in ARM.

Adult↗
PubMed2003

Quick-freeze/deep-etch visualization of age-related lipid accumulation in Bruch's membrane.

PURPOSE: To examine age-related changes in the ultrastructure of Bruch's membrane with quick-freeze/deep-etch (QFDE) and conventional thin-section transmission electron microscopy (TEM). METHODS: Four eyes from human donors aged 27, 41, 76, and 78 years were preserved within 4 hours of death. Full-thickness tissue blocks from the macula were prepared for TEM or for QFDE. RESULTS: Ultrastructure seen by conventional TEM was revealed in greater detail by QFDE. Cholesterol-containing particles (mean diameter, 80 nm) formed a thin densely packed layer external to the basal lamina of the retinal pigment epithelium (RPE) only in older eyes. The mesh size of the RPE basal lamina was smaller than the particles, and it appeared larger in older eyes. QFDE also revealed less decorated collagen fibrils in older eyes. CONCLUSIONS: The data suggest that the predilection of a extremely thin sublayer of inner Bruch's membrane for accumulating lipid particles may eventually lead to a confluent lipid wall capable of isolating the retina from its blood supply. If these lipids originate in the retinal pigment epithelium, then they are unlikely to have passed through the basal lamina in this form. The age-related increase in lipid particles corresponds with an age-related increase in hydraulic resistance determined in excised Bruch's membrane/choroid by others. QFDE will be useful for future modeling studies of Bruch's membrane transport and to identify those moieties responsible for deleterious age-related transport changes in Bruch's membrane.

Adult↗
PubMed2002

Photoreceptor degeneration and dysfunction in aging and age-related maculopathy.

The relative rate of rod and cone degeneration is a fundamental characteristic of any disorder affecting photoreceptors, including aging and age-related maculopathy (ARM). The human macula consists of a small cone-dominated fovea surrounded by a rod-dominated parafovea. In aging and early ARM, rods degenerate before cones, a decline in scotopic (rod-mediated) sensitivity is more prominent than a decline in photopic (cone-mediated) sensitivity, and the time course of dark adaptation of rods slows dramatically. The topography of rod dysfunction and loss in early ARM matches the location of pathology in the retinal pigment epithelium (RPE)/Bruch's membrane complex visible in the ocular fundus. Rod dysfunction and loss in aging and ARM may be due to retinoid deficiency at the level of the photoreceptors cause by impaired retinoid translocation across the RPE/Bruch's membrane complex, a hypothesis deserving of further investigation.

Aging↗
PubMed2002

Phenotypic variation of retinal pigment epithelium in age-related macular degeneration.

PURPOSE: To determine whether retinal pigment epithelium (RPE) in eyes with age-related macular degeneration (ARMD) express vimentin and alpha smooth muscle actin (alphaSMA), two cytoskeletal proteins associated with phenotypic variation in culture. METHODS: Six eyes with late ARMD and three age-matched control eyes were preserved in buffered 4% paraformaldehyde and cryosectioned at 10 microm. Stages of RPE morphology and pigmentation were assessed by the Alabama Age-Related Macular Degeneration Grading System. Vimentin, alphaSMA, and glial fibrillary acidic protein (GFAP) expression was detected by indirect immunofluorescence. These results were compared with regional variations in disease severity. RESULTS: RPE changes in ARMD included acquired expression of vimentin, but alphaSMA-positive cells were rare. GFAP expression increased in Müller cells in the neural retina in association with RPE changes and photoreceptor degeneration. CONCLUSIONS: The initial stages of RPE changes in eyes with ARMD mimic those reported for cultured RPE cells. The absence of alphaSMA-positive cells in regions of RPE atrophy suggests that RPE are lost rather than persist in a dedifferentiated state.

Actins↗
PubMedDate not supplied

Drusen and lipid-filled retinal pigment epithelium cells in a rhesus macula.

A middle-aged rhesus monkey with detailed clinical history exhibited progression of a macular abnormality with a variety of clinical drusen and pigment changes typical of the Cayo Santiago phenotype. Numerous frozen sections of one sample of the macular retina/retinal pigment epithelium (RPE)/choroid showed a single classical druse but extensive single and clustered lipid-filled RPE cells. The monkey exhibited functional outer retinal decline and an insignificant number of 'window defects' as found among signs of relatively benign human macular aging. The clinical and histologically defined results agree if lipid-filled RPE cells are included among the clinically apparent signs of drusen.

Animals↗