A review on PLGA particles as a sustained drug-delivery system and its effect on the retina.

In this review, the designs and recent developments of polymer-based drug delivery of Poly(lactic-co-glycolic acid) (PLGA) will be discussed for the possible treatment of age-related macular degeneration (AMD). PLGA is a versatile co-polymer that consists of synthetic lactic acid and glycolic acid monomers that are constructed to produce nanoparticles, microparticles, and scaffolds for the intraocular delivery of various drugs. As an FDA-approved polymer, PLGA has historically been well-suited for systemic slow-sustained release therapies due to its performance in biodegradability and biocompatibility. This review will examine recent in vitro and in vivo studies that provide evidence for PLGA-based particles as a therapeutic drug carrier for the treatment of AMD. Anti-angiogenic and antiproliferative effects of small peptides, small molecules, RNA molecules, and proteins within PLGA particles are briefly discussed. AMD is a leading cause of central vision loss in people over 55 years and the number of those afflicted will rise as the aging population increases. AMD has two forms that are often sequential. Dry AMD and wet AMD account for 85-90% and 10-15% of cases, respectively. The distinct categories of PLGA-based drug delivery vehicles are important for dispensing novel small molecules, RNA molecules, peptides, and proteins as a long-term effective treatment of AMD.

Using Human 'Personalized' Cybrids to Identify Drugs/Agents That Can Regulate Chronic Lymphoblastic Leukemia Mitochondrial Dysfunction.

This study uses personalized chronic lymphoblastic leukemia (CLL) cybrid cells to test various drugs/agents designed to improve mitochondrial function and cell longevity. Age-matched control (NL) and CLL cybrids were created. The NL and CLL cybrids were treated with ibrutinib (Ibr-10 µM), mitochondrial-targeted nutraceuticals such as alpha lipoic acid (ALA-1 mM), amla (Aml-300 µg), melatonin (Mel-1 mM), resveratrol (Res-100 µM) alone, or a combination of ibrutinib with nutraceuticals (Ibr + ALA, Ibr + Aml, Ibr + Mel, or Ibr + Res) for 48 h. MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazoliumbromide), H2DCFDA(2',7' Dichlorodihydrofluorescein diacetate), and JC1 assays were used to measure the cellular metabolism, intracellular ROS levels, and mitochondrial membrane potential (∆ψm), respectively. The expression levels of genes associated with antioxidant enzymes (SOD2, GPX3, and NOX4), apoptosis (BAX and CASP3), and inflammation (IL6, IL-1ß, TNFα, and TGFß) were measured using quantitative real-time PCR (qRT-PCR). CLL cybrids treated with Ibr + ALA, Ibr + Aml, Ibr + Mel, and Ibr + Res had (a) reduced cell survivability, (b) increased ROS production, (c) increased ∆ψm levels, (d) decreased antioxidant gene expression levels, and (e) increased apoptotic and inflammatory genes in CLL cybrids when compared with ibrutinib-alone-treated CLL cybrids. Our findings show that the addition of nutraceuticals makes the CLL cybrids more pro-apoptotic with decreased cell survival compared with CLL cybrids exposed to ibrutinib alone.

Effects of fluoroquinolones and tetracyclines on mitochondria of human retinal MIO-M1 cells.

Our goal was to explore the detrimental impacts of ciprofloxacin (CPFX) and tetracycline (TETRA) on human retinal Müller (MIO-M1) cells in vitro. Cells were exposed to 30, 60 and 120 µg/ml of CPFX and TETRA. The cellular metabolism was measured with the MTT assay. The JC-1 and CM-H2DCFDA assays were used to evaluate the levels of mitochondrial membrane potential (MMP) and ROS (reactive oxygen species), respectively. Mitochondrial DNA (mtDNA) copy number, along with gene expression levels associated with apoptotic (BAX, BCL2-L13, BCL2, CASP-3 and CASP-9), inflammatory (IL-6, IL-1ß, TGF-α, TGF-ß1 and TGF-ß2) and antioxidant pathways (SOD2, SOD3, GPX3 and NOX4) were analyzed via Quantitative Real-Time PCR (qRT-PCR). Bioenergetic profiles were measured using the Seahorse® XF Flux Analyzer. Cells exposed 24 h to 120 µg/ml TETRA demonstrated higher cellular metabolism compared to vehicle-treated cells. At each time points, (i) all TETRA concentrations reduced MMP levels and (ii) ROS levels were reduced by TETRA 120 µg/ml treatment. TETRA caused (i) higher expression of CASP-3, CASP-9, TGF-α, IL-1B, GPX3 and SOD3 but (ii) decreased levels of TGF-B2 and SOD2. ATP production and spare respiratory capacity declined with TETRA treatment. Cellular metabolism was reduced with CPFX 120 µg/ml in all cultures and 60 µg/ml after 72 h. The CPFX 120 µg/ml reduced MMP in all cultures and ROS levels (72 h). CPFX treatment (i) increased expression of CASP-3, CASP-9, and BCL2-L13, (ii) elevated the basal oxygen consumption rate, and (iii) lowered the mtDNA copy numbers and expression levels of TGF-B2, IL-6 and IL-1B compared to vehicle-control cells. We conclude that clinically relevant dosages of bactericidal and bacteriostatic antibiotics can have negative effects on the cellular metabolism and mitochondrial membrane potential of the retinal MIO-M1 cells in vitro. It is noteworthy to mention that apoptotic and inflammatory pathways in exposed cells were affected significantly This is the first study showing the negative impact of fluoroquinolones and tetracyclines on mitochondrial behavior of human retinal MIO-M1 cells.

Differential mitochondrial and cellular responses between H vs. J mtDNA haplogroup-containing human RPE transmitochondrial cybrid cells.

Mitochondrial dysfunction is associated with several retinal degenerative diseases including Age-related Macular Degeneration (AMD). Human mitochondrial DNA (mtDNA) haplogroups are inherited from a common ancestral clan and are defined by specific sets of genetic differences. The purpose of this study was to determine and compare the effects of mtDNA haplogroups H and J on transcriptome regulation and cellular resilience to oxidative stress in human RPE cytoplasmic hybrid (cybrid) cell lines in vitro. ARPE-19 cybrid cell lines containing mtDNA haplogroups H and J were created by fusing platelets obtained from normal individuals containing H and J haplogroups with mitochondria-deficient (Rho0) ARPE-19 cell lines. These cybrids were exposed to oxidative stress using 300 µM hydrogen peroxide (H2O2), following which mitochondrial structural dynamics was studied at varying time points using the mitochondrial markers - TOMM20 (Translocase of Outer Mitochondrial Membrane 20) and Mitotracker. To evaluate mitochondrial function, levels of ROS, ΔΨm and [Ca2+]m were measured using flow cytometry, and ATP levels were measured using luminescence. The H and J cybrid cell transcriptomes were compared using RNAseq to determine how changes in mtDNA regulate gene expression. Inflammatory and angiogenic markers were measured using Luminex assay to understand how these mtDNAs influenced cellular response to oxidative stress. Actin filaments' morphology was examined using confocal microscopy. Following exposure to H2O2 stress, the J cybrids showed increased mitochondrial swelling and perinuclear localization, disturbed fission and fusion, increased calcium uptake (p < 0.05), and higher secreted levels of TNF-α and VEGF (p < 0.001), compared to the H cybrids. Calcium uptake by J cybrids was reduced using an IP3R inhibitor. Thirteen genes involved in mitochondrial complex I and V function, fusion/fission events, cellular energy homeostasis, antioxidant defenses, and inflammatory responses, were significantly downregulated with log2 fold changes ranging between -1.5 and -5.1. Actin levels were also significantly reduced in stressed J cybrids (p ≤ 0.001) and disruption in actin filaments was observed. Thirty-eight genes involved in mitochondrial and cellular support functions, were upregulated with log2 fold changes of +1.5 to +5.9 in J cybrids compared to H cybrids. Our results demonstrate significant structural and functional differences between mtDNA haplogroups H vs. J -containing cybrid cells. Our study suggests that the J mtDNA haplogroup can alter the transcriptome to increase cellular susceptibility to stress and retinal degenerations.

Inside out: Relations between the microbiome, nutrition, and eye health.

Age-related macular degeneration (AMD) is a complex disease with increasing numbers of individuals being afflicted and treatment modalities limited. There are strong interactions between diet, age, the metabolome, and gut microbiota, and all of these have roles in the pathogenesis of AMD. Communication axes exist between the gut microbiota and the eye, therefore, knowing how the microbiota influences the host metabolism during aging could guide a better understanding of AMD pathogenesis. While considerable experimental evidence exists for a diet-gut-eye axis from murine models of human ocular diseases, human diet-microbiome-metabolome studies are needed to elucidate changes in the gut microbiome at the taxonomic and functional levels that are functionally related to ocular pathology. Such studies will reveal new ways to diminish risk for progression of- or incidence of- AMD. Current data suggest that consuming diets rich in dark fish, fruits, vegetables, and low in glycemic index are most retina-healthful during aging.

MOTS-c, the Most Recent Mitochondrial Derived Peptide in Human Aging and Age-Related Diseases.

MOTS-c, a 16 amino acid mitochondrial derived peptide, is encoded from the 12S rRNA region of the mitochondrial genome. Under stress conditions, MOTS-c translocates to the nucleus where it regulates a wide range of genes in response to metabolic dysfunction. It is colocalized to mitochondria in various tissues and is found in plasma, but the levels decline with age. Since MOTS-c has important cellular functions as well as a possible hormonal role, it has been shown to have beneficial effects on age-related diseases including Diabetes, Cardiovascular diseases, Osteoporosis, postmenopausal obesity and Alzheimer. Aging is characterized by gradual loss of (mitochondrial) metabolic balance, decreased muscle homeostasis and eventual diminished physical capability, which potentially can be reversed with MOTS-c treatment. This review examines the latest findings on biological effects of MOTS-c as a nuclear regulatory peptide and focuses on the role of MOTS-c in aging and age-related disorders, including mechanisms of action and therapeutic potential.

Differential effects of risuteganib and bevacizumab on AMD cybrid cells.

PURPOSE: Intravitreal injections of anti-vascular endothelial growth factor (VEGF) treatments are currently used to treat wet age-related macular degeneration (AMD), diabetic retinopathy, and macular edema. Chronic, repetitive treatments with anti-VEGF may have unintended consequences beyond the inhibition of angiogenesis. Most recently, clinical trials have been conducted with risuteganib (RSG, Luminate®), which is anti-angiogenic and has neuroprotective and anti-inflammatory properties. Mitochondrial damage and dysfunction play a major role in development of AMD. Transmitochondrial cybrids are cell lines established by fusing human retinal pigment epithelial (RPE) cells that are Rho0 (lacking mtDNA) with platelets isolated from AMD subjects or age-matched normal subjects. Cybrid cell lines have identical nuclei but mitochondria from different subjects, enabling investigation of the functional consequences of damaged AMD mitochondria. The present study compares the responses of AMD cybrids treated with bevacizumab (Bmab, Avastin®) versus risuteganib (RSG, Luminate®). METHODS: Cybrids were created by fusing mtDNA depleted ARPE-19 cells with platelets from AMD or age-matched normal patients. AMD (n = 5) and normal (n = 3) cybrids were treated for 48 h with or without 1x clinical dose of 1.25 mg/50 µl (25,000 µg/ml) of Bmab or 1.0 mg/50 µl (20,000 µg/ml) of RSG. Cultures were analyzed for levels of cleaved caspase 3/7 and NucLight Rapid Red staining (IncuCyte® Live Cell Imager), mitochondrial membrane potential (ΔΨm, JC1 assay) or reactive oxygen species (ROS, H2DCFDA assay). Expression levels of genes related to the following pathways were analyzed with qRT-PCR: Apoptosis (BAX, BCL2L13, CASP-3, -7, -9); angiogenesis (VEGFA, HIF1α, PDGF); integrins (ITGB-1, -3, -5, ITGA-3, -5, -V); mitochondrial biogenesis (PGC1α, POLG); oxidative stress (SOD2, GPX3, NOX4); inflammation (IL-6, -18, -1ß, IFN-ß1); and signaling (P3KCA, PI3KR1). Statistical analyses were performed using GraphPad Prism software. RESULTS: The untreated AMD cybrids had significantly higher levels of cleaved caspase 3/7 compared to the untreated normal cybrids. The Bmab-treated AMD cybrids showed elevated levels of cleaved caspase 3/7 compared to untreated AMD or RSG-treated AMD cybrids. The Bmab-treated cybrids had lower ΔΨm compared to untreated AMD or RSG-treated AMD cybrids. The ROS levels were not changed with Bmab or RSG treatment. Results showed that Bmab-treated cybrids had higher expression levels of inflammatory (IL-6, IL1-ß), oxidative stress (NOX4) and angiogenesis (VEGFA) genes compared to untreated AMD, while RSG-treated cybrids had lower expression levels of apoptosis (BAX), angiogenesis (VEGFA) and integrin (ITGB1) genes. CONCLUSIONS: These data suggest that the mechanism(s) of action of RSG, an integrin regulator, and Bmab, a recombinant monoclonal antibody, affect the AMD RPE cybrid cells differently, with the former having more anti-apoptosis properties, which may be desirable in treating degenerative ocular diseases.

Mitochondria: The Retina's Achilles' Heel in AMD.

Strong experimental evidence from studies in human donor retinas and animal models supports the idea that the retinal pathology associated with age-related macular degeneration (AMD) involves mitochondrial dysfunction and consequent altered retinal metabolism. This chapter provides a brief overview of mitochondrial structure and function, summarizes evidence for mitochondrial defects in AMD, and highlights the potential ramifications of these defects on retinal health and function. Discussion of mitochondrial haplogroups and their association with AMD brings to light how mitochondrial genetics can influence disease outcome. As one of the most metabolically active tissues in the human body, there is strong evidence that disruption in key metabolic pathways contributes to AMD pathology. The section on retinal metabolism reviews cell-specific metabolic differences and how the metabolic interdependence of each retinal cell type creates a unique ecosystem that is disrupted in the diseased retina. The final discussion includes strategies for therapeutic interventions that target key mitochondrial pathways as a treatment for AMD.

A two-step method for identifying photopigment opsin and rhodopsin gene sequences underlying human color vision phenotypes.

Purpose: To present a detailed, reliable long range-PCR and sequencing (LR-PCR-Seq) procedure to identify human opsin gene sequences for variations in the long wavelength-sensitive (OPN1LW), medium wavelength-sensitive (OPN1MW), short wavelength-sensitive (OPN1SW), and rhodopsin (RHO) genes. Methods: Color vision was assessed for nine subjects using the Farnsworth-Munsell 100 hue test, Ishihara pseudoisochromatic plates, and the Rabin cone-contrast threshold procedure (ColorDX, Konan Medical). The color vision phenotypes were normal trichromacy (n = 3), potential tetrachromacy (n = 3), dichromacy (n = 2), and unexplained low color vision (n = 1). DNA was isolated from blood or saliva and LR-PCR amplified into individual products: OPN1LW (4,045 bp), OPN1MW (4,045 bp), OPN1SW (3,326 bp), and RHO (6,715 bp). Each product was sequenced using specific internal primer sets. Analysis was performed with Mutation Surveyor software. Results: The LR-PCR-Seq technique identified known single nucleotide polymorphisms (SNPs) in OPN1LW and OPN1MW gene codons (180, 230, 233, 277, and 285), as well as those for lesser studied codons (174, 178, 236, 274, 279, 298 and 309) in the OPN1LW and OPN1MW genes. Additionally, six SNP variants in the OPN1MW and OPN1LW genes not previously reported in the NCBI dbSNP database were identified. An unreported poly-T region within intron 5(c.36+126) of the rhodopsin gene was also found, and analysis showed it to be highly conserved in mammalian species. Conclusions: This LR-PCR-Seq procedure (single PCR reaction per gene followed by sequencing) can identify exonic and intronic SNP variants in OPN1LW, OPN1MW, OPN1SW, and rhodopsin genes. There is no need for restriction enzyme digestion or multiple PCR steps that can introduce errors. Future studies will combine the LR-PCR-Seq with perceptual behavior measures, allowing for accurate correlations between opsin genotypes, retinal photopigment phenotypes, and color perception behaviors.

Age-related macular degeneration (AMD) mitochondria modulate epigenetic mechanisms in retinal pigment epithelial cells.

Mitochondrial damage and epigenetic modifications have been implicated in the pathogenesis of Age-related Macular Degeneration (AMD). This study was designed to investigate the effects of AMD/normal mitochondria on epigenetic regulation in human transmitochondrial retinal pigment epithelial (RPE) cells in vitro. Human RPE cybrid cell lines were created by fusing mitochondria-deficient (Rho0) ARPE-19 cells with platelets obtained from either AMD patients (AMD cybrids) or normal subjects (normal cybrids). Therefore, all cybrids had identical nuclei (derived from ARPE-19 cells) but mitochondria derived from either AMD patients or age-matched normal subjects. AMD cybrids demonstrated increased RNA/protein levels for five methylation-related and four acetylation-related genes, along with lower levels of two methylation and three acetylation genes compared to normal cybrids. Demethylation using 5-Aza-2'-deoxycytidine (DAC) led to decreased expression of VEGF-A gene in AMD cells. Trichostatin A (TSA), an HDAC inhibitor, also influenced protein levels of VEGF-A, HIF1α, NFκB, and CFH in AMD cells. Our findings suggest that retrograde signaling leads to mitochondria-nucleus interactions that influence the epigenetic status of the RPE cells and this may help in the identification of future potential therapeutic targets for AMD.

Effects of bevacizumab, ranibizumab, and aflibercept on phagocytic properties in human RPE cybrids with AMD versus normal mitochondria.

PURPOSE: A critical biological function of retina pigment epithelium (RPE) cells is phagocytosis of photoreceptor outer segment (POS) disc membranes. Mitochondrial damage and dysfunction are associated with RPE cells of age-related macular degeneration (AMD) retinas. In this study, we use a transmitochondrial cybrid model to compare the phagocytic properties of RPE cells that contain AMD mitochondria versus age-matched normal mitochondria and their response to treatment with anti-vascular endothelial growth factor (VEGF) drugs: bevacizumab, ranibizumab, and aflibercept. METHODS: Cybrids, which are cell lines with identical nuclei but mitochondria (mt) from different subjects, are created by fusing mtDNA depleted ARPE-19 cells with platelets from AMD or age-matched normal patients. AMD (n = 5) and normal (n = 5) cybrids were treated with 1 µm fluorescent latex beads (1.52 × 107 beads/mL) and either 2.09 µM of bevacizumab, 2.59 µM of ranibizumab, or 5.16 µM of aflibercept. These doses of anti-VEGF drugs are equivalent to intravitreal injections given to AMD patients with choroidal neovascularization. Flow cytometry was performed using the ImageStreamX Mark II to assess phagocytic bead-uptake. The average fold values for bead-uptake and SEM were calculated using GraphPad Prism software. RESULTS: Normal cybrids showed decreased bead-uptake with a fold value of 0.65 ±â€¯0.103 (p = 0.01) after treatment with bevacizumab, 0.80 ±â€¯0.034 (p = 0.0003) with ranibizumab, and 0.81 ±â€¯0.053 (p = 0.007) with aflibercept compared to the untreated normal cybrids (baseline fold of 1). The bevacizumab-treated, ranibizumab-treated, and aflibercept-treated AMD cybrids had decreased bead-uptake with a fold value of 0.71 ±â€¯0.061 (p = 0.001), 0.70 ±â€¯0.101 (p = 0.02), and 0.74 ±â€¯0.125 (p = 0.07), respectively, compared to the untreated AMD cybrids (baseline fold of 1). CONCLUSIONS: Our initial findings showed that when treated with bevacizumab and ranibizumab, both AMD cybrids and age-matched normal cybrids had a significant decrease in bead-uptake. A similar decrease in bead-uptake was found in normal cybrids treated with aflibercept and while the AMD values trended lower, they were not significant. This data suggests that anti-VEGF drugs can cause loss of phagocytic function.

Axial mechanical and structural characterization of keratoconus corneas.

PURPOSE: Previous studies indicate that there is an axial gradient of collagen lamellar branching and anastomosing leading to regional differences in corneal tissue stiffness that may control corneal shape. To further test this hypothesis we have measured the axial material stiffness and quantified the collagen lamellar complexity in ectatic and mechanically weakened keratoconus corneas (KC). METHODS: Acoustic radiation force elastic microscopy (ARFEM) was used to probe the axial mechanical properties of the cone region of three donor KC buttons. 3 Dimensional second harmonic generation microscopy (3D-SHG) was used to qualitatively evaluate lamellar organization in 3 kC buttons and quantitatively measure lamellar branching point density (BPD) in a separate KC button that had been treated with epikeratophakia (Epi-KP). RESULTS: The mean elastic modulus for the KC corneas was 1.67 ±â€¯0.44 kPa anteriorly and 0.970 ±â€¯0.30 kPa posteriorly, substantially below that previously measured for normal human cornea. 3D-SHG of KC buttons showed a simplified collagen lamellar structure lacking noticeable angled lamellae in the region of the cone. BPD in the anterior, posterior, central and paracentral regions of the KC cornea were significantly lower than in the overlying Epi-KP lenticule. Additionally, BPD in the cone region was significantly lower than the adjacent paracentral region in the KC button. CONCLUSIONS: The KC cornea exhibits an axial gradient of mechanical stiffness and a BPD that appears substantially lower in the cone region compared to normal cornea. The findings reinforce the hypothesis that collagen architecture may control corneal mechanical stiffness and hence corneal shape.

Mitochondrial DNA variants can mediate methylation status of inflammation, angiogenesis and signaling genes.

Mitochondrial (mt) DNA can be classified into haplogroups representing different geographic and/or racial origins of populations. The H haplogroup is protective against age-related macular degeneration (AMD), while the J haplogroup is high risk for AMD. In the present study, we performed comparison analyses of human retinal cell cybrids, which possess identical nuclei, but mtDNA from subjects with either the H or J haplogroups, and demonstrate differences in total global methylation, and expression patterns for two genes related to acetylation and five genes related to methylation. Analyses revealed that untreated-H and -J cybrids have different expression levels for nuclear genes (CFH, EFEMP1, VEGFA and NFkB2). However, expression levels for these genes become equivalent after treatment with a methylation inhibitor, 5-aza-2'-deoxycytidine. Moreover, sequencing of the entire mtDNA suggests that differences in epigenetic status found in cybrids are likely due to single nucleotide polymorphisms (SNPs) within the haplogroup profiles rather than rare variants or private SNPs. In conclusion, our findings indicate that mtDNA variants can mediate methylation profiles and transcription for inflammation, angiogenesis and various signaling pathways, which are important in several common diseases.

Increased expression of ApoE and protection from amyloid-beta toxicity in transmitochondrial cybrids with haplogroup K mtDNA.

Mitochondrial (mt) DNA haplogroups, defined by specific single nucleotide polymorphism (SNP) patterns, represent populations of diverse geographic origins and have been associated with increased risk or protection of many diseases. The H haplogroup is the most common European haplogroup while the K haplogroup is highly associated with the Ashkenazi Jewish population. Transmitochondrial cybrids (cell lines with identical nuclei, but mtDNA from either H (n=8) or K (n=8) subjects) were analyzed by the Seahorse flux analyzer, quantitative polymerase chain reaction (Q-PCR) and immunohistochemistry (IHC). Cybrids were treated with amyloid-ß peptides and cell viabilities were measured. Other cybrids were demethylated with 5-aza-2'-deoxycytidine (5-aza-dC) and expression levels for APOE and NFkB2 were measured. Results show K cybrids have (a) significantly lower mtDNA copy numbers, (b) higher expression levels for MT-DNA encoded genes critical for oxidative phosphorylation, (c) lower Spare Respiratory Capacity, (d) increased expression of inhibitors of the complement pathway and important inflammasome-related genes; and (e) significantly higher levels of APOE transcription that were independent of methylation status. After exposure to amyloid-ß1-42 peptides (active form), H haplogroup cybrids demonstrated decreased cell viability compared to those treated with amyloid-ß42-1 (inactive form) (p<0.0001), while this was not observed in the K cybrids (p=0.2). K cybrids had significantly higher total global methylation levels and differences in expression levels for two acetylation genes and four methylation genes. Demethylation with 5-aza-dC altered expression levels for NFkB2, while APOE transcription patterns were unchanged. Our findings support the hypothesis that mtDNA-nuclear retrograde signaling may mediate expression levels of APOE, a key factor in many age-related diseases. Future studies will focus on identification of the mitochondrial-nuclear retrograde signaling mechanism(s) contributing to these mtDNA-mediated differences.

Inherited mitochondrial DNA variants can affect complement, inflammation and apoptosis pathways: insights into mitochondrial-nuclear interactions.

Age-related macular degeneration (AMD) is the leading cause of vision loss in developed countries. While linked to genetic polymorphisms in the complement pathway, there are many individuals with high risk alleles that do not develop AMD, suggesting that other 'modifiers' may be involved. Mitochondrial (mt) haplogroups, defined by accumulations of specific mtDNA single nucleotide polymorphisms (SNPs) which represent population origins, may be one such modifier. J haplogroup has been associated with high risk for AMD while the H haplogroup is protective. It has been difficult to assign biological consequences for haplogroups so we created human ARPE-19 cybrids (cytoplasmic hybrids), which have identical nuclei but mitochondria of either J or H haplogroups, to investigate their effects upon bioenergetics and molecular pathways. J cybrids have altered bioenergetic profiles compared with H cybrids. Q-PCR analyses show significantly lower expression levels for seven respiratory complex genes encoded by mtDNA. J and H cybrids have significantly altered expression of eight nuclear genes of the alternative complement, inflammation and apoptosis pathways. Sequencing of the entire mtDNA was carried out for all the cybrids to identify haplogroup and non-haplogroup defining SNPs. mtDNA can mediate cellular bioenergetics and expression levels of nuclear genes related to complement, inflammation and apoptosis. Sequencing data suggest that observed effects are not due to rare mtDNA variants but rather the combination of SNPs representing the J versus H haplogroups. These findings represent a paradigm shift in our concepts of mt-nuclear interactions.

Increased retinal mtDNA damage in the CFH variant associated with age-related macular degeneration.

Age-related macular degeneration (AMD) is a major cause of blindness among the elderly in the developed world. Genetic analysis of AMD has identified 34 high-risk loci associated with AMD. The genes at these high risk loci belong to diverse biological pathways, suggesting different mechanisms leading to AMD pathogenesis. Thus, therapies targeting a single pathway for all AMD patients will likely not be universally effective. Recent evidence suggests defects in mitochondria (mt) of the retinal pigment epithelium (RPE) may constitute a key pathogenic event in some AMD patients. The purpose of this study is to determine if individuals with a specific genetic background have a greater propensity for mtDNA damage. We used human eyebank tissues from 76 donors with AMD and 42 age-matched controls to determine the extent of mtDNA damage in the RPE that was harvested from the macula using a long extension polymerase chain reaction assay. Genotype analyses were performed for ten common AMD-associated nuclear risk alleles (ARMS2, TNFRSF10A, CFH, C2, C3, APOE, CETP, LIPC, VEGF and COL10A1) and mtDNA haplogroups. Sufficient samples were available for genotype association with mtDNA damage for TNFRSF10A, CFH, CETP, VEGFA, and COL10A1. Our results show that AMD donors carrying the high risk allele for CFH (C) had significantly more mtDNA damage compared with donors having the wild-type genetic profile. The data from an additional 39 donors (12 controls and 27 AMD) genotyped for CFH alleles further supported these findings. Taken together, these studies provide the rationale for a more personalized approach for treating AMD by uncovering a significant correlation between the CFH high risk allele and accelerated mtDNA damage. Patients harboring this genetic risk factor may benefit from therapies that stabilize and protect the mt in the RPE.

Molecular and bioenergetic differences between cells with African versus European inherited mitochondrial DNA haplogroups: implications for population susceptibility to diseases.

The geographic origins of populations can be identified by their maternally inherited mitochondrial DNA (mtDNA) haplogroups. This study compared human cybrids (cytoplasmic hybrids), which are cell lines with identical nuclei but mitochondria from different individuals with mtDNA from either the H haplogroup or L haplogroup backgrounds. The most common European haplogroup is H while individuals of maternal African origin are of the L haplogroup. Despite lower mtDNA copy numbers, L cybrids had higher expression levels for nine mtDNA-encoded respiratory complex genes, decreased ATP (adenosine triphosphate) turnover rates and lower levels of reactive oxygen species production, parameters which are consistent with more efficient oxidative phosphorylation. Surprisingly, GeneChip arrays showed that the L and H cybrids had major differences in expression of genes of the canonical complement system (5 genes), dermatan/chondroitin sulfate biosynthesis (5 genes) and CCR3 (chemokine, CC motif, receptor 3) signaling (9 genes). Quantitative nuclear gene expression studies confirmed that L cybrids had (a) lower expression levels of complement pathway and innate immunity genes and (b) increased levels of inflammation-related signaling genes, which are critical in human diseases. Our data support the hypothesis that mtDNA haplogroups representing populations from different geographic origins may play a role in differential susceptibilities to diseases.

Effects of light on retinal pigment epithelial cells, neurosensory retinal cells and Müller cells treated with Brilliant Blue G.

BACKGROUND: The aim of this study is to evaluate the safety profile of Brilliant Blue G (BBG) with and without exposure to light (L) on three different retinal cell lines. METHOD: ARPE-19, R28 and MIO-M1 cells were treated with BBG: 0.125 mg/mL (0.5x clinical concentration), 0.25 mg/mL (1x) or 0.5 mg/mL (2x) with or without surgical illumination of halogen light exposure for 10 min, 15 min or 30 min. Cells were further cultured after 24 h and then analysed for cell viability, late stages of apoptosis and mitochondrial damage associated with early apoptosis using assays that measure trypan blue dye exclusion, increases in caspase-3/7 activity or changes in mitochondrial membrane potential (ΔΨm), respectively. RESULT: All three cell lines that were exposed to BBG in the presence or absence of light exposure for 30 min were found to have cell viability and caspase-3/7 activity levels similar to the untreated cultures. The mitochondrial membrane potential (ΔΨm) was decreased significantly at the 2x + L dose and 2x dose in all three retinal cell lines compared to their respective untreated control cells. At the lower doses of BBG, with or without exposure to light, the ΔΨm values were similar to the untreated control cultures. CONCLUSION: Exposure to BBG dye concentrations that are used clinically (0.125 mg/mL and 0.25 mg/mL) in the presence up to 30 min of surgically equivalent light intensity is safe for retinal cells.

Effects of Humanin G (HNG) on angiogenesis and neurodegeneration markers in Age-related Macular Degeneration (AMD).

Advanced stages of Age-related Macular Degeneration (AMD) are characterized by retinal neurodegeneration and aberrant angiogenesis, and mitochondrial dysfunction contributes to the pathogenesis of AMD. In this study, we tested the hypothesis that Humanin G (HNG), a cytoprotective mitochondrial-derived peptide, positively regulates cell proliferation, cell death, and the protein levels of angiogenesis and neurodegeneration markers, in normal (control) and AMD RPE transmitochondrial cybrid cell lines. These normal and AMD RPE transmitochondrial cybrid cell lines had identical nuclei derived from mitochondria-deficient ARPE-19 cell line, but differed in mitochondrial DNA (mtDNA) content that was derived from clinically characterized AMD patients and normal (control) subjects. Cell lysates were extracted from untreated and HNG-treated AMD and normal (control) cybrid cell lines, and the Luminex XMAP multiplex assay was used to examine the protein levels of angiogenesis and neurodegeneration markers. Humanin G reduced Caspase-3/7-mediated apoptosis, improved cell proliferation, and normalized the protein levels of angiogenesis and neurodegeneration markers in AMD RPE cybrid cell lines, thereby suggesting Humanin G's positive regulatory role in AMD.