Tear Proteins Altered in Patients with Persistent Eye Pain after Refractive Surgery: Biomarker Candidate Discovery.

Some patients develop persistent eye pain after refractive surgery, but factors that cause or sustain pain are unknown. We tested whether tear proteins of patients with pain 3 months after surgery differ from those of patients without pain. Patients undergoing refractive surgery (laser in situ keratomileusis or photorefractive keratectomy ) were recruited from 2 clinics, and tears were collected 3 months after surgery. Participants rated their eye pain using a numerical rating scale (NRS, 0-10; no pain-worst pain) at baseline, 1 day, and 3 months after surgery. Using tandem mass tag proteomic analysis, we examined tears from patients with pain [NRS ≥ 3 at 3 months (n = 16)] and patients with no pain [NRS ≤ 1 at 3 months (n = 32)] after surgery. A subset of proteins (83 of 2748 detected, 3.0%) were associated with pain 3 months after surgery. High-dimensional statistical models showed that the magnitude of differential expression was not the only important factor in classifying tear samples from pain patients. Models utilizing 3 or 4 proteins had better classification performance than single proteins and represented differences in both directions (higher or lower in pain). Thus, patterns of protein differences may serve as biomarkers of postsurgical eye pain as well as potential therapeutic targets.

Analysis of the longitudinal stability of human plasma miRNAs and implications for disease biomarkers.

There is great interest in developing clinical biomarker assays that can aid in non-invasive diagnosis and/or monitoring of human diseases, such as cancer, cardiovascular disease, and neurological diseases. Yet little is known about the longitudinal stability of miRNAs in human plasma. Here we assessed the intraindividual longitudinal stability of miRNAs in plasma from healthy human adults, and the impact of common factors (e.g., hemolysis, age) that may confound miRNA data. We collected blood by venipuncture biweekly over a 3-month period from 22 research participants who had fasted overnight, isolated total RNA, then performed miRNA qPCR. Filtering and normalization of the qPCR data revealed amplification of 134 miRNAs, 74 of which had high test-retest reliability and low percentage level drift, meaning they were stable in an individual over the 3-month time period. We also determined that, of nuisance factors, hemolysis and tobacco use have the greatest impact on miRNA levels and variance. These findings support that many miRNAs show intraindividual longitudinal stability in plasma from healthy human adults, including some reported as candidate biomarkers for Alzheimer's disease.

RNA isolation from micro-quantity of articular cartilage for quantitative gene expression by microarray analysis.

Isolation of quality RNA from articular cartilage has been challenging due to low cellularity and the high abundance of extracellular matrix and proteoglycan proteins. Recently developed methods for isolation of high quality RNA from cartilage are more applicable to larger cartilage specimens typically weighing at least 25 mg. While these methods generate RNA suitable for analysis, they are less successful with smaller tissue inputs. For the study of small focal defect cartilage specimens an improved RNA extraction method is needed. Here we report a protocol for direct RNA isolation from less than 3 mg of wet weight rabbit articular cartilage for quantitative microarray gene profiling. This protocol is useful for identifying differentially expressed genes in chondrocytes following focal cartilage repair and can potentially be adopted for gene expression analysis of cartilage biopsy specimens from human joints.

Analysis of extracellular RNA in cerebrospinal fluid.

We examined the extracellular vesicle (EV) and RNA composition of pooled normal cerebrospinal fluid (CSF) samples and CSF from five major neurological disorders: Alzheimer's disease (AD), Parkinson's disease (PD), low-grade glioma (LGG), glioblastoma multiforme (GBM), and subarachnoid haemorrhage (SAH), representing neurodegenerative disease, cancer, and severe acute brain injury. We evaluated: (I) size and quantity of EVs by nanoparticle tracking analysis (NTA) and vesicle flow cytometry (VFC), (II) RNA yield and purity using four RNA isolation kits, (III) replication of RNA yields within and between laboratories, and (IV) composition of total and EV RNAs by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and RNA sequencing (RNASeq). The CSF contained ~106 EVs/µL by NTA and VFC. Brain tumour and SAH CSF contained more EVs and RNA relative to normal, AD, and PD. RT-qPCR and RNASeq identified disease-related populations of microRNAs and messenger RNAs (mRNAs) relative to normal CSF, in both total and EV fractions. This work presents relevant measures selected to inform the design of subsequent replicative CSF studies. The range of neurological diseases highlights variations in total and EV RNA content due to disease or collection site, revealing critical considerations guiding the selection of appropriate approaches and controls for CSF studies.

BEVACIZUMAB LEVELS IN BREAST MILK AFTER LONG-TERM INTRAVITREAL INJECTIONS.

PURPOSE: The purpose of this study is to determine whether bevacizumab is detectable in the breast milk of nursing mothers. METHODS: Breast milk samples were collected from 2 patients receiving monthly intravitreal bevacizumab injections for choroidal neovascularization over the course of 16 months. Enzyme-linked immunosorbent assay and Western blot analysis was used to determine the levels of bevacizumab in the milk samples. RESULTS: An enzyme-linked immunosorbent assay was developed using antibodies specific to bevacizumab in which the sensitivity threshold was 3 ng/mL. All breast milk samples assayed from the two patients actively undergoing treatment did not have detectable levels of bevacizumab. Samples collected 1.5 hours and 7 hours after an injection and 2 randomly chosen samples were negative by Western blot analysis. CONCLUSION: A sensitive assay to detect bevacizumab in breast milk samples assayed suggests that intravitreal injections do not result in detectable bevacizumab in breast milk.

The related transcriptional enhancer factor-1 isoform, TEAD4(216), can repress vascular endothelial growth factor expression in mammalian cells.

Increased cellular production of vascular endothelial growth factor (VEGF) is responsible for the development and progression of multiple cancers and other neovascular conditions, and therapies targeting post-translational VEGF products are used in the treatment of these diseases. Development of methods to control and modify the transcription of the VEGF gene is an alternative approach that may have therapeutic potential. We have previously shown that isoforms of the transcriptional enhancer factor 1-related (TEAD4) protein can enhance the production of VEGF. In this study we describe a new TEAD4 isoform, TEAD4(216), which represses VEGF promoter activity. The TEAD4(216) isoform inhibits human VEGF promoter activity and does not require the presence of the hypoxia responsive element (HRE), which is the sequence critical to hypoxia inducible factor (HIF)-mediated effects. The TEAD4(216) protein is localized to the cytoplasm, whereas the enhancer isoforms are found within the nucleus. The TEAD4(216) isoform can competitively repress the stimulatory activity of the TEAD4(434) and TEAD4(148) enhancers. Synthesis of the native VEGF(165) protein and cellular proliferation is suppressed by the TEAD4(216) isoform. Mutational analysis indicates that nuclear or cytoplasmic localization of any isoform determines whether it acts as an enhancer or repressor, respectively. The TEAD4(216) isoform appears to inhibit VEGF production independently of the HRE required activity by HIF, suggesting that this alternatively spliced isoform of TEAD4 may provide a novel approach to treat VEGF-dependent diseases.

Subretinal transplantation of forebrain progenitor cells in nonhuman primates: survival and intact retinal function.

PURPOSE: Cell-based therapy rescues retinal structure and function in rodent models of retinal disease, but translation to clinical practice will require more information about the consequences of transplantation in an eye closely resembling the human eye. The authors explored donor cell behavior using human cortical neural progenitor cells (hNPC(ctx)) introduced into the subretinal space of normal rhesus macaques. METHODS: hNPC(ctx) transduced with green fluorescent protein (hNPC(ctx)-GFP) were delivered bilaterally into the subretinal space of six normal adult rhesus macaques under conditions paralleling those of the human operating room. Outcome measures included clinical parameters of surgical success, multifocal electroretinogram (mfERG), and histopathologic analyses performed between 3 and 39 days after engraftment. To test the effects of GFP transduction on cell bioactivity, hNPC(ctx)-GFP from the same batch were also injected into Royal College of Surgeons (RCS) rats and compared with nonlabeled hNPC(ctx). RESULTS: Studies using RCS rats indicated that GFP transduction did not alter the ability of the cells to rescue vision. After cells were introduced into the monkey subretinal space by a pars plana transvitreal approach, the resultant detachment was rapidly resolved, and retinal function showed little or no disturbance in mfERG recordings. Retinal structure was unaffected and no signs of inflammation or rejection were seen. Donor cells survived as a single layer in the subretinal space, and no cells migrated into the inner retina. CONCLUSIONS: Human neural progenitor cells can be introduced into a primate eye without complication using an approach that would be suitable for extrapolation to human patients.

Identification of novel alternatively spliced isoforms of RTEF-1 within human ocular vascular endothelial cells and murine retina.

PURPOSE: Identification of transcription factors that regulate the transcription of the vascular endothelial growth factor (VEGF) gene may facilitate understanding of the etiology and progression of ocular neovascular diseases. The purpose of this study was to determine whether transcriptional enhancer factor 1-related (RTEF-1) was present within ocular vascular endothelial cells and whether it played a role in the control of the transcription of the VEGF gene. METHODS: Primary cultures of human retinal vascular endothelial cells (RVECs) were maintained under normoxic or hypoxic conditions before isolation of mRNA. RT-PCR was performed to detect RTEF-1 transcripts. Amplified products were cloned into an expression plasmid. Human VEGF promoter and deletion constructs were cloned into a pSEAP reporter vector. Various RTEF-1 isoforms and VEGF promoter constructs were coelectroporated into human cells, and reporter expression levels were determined. Retinal tissue from a mouse model of retinopathy of prematurity (ROP) was analyzed by RT-PCR for the presence of RTEF-1 transcripts. RESULTS: Full-length 1305-bp and novel 936-bp RTEF-1 transcripts were identified in cultured human RVECs under normoxic conditions. A novel 447-bp isoform was present in cells maintained in a hypoxic environment. Four of the 11 translated exons predicted to code for the 1305-bp product were spliced out of the 936-bp transcript. The 1305-bp product enhanced expression from the VEGF promoter 4-fold greater than background, whereas the 936-bp and the 447-bp isoforms enhanced expression 3x and 12x, respectively. Analysis with deletion promoter constructs determined that all isoforms required the presence of Sp1 elements for efficient activation and that the hypoxia response element (HRE) was not essential for enhancement. Transcripts for novel RTEF-1 isoforms were also identified in neural retinal tissue of mice. Different murine-specific isoforms were present at different stages of postnatal development. CONCLUSIONS: Novel RTEF-1 transcripts are present within human ocular vascular endothelial cells and mouse neural retina during normal and ROP development, and alternatively spliced products are produced under hyperoxic and hypoxic conditions. Alternative spliced variants of human RTEF-1 transcripts are able to potentiate expression from the VEGF 5' proximal promoter region.

Evaluation of a novel short polyadenylation signal as an alternative to the SV40 polyadenylation signal.

The soluble neuropilin-1 (sNRP-1) gene employs an extremely short dual function polyadenylation (pA) signal/stop codon that is efficient for termination of gene transcription and translation in vivo. However, the functionality and usefulness of this signal in regard to other genes is unknown. This quantitative study compares the levels of humanized Renilla green fluorescent protein (hrGFP) mRNA polyadenylated with either the sNRP-1 pA signal or the much larger, more widely used SV40 pA signal. We show that the overall starting copy number of hrGFP for equally loaded RNAs is equivalent between the two groups. Our data show little to no difference between levels of mRNA generated by the sNRP-1 polyadenylation signal and the SV40 polyadenylation signal despite a remarkable size difference in signal length. An extremely short polyadenylation signal could potentially alleviate gene insert size restrictions associated with cloning or with therapeutic vectors such as adeno-associated virus.

Gene therapy for proliferative ocular diseases.

Proliferative ocular diseases encompass a wide variety of pathological processes with adverse cellular differentiation, proliferation and migration as common features. Pathologies may involve neovascular responses associated with diabetic retinopathy, retinopathy of prematurity or age-related macular degeneration. These diseases are quite prevalent and account for substantial visual impairment and blindness worldwide. Although treatment strategies are largely surgical, advances in our understanding of the proteins crucial to cell transdifferentiation, proliferation and migration, along with better gene transfer techniques, have greatly increased the potential for biological treatment options. In this report, the most common proliferative ocular vascular diseases and existing therapeutic modalities will be reviewed and an overview of possible gene therapy options will be discussed, along with potential candidate genes.

Corneal transduction to inhibit angiogenesis and graft failure.

PURPOSE: To test whether lentivirus-mediated expression of an endostatin::kringle-5 (E::K-5) fusion gene has an inhibitory effect on neovascularization and failure of corneal transplants. METHODS: A lentiviral vector containing a fusion transgene comprising the human endostatin gene and the kringle-5 domain of the human plasminogen gene (E::K-5) was used for transduction of corneal buttons ex vivo. The corneal buttons were transplanted after overnight incubation in media containing either lentivirus or PBS. Sixteen rabbits underwent allogenic penetrating keratoplasty in one eye. The area of neovascularization from the limbus to within the graft was documented after surgery. RT-PCR was performed to demonstrate the presence of transgene mRNA within the graft. Histopathology was used to analyze neovascularization, inflammation, and rejection morphology. RESULTS: Less neovascularization was observed in corneas treated with the lentivirus E::K-5 fusion vector. Early onset and profound neovascularization was observed in control eyes. E::K-5-treated animals did not have graft failure, whereas five of the six control animals had graft failure, as classified by opacification of the graft. All E::K-5 transduced corneas tested were positive by RT-PCR for the unique fusion gene sequence. Histopathology corroborated a significant increase of blood vessel presence and inflammatory reaction in control compared with treated eyes. CONCLUSIONS: Corneas transduced with a lentivirus containing an endostatin::kringle-5 fusion gene demonstrated an inhibition of neovascularization and graft failure. E::K-5 gene transduction through a lentiviral vector system may be a useful adjunct to prevent graft neovascularization and corneal graft rejection in high-risk corneal transplants with antecedent rejection or neovascularization.

Electronegative electroretinogram in mucolipidosis IV.

OBJECTIVE: To demonstrate the progression of electroretinographic (ERG) findings in mucolipidosis IV. METHODS: Two patients with mucolipidosis IV were examined clinically and their condition was followed up for ophthalmic manifestations of the disease. Electroretinograms were performed on both patients, and conjunctival biopsy specimens were analyzed for characteristic ultrastructural inclusion bodies using light and electron microscopy. Genomic DNA isolated from peripheral blood was screened for 2 major founder mutations in the ML4 gene using polymerase chain reaction and restriction fragment length polymorphism analyses. Haplotypes were confirmed by automated sequencing of polymerase chain reaction products. RESULTS: In patient 1, an ERG obtained at 12 months of age showed mildly subnormal amplitude of rod-mediated and cone-mediated responses and significantly prolonged rod and cone b-wave implicit times. An ERG obtained when the patient was 6.6 years old disclosed marked progression with greater loss of b-wave than a-wave responses to rod-and-cone-mediated activity. Scotopic ERG at the highest intensity was electronegative in configuration. In patient 2, ERG showed minimal rod-mediated responses, severely subnormal cone-mediated responses, and prolonged cone b-wave implicit times. Again, electronegative configuration of the scotopic bright flash response indicated greater disturbance of b-wave generators. CONCLUSIONS: Novel ERG findings in 2 cases of mucolipidosis IV are reported with associated clinical courses, histopathologic abnormality, and genetic studies. In both cases ERGs demonstrate an electronegative configuration, suggesting that the primary retinal disturbance in mucolipidosis IV may occur at or proximal to the photoreceptor terminals.