LEDGF(1-326) decreases P23H and wild type rhodopsin aggregates and P23H rhodopsin mediated cell damage in human retinal pigment epithelial cells

AAV delivery of GRP78/BiP promotes adaptation of human RPE cell to ER stress

Adeno associated virus (AAV)-mediated gene delivery of GRP78 (78 kDa glucose-regulated protein) attenuates the condition of endoplasmic reticulum (ER) stress and prevents apoptotic loss of photoreceptors in Retinitis pigmentosa (RP) rats. In the current study we overexpressed Grp78 with the help of AAV-2 in primary human retinal pigmented epithelium (hRPE) cell cultures and examined its effect on cell response to ER stress. The purpose of this work was studying potential stimulating effect of GRP78 on adaptation/pro-survival of hRPE cells under ER stress, as an in vitro model for RPE degeneration. To investigate the effect of Grp78 overexpression on unfolded protein response (UPR) markers under ER stress, hRPE primary cultures were transduced by recombinant virus rAAV/Grp78, and treated with ER stressor drug, tunicamycin. Expression changes of four UPR markers including GRP78, PERK, ATF6α, and GADD153/CHOP, were assessed by real-time PCR and western blotting. We found that GRP78 has a great contribution in modulation of UPR markers to favor adaptive response in ER-stressed hRPE cells. In fact, GRP78 overexpression affected adaptation and apoptotic phases of early UPR, through enhancement of two master regulators/ER stress sensors (PERK and ATF6α) and down-regulation of a key pro-apoptotic cascade activator (GADD153/CHOP). Together these findings demonstrate the promoting effect of GRP78 on adaptation/pro-survival of hRPE cells under ER stress. This protein with anti-apoptotic actions in the early UPR and important role in cell fate regulation, can be recruited as a useful candidate for future investigations of RPE degenerative diseases.

The Clinical Relevance of Anti-DFS70 Autoantibodies

Despite all the progress in the establishment of specific autoantibody assays, screening for antinuclear antibodies (ANA) by indirect immunofluorescence on HEp-2 cells for quality-oriented laboratory diagnosis of ANA associated rheumatic diseases (AARD) remains indispensable but is not without limitations. Recent data on the relevance of the dense fine speckled (DFS) pattern and anti-DFS70 antibodies disclosed novel possibilities to optimize the serological stepwise diagnostics of AARD. The DFS pattern on HEp-2 cells is well differentiated from the classic "homogeneous" ANA pattern associated with dsDNA antibodies. This is the most frequent pattern in high titer ANA-positive healthy persons. The most characteristic ANA specificity associated with DFS pattern is the anti-DFS70 antibody (synonym LEDGF antibody). The prevalence of anti-DFS70 antibodies in AARD patients is significantly lower compared with the prevalence in ANA-positive healthy persons. There is a negative association between anti-DFS70 antibodies and AARD, especially if no concomitant AARD-specific autoantibodies are found. Isolated anti-DFS70 antibodies are detectable in less than 1 % of AARD but are detectable in 2-22 % of healthy persons. In the presence of an isolated anti-DFS70 antibody, the posttest probability for AARD is reduced significantly. The significance of anti-DFS70 antibodies as a criterion that helps to exclude AARD is also confirmed by follow-up studies on anti-DFS70 antibodies of positive, healthy individuals, who did not develop any AARD during a 4 year observation period. Consequently, anti-DFS70 antibodies are valuable novel biomarkers for better interpretation of positive ANA in cases of negative AARD-associated autoantibodies and should be integrated in modified test algorithms to avoid unnecessary referrals and examinations of ANA-positive persons.

The significance of autoantibodies to DFS70/LEDGFp75 in health and disease: integrating basic science with clinical understanding

Antinuclear autoantibodies (ANAs) displaying the nuclear dense fine speckled immunofluorescence (DFS-IIF) pattern in HEp-2 substrates are commonly observed in clinical laboratory referrals. They target the dense fine speckled autoantigen of 70 kD (DFS70), most commonly known as lens epithelium-derived growth factor p75 (LEDGFp75). Interesting features of these ANAs include their low frequency in patients with systemic autoimmune rheumatic diseases (SARD), elevated prevalence in apparently healthy individuals, IgG isotype, strong trend to occur as the only ANA specificity in serum, and occurrence in moderate to high titers. These autoantibodies have also been detected at varied frequencies in patients with diverse non-SARD inflammatory and malignant conditions such as atopic diseases, asthma, eye diseases, and prostate cancer. These observations have recently stimulated vigorous research on their clinical and biological significance. Some studies have suggested that they are natural, protective antibodies that could serve as biomarkers to exclude a SARD diagnosis. Other studies suggest that they might be pathogenic in certain contexts. The emerging role of DFS70/LEDGFp75 as a stress protein relevant to human acquired immunodeficiency syndrome, cancer, and inflammation also points to the possibility that these autoantibodies could be sensors of cellular stress and inflammation associated with environmental factors. In this comprehensive review, we integrate our current knowledge of the biology of DFS70/LEDGFp75 with the clinical understanding of its autoantibodies in the contexts of health and disease.

Functional principal component analysis reveals discriminating categories of retinal pigment epithelial morphology in mice

PURPOSE

To determine whether multivariate, functional principal component analysis of the size and shape of retinal pigment epithelial (RPE) cell morphology allows discrimination of mouse RPE genotypes and age.

METHODS

Flatmounts of RPE sheets obtained from C57BL/6J (n = 50) and rd10 (n = 61) mice at postnatal days 30 to 720 were stained for zonula occludens-1 (ZO-1) and imaged with confocal microscopy. A total of 111 flatmounts were prepared. Twenty-one morphometric measurements were made on tiled, composite images of complete flatmounts, including cell location, area, and eccentricity, using automated image analysis software for quantitatively measuring cell phenotypes.

RESULTS

In young (≤61-day-old) C57BL/6J mice, the RPE morphology resembled a regular hexagonal array of cells of uniform size throughout the retina, except near the ciliary body, where the shapes of RPE resembled a soft network. Old (≥180-day-old) C57BL/6J eyes had a subpopulation of large cells. A clear disruption of the regular cell size and shape appeared in rd10 mutants. Aspect ratio and cell area gave rise to principal components that predictively classified mouse age and genotype.

CONCLUSIONS

Quantitative differences in the RPE sheet morphology allowed discrimination of rd10 from C57BL/6J strains despite the confounding effect of aging. This has implications for RPE sheet morphology as a potential early biomarker for diagnosis of eye disease and prognosis of the eye at early stages when disease is subtle. We conclude that an RPE cell's area and aspect ratio are very early quantitative indicators that predict progression to advanced RPE disease as manifested in rd10.

Biosynthesis, characterization, and efficacy in retinal degenerative diseases of lens epithelium-derived growth factor fragment (LEDGF1-326), a novel therapeutic protein

For vision-threatening retinitis pigmentosa and dry age-related macular degeneration, there are no United States Food and Drug Administration (FDA)-approved treatments. We identified, biosynthesized, purified, and characterized lens epithelium-derived growth factor fragment (LEDGF1-326) as a novel protein therapeutic. LEDGF1-326 was produced at about 20 mg/liter of culture when expressed in the Escherichia coli system, with about 95% purity and aggregate-free homogeneous population with a mean hydrodynamic diameter of 9 ± 1 nm. The free energy of unfolding of LEDGF1-326 was 3.3 ± 0.5 kcal mol(-1), and melting temperature was 44.8 ± 0.2 °C. LEDGF1-326 increased human retinal pigment epithelial cell viability from 48.3 ± 5.6 to 119.3 ± 21.1% in the presence of P23H mutant rhodopsin-mediated aggregation stress. LEDGF1-326 also increased retinal pigment epithelial cell FluoSphere uptake to 140 ± 10%. Eight weeks after single intravitreal injection in Royal College of Surgeons (RCS) rats, LEDGF1-326 increased the b-wave amplitude significantly from 9.4 ± 4.6 to 57.6 ± 8.8 μV for scotopic electroretinogram and from 10.9 ± 5.6 to 45.8 ± 15.2 μV for photopic electroretinogram. LEDGF1-326 significantly increased the retinal outer nuclear layer thickness from 6.34 ± 1.6 to 11.7 ± 0.7 μm. LEDGF1-326 is a potential new therapeutic agent for treating retinal degenerative diseases.