Gertrud Haas

Phagocytosis of Human Retinal Pigment Epithelial Cells: Evidence of a Diurnal Rhythm, Involvement of the Cytoskeleton and Interference of Antiviral Drugs

Retinal pigment epithelial (RPE) cells provide crucial functions for the maintenance of the retinal environment. We investigated the phagocytotic mechanisms of RPE cells evaluating the question whether particle uptake underlies a diurnal rhythm. Additionally, a possible connection of volume regulation and the phagocytotic function of RPE cells was studied. As antiviral nucleoside analogues influence cell-volume-regulating mechanisms, we tested several antiviral drugs. Cultured primary RPE cells and a permanent cell line (ARPE-19) were tested for uptake of europium-labeled microspheres quantified by time-resolved fluorometry. Cells were also exposed to cyclic illumination or continuous light and dark culture conditions. Inhibitors of cytoskeleton (microtubuli, actin) and osmotic swelling were also tested. Ingested FITC-labeled microparticles were found in phagosomes strongly associated which the cytoskeleton as they could not be easily moved by laser tweezer microscopy. Phagocytosis was observed predominately during dark intervals and was reduced by continuous light exposure. The diurnal rhythm of unsynchronized RPE cultures was abolished by microtubule inhibitors although no inhibition of overall particle uptake by cytoskeletal blockers was observed. Hypoosmotic swelling of RPE also decreased phagocytosis. Acyclovir was found inhibitory in ARPE-19 cells, whereas azidothymidine showed a protracted inhibiting activity on primary RPE cells and ganciclovir was inactive in both cell types. The presence of a diurnal rhythm also in culture indicates genetic determination of light-regulated particle uptake. This mechanism appears to be influenced by the regulation of cell volume and microtubule function. Inhibition of RPE function by antiviral drugs is a novel finding and in accordance with interferences of the tested drugs with cellular chloride channels described earlier. It may give a hint towards possible ocular side effects in the long-term use of nucleoside-analogous substances.

Neurokinin A and neurokinin B in the human retina

Very recently, the authors found levels of neurokinin (NK) A-like immunoreactivities in the human retina which were more than five times higher than those of substance P (SP). The present study aimed to find out how many of these immunoreactivities can be attributed to NKA and NKB and then the exact distribution pattern of both NKA and NKB was evaluated in the human retina and compared with that of SP. For this purpose, NKA-like immunoreactivities were characterized in the human retina by reversed phase HPLC followed by radioimmunoassay using the K12 antibody which recognizes both NKA and NKB. Furthermore, the retinae from both a 22- and 70-year-old donor were processed for double-immunofluorescence NKA/SP and NKB/SP. The results showed that NKA contributes to approximately two thirds and NKB to approximately one third of the immunoreactivities measured with the K12 antibody. NKA was found to be localized in sparse amacrine cells in the proximal inner nuclear layer, in displaced amacrine cells in the ganglion cell layer with processes ramifying in stratum 3 of the inner plexiform layer and also in sparse ganglion cells. By contrast, staining for NKB was only observed in ganglion cells and in the nerve fiber layer. Double-immunofluorescence revealed cellular colocalization of NKA with SP and also of NKB with SP. Thus, the levels of NKA and NKB are more than three and two times higher than those of SP, respectively. Whereas the distribution pattern of NKA is typical for neuropeptides, the localization of NKB exclusively in ganglion cells is atypical and unique.

Involvement of protein kinase C in phagocytosis of human retinal pigment epithelial cells and induction of matrix metalloproteinase secretion.

Protein kinase C (PKC) is involved in cell activation. We investigated PKC-mediated pathways and secretion of matrix metalloproteinases (MMPs) in phagocytosis by human retinal pigment epithelial cells (RPE). We used time-resolved fluorometry for europium-labeled microsphere uptake and gel zymography to assay the influence of PKC modulators. PKC inhibitors blocked phagocytosis by RPE. ARPE-19, a human RPE-cell line, showed reduced secretion of MMP-2, although MMP-9 secretion by PKC activation was conserved in both cell types, namely in the primary RPEs and in the RPE-cell line. Particle uptake by RPE cells requires activation of PKC; the use of PKC inhibitors as new anticancer drugs may possibly cause ocular side-effects.

PE-11, a peptide derived from chromogranin B, in the rat eye

The aim of the study was to investigate the presence and distribution of PE-11, a peptide derived from chromogranin B, in the rat eye. For this purpose, newborn rats were injected with a single dosage of 50mg/kg capsaicin subcutaneously under the neck fold and after three months, particular eye tissues were dissected and the concentration of PE-11-like immunoreactivity was determined by radioimmunoassay. Furthermore, PE-11-like immunoreactivities were characterized in an extract of the rat eye by reversed phase HPLC. Then, the distribution pattern of PE-11 was investigated in the rat eye and rat trigeminal ganglion by immunofluorescence. As a result, PE-11 was present in each tissue of the rat eye and capsaicin pretreatment led to a 88.05% (±7.07) and a 64.26% (±14.17) decrease of the levels of PE-11 in the cornea and choroid/sclera, respectively, and to a complete loss in the iris/ciliary body complex. Approximately 70% of immunoreactivities detected by the PE-11 antiserum have been found to represent authentic PE-11. Sparse nerve fibers were visualized in the corneal and uveal stroma, surrounding blood vessels at the limbus, ciliary body and choroid and in association with the dilator and sphincter muscle. Furthermore, immunoreactivity was present in the corneal endothelium. In the retina and optic nerve, glia was labeled. In the rat trigeminal ganglion, PE-11-immunoreactivity was visualized in small and medium sized ganglion cells with a diameter of up to 30μm. In conclusion, there is unequivocal evidence that PE-11 is a constituent of capsaicin-sensitive sensory neurons innervating the rat eye and the distribution pattern is typically peptidergic in the peripheral innervation but in the retina completely atypical for neuropeptides and unique.

The Effect of Aluminium on the Morphologic Appearance, Viability and Phagocytic Activity of ARPE-19 Cells

Purpose: Aluminium is known to have toxic effects on the central nervous system. We wanted to explore the effects of aluminium on cultured ARPE-19 cells, in particular, changes in the morphologic appearance, viability and in the phagocytic activity of these cells. Methods: After addition of different concentrations of aluminium to the cell cultures, cellular morphology was evaluated by photomicrographs; viability was determined by mitochondrial activity measurement and phagocytosis by uptake of europium-labeled FluoSpheres. Results: Pretreatment of the cells with aluminium led to the formation of clots in the cell culture and there was a relative weak dose-dependent decrease in viability. However, phagocytic activity was severely impaired at each concentration with a peak decrease of 92.45% (± 8.21) at 1000 μmol. Conclusions: Exposure to aluminium occurs mainly through contaminated food and beverages. Given that sufficient concentrations accumulate in the RPE, inhibition of the phagocytic activity of RPE cells might represent a novel important side effect of this metal. Although no conclusions can be drawn from in vitro results on the effect in vivo, it seems that caution is recommended with consumption of food with high concentrations of aluminium. The reduced viability of RPE cells, however, is clinically less relevant since the effect was relative weak in vitro.

Reduced-Fluence Photodynamic Therapy Combined with Ranibizumab for Nonproliferative Macular Telangiectasia Type 2

Purpose: To report the efficacy of reduced-fluence photodynamic therapy (PDT) combined with intravitreal ranibizumab for the treatment of nonproliferative macular telangiectasia (MacTel) type 2. Methods: Noncomparative, interventional, retrospective case series; 5 eyes of 4 patients were studied. Patients were treated with reduced-fluence PDT and intravitreal ranibizumab within 24 h. After initial treatment, follow-up was at least 12 months in all patients. Results: At baseline median logMAR (logarithm of the minimal angle of resolution) best-corrected visual acuity (BCVA) was 1.0 (range, 1.0-0.3). At 3 months of follow-up vision increased in 3 out of 5 eyes and median BCVA was 0.4 (range, 1.0-0.2). The gain of BCVA ranged from 6 lines to 1 line. Visual acuity remained stable in the other 2 study eyes. No eyes lost vision at 3 months of follow-up. At 12 months of follow-up median logMAR BCVA was 0.7 (range, 1.3-0.3). Two eyes had maintained their gain in BCVA compared to baseline. Two eyes lost vision compared to baseline and 1 eye showed unchanged visual acuity at 12 months of follow-up. Conclusion: A combination therapy with reduced-fluence PDT and intravitreal ranibizumab might be a valuable treatment option for eyes with progressive vision loss due to nonproliferative MacTel type 2.

The involvement of NK1 and Y2 receptor in the development of laser-induced CNVs in C57Bl/6N mice

Purpose: to explore whether the NK1 and Y2 receptors are involved in the pathogenesis of laser‐induced CNV (choroidal neovascularization) in C57Bl/6N mice. Methods: CNV was induced by laser damage of Bruchs membrane and the CNV volume was determined by OCT and/or flatmount preparation. First, the development of the CNV volume over time was evaluated. Second, the CNV development in NK1‐ and Y2 KO mice was analyzed. Third, the effect on the development as well as the regression of CNV by intravitreal injections of the NK1 antagonist SR140333 and the Y2 antagonist BIIEO246 separately and each in combination with Eylea®, was investigated. Furthermore, flatmount CNV volume measurements were correlated to volumes obtained by the in vivo OCT technique. Results: CNV volume peak was observed at day 4 after laser treatment. Compared to wild type mice, NK1 and Y2 KO mice showed significantly smaller CNV volumes. Eylea® and the Y2 antagonist significantly reduced the volume of the developing CNV. In contrast to Eylea® there was no effect of either antagonist on the regression of CNV, additionally no additive effect upon combined Eylea®/antagonist treatment was observed. There was a strong positive correlation between CNV volumes obtained by OCT and flatmount. Conclusion: NK1 and Y2 receptors mediate the development of laser‐induced CNVs in mice. They seem to play an important role at the developmental stage of CNVs, whereas VEGF via VEGF receptor may be an important mediator throughout the CNV existence. In vivo OCT correlates with flatmount CNV volume, representing a useful tool for in vivo evaluations of CNV over time.

Chirurgische Methoden in der Behandlung des Aderhautmelanoms

Significant advancements have been made in the last decades in the treatment of uveal melanoma. Radiation therapy can achieve, depending on the method, local tumour control in up to 98% of cases. Surgical modalities have been implemented in the ocular therapy for uveal melanoma either to treat/prevent radiation complications, such as so-called toxic tumour syndrome, or to primarily treat the tumour with or without adjunctive radiotherapy. These include endoresection and transscleral resection for melanomas of the choroid/ciliary body or irido-trabeculo-cyclectomy for melanomas of the iris-ciliary body. Furthermore, tumour biopsy is playing a progressively more important role in the diagnosis, treatment and follow-up planning of melanoma cases. This paper focuses on the background, the surgical technique as well as the results and complications of tumour excisional and biopsy surgery.

Decreased Vision as Initial Presenting Symptom of Acute Lymphoblastic Leukemia: A Case Report.

This case illustrates that hematologic disorders must be considered as a potentially life-threatening cause for vision loss. Proper laboratory workup and timely interdisciplinary approach are essential to ensure the best possible care for ophthalmic patients. Historically, before the use of bone marrow biopsy, the ophthalmologist was often asked to assist in the diagnosis of leukemia. Since ophthalmological symptoms may be the initial presenting signs of leukemia as highlighted in this case, the ophthalmogist is still of crucial importance.

Degenerative Makulopathien (bei jüngeren Patienten)

Makulopathien sind Erkrankungen und daraus resultierende Funktionseinschrankungen der Netzhautmitte (Makula). Den fortschreitenden Funktionsverlust durch chronische Veranderung von Gewebe in der Makula bezeichnet man als Makuladegeneration. In diesem Artikel werden folgende Netzhauterkrankungen mit Befall des Netzhautzentrums bei jungeren Menschen beschrieben: Davon abzugrenzen ist die altersassoziierte Makuladegeneration (AMD) des alteren Menschen.