11-cis-retinal and Retinitis

Just as the discovery of 'inborn errors of metabolism' in humans contributed to our basic understanding of normal enzymatic pathways, so can genetic defects in signal transduction help to elucidate the functions normally subserved by different GPCR pathways. Identification and characterization of naturally occurring GPCR mutations not only has inherent value in understanding the molecular basis of disease, but can also accelerate progress in understanding the fundamental mechanisms involved in GPCR synthesis, transport to the membrane, ligand binding, activation and deactivation.

Topics: GTP-Binding Proteins; Humans; Male; Mutation; Phenotype; Polymorphism, Genetic; Puberty, Precocious; Receptors, Cell Surface; Retinitis; Rhodopsin; Thyroid Diseases

Oxidative stress and inflammation have key roles in the light damage (LD) model of retinal degeneration as well as in age-related macular degeneration (AMD). We sought to determine if lipoic acid (LA), an antioxidant and iron chelator, protects the retina against LD.. Balb/c mice were treated with LA or control saline via intraperitoneal injection, and then were placed in constant cool white light-emitting diode (LED) light (10,000 lux) for 4 hours. Retinas were evaluated at several time points after LD. Photoreceptor apoptosis was assessed using the TUNEL assay. Retinal function was analyzed via electroretinography (ERG). Retinal degeneration was assessed after LD by optical coherence tomography (OCT), TUNEL analysis, and histology. The mRNAs of several oxidative stress, inflammation, and iron-related genes were quantified by quantitative PCR (qPCR).. The LD resulted in substantial photoreceptor-specific cell death. Dosing with LA protected photoreceptors, decreasing the numbers of TUNEL-positive photoreceptors and increasing the number of surviving photoreceptors. The retinal mRNA levels of genes indicating oxidative stress, inflammation, and iron accumulation were lower following LD in mice treated with LA than in control mice. The ERG analysis demonstrated functional protection by LA.. Systemic LA is protective against light-induced retinal degeneration. Since this agent already has proven protective in other retinal degeneration models, and is safe and protective against diabetic neuropathy in patients, it is worthy of consideration for a human clinical trial against retinal degeneration or AMD.

Topics: Animals; Antioxidants; Apoptosis; cis-trans-Isomerases; Electroretinography; Gene Expression; In Situ Nick-End Labeling; Iron Chelating Agents; Light; Male; Mice; Mice, Inbred BALB C; Oxidative Stress; Retina; Retinal Degeneration; Retinitis; Rhodopsin; Thioctic Acid; Tomography, Optical Coherence

Lutein has been the focus of recent study as a possible therapeutic approach for retinal diseases, but the molecular mechanism of its neuroprotective effect remains to be elucidated. The aim of this study was to investigate, with the use of a mouse endotoxin-induced uveitis (EIU) model, the neuroprotective effects of lutein against retinal neural damage caused by inflammation.. EIU was induced by intraperitoneal injection of lipopolysaccharide (LPS). Each animal was given a subcutaneous injection of lutein or vehicle three times: concurrently with and 3 hours before and after the LPS injection. Analysis was carried out 24 hours after EIU induction. Levels of rhodopsin protein and STAT3 activation were analyzed by immunoblotting. Lengths of the outer segments of the photoreceptor cells were measured. Dark-adapted full-field electroretinograms were recorded. Oxidative stress in the retina was analyzed by dihydroethidium and fluorescent probe. Expression of glial fibrillary acidic protein (GFAP) was shown immunohistochemically.. The EIU-induced decrease in rhodopsin expression followed by shortening of the outer segments and reduction in a-wave amplitude were prevented by lutein treatment. Levels of STAT3 activation, downstream of inflammatory cytokine signals, and reactive oxygen species (ROS), which are both upregulated during EIU, were reduced by lutein. Pathologic change of Müller glial cells, represented by GFAP expression, was also prevented by lutein.. The present data revealed that the antioxidant lutein was neuroprotective during EIU, suggesting a potential approach for suppressing retinal neural damage during inflammation.

Topics: Animals; Antioxidants; Disease Models, Animal; Electroretinography; Escherichia coli; Glial Fibrillary Acidic Protein; Immunoenzyme Techniques; In Situ Nick-End Labeling; Lipopolysaccharides; Lutein; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Neuroglia; Neuroprotective Agents; Oxidative Stress; Reactive Oxygen Species; Retinitis; Reverse Transcriptase Polymerase Chain Reaction; Rhodopsin; STAT3 Transcription Factor; Uveitis, Posterior

Inflammatory cytokines cause tissue dysfunction. We previously reported that retinal inflammation down-regulates rhodopsin expression and impairs visual function by an unknown mechanism. Here, we demonstrate that rhodopsin levels were preserved by suppressor of cytokine signaling 3 (SOCS3), a negative feedback regulator of STAT3 activation. SOCS3 was expressed mainly in photoreceptor cells in the retina. In the SOCS3-deficient retinas, rhodopsin protein levels dropped sooner, and the reduction was more profound than in the wild type. Visual dysfunction, measured by electroretinogram, was prolonged in retina-specific SOCS3 conditional knock-out mice. Visual dysfunction and decreased rhodopsin levels both correlated with increased STAT3 activation enhanced by SOCS3 deficiency. Interleukin 6, one of the inflammatory cytokines found during retinal inflammation, activated STAT3 and decreased rhodopsin protein in adult retinal explants. This was enhanced by inhibiting SOCS3 function in vitro, indicating that rhodopsin reduction was not a secondary effect in the mutant mice. Interestingly, in the inflamed SOCS3-deficient adult retina, rhodopsin decreased post-transcriptionally at least partly through ubiquitin-proteasome-dependent degradation accelerated by STAT3 activation and not transcriptionally as in the developing retina, on which we reported previously. A STAT3-dependent E3 ubiquitin ligase, Ubr1, was responsible for rhodopsin degradation and was up-regulated in the inflamed SOCS3-deficient retinas. These results indicate that in wild-type animals, a decrease in rhodopsin during inflammation is minimized by endogenous SOCS3. However, when STAT3 activation exceeds some threshold beyond the compensatory activity of endogenous SOCS3, rhodopsin levels decrease. These findings suggest SOCS3 as a potential therapeutic target molecule for protecting photoreceptor cell function during inflammation.

Topics: Animals; Down-Regulation; Interleukin-6; Mice; Mice, Mutant Strains; Photoreceptor Cells, Vertebrate; Proteasome Endopeptidase Complex; Retinitis; Rhodopsin; STAT3 Transcription Factor; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Ubiquitin; Ubiquitin-Protein Ligases; Vision, Ocular

Experimental autoimmune retinitis induced by immunization with rhodopsin was investigated in the Lewis rat using transmission electron microscopy and light microscopy. The first signs of retinitis consisted of scattered infiltrations of lymphocytes and other mononuclear cells, predominantly in the inner nuclear layer and outer plexiform layer. Occasionally, some macrophages were detected in the photoreceptor cell layer. Eyes exhibiting a clinically moderate or severe inflammation contained areas of normal retina coexistent with mildly to severely inflamed foci. The central retina was more frequently affected than the peripheral area. In moderately inflamed foci, macrophages infiltrated the photoreceptor cell layer, damaging and eliminating its structures. Inflammatory cells penetrated the photoreceptor outer segment layer which remained unaltered so far in spite of a high serum anti-(rhod)opsin antibody titer. In stages of severe inflammation, massive infiltrations of macrophages and polymorphonuclear cells destroyed the photoreceptor cells focally, leaving the retinal pigment epithelium virtually unaffected. Adjacent to these foci the pigment epithelial cells sometimes exhibited increased numbers of phagosomes and swelling. The locations of the cell infiltrations and lesions in progressive stages of development suggest that the rod outer segments are the target for the autoimmune damage. The described patterns of inflammation were compared with those of previous studies using other animal species and inciting antigens. Especially in rhodopsin-induced retinitis, the blood-retina barrier at the level of the Bruch's membrane/pigment epithelium appears to be highly resistant to cytotoxic cells. The present observations are in agreement with the concept that the cellular immune response plays a major role in the pathogenesis of (rhod)opsin-induced retinitis.

Topics: Animals; Autoantigens; Autoimmune Diseases; Female; Immunity, Cellular; Immunization; Macrophages; Microscopy, Electron; Photoreceptor Cells; Pigment Epithelium of Eye; Rats; Rats, Inbred Lew; Retina; Retinitis; Rhodopsin

The rod visual pigment, rhodopsin, and its illuminated form, opsin, were used to induce experimental autoimmune uveoretinitis in rats. Rhodopsin appears to be more pathogenic than opsin. A dose of 250 micrograms rhodopsin injected in Freund's complete adjuvant and pertussis adjuvant induces nongranulomatous inflammation with higher frequency, which starts earlier and is more severe than that induced by opsin. Two weeks postinjection, the mean score of rhodopsin-injected animals is more than twice as high as that of opsin-injected animals. The high pathogenicity of rhodopsin appears to be related to the biochemical integrity of the protein and depends on its state of illumination. The levels of the immune responses (both cellular and humoral) measured at day 10 postinjection do not account for the pronounced difference in pathogenicity between rhodopsin and opsin. The developmental patterns of severe uveoretinitis induced by rhodopsin or opsin were histologically evaluated and appear to be similar. In both cases we observed dense mononuclear and polymorphonuclear cell infiltrations in the retina and anterior uvea. Only in the severe stages does the choroid become involved. However, rhodopsin causes more pronounced involvement of the ciliary body, pars plana, and anterior chamber. The inflammation finally results in total elimination of the photoreceptor cell layer.

Topics: Animals; Autoimmune Diseases; Cattle; Eye Proteins; Female; Photoreceptor Cells; Rats; Rats, Inbred Lew; Retinal Pigments; Retinitis; Rhodopsin; Rod Opsins; Uveitis

We have studied the clinicopathological features of experimental autoimmune uveoretinitis (EAU) induced in Lewis rats by injection of different doses of rhodopsin and its illuminated form opsin. Rhodopsin consistently appears to be more pathogenic than opsin. Injected in Freund's complete adjuvant and pertussis adjuvant 50 micrograms of rhodopsin induces a frequency of severe EAU similar to 250 micrograms of opsin. Intensity, frequency and location of ocular inflammation are markedly dose dependent. At high dose (100-250 micrograms), rhodopsin induces severe bilateral uveoretinitis in all animals, which starts with acute inflammation of the anterior eye segment at day 10-12 followed by chorioretinitis (predominantly retinitis) which results in complete elimination of the photoreceptor cells. At low dose (20 micrograms), rhodopsin induces mild transient inflammation in 60% of the animals, mainly consisting of mild posterior retinitis which starts at day 20 and leads to a typical multiple focal destruction of the photoreceptor cells. Intermediate doses cause an intermediate type of disease. Omission of pertussis adjuvant lowers the frequency of severe disease at low doses of rhodopsin, delays its onset and changes its features. The last characteristic has been observed in particular at intermediate doses (50-100 micrograms). In these cases, EAU usually starts by cell infiltration of the vitreous, while the anterior segment is only mildly affected. Without pertussis adjuvant the pathogenicity of opsin is low. Even in both adjuvants severe EAU can only be evoked by a high dose of opsin. Although there exists a marked difference in uveitogenicity between rhodopsin and opsin, the immunogenicity is similar and seems not to be correlated with their pathogenicity.

Topics: Animals; Autoimmune Diseases; Dose-Response Relationship, Immunologic; Eye Proteins; Female; Rats; Rats, Inbred Lew; Retinal Pigments; Retinitis; Rhodopsin; Rod Opsins; Time Factors; Uveitis

Patients with acute and chronic central serous retinopathy (CSR) were studied by psychophysical and photochemical means to establish the extent of visual depression and to investigate the basis of rod dysfunction in this disorder. In acute disease with serous detachment of the retina, the loss of sensitivity attains 3 log units and parallels the height of retinal elevation as does its recovery with resolution of the episode. Immediately after resolution, there is a residual 0.5 log unit threshold elevation. In chronic disease, marked loss of function exists over areas of abnormal retinal pigment epithelium in the absence of clinically detectable serous detachment. Although rhodopsin levels are low in both acute and chronic CSR, this relative lack of visual pigment does not totally account for the functional deficits in either situation.

Topics: Fluorescein Angiography; Humans; Photoreceptor Cells; Retina; Retinal Detachment; Retinal Diseases; Retinitis; Rhodopsin; Visual Perception

In Vertebrate retinal rod outer segments, a soluble "48 K" protein binds to disk membranes upon illumination in presence of ATP or GTP (H. Kühn, Biochemistry, 17, 1978, p. 4389). Its binding to photoexcited rhodopsin implies a probable role of the "48 K" protein in the ATP dependent regulation of the photoinduced enzymatic cascade which controls the hydrolysis of cGMP. The "retinal S antigen" is also a soluble protein located in photoreceptor cells which is known to be an organ-specific auto-antigen inducing experimental autoimmune uveoretinitis. Using extracts of purified cattle and frog rod outer segments, purified bovine S antigen, and monoclonal antibodies against S antigen, we found that both proteins exhibit identical characteristics with respect to: their migration in SD S-gel electrophoresis; their binding to rod disc membranes upon illumination in presence of ATP or GTP; their immunological reactivity with monoclonal antibodies.

Topics: Animals; Antigens; Anura; Arrestin; Autoimmune Diseases; Cattle; Eye Proteins; Photic Stimulation; Photoreceptor Cells; Protein Binding; Retinal Pigments; Retinitis; Rhodopsin; Uveitis

24 different antigenic preparations from bovine or guinea pig retina and 3 from bovine uvea were tested for their ability to induce uveo-retinitis in guinea pigs. Each animal received one injection into the hind foot pads of 0.1 ml og the tissue preparation mixed with an equal volume of complete Freund's adjuvant. The intensity of the disease was assessed by clinical and histological criteria. Homogenates and extracts from whole guinea pig retina are more active than the same preparations from bovine retina. Autologous retinal extract is slightly more active than homologous in low doses. In bovine retina, the autoantigen(s) is localized in the photoreceptor structures and the pigment epithelium. Bovine uveal preparations seem to be inactive when the epithelium has been removed. Purified outer segments are very active, as well as soluble extracts of outer segments. Highly purified bovine rhodopsin has no immunopathogenic activity. A soluble autoantigen (autoantigen S) has been isolated by preparative isoelectrofocusing from retinas of several species. Autoantigen S from guinea pig induces the disease in guinea pigs at a dose of a few micrograms.

Topics: Animals; Antigens; Autoantigens; Autoimmune Diseases; Cattle; Disease Models, Animal; Eye Proteins; Freund's Adjuvant; Guinea Pigs; Isoelectric Focusing; Phosphoric Diester Hydrolases; Photoreceptor Cells; Pigment Epithelium of Eye; Retina; Retinitis; Rhodopsin; Solubility; Species Specificity; Uvea; Uveitis

Chorio-retinal lesions induced in guinea pigs after one inoculation of bovine rod outer segments (ROS) with complete Freund's adjuvant are described with light and electron microscopy. The auto-antigenic activity of different preparations from bovine retina and uvea is compared for their efficacy to induce the disease. ROS are much more active than total retina homogenate. Pigment epithelium is active, and the effect of choroid is impaired after removal of pigment epithelium from the surface of the choroid. Purification of ROS by several sucrose flotations does not reduce their activity. Almost complete extraction of soluble antigens from pure ROS by buffer washings, controlled with isoelectrofocusing and immunodiffusion, decreases only slightly their pathogenicity. Rhodopsin, extracted using cetyltrimethylammonium bromide from pure washed ROS, induced prominent chorio-retinal damage at the dose of 500 mug. It seems likely that besides soluble retinal auto-antigens, outer segments contain a pathogenic insoluble antigen which seems to be linked to rhodopsin or to be rhodopsin itself.

Topics: Animals; Autoantigens; Autoimmune Diseases; Cattle; Choroiditis; Epitopes; Guinea Pigs; Photoreceptor Cells; Retina; Retinitis; Rhodopsin; Solubility; Uveitis

An account is given of investigations into the mechanisms of dark-adaptation in the retina of man and of the skate and other fish. Working hypotheses as to the possible sites of abnormal function in the various disorders of which night blindness is a feature are presented.

Topics: Animals; Dark Adaptation; Electrophysiology; Electroretinography; Fishes; Humans; Night Blindness; Photoreceptor Cells; Retina; Retinitis; Rhodopsin; Vision Disorders