Prevention of nerve edema and increased blood-nerve barrier permeability-surface area product in galactosemic rats by aldose reductase or thromboxane synthetase inhibitors.

Nerve water content and the permeability-surface area product (PA) to [3H]-or [14C]sucrose at the blood-nerve barrier were determined in unanesthetized control rats fed a normal diet and in rats fed galactose with or without an aldose reductase inhibitor (Statil or AL 1576) or a thromboxane synthetase inhibitor (CGS 12970). Nerve water content was determined by taking the difference between dry and wet weights of whole tibial nerves. PA was determined by an intravenous bolus injection of radiotracer with multiple-time-point graphic and quantitative autoradiographic methods. The mean nerve water content in galactosemic rats was 15% higher than in control rats after 7-11 mo on the diet. Statil and AL 1576 prevented nerve edema, but CGS 12970 was only partially effective in preventing an increase in nerve water content in galactose-fed rats. In galactosemic rats, the mean PA to sucrose at the blood-nerve barrier, calculated from nerve dry weight, was twofold higher than in control rats. Treatment with Statil, AL 1576, or CGS 12970 prevented increased PA. Our results suggest that nerve edema and increased blood-nerve barrier PA are secondary to polyol production and can be prevented by inhibiting aldose reductase.

Biochemical characterization of a virus isolate, recovered from a patient with herpes keratitis, that was clinically resistant to acyclovir.

In vitro susceptibility assays of herpes simplex virus (HSV) do not necessarily correlate with treatment outcome. An HSV type 1 (HSV-1) isolate, N4, recovered from a patient who presented with herpes keratitis with localized immunosuppression, was characterized for susceptibility. Although the 50% inhibitory concentration (IC(50)) for this isolate was less than the accepted breakpoint for defining resistance to acyclovir (>2.0 microg/mL), the following lines of evidence suggest that the isolate was acyclovir resistant: (1) the clinical history confirmed that the infection was nonresponsive to acyclovir; (2) the in vitro susceptibility was similar to that of a thymidine kinase (TK)-negative, acyclovir-resistant virus SLU360; (3) the IC(50) of acyclovir was more than 10 times the IC(50) for an acyclovir-susceptible control strain; (4) plaque-purified clonal isolates were resistant to acyclovir (IC(50)s, >2.0 microg/mL); and (5) biochemical studies indicated that the HSV-1 N4 TK was partially impaired for acyclovir phosphorylation. Although residue changes were found in both the viral tk and pol coding regions of HSV-1 N4, characterization of a recombinant virus expressing the HSV-1 N4 polymerase suggested that the TK and Pol together conferred the acyclovir-resistance phenotype.

Retinal toxicity of intravitreal gentamicin. An electron microscopic study.

Retinal ultrastructure was examined at various intervals following a single intravitreal injection of 100-4,000 micrograms of gentamicin in rabbit eyes. Three days after injections of 100-500 micrograms, numerous abnormal lamellar lysosomal inclusions were observed in the retinal pigment epithelium (RPE) and in macrophages in the subretinal space. These changes were typical of drug-induced lipid storage and were comparable to inclusions reported in kidney and other tissues as manifestations of gentamicin toxicity. One week after similar injections, focal areas of RPE necrosis and hyperplasia with disruption of outer segments appeared, but the inner segments and inner retina were intact. Doses of 800-4,000 micrograms produced a combined picture of RPE/macrophage lipidosis within the first 3 days, with increasing, superimposed, inner, retinal necrosis. This study provides the first evidence of lysosomal alterations in ocular tissues following the intravitreal injection of gentamicin and implicates the RPE as the primary site of observed toxicity.

Role and expression of CD40 on human retinal pigment epithelial cells.

PURPOSE: To examine the CD40 costimulatory molecule expression on normal resting or activated adult human retinal pigment epithelium (hRPE) cells and to evaluate its role as an activation molecule considering the potential antigen presentation functions of hRPE cells. METHODS: Expression of HLA-DR and costimulatory (CD40, B7.1, B7.2, CD54, and CD58) molecules on hRPE cells was analyzed by flow cytometry. CD40 triggering was performed using soluble CD40L or cocultures with CD40L transfected fibroblasts. Interleukin (IL)-6, -8, -10, and -12 secretions were measured by enzyme-linked immunosorbent assay. Antigen presentation function of hRPE cells was assessed by coculturing hRPE cells with allogeneic T cells. T-cell proliferation was measured by [(3)H]-thymidine incorporation, and T-cell apoptosis by measurement of caspase-3 activity. RESULTS: Interferon (IFN)gamma-activated hRPE cells expressed CD40, but not B7.1 or B7.2. Although interferongamma enhanced IL-6 and IL-8 production, CD40 triggering of IFNgamma-activated hRPE cells did not induce IL-12 secretion. hRPE cells did not stimulate allogeneic resting T cells and downregulated phytohemagglutinin-activated allogeneic T cells via a cell-to-cell contact-dependent mechanism. Some induction of apoptosis was detected. CONCLUSIONS: CD40 is expressed on IFNgamma-activated hRPE cells. Its ligation leads to an increased production of IL-6 and IL-8 but fails to induce B7.1 or B7. 2 expression, or to induce IL-12 secretion. Accordingly, hRPE cells do not activate allogenic T cells but inhibit T-cell proliferation, partly through induction of apoptosis. These results suggest that hRPE cells could be implicated more in a deviant antigen presentation. If the exact molecular mechanisms are unclear, it is likely that CD40-CD40L interaction could play a role in this process.

Cryopexy enhances experimental autoimmune uveoretinitis (EAU) in rats.

Treatment of rat eyes with cryopexy enhanced the development of experimental autoimmune uveitis (EAU) in these eyes. The enhancement of EAU by cryopexy was particularly pronounced when the disease was induced by active immunization in rats of a low responder strain (Wistar Furth), or by adoptive transfer with lymphocytes sensitized against S-antigen. The disease enhancement was expressed by earlier onset of clinical symptoms and by more severe inflammatory changes. Histological examination of cryopexy-treated eyes showed focal necrosis and inflammation, confined to the affected sites. Immunohistochemical analysis of the inflammatory infiltration revealed it consists mainly of macrophages and T-lymphocytes of the helper and suppressor subsets. In addition, increased expression of class II antigens was observed in affected areas, on both inflammatory and resident ocular cells. Using electron microscopy and Evans blue angiography we could show breakdown of the blood-retinal barrier at the treated sites. Histological examination of eyes with EAU following cryopexy showed localization of the early inflammation at the injured site. The data are interpreted to suggest that the enhanced EAU in cryopexy-treated eyes is mainly due to the breakdown of the blood-retinal barrier, the accumulation of lymphoid cells and the increased expression of class II antigens, which facilitates antigen presentation.

Angiography with fluorescein-labeled dextrans in a primate model of uveitis.

Sequential fluorescein angiography, using fluorescein-labeled dextran molecules of several different sizes, was carried out in monkeys with intraocular inflammation induced with interphotoreceptor retinoid-binding protein. The vascular leakage seen with the dextrans was compared with that seen with standard fluorescein sodium angiography. The angiograms demonstrated that different-sized leaks appear in the retinal vessels in adjacent areas during the course of the inflammation. Most retinal vessels leaked only fluorescein sodium and no dextran of any size, suggesting that it is the unbound fluorescein that leaks out of these vessels and not fluorescein bound to plasma albumin. It was not possible to tell by clinical examination which areas would leak the larger-molecular weight tracers. Ultrastructural studies of the veins leaking the dextrans revealed areas of abnormal endothelial tight junctions, whereas the tight junctions were normal in areas where leakage occurred with fluorescein alone.

Multiple arterial ectasias in patients with sarcoidosis and uveitis.

PURPOSE: To describe and evaluate the cause of a clinical entity characterized by bilateral intraocular inflammation, multiple arterial ectasias including beading, macroaneurysms, comma-like ectasias and kinking, with vasculitis, staining of the optic disk and multiple peripheral round punched-out hypopigmented chorioretinal scars in elderly patients. The formation and the course of the arterial ectasias is analyzed. METHODS: Seven patients with this syndrome were evaluated by clinical examination, fluorescein angiography, and systemic investigations. RESULTS: Three of the seven patients had a biopsy characteristic of sarcoidosis, two others showed positive bronchoalveolar lavage, as well as other analyses and tests suggesting sarcoidosis, and two showed other findings suggestive of sarcoidosis. The patients were all over 60 years of age and had arterial hypertension. In two patients, an arterial ectasia developed at the site of previous focal inflammation. The macroaneurysms either remained unchanged, became comma-like ectasias, arterial kinks, or completely vanished. CONCLUSION: Elderly patients with multiple arterial ectasias, uveitis, disk staining, and peripheral chorioretinitis should be thoroughly investigated for sarcoidosis. We suggest that sarcoidosis may cause some degree of arteritis, which may weaken the arterial wall, with resulting ectasia. Arterial hypertension may play a role in the formation of the ectasias by increasing the pressure on the arterial wall weakened by inflammation.

Comparative toxicity of intravitreal aminoglycoside antibiotics.

We compared the toxicity of the aminoglycoside antibiotics (tobramycin, amikacin, netilmicin, and kanamycin) by ophthalmoscopy, light and electron microscopy, and electro-retinography after intravitreal injection in rabbits in doses ranging from 100 to 3,000 micrograms. The earliest manifestations of toxicity were confined to the outer retina with each drug, with lamellar lysosomal inclusions in the retinal pigment epithelium as the earliest finding. However, the aminoglycosides displayed marked differences in the threshold dose required to produce toxic reactions, permitting the following ordering of toxicity: (most toxic) gentamicin greater than netilmicin = tobramycin greater than amikacin = kanamycin (least toxic).

Chorioretinal post-transplant lymphoproliferative disorder induced by the Epstein-Barr virus.

BACKGROUND: The Epstein-Barr virus (EBV) is responsible for the lymphoproliferative disorders observed in transplanted patients. METHODS: The case history is described of a 59 year old man with a chorioretinal lesion who had received a single lung transplant and was on immunosuppressive treatment. Immunoglobulin gene rearrangement and EBV detection by polymerase chain reaction (PCR) with semiquantification were used on the vitreous material. RESULTS: A proliferation of B lymphocytes with a monoclonal subpopulation was found by PCR on the vitreous sample. The large amounts of EBV genomes found in the vitreous suggest that EBV was the cause of the lymphoproliferation. Healing of the lesion was achieved by a decrease in immunosuppressive treatment and the use of nucleotide analogues. CONCLUSION: The diagnosis of ocular post-transplant lymphoproliferative disorder (PTLD) can be made by PCR on vitreous material. Early diagnosis and treatment can lead to regression of limited monoclonal lesions.

Retinal pigment epithelial cells phagocytosis of T lymphocytes: possible implication in the immune privilege of the eye.

AIM: To investigate the capability of retinal pigment epithelium (RPE) cells to phagocytose T lymphocytes and to further analyse the immunobiological consequences of this phagocytosis. METHODS: Human RPE cells pretreated or not by cytochalasin, a phagocytosis inhibitor, were co-cultured with T lymphocytes for different time points. Phagocytosis was investigated by optic microscopy, electron microscopy, and flow cytometry. T cell proliferation was measured by (3)H thymidine incorporation. RPE interleukin 1beta mRNA expression was quantified by real time PCR. RESULTS: RPE cells phagocytose apoptotic and non-apoptotic T lymphocytes, in a time dependent manner. This is an active process mediated through actin polymerisation, blocked by cytochalasin E treatment. Inhibition of RPE cell phagocytosis capabilities within RPE-T cell co-cultures led to an increase of lectin induced T cell proliferation and an upregulation of interleukin 1beta mRNA expression in RPE cells. CONCLUSIONS: It is postulated that T lymphocyte phagocytosis by RPE cells might, by decreasing the total number of T lymphocytes, removing apoptotic lymphocytes, and downregulating the expression of IL-1beta, participate in vivo in the induction and maintenance of the immune privilege of the eye, preventing the development of intraocular inflammation.

CXCR4 expression in vitreoretinal membranes.

BACKGROUND/AIM: Proliferative vitreoretinopathy (PVR) and macular pucker (MP) vitreoretinal membranes are caused by abnormal cell migration. By their role in chemotactism, chemokine receptors represent good candidates to sustain this process. The authors thus investigated the expression of one of them, CXCR4, in these pathologies. METHODS: Three PVR and four MP membranes were surgically removed and processed for immunochemical studies with antibodies for CXCR4, cytokeratins or smooth muscle actin. RESULTS: CXCR4 expression was found in all membranes. There was no relation between severity of PVR or MP and presence of CXCR4. In addition, there was no difference in CXCR4 expression between MP and PVR. CONCLUSION: CXCR4 is expressed in PVR and MP. Further experiments are needed to test if CXCR4 and other chemokine receptors are implicated in vitreoretinal membrane formation.

Discontinuation of maintenance therapy for CMV retinitis in AIDS patients on highly active antiretroviral therapy.

The use of highly active antiretroviral therapy (HAART) has dramatically modified the natural history of cytomegalovirus retinitis (CMVR) in AIDS patients. In this context, we discontinued maintenance therapy in eight AIDS patients with previous CMVR and a good and persistent immune and virological response to HAART (CD(4) >/= 75/mm(3) in all patients, viral load

Neovascularization of the optic disc after highly active antiretroviral therapy in an AIDS patient with cytomegalovirus retinitis--A new immune recovery-related ocular disorder?

A patient with AIDS and cytomegalovirus (CMV) retinitis developed a massive bilateral peripheral occlusive vasculopathy with a bilateral neovascularization of the optic disc five weeks after the introduction of highly active antiretroviral therapy (HAART). No associate cause of occlusive vasculopathy was found. Occlusive vasculopathy and optic disc neovascularization may be an immune recovery-related ocular disorder.

Permeability of the blood-retinal and blood-aqueous barriers in galactose-fed rats.

Blood-retinal barrier (BRB) and blood-aqueous barrier (BAB) permeability were assessed by various methods to clarify conflicting reports on whether blood-retinal barrier permeability changes occur in diabetic and galactose-fed rats and to assess the potential role of aldose reductase in this process. Different molecular weight probes were utilized in rats fed for 7-11 months either a normal diet or a diet containing 50% galactose with/without the aldose reductase inhibitor AI1576 or Ponalrestat. BRB and BAB were assessed through radiolabelled sucrose permeability studies in eyes where the anterior segment was frozen during dissection compared to eyes where the anterior segments were not frozen and by quantitative autoradiography. In addition, histological studies using Evans Blue dye, microperoxidase and horseradish peroxidase were conducted. In untreated galactose-fed rats a 4-fold increase in the mean permeability surface area product (PA) to sucrose at the BRB was observed when the aqueous humor was not frozen during retinal dissection. However, no increase in the mean PA to sucrose was observed when the aqueous humor of similar eyes was frozen during dissection. Similarly, no retinal vessel permeability increase was observed by either quantitative autoradiography of [3H]-sucrose after 15 minutes of circulation or histological studies with microperoxidase, horseradish peroxidase or Evans Blue dye. Examination of the BAB revealed an increase in the permeability of iris vessels but not the ciliary body in galactose-fed rats which was reduced by treatment with the aldose reductase inhibitor AI1576. These data indicate that while BRB permeability is not increased in galactose-fed rats, BRB permeability measurements with isotopes are subject to possible contamination from the aqueous humor in untreated galactose-fed rats, which can result in false observations of increased BRB permeability.

[Treatment of uveitis with immunosuppressives: antimetabolites and alkylating agents]. / Traitement des uveites par les immunosuppresseurs: antimétabolites et agents alkylants.

Oral corticosteroids remain the main therapeutical choice in patients with uveitis not responding to topical treatment, however their chronic use can be very toxic, especially for bones (osteoporosis or growth retardation). Immunosuppresive agents are used as corticosteroid sparing agents and/or as agents able to control refractory uveitis in sight threatening uveitis. Cyclosporin A is very efficacious but is nephrotoxic, in particular in old people. Methotrexate is well tolerated in young people, is not carcinogenic but not very active. Azathioprine is well tolerated but it's carcinogenic effect and its delayed action are helpful in chronic uveitis of old women. Cyclophosphamide and intravenous steroids are helpful for emergencies. Chlorambucil is toxic and carcinogenic but might lead to an increased rate of remission and might be useful as a short treatment. In any case, a careful and regular follow-up in collaboration with a competent internist is mandatory.

[Progressive non-inflammatory lesions of the vitreous and intermediate uveitis]. / Trouble non inflammatoire progressif du vitré et uvéite intermédiaire.

A 77 year old man presented with a decreased vision, quite anterior segments, vitreous haze (++) (cells and flare) OD > OS, snow banks and snow balls at the inferior pars plana, suggesting an intermediate uveitis. Two subTenon injections of steroids were performed on the right eye, with improvement of his right visual acuity from 5 to 10/10. Cells and snow balls disappeared but the vitreous became more fluffy and more organized. Investigations did not demonstrate any systemic disease. The vitreous haze progressed bilaterally and failed to respond to systemic steroids. A year later, visual acuity was limited to hand movements (OD) and remained at 9/10 (OS). The vitreous haze + (OD) and ++ (OS) was extremely fluffy and moderately organized without inflammatory cells. Vitrectomy was performed in both eyes. Non inflammatory fibro-cellular membranes in a dense collagenous network with amorphous precipitates were observed in electron microscopy. One year later, he developed a systemic B-cell lymphoma. This unusual case illustrates the possible evolution of intermediate uveitis in a secondary PVR-like progressive non inflammatory vitreous haze with a particular increase of the amount of collagen fibrils and amorphous precipitates responsible for the fluffy aspect of the vitreous failing to respond to steroids.

[Ocular Behcet's disease: procedural aspects]. / Behçet oculaire: aspects pratiques.

The diagnosis of ocular Behçet is clinical. This affection is characterised by a bilateral anterior and/or posterior recurrent non granulomatous intraocular inflammation. The treatment consists in the use of one or several associated immunomodulators and immunosuppressors. In order to decrease the drug toxicity we prefer to increase the number of associated drugs than to increase the doses in severe resistant cases. The prognosis can be significantly improved by a very strict control of chronic inflammation and of each exacerbation. Interferon alpha could be a good new treatment in the future.

Endogenous mycotic endophthalmitis in an infant.

We report a case of atypical bilateral endogenous mycotic endophthalmitis in an infant. A diagnostic vitrectomy was done on the left eye. Electron microscope examination of the vitreous demonstrated fungal mycelia. Intravenous treatment with amphotericin B seemed effective for treating the infection of the right eye, but a vitrectomy was necessary to prevent deprivation amblyopia and retinal traction, secondary to persistence of a dense vitreous membrane.

[Intravenous corticosteroid megadose treatment in ocular Behçet disease]. / Traitement par mégadoses intraveineuses de corticoides dans l'atteinte oculaire de la maladie de Behçet.

Ocular Behçet's disease is characterized by a very poor visual prognosis. Twelve patients which had a maintenance treatment with immunosuppressors received 30 intravenous i.v. bolus of corticoids for uncontrolled severe retinal vasculitis (macular edema 58% of cases) and papillitis (100% of cases) (1 bolus treatment = 0.5-2 g of i.v. methylprednisolone once a day, for 3 days). In addition, oral immunosuppression was moderately increased in order to prevent further recurrences. Tolerance was good in all cases. Visual acuity (VA) remained stable or improved after one month in 87% of cases following the bolus treatment. In 92%, the VA remained stable or improved for a mean follow-up of 6 years. These good results suggest that intravenous bolus of steroids is a safe and efficient therapy which may prevent further decrease of the visual acuity and may reduce the side effects of the immunosuppressive treatment needed to control severe posterior uveitis in Behçet's disease.

[Chorioretinal lymphoproliferative disorder induced by Epstein-Barr virus in lung transplantation]. / Désordre lymphoprolifératif chorioretinien induit par le virus Epstein-Barr chez un greffe pulmonaire.

The Epstein-Barr virus (EBV) is the causative factor of the posttransplant lymphoproliferative syndromes. Some ocular cases were described. We report the case of a lung-transplanted 59 year old man who presented a chorioretinal lymphoproliferative syndrome. A B-cell monoclonality and numerous EBV genome copies were demonstrated in vitreous material by PCR. We suspect an intermediate stage between polyclonal lymphoproliferative syndrome and malignant lymphoma. A treatment with nucleoside analogs and immunosuppression decrease was successful. The positive clinical evolution was associated with a reduction of the EBV genome quantity.