Nicholas J. Butler

Bystander effect produced by radiolabeled tumor cells in vivo

The bystander effect, originating from cells irradiated in vitro, describes the biologic response(s) of surrounding cells not directly targeted by a radiation insult. To overcome the limitations of in vitro tissue culture models and determine whether a bystander effect that is initiated by the in vivo decay of a radionuclide can be demonstrated in an animal, the ability of 5-[125I]iodo-2′-deoxyuridine (125IUdR)-labeled tumor cells to exert a damaging effect on neighboring unlabeled tumor cells growing s.c. in nude mice has been investigated. When mice are injected with a mixture of human colon LS174T adenocarcinoma cells and LS174T cells prelabeled with lethal doses of DNA-incorporated 125I, a distinct inhibitory effect on the growth of s.c. tumor (derived from unlabeled cells) is observed. Because (i) the 125I present within the cells is DNA-bound, (ii) ≈99% of the electrons emitted by the decaying 125I atoms have a subcellular range (<0.5 μm), and (iii) the overall radiation dose deposited by radiolabeled cells in the unlabeled cells within the growing tumor is <10 cGy, we conclude that the results obtained are a consequence of a bystander effect that is generated in vivo by factor(s) present within and/or released from the 125IUdR-labeled cells. These in vivo findings significantly impact the current dogma for assessing the therapeutic potential of internally administered radionuclides. They also call for reevaluation of the approaches currently used for estimating the risks to individuals and populations inadvertently exposed internally to radioactivity as well as to patients undergoing routine diagnostic nuclear medical procedures.

Adalimumab therapy for refractory uveitis: results of a multicentre, open-label, prospective trial

Objective Tumour necrosis factor (TNF) blockers have been demonstrated to be effective in the treatment of systemic and ocular inflammatory diseases. We conducted a prospective, multicentre, open-label Phase II clinical trial to assess the effectiveness and safety of adalimumab, a fully human anti-TNF monoclonal antibody, in treating refractory uveitis. Methods Subjects with non-infectious uveitis refractory to corticosteroids and at least one other immunosuppressive medication were enrolled. Treatment outcome was ascertained by a composite endpoint comprised of visual acuity, intraocular inflammation, ability to taper immunosuppressives, and posterior segment imaging. Clinical response was defined by improvement in at least one parameter, worsening in none, and well controlled intraocular inflammation. Week 10 responders were permitted to continue receiving adalimumab for the study duration of 50 weeks. Results Twenty-one of 31 patients (68%) were characterised as clinical responders at 10 weeks, of whom 12 patients (39%) exhibited durable response after 50 weeks. The most common reason for study termination was primary or secondary inefficacy. No patients experienced treatment-limiting toxicity clearly related to study therapy. Conclusions Adalimumab was safe and effective in 68% of refractory uveitis patients 10 weeks after study enrolment, and maintained in 39% after 1 year. Ongoing study is required to determine the place of adalimumab and other TNF blockers in the treatment of uveitis.

Ocular toxoplasmosis II: clinical features, pathology and management

The term, ocular toxoplasmosis, refers to eye disease related to infection with the parasite, Toxoplasma gondii. Recurrent posterior uveitis is the typical form of this disease, characterized by unilateral, necrotizing retinitis with secondary choroiditis, occurring adjacent to a pigmented retinochoroidal scar and associated with retinal vasculitis and vitritis. Multiple atypical presentations are also described, and severe inflammation is observed in immunocompromised patients. Histopathological correlations demonstrate focal coagulative retinal necrosis, and early in the course of the disease, this inflammation is based in the inner retina. For typical ocular toxoplasmosis, a diagnosis is easily made on clinical examination. In atypical cases, ocular fluid testing to detect parasite DNA by polymerase chain reaction or to determine intraocular production of specific antibody may be extremely helpful for establishing aetiology. Given the high seroprevalence of toxoplasmosis in most communities, serological testing for T. gondii antibodies is generally not useful. Despite a lack of published evidence for effectiveness of current therapies, most ophthalmologists elect to treat patients with ocular toxoplasmosis that reduces or threatens to impact vision. Classic therapy consists of oral pyrimethamine and sulfadiazine, plus systemic corticosteroid. Substantial toxicity of this drug combination has spurred interest in alternative antimicrobials, as well as local forms of drug delivery. At this time, however, no therapeutic approach is curative of ocular toxoplasmosis.

Clinical Features and Incidence Rates of Ocular Complications in Patients With Ocular Syphilis

PURPOSE To describe the clinical outcomes of ocular syphilis. DESIGN Retrospective chart review. METHODS The charts of patients with ocular syphilis (regardless of human immunodeficiency virus [HIV] status) seen in a uveitis referral center between 1984 and 2014 were reviewed. RESULTS The study included 35 patients (61 eyes). Panuveitis was the most common type of ocular inflammation (28 eyes), independent of HIV status. Thirty-three of 35 patients received systemic antibiotics with 24 patients treated with intravenous (IV) penicillin only. When compared to the HIV-positive patients, HIV-negative patients with ocular syphilis were older (P < .001), were more likely to be female (P = .004), and had poorer visual acuity at presentation (P = .01). During follow-up, the incidence rates of visual impairment were 0.29 per eye-year (EY; 95% confidence interval [CI]: 0.06/EY-0.86/EY) and 0.12/EY (95% CI: 0.01/EY-0.42/EY) among the HIV-negative and the HIV-positive patients, respectively. The incidence of blindness was 0.07/EY (95% CI: 0.009/EY-0.27/EY) and 0.06/EY (95% CI: 0.002/EY-0.35/EY) among the HIV-negative and the HIV-positive patients, respectively. Longer duration of uveitis prior to diagnosis and chorioretinitis in the macula at presentation were associated with ≥ 2 Snellen lines of visual loss (P < .01) and visual acuity loss to 20/50 or worse (P = .03) in HIV-negative patients, respectively. CONCLUSIONS Syphilis is an uncommon cause of ocular inflammation in both HIV-negative and HIV-positive patients. Visual loss and ocular complications were common among HIV-negative patients even with systemic antibiotic treatment. Delay of diagnosis and chorioretinitis in the macula were associated with visual loss in these patients.

Rituximab therapy for refractory scleritis: results of a phase I/II dose-ranging, randomized, clinical trial.

OBJECTIVE To determine whether rituximab, a monoclonal antibody against the B-lymphocyte antigen CD20, is effective in the treatment of refractory noninfectious scleritis. DESIGN Prospective, dose-ranging, randomized, double-masked phase I/II clinical trial. PARTICIPANTS Twelve patients with noninfectious scleritis refractory to systemic corticosteroid and ≥1 other systemic immunosuppressive agent were enrolled from January 2007 to March 2010. INTERVENTION Subjects were randomly assigned to 500 (n = 5) or 1000 mg (n = 7) dosing arms of rituximab intravenous infusions (500 or 1000 mg), given at study days 1 and 15. Initial responders with breakthrough inflammation after study week 24 were offered treatment with an additional cycle of 2 open-label rituximab 1000 mg infusions. MAIN OUTCOME MEASURES Primary outcomes were reduction of inflammation, as measured with a validated scleritis disease grading scale (SGS) and reduction in corticosteroid dose by ≥50%. Patients were characterized as responders to study therapy if ≥1 of these endpoints showed improvement and neither showed evidence of worsening. Secondary outcomes were improvement in visual acuity, reduction in pain, and improvement in patient and physician-reported global health assessment. RESULTS Of 12 enrolled patients, 9 met the SGS endpoint at or before week 24, and 4 additionally were able to reduce corticosteroid dose by ≥50%. With regard to secondary outcome measures, 11 and 9 patients showed improvement in patient and physician global health scores, respectively, and 7 patients had reduction in pain. Of 9 initial responders, 7 experienced breakthrough inflammation after 24 weeks and were treated with a second cycle of rituximab infusions. Four patients had significant objective or subjective worsening within 8 weeks of receiving rituximab; this event was averted in subsequent patients by treatment with peri-infusional oral corticosteroid. No other significant adverse events were noted. No differences in efficacy, toxicity, or likelihood of retreatment were noted between the dosing arms. CONCLUSIONS Rituximab was effective treatment for 9 of 12 enrolled patients with refractory, noninfectious scleritis at 24 weeks, although 7 required reinfusion with rituximab to maintain inflammatory control. The treatment was well-tolerated, and peri-infusional inflammatory exacerbations were managed successfully with oral corticosteroids. Further long-term studies are warranted to determine the safety and efficacy of rituximab in treating noninfectious scleritis and other ocular inflammatory diseases.

Ocular toxoplasmosis I: parasitology, epidemiology and public health

Ocular toxoplasmosis results from retinal infection with the protozoan, Toxoplasma gondii. This parasite, which exists as multiple clonal subpopulations and in three stages, is capable of replication in any nucleated cell of its primary feline or multiple paratenic hosts. Human seroprevalence of toxoplasmosis is high across the globe, but with geographic variation. While prevalence of ocular toxoplasmosis is not well documented, toxoplasmic retinochoroiditis is the commonest form of posterior uveitis in many countries. Correlation of parasite genotype with disease is an important area of new research. Ocular infection with T. gondii often follows ingestion of bradyzoites in undercooked infected meat. Oocysts may survive for an extended period in the environment, and water contaminated with oocysts is an important source in toxoplasmosis epidemics. Ocular toxoplasmosis is preventable by a combination of community activities and personal measures. Public health action is well justified by the considerable burden of congenital and postnatal infections.

Current status of HIV infection and ocular disease.

Purpose of review In the present era of highly active antiretroviral therapy (HAART), the challenges that HIV/AIDS patients face with regard to ocular complications has changed immensely; nonetheless, significant ocular morbidity persists. We present an update on these challenges, focusing particularly on the relevant literature from the past 12–18 months. Recent findings Although its incidence has decreased substantially in the HAART era, cytomegalovirus (CMV) retinitis remains an important cause of ocular morbidity and predictor of mortality. Presently, patients with less than 50 CD4+ T-cells/&mgr;L have an approximately equal risk of developing this potentially blinding ocular complication compared with the pre-HAART era. Less is understood about the current epidemiological considerations of ocular syphilis and HIV; however, patients with HIV may have increased likelihood of posterior syphilitic uveitis. Regarding the neuroretinal disorder associated with HIV, new ophthalmic imaging modalities are helping to uncover potentially associated structural alterations. Summary Future challenges in the fight against HIV/AIDS-related eye disease will involve identifying additional factors conferring increased risk of CMV retinitis, understanding the scope of ocular syphilis and other eye infections in HIV patients, and furthering our understanding of the structural changes in neuroretinal disorder as an indicator of other end-organ damage.

Consensus on the Diagnosis and Management of Nonparaneoplastic Autoimmune Retinopathy Using a Modified Delphi Approach

PURPOSE To develop diagnostic criteria for nonparaneoplastic autoimmune retinopathy (AIR) through expert panel consensus and to examine treatment patterns among clinical experts. DESIGN Modified Delphi process. METHODS A survey of uveitis specialists in the American Uveitis Society, a face-to-face meeting (AIR Workshop) held at the National Eye Institute, and 2 iterations of expert panel surveys were used in a modified Delphi process. The expert panel consisted of 17 experts, including uveitis specialists and researchers with expertise in antiretinal antibody detection. Supermajority consensus was used and defined as 75% of experts in agreement. RESULTS There was unanimous agreement among experts regarding the categorization of autoimmune retinopathies as nonparaneoplastic and paraneoplastic, including cancer-associated retinopathy and melanoma-associated retinopathy. Diagnostic criteria and tests essential to the diagnosis of nonparaneoplastic AIR and multiple supportive criteria reached consensus. For treatment, experts agreed that corticosteroids and conventional immunosuppressives should be used (prescribed) as first- or second-line treatments, though a consensus agreed that biologics and intravenous immunoglobulin were considered appropriate in the treatment of nonparaneoplastic AIR patients regardless of the stage of disease. Experts agreed that more evidence is needed to treat nonparaneoplastic AIR patients with long-term immunomodulatory therapy and that there is enough equipoise to justify randomized, placebo-controlled trials to determine if nonparaneoplastic AIR patients should be treated with long-term immunomodulatory therapy. Regarding antiretinal antibody detection, consensus agreed that a standardized assay system is needed to detect serum antiretinal antibodies. Consensus agreed that an ideal assay should have a 2-tier design and that Western blot and immunohistochemistry should be the methods used to identify antiretinal antibodies. CONCLUSIONS Consensus was achieved using a modified Delphi process to develop diagnostic criteria for nonparaneoplastic AIR. There is enough equipoise to justify randomized, placebo-controlled trials to determine whether patients with nonparaneoplastic AIR should be treated with long-term immunomodulatory therapy. Efforts to develop a standardized 2-tier assay system for the detection of antiretinal antibodies have been initiated as a result of this study.

Interferon alpha 2b in the Treatment of Uveitic Cystoid Macular Edema

Purpose: To determine the efficacy of interferon alpha 2b in the treatment of refractory, uveitic cystoid macular edema (CME). Methods: Retrospective chart review of 4 patients attending the uveitis clinic at the Casey Eye Institute, Oregon Health & Science University. Results: All 4 patients had uveitis and refractory CME, resistant to a variety of immunosuppressants. All patients, except one with severe scleral thinning, had tried and failed therapy with locally injected corticosteroids. Treatment with systemic interferon alpha 2b produced dramatic improvement in CME (central macular thickness: 563 to 267 µm, p = .002) and visual acuity (logMAR: +0.81 to +0.45, p = .0004) in all 4 cases. All patients have been able to reduce the interferon dosage, but none has discontinued it completely. All patients had some mild adverse response that did not necessitate stopping therapy. Conclusions: Interferon alpha 2b is an effective option to treat refractory CME secondary to uveitis.

Lack of Consensus in the Diagnosis and Treatment for Ocular Tuberculosis among Uveitis Specialists

Abstract Purpose: To assess the approach of specialists to ocular tuberculosis (TB). Methods: The American Uveitis Society (AUS) Listserv was surveyed using two clinical cases and general questions. Results: Of 196 members, 87 responded (44.4%), of whom 64 were affiliated with practices in North America, while 23 were outside of North America. The survey provided normative data on how physicians evaluate patients with uveitis as well as opinions about ocular TB. Responses varied widely on such issues as (1) the pretest probability that a patient with granulomatous panuveitis had TB uveitis (range 1–75%) or that a patient with a risk factor for TB had ocular TB (range 0–90%); (2) the optimal duration of anti-TB therapy; and (3) whether therapy should be discontinued after 2 months in nonresponders. Conclusions: Consensus is lacking among uveitis specialists for the diagnosis or management of ocular TB.