Nouveaux concepts étiologiques dans l’uvéite

Uveitis remains an important cause of visual impairment, particularly in young patients. Idiopathic forms of intraocular inflammation should no longer be regarded as a presumed clinical entity, and the ophthalmologist must reconsider the specific etiology of primary uveitis when the clinical examination does not yield a definitive diagnosis or when the course of the disease on corticosteroids remains atypical. Laboratory tests based on serum analysis have limited value and should not be considered as diagnostic proof in different clinical presentations. The diagnostic management of infectious uveitis has been greatly improved by the use of molecular techniques applied to ocular fluids and tissues. Polymerase chain reaction (PCR) technology is a powerful tool that should be proposed in atypical cases of uveitis or retinitis of unclear but potentially infectious origin. This strategy is a major step before using unconventional and new immunomodulatory agents such as anti-TNF-alpha molecules. Under strict experimental conditions including adequate testing to rule out a possible contamination, PCR and its variants have changed our practical approach to intraocular inflammatory disorders and have provided new details for the understanding of infectious uveitis. The concept of pathogen-induced intraocular inflammation can be revisited in the light of molecular data obtained after anterior chamber paracentesis or diagnostic vitrectomy.

Prévention ophtalmologique de l’intoxication rétinienne induite par les antipaludéens de synthèse

INTRODUCTION

Antimalarial drugs induce severe retinal toxicity. The aims of this study were to evaluate the strategy of screening clinical and preclinical intoxication due to antimalarial agents in two centres of reference and to describe the results of ophthalmologic examination.

PATIENTS AND METHODS

Patients referred for ophthalmologic evaluation in connection with antimalarial agents therapy in the Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts from October 1999 to December 2000 and in the Hôpital Lariboisière from January 1995 to December 1998 were investigated. A retrospective review of results of ophthalmologic examination, electroretinogram, electro-oculogram, colour vision test and central visual field was conducted to assess retinal intoxication.

RESULTS

Among 705 patients recruited in the Centre des Quinze-Vingts, 10 out of 133 who were never treated had an electrophysiological contra-indication to the treatment. Among the 572 other patients, 31 presented with preclinical intoxication (5.4 p. 100) and 8 other patients presented with clinical intoxication. Among 925 patients recruited in the Hôpital Lariboisière, 37 presented with preclinical intoxication (4 p. 100) and four patients presented with clinical intoxication.

DISCUSSION

The antimalarial drugs clinical intoxication is rare but nevertheless real. Screening for preclinical intoxication can prevent the evolution toward irreversible retinal intoxication. Diagnosis of preclinical intoxication is established through the confrontation of results of different tests and their evolution. The multifocal electroretinogram remains to be evaluated.

CONCLUSION

Ophthalmologic monitoring including funduscopy, should be recommended at least once a year. Visual field seems to become interesting in the screening. Electroretinogram and electro-oculogram remain useful quantitative and obvious tests. A prospective study to assess the optimal way to prevent retinal intoxication is mandatory.

Névrite optique rétrobulbaire associée au traitement par infliximab

Infliximab is a chimeric human-murine monoclonal antibody of the IgG1 type with a high affinity and specificity for tumor necrosis factor alpha (TNFalpha). Infliximab was used in Crohn disease, rheumatoid arthritis, spondyloarthropathy, juvenile idiopathic arthritis, Behcet's disease, Wegener's granulomatosis, HLA-B27-associated uveitis and chronic severe refractory uveitis. Reported adverse effects of this treatment were infections, development of antinuclear antibodies and anti double-stranded DNA, lymphomas, and exacerbation of demyelinating disease. We report a case of infliximab-associated optic neuritis with favorable outcome after systemic steroid treatment.

Necrotising retinopathies simulating acute retinal necrosis syndrome

AIM

To determine an aetiological diagnosis in patients presenting with necrotising retinopathies that simulate acute retinal necrosis (ARN).

METHODS

Retrospective non-comparative case series. The charts of 16 patients presenting with a clinical impression of ARN at Pitie-Salpetriere Hospital, Paris, France, between 1994 and 1999, who required initial antiviral therapy were reviewed. All of the patients had extensive laboratory tests. Anterior chamber paracentesis was performed on 14 patients and evaluated by polymerase chain reaction (PCR) and/or the Witmer-Goldmann coefficient to determine the cause of retinitis. Three of the 14 cases also had diagnostic vitrectomy. Responses to specific treatment, initiated based on laboratory results, and the final outcome were evaluated.

RESULTS

Seven of the 16 patients were female and nine were male. The retinitis was bilateral in five patients and unilateral in 11 patients. The average age of the patients at presentation was 53.6 years. 13 patients were immune deficient for various reasons. Upon initial presentation, the patients' visual acuities were less than 20/200 in 68% of the affected eyes. The final diagnoses, based on laboratory data and therapeutic response were toxoplasmic retinochoroiditis (62.5%), syphilitic retinitis (12.5%), aspergillus endophthalmitis (12.5%), Behcet's disease (6.2%), and intraocular lymphoma (6.2%). Visual acuity was stabilised or improved in 12 patients (75%). Two patients with aspergillosis died despite antifungal therapy.

CONCLUSIONS

Toxoplasmic retinochoroiditis is the major cause of retinal necrosis that simulates ARN, and PCR analysis of the aqueous humour is helpful in establishing the diagnosis. Such atypical toxoplasma retinochoroiditis may be associated with poor visual outcome.

Lymphome oculaire de type MALT simulant une sclérite ou une uvéite postérieure

PURPOSE

Diagnostic and therapeutic management of masquerade syndromes associated with MALT-type lymphoma.

PATIENTS AND METHOD

We report the cases of three patients referred for acute or chronic severe loss of visual acuity. All of them suffered from uveitis or scleritis resistant to corticoid treatment. Each one had posterior uveitis associated with retinochoroidal infiltration, anterior scleritis associated with uveal effusion syndrome, or bilateral pan-uveitis associated with serous retinal detachment. Two patients had medical records of systemic malignancies. They underwent an extensive work-up. Search for an infectious, immune or malignant disease was negative but orbital imaging showed a posterior scleral thickening in all cases.

RESULTS

Diagnosis of mucosa-associated lymphoid tissue (MALT) ocular lymphoma was assessed in all cases after scleral biopsy. Immunohistochemical analysis showed CD20(+) and CD5(-) scleral lymphocyte infiltrates. The three patients underwent chemotherapy associated with radiotherapy. Lesions were stabilized in the first case, whereas six lines of visual acuity improvement was noted in the second one, and full recovery was achieved after treatment in the third case.

DISCUSSION

Clinical manifestations of this ocular lesion seem to be multiple, masquerading as different types of posterior uveitis or scleritis. In the three cases, we did found other systemic locations of MALT-type lymphoma. Diagnosis was mainly based on pathological analysis. Fast visual recovery in two cases demonstrated the importance of an early diagnosis and a specific treatment. All cases of chronic and corticoid-resistant posterior uveitis require a specialized radiological evaluation followed, if necessary, by multiple orbital biopsies.

Infliximab in refractory uveitis due to Behçet's disease

OBJECTIVE

To report 4 cases of refractory panuveitis due to Behçet's disease treated with a novel therapy: infliximab.

METHODS

Retrospective study of 3 women and 1 man of Causasian origin with Behçet's disease complicated with panuveitis. Their uveitis was relapsing from 48 to 96 months and was resistant to the combination of colchicine (n = 4), high-dose prednisone (n = 4), pentoxyphilline (n = 2) and various immunossuppressors and/or immunomodulators given successively: intravenous cyclophosphamide (n = 4), azathioprine (n = 3), interferon alpha (n = 3), cyclosporine A (n = 2), oral cyclophosphamide (n = 1), mycophenolate mofetil (n = 1), methotrexate (n = 1), high-dose immunoglobulin (n = 1). Combination with respectively 1, 3, 4 and 5 immunossuppressors and/or immunomodulators failed before institution of infliximab. After informed consent was obtained, infliximab was administered as a single infusion of 5 mg/kg (maximum dose: 400 mg) at day 1, at week 2, 6 and then every 8 weeks.

RESULTS

With a follow-up ranging from 7 to 22 months, infliximab was efficient in all cases. The mean prednisone dose decreased from 45 mg to 13 mg daily. Total recovery of visual acuity was observed in half of the cases. Infliximab was well tolerated without fever, severe sepsis or autoimmune manifestation.

CONCLUSION

Infliximab may be efficient in refractory uveitis due to Behçet's disease. The optimal dose, rhythm and duration of infliximab infusions need to be standardized.

Les uvéites virales

Viral eye diseases are common and associated with different well-known forms of uveitis. However, experimental models and clinical observations have led to an infectious, in particular a viral etiology in different autoimmune conditions. The use of molecular techniques is particularly informative, not only to characterize the previously well-known subgroup of presumed viral uveitis, but also to define the role of these agents or emerging viruses in atypical forms of autoimmune uveitis resistant to conventional therapy. PCR detection of viral DNA in patients with uveitis is a rapid, sensitive and accurate procedure. Therefore, aqueous humor could be analyzed when uveitis is unresponsive to anti-inflammatory molecules, in order to exclude a viral condition and dramatically modify the therapeutic management. Several new viral entities have recently been identified such as cytomegalovirus-associated chronic anterior uveitis and non-necrotizing herpetic retinopathies in immunocompetent hosts. Systemic antiviral drugs should be proposed rapidly in order to control viral replication before the use of corticosteroids. Maintenance therapy based on low-dose antivirals can reduce the rate of recurrence and should be considered.

Prise en charge diagnostique et thérapeutique des rétinites nécrosantes herpétiques

PURPOSE

To study the viral cause and present the management of necrotizing herpetic retinopathies.

METHODS

Charts of patients presenting with acute retinal necrosis (ARN) or progressive outer retinal necrosis (PORN) diagnosed between March 1997 and June 2001 were retrospectively reviewed. Intraocular specimens were obtained in 33 cases to determine the viral cause using polymerase chain reaction-based assays and/or detection of intraocular antibody production.

RESULTS

The mean age was 43.4 Years. Herpesvirus genome was identified in 29 patients (80.5%). In the ARN group (32 patients, 38 eyes), herpes simplex virus (HSV) DNA was found in 11 patients (34.4%), varicella-zoster virus (VZV) in nine patients (28.1%), and cytomegalovirus (CMV) in four patients (12.5%). One patient (3.1%) presented an Epstein-Barr virus (EBV) infection. ARN was bilateral at initial examination in six patients and secondary bilateralization was observed in four patients. In the PORN group (four patients, eight eyes), the retinitis was bilateral and VZV DNA was detected in all cases. Two patients were treated with intravenous acyclovir, six with foscarnet alone, ten with intravenous foscarnet + acyclovir, 18 with intravenous foscarnet and intravitreous ganciclovir injections. Complications of necrotizing herpetic retinitis were cataract (26%), optic nerve atrophy (23.9%), and retinal detachment (17.4%). Final visual acuity was less or equal to 20/200 in 47.8% of cases.

CONCLUSIONS

It is important to determine the specific viral etiology since progression and prognosis may be different in herpetic necrotizing retinitis caused by HSV, VZV, or CMV. Visual prognosis is improved by intensive antiviral therapy, but remains poor if complications occur.

Uvéites chroniques sévères : classification, démarche diagnostique et principes thérapeutiques

PURPOSE

Severe chronic and refractory uveitis is a major diagnostic and therapeutic challenge for ophthalmologists and internists. Molecular tools, such as PCR but also new imaging techniques, have significantly changed the diagnostic approach during the last 10 years. Presumed and empirical diagnosis should be excluded in the face of atypical clinical presentations.

CURRENT KNOWLEDGE AND KEY POINTS

A retrospective study based on 927 consecutive patients presenting with severe uveitis between 1991-1996, has recently defined the epidemiological characteristics and the visual outcome of this group of patients. An associated condition was determined in 67.5% of cases, divided in 4 different subgroups: infectious uveitis; uveitis associated with a systemic disease; eye-limited, presumed immune-mediated disorder and idiopathic eye-limited disorder. The management of patients with sight-threatening forms of uveitis is efficiently performed in collaboration with internists and depends on a complete diagnostic procedure and a well-adapted treatment.

FUTURE PROSPECTS AND PROJECTS

Extensive work-up is mandatory when the therapeutic response seems atypical with resistance to corticosteroids and classical immunosuppressive drugs. Infectious uveitis should be excluded in severe and intractable forms of uveitis. Thereafter, new therapeutic strategies based on type I interferon and anti-TNF molecules can be proposed in order to decrease the potential risk of blindness in this young group of patients.

[Extensive toxoplasmic retinochoroiditis. Diagnostic and therapeutic management]

INTRODUCTION

To assess the diagnostic and therapeutic management of extensive toxoplasmic retinochoroiditis.

PATIENTS AND METHODS

The files of all patients referred between December 1999 and December 2001 for the management of a severe, potentially sight-threatening toxoplasmic retinochoroiditis were retrospectively analyzed. The therapeutic strategy and the progression of intraocular inflammation are reported.

RESULTS

Thirteen eyes of seven patients were finally included in the study. The sex ratio (F/M) and the mean age were respectively 4/3 and 44.5 years. Most of the patients were immunocompromised. Both eyes were initially affected in five cases. The diagnosis was confirmed by polymerase chain reaction (PCR) after anterior chamber paracentesis in six cases. Retinal detachment was observed in three cases, initially or during follow-up. All patients were treated with a combination of sulfadiazine and pyrimethamine, but azithromycin was necessary in two cases. Clindamycin was used in two cases of allergy to sulfadiazine. Corticosteroids were associated in five cases. For all patients, infection and inflammation were finally controlled. The visual acuity improved more than two lines in four eyes and remained stable in seven other eyes.

DISCUSSION

Clinical diagnosis is still a challenge in severe cases of extensive toxoplasmic retinochoroiditis. PCR is helpful in identifying Toxoplasma gondii DNA. A systemic immunosuppression is frequently associated with a positive PCR. Treatment is based on a standard antiparasitic association and steroids must be discussed for each case according to the intensity of inflammation and the degree of immunosuppression.

CONCLUSION

Extensive ocular toxoplasmosis is a serious condition. The final prognosis depends on the location of the necrotic lesions, rapid diagnosis, and efficient treatment.

Diagnostische Vitrektomie bei Uveitis

Recent developments in molecular biology allow novel diagnostic approaches in intraocular inflammation. Genetic markers as well as species-specific sequences are used for the diagnostics of infection or masquerade syndromes. This article provides state-of-the art information about diagnostic vitrectomy.

Polymerase chain reaction analysis of aqueous humour samples in necrotising retinitis

AIM

To evaluate the diagnostic value of polymerase chain reaction (PCR) performed on aqueous humour for the detection of viral DNA in patients with necrotising herpetic retinitis.

METHODS

The clinical features and laboratory results of 22 patients (29 eyes) presenting with necrotising herpetic retinitis between March 1999 and June 2001 were reviewed retrospectively. Aqueous humour was obtained after anterior chamber paracentesis and PCR was performed in all cases.

RESULTS

Viral DNA was detected in the aqueous humour of 19 patients (86.4%). Epstein-Barr virus (EBV) seroconversion was evidenced in one additional patient. In the acute retinal necrosis (ARN) group (n = 19), varicella zoster virus (VZV) DNA was identified in six patients, herpes simplex virus 1 (HSV-1) DNA in two patients, herpes simplex virus 2 (HSV-2) DNA in four patients, and cytomegalovirus (CMV) genome in four patients. In the progressive outer retinal necrosis (PORN) group (n = 3), VZV DNA was detected in all patients. No sample was positive for more than one virus.

CONCLUSIONS

PCR analysis of aqueous humour in patients with clinical features of necrotising viral retinitis can provide specific aetiological orientation and the method appears to be safe and highly sensitive.

[Intraocular pressure elevation after subtenon injection of triamcinolone acetonide during uveitis]

INTRODUCTION

New therapeutic concepts in the management of ocular inflammation have led to the development of periocular and intravitreal injections. Such treatment modalities can induce intraocular pressure elevation.

PATIENTS AND METHODS

Periocular injections have been given to patients suffering from strictly unilateral or bilateral but asymmetrical and noninfectious posterior uveitis. A history of corticosteroid-induced glaucoma was a contraindication to such treatment. A retrospective review of cases who were given subtenon triamcinolone acetonide injection between May and October 2001 was undertaken to evaluate the efficacy of the treatment and the risk of intraocular pressure elevation. Ocular pressure was measured before and after the injection and the efficacy of the treatment was evaluated by measurements of visual acuity and fluorescein angiography.

RESULTS

One or several injections were given to 61 patients. Intraocular pressure rose in 13 patients (21.3%). Medical treatment was unsuccessful in three cases and surgical excision of periocular corticosteroid deposit was required. Therefore, intraocular pressure was controlled with no other medication. Treatment was considered effective in 32 patients (52.45%): improvement of visual acuity (more than two lines) or control of inflammation on fluorescein angiography.

DISCUSSION

and conclusions: Periocular subtenon injection of triamcinolone acetonide in posterior noninfectious uveitis is a safe procedure. Intraocular pressure elevation is not frequent and can be controlled through medical treatment or surgical excision of a residual deposit, in which pharmacologically active triamcinolone can be present several months after the injection.

[Total eclipse of the sun in August 11, 1999: a program of prevention and surveillance of ocular complications]

Watching directly at the sun without appropriate protection, particularly during a solar eclipse, can cause severe retinal injuries. On 11 August 1999, a total solar eclipse crossed France. The Direction Générale de la Santé implemented a prevention strategy. A formal agreement was developed with manufacturers and importers of protective glasses and more than 30 million glasses, conformed with safety standards, were distributed in France. Information campaign reach the whole population in France. In order to evaluate the impact of this campaign, The National Institute of Public Health in France implemented a nation-wide surveillance of ocular complications related to the eclipse. Information on patients was collected using a standardised questionnaire. The questionnaire was sent to the 5,600 private and public sector ophthalmologists practising in France and to five hundred hospital emergency units. A total of 147 patients were reported to have had a retinal injury associated with viewing the eclipse. Seventeen cases were severe (visual acuity < 2/10th) of whom 7 had bilateral injury. Forty-four per cent of patients were aged 15 to 29 years and 46% viewed the eclipse in three regions in the south of France which were sunny on 11th August. One hundred and six patients (67% aged 30 years and more) presented with keratitis. Thirty-six per cent occurred in 2 northern regions of France, which were overcast on the day. A hundred patients watched the whole eclipse without any protection, 74 reported to have removed their EC glasses, and 32 used non-appropriate devices. Only 4 patients presenting with retinal injury reported having used the EC glasses the whole time whilst viewing the eclipse. France is the only country in Europe to have implemented an exhaustive prospective surveillance of ocular injuries related to the solar eclipse. According to current data, the quality and availability of EC glasses did not contribute significantly to ocular injuries. Clinical and epidemiological studies are being conducted in order to further document the evolution of patients presenting with retinal injuries, the circumstances of observation, and their comprehension of preventive messages.

[Current status of retinal detachment in AIDS patients]

Cytomegalovirus retinitis is the most common opportunistic ocular infection in patients with AIDS affecting 30 to 40% of the patients. It usually occurs in patients in the terminal stage of the disease presenting with low CD4+ count (<50/mm(3)). Retinal detachment (RD) is a frequent complication of this disease, with an incidence varying from 18% to 29%. Risk factors for development of rhegmatogenous RD in patients with CMV retinitis were peripheral involvement greater than 25%, the presence of active retinitis, greater patient age and lower CD4+ cell counts. Multiple or single holes, as well as micro holes, were observed in areas of retinal necrosis leading to complex retinal detachments. Strong vitreoretinal adherences in these young patients, associated with chronic inflammation, were important elements in the pathophysiology of retinal detachment in AIDS patients. For localized RD, demarcating laser photocoagulation may delayed or avoided vitreoretinal surgery. For RD with macula off, good anatomical results have been obtained by repairing CMV retinitis-related retinal detachments using primary vitrectomy and instillation of silicone oil. Despite good anatomical results, poor long term functional results are related to optic atrophy. Since the introduction of highly active antiretroviral therapy (HAART), retinal detachment incidence has nevertheless dramatically decreased. Under HAART, CMV retinitis remains quiescent for long periods of time with a reduction of retinal detachment incidence of approximately 77%. For some patients on HAART, retinal reattachment can be obtained using vitrectomy, posterior hyaloid removal, and intraocular tamponade with SF-6 gas.

Efficacy of interferon alfa-2a in severe and refractory uveitis associated with Behçet's disease

PURPOSE

To evaluate the efficacy of interferon alfa-2a (IFN alfa) in severe uveitis associated with Behçet's disease, that is refractory to steroids and conventional immunosuppressive agents.

PATIENTS AND METHODS

Patients with Behçet's disease (according to the International Study Group criteria), who relapsed despite steroids and immunosuppressive agents, were included in this retrospective study. Ophthalmological examination, laser flare photometry, and fluorescein angiography associated with laboratory tests were performed at regular intervals. IFN alfa (3 millions units thrice a week) was injected subcutaneously.

RESULTS

Eight patients (sex ratio: 1) were included between May 1995 and January 1999. The mean age was 29.1 years (14-54 years) and the disease was present between 11 and 167 months before the administration of IFN alfa. IFN alfa was efficient in all cases with a mean follow-up of 22 months (10-55 months). Steroids were tapered from a mean dosage of 47 mg/d to a mean dosage of 8.5 mg/d. Ocular inflammation was controlled and visual acuity improved in all cases. Treatment was generally well tolerated despite a constant but transient flu-like syndrome. IFN alfa was tapered in three patients and stopped in one case without any relapse after five months.

CONCLUSIONS

Within the limitations of this retrospective study, low-dose IFN alfa seems to be well tolerated, promising in the management of refractory forms of uveitis due to Behçet's disease, and effective in allowing a reduction of steroid dosage. A prospective controlled study is necessary to confirm these preliminary results.

Ocular tuberculosis

Despite the use of highly sensitive molecular tools, such as polymerase chain reaction, for the detection of Mycobacterium tuberculosis, ocular tuberculosis remains a subject of controversy. The diagnosis is often presumptive in the absence of ocular biopsies. Choroiditis is the most common ocular manifestation in patients with pulmonary and systemic tuberculosis. Indocyanine green angiography seems to be an interesting method to determine choroidal involvement. PCR technology is proposed to evaluate the presence of the tubercule bacillus DNA in ocular fluids and tissues when conventional microbiologic methods fail to confirm a bacterial etiology. Most of the presumed cases of ocular tuberculosis should be treated with associations of antituberculous drug, especially when a systemic steroid regimen is required.

Ocular and central nervous system lymphoma: clinical features and diagnosis

PURPOSE

To evaluate the clinical, angiographic, and cytopathologic features of ocular and central nervous system (CNS) lymphoma.

PATIENTS AND METHODS

Retrospective study of 44 patients over a 10-year period.

RESULTS

A total of 36 women and six men, mean age 54 years (range: 36-90 years), were included. The mean time interval between onset of ocular symptoms and diagnosis was 40 months (range: 1-144 months). Ocular involvement was bilateral in 84% of the cases. Laser flare photometry readings averaged 9.6 photons/ms (2.9-78.3 photons/ms). Vitritis was constant. Funduscopy revealed RPE abnormalities in 60.49% of the cases and punctuate retinal infiltrates in 33.5%. The most common findings with fluorescein angiography were window defects and hypofluorescent round lesions. Patients had CNS involvement in 66% of the cases. Cytologic examination of the vitreous samples showed high-grade B lymphoma in 86% of the cases. Interleukin-10 dosage, when performed, showed elevated levels averaging 2352 pg/ml in all vitreous samples. Molecular biology based on PCR confirmed the diagnosis in 12 patients. Treatment included systemic chemotherapy alone or associated with radiotherapy in various regimens. Fourteen patients died during follow-up. Only 12 patients were in complete remission.

CONCLUSION

The prognosis of the disease remains poor. However, the new diagnostic tools and therapeutic strategies may improve the diagnostic delay and the survival outcome.

Acyclovir-resistant bilateral keratitis associated with mutations in the HSV-1 thymidine kinase gene

PURPOSE

To evaluate the contribution of molecular methods for the diagnosis of an acyclovir-resistant HSV-1 bilateral keratitis in an AIDS patient and to report a new point mutation in the nucleotide sequence of the thymidine kinase (tk) gene involved.

METHODS

A 31 year old HIV-positive female presented with severe, active, bilateral and sight-threatening keratitis of 6 months duration, which was treated unsuccessfully with acyclovir. After corneal biopsy, samples were analysed by standard virological procedures, in situ hybridization, and PCR. The tk gene was cloned and subsequently sequenced.

RESULTS

Conventional virological methods remained inconclusive. However, in situ hybridization and PCR rapidly confirmed the diagnosis of HSV-1 keratitis. The tk gene sequence revealed the presence of five variations previously described in two reference strains, but also a new point mutation at nucleotide position 431 which leads to an amino-acid change at position 144 that supported the hypothesis of a putatively altered functional form of the enzyme. Intravenous foscarnet treatment in an induction regimen was effective and cicatrization occurred within 3 weeks.

CONCLUSIONS

PCR and in situ hybridization are effective and powerful techniques when other virological procedures are non-contributive, particularly in immunocompromised patients previously treated with antiviral drugs. The new point mutation identified in the tk gene may be associated with resistance to acyclovir.

Cytomegalovirus: virological facts for clinicians

Human cytomegalovirus (HCMV) is a complex DNA virus encoding more than 200 viral proteins. This highly adapted opportunist agent has developed several ways to evade the immune system. Among all clinical features due to HCMV, retinitis occurs especially in severely immunosuppressed patients, particularly during the end phase of HIV infection. Highly active antiretroviral therapy (HAART) has significantly reduced the incidence of this complication. However, in this HAART era, we observe the emergence of new clinical patterns in patients presenting with cicatricial HCMV retinitis. These patterns could be potentially related to immune mechanisms directed against viral antigens expressed at the surface of retinal cells that are still latently infected without any viral replication. We used a model of human retinal pigment epithelial (RPE) cells to evaluate virus-host interactions in the presence of different cytokines in the eye which play a major role in immunological or infectious conditions. Two different enzymatic pathways seem to be particularly involved during infection. Lack of tryptophan and production of nitric oxide seem to block HCMV replication in RPE cells. We propose a model to explain some of the mechanisms involved during severe immunosuppression and also after immune recovery.

CMV retinitis in the era of HAART

Since 1996, major advances in the treatment of AIDS have markedly changed the incidence and the prognosis of CMV retinitis. Highly active antiretroviral therapy (HAART) is a combination of nucleoside reverse transcriptase inhibitors and protease inhibitors. This new therapeutic strategy is highly efficient in reducing the HIV viral load and increasing CD(4)+ T-lymphocyte count. These biological effects are associated with an improvement of immune functions. Clinically, the completely quiescent CMV retinitis and the unusual prolonged relapse-free interval suggest a certain restoration of immune functions, making possible the discontinuation of maintenance therapy. For most authors, the decision to stop anti-CMV maintenance therapy is based on a CD4+ cell count >100 cells/microl with a low HIV viral load for at least four months. The improvement of CMV retinitis on HAART may also be associated with an intraocular inflammation called immune recovery vitritis. For some patients, this vitritis may be associated cystoid macular edema and an epiretinal membrane responsible for visual loss.

Entry of human cytomegalovirus into retinal pigment epithelial and endothelial cells by endocytosis

PURPOSE

Human retinal pigment epithelial (RPE) cells and endothelial cells (HUVECs) are targets of human cytomegalovirus (HCMV) infection in vivo with significantly protracted replication in vitro compared with that in fibroblasts. This study analyzes the kinetics and mechanisms of HCMV entry into both cell types.

METHODS

RPE cells were obtained from donor eyes. HUVECs were isolated from human umbilical cords. HCMV entrance was followed by electron microscopy and immunofluorescence in the presence of lysosomotropic agents and cytochalasin B.

RESULTS

Human cytomegalovirus entered into RPE cells and HUVECs as early as 5 minutes after virus- cell contact. Entry was mediated by endocytosis, whereas HCMV enters fibroblasts through fusion. Most internalized viral particles and dense bodies appeared to be degraded within vacuoles. Viral entry, transport of viral proteins to the nucleus, and onset of viral transcription (immediate early [IE] protein expression) were significantly blocked by cytochalasin B. Lysosomotropic agents did not significantly reduce IE expression in RPE cells or HUVECs.

CONCLUSIONS

This study shows that HCMV penetrates these highly specialized relevant cells via endocytosis. The low level of infection and the delay in the onset of HCMV expression seen in these cells compared with fibroblasts may be related to the sequestration and degradation of incoming viral particles in endocytic vacuoles.

Kinetics of transcription of human cytomegalovirus chemokine receptor US28 in different cell types

In permissive cells, human cytomegalovirus encodes the protein US28, a functional CC chemokine receptor. US28 polyadenylated mRNA could be detected by RT-PCR as early as 2 h post-infection. US28 mRNA appeared after major IE1 transcripts (UL123), but before transcripts of the early genes pp65 (UL83) and gB (UL55), and the late gene pp150 (UL32). This temporal appearance indicates that US28 is transcribed earlier than previously reported. Furthermore, US28 mRNA could be detected in semi- and non-permissive cells.

Role of IFN-gamma-induced indoleamine 2,3 dioxygenase and inducible nitric oxide synthase in the replication of human cytomegalovirus in retinal pigment epithelial cells

An in vitro model of human CMV infection of primary retinal pigment epithelial (RPE) cells was used to study the effects of cytokines on CMV replication in these cells, which are targets of CMV infection in vivo. IFN-gamma and IFN-beta were potent inhibitors of CMV replication in RPE cells, while TNF-alpha, IL-1beta, or TGF-beta2 did not affect viral replication. Inhibition by IFN-gamma, and to a lesser extent IFN-beta, was almost completely reversed by addition of L-tryptophan to the culture medium, strongly implicating the indoleamine 2,3 dioxygenase (IDO) pathway. Polyadenylated IDO mRNA accumulation was detected as early as 2 h after IFN stimulation. Furthermore, CMV blocked the production of nitric oxide by the inducible form of nitric oxide synthase. This inhibition depended on a functional viral genome. However, exogenous nitric oxide significantly inhibited viral protein expression in RPE cells. Thus, CMV infection blocks the inducible nitric oxide synthase pathway activated by IFN-gamma and IL-1beta, but cannot counteract the IFN-induced IDO pathway, which ultimately controls its replication in primary human RPE cells.

Cystoid macular oedema and cytomegalovirus retinitis in patients with HIV disease treated with highly active antiretroviral therapy

BACKGROUND

Although cystoid macular oedema (CMO) is a rare cause of visual loss in AIDS related cytomegalovirus (CMV) retinitis, nine cases are reported of CMO occurring in HIV infected patients with a prior diagnosis of CMV who were receiving highly active antiretroviral therapy (HAART).

METHODS

Medical and ophthalmological records of nine AIDS patients with inactive CMV retinitis were retrospectively analysed. Ophthalmic examination data, laboratory findings, and the systemic antiviral treatment were studied. Ophthalmic examination included visual acuity, anterior chamber flare measured with the laser flare cell meter (LCFM), vitreous haze quantification according to the Nussenblatt grading system, and fluorescein angiography.

RESULTS

Nine HIV infected patients, eight men and one woman, mean age 39 years (range 29-53 years) presented with inactive CMV retinitis and CMO. On fluorescein angiography, CMO was present only in eyes (14 eyes) with signs of previous CMV retinitis. CMV retinitis was inactive in all of them. Visual acuity ranged from 20/200 to 20/30. In 10 eyes with CMV retinitis, anterior chamber flare measured with the LCFM ranged from 18.5 to 82 photons/ms (mean 35.42 ph/ms). A significant vitreous inflammation (1.5+) was observed in eight eyes. All patients had been treated with anti-CMV drugs for a mean period of 18 months (range 12-36 months). All nine patients received HAART with a combination of two nucleotide analogue reverse transcriptase inhibitors and one protease inhibitor for a mean period of 14 months (range 9-18 months). The HIV viral load was below detectable levels (< 200 copies/ml) in eight patients and low (3215 copies/ml) in one. At the time of CMO, the median CD4+ lymphocyte count was 232 cells x 10(6)/l (range 99-639).

CONCLUSION

In AIDS patients, the usual absence of intraocular inflammation in eyes affected by CMV retinitis has been tentatively explained by the profound cellular immunodeficiency. In these patients, treated with HAART, CD4+ counts were increased for several months (mean 14 months). In their eyes, CMV retinitis was associated with significant ocular inflammation and CMO. These findings could be related to the restoration of immune competence after HAART as recently shown.

Whipple's syndrome (uveitis, B27-negative spondylarthropathy, meningitis, and lymphadenopathy) associated with Arthrobacter sp. infection

OBJECTIVE

To report an unusual case of Whipple's disease, including uveitis, seronegative spondylarthropathy, meningitis, and lymphadenopathy, associated with an Arthrobacter sp. infection.

DESIGN

Interventional case report.

PATIENT AND INTERVENTION

A 60-year-old white man presenting with severe chronic uveitis and systemic inflammatory manifestations was treated efficiently for Whipple's disease after histopathologic analysis of vitreous and inguinal adenopathy biopsy specimens. The authors performed a retrospective, laboratory-based evaluation of stored tissue specimens.

MEASUREMENTS

Molecular analysis based on 16S ribosomal RNA gene amplification was applied to pretreatment biopsy specimens of inguinal lymph node to identify a causative bacterial agent.

RESULTS

Tropheryma whippelii genome was not detected in these specimens. However, an amplification product was obtained after the first polymerase chain reaction run and subsequently was sequenced. It corresponded to an Arthrobacter sp., a gram-positive agent presenting diagnostic patterns and therapeutic management similar to those of Whipple's disease caused by T. whippelii.

CONCLUSION

The absence of T. whippelii identification by molecular amplification during a clinically and histologically oriented Whipple's syndrome should not rule out the diagnosis. Arthrobacter infection may represent a new bacterial etiology of systemic inflammatory disorders involving the eye and associated with periodic acid-Schiff-positive inclusions.

Chemokine sequestration by viral chemoreceptors as a novel viral escape strategy: withdrawal of chemokines from the environment of cytomegalovirus-infected cells

Human cytomegalovirus (HCMV), a betaherpesvirus, has developed several ways to evade the immune system, notably downregulation of cell surface expression of major histocompatibility complex class I heavy chains. Here we report that HCMV has devised another means to compromise immune surveillance mechanisms. Extracellular accumulation of both constitutively produced monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor-superinduced RANTES (regulated on activation, normal T cell expressed and secreted) was downregulated in HCMV-infected fibroblasts in the absence of transcriptional repression or the expression of polyadenylated RNA for the cellular chemokine receptors CCR-1, CCR-3, and CCR-5. Competitive binding experiments demonstrated that HCMV-infected cells bind RANTES, MCP-1, macrophage inflammatory protein (MIP)-1beta, and MCP-3, but not MCP-2, to the same receptor as does MIP-1alpha, which is not expressed in uninfected cells. HCMV encodes three proteins with homology to CC chemokine receptors: US27, US28, and UL33. Cells infected with HCMV mutants deleted of US28, or both US27 and US28 genes, failed to downregulate extracellular accumulation of either RANTES or MCP-1. In contrast, cells infected with a mutant deleted of US27 continues to bind and downregulate those chemokines. Depletion of chemokines from the culture medium was at least partially due to continuous internalization of extracellular chemokine, since exogenously added, biotinylated RANTES accumulated in HCMV-infected cells. Thus, HCMV can modify the chemokine environment of infected cells through intense sequestering of CC chemokines, mediated principally by expression of the US28-encoded chemokine receptor.