Noncytomegalovirus-related chorio-retinal manifestations of the acquired immunodeficiency syndrome

Nontubercular Mycobacteria Associated Uveitis in HIV Positive Patients

PURPOSE

To report clinical features and outcomes of nontuberculous mycobacteria (NTM) presenting as uveitis in HIV positive patients.

MATERIALS AND METHODS

Retrospective study of HIV positive patients who were diagnosed as uveitis due to NTM.

RESULTS

Six eyes of four HIV positive patients with NTM were studied. Average age at presentation was 35.5 years (range 30-38). With specific PCR primers, Mycobacterium avium was detected in three patients (75%) and Mycobacterium fortuitum in one patient (25%). Culture was positive in two cases. Two eyes (33.33%) each had endophthalmitis and necrotizing retinitis like picture, one eye (16.66%) each had chorioretinitis and frosted branch angitis like. Visual acuity improved in two eyes (33.33%), worsened in three eyes (50%), and remained unchanged in one eye (16.6%).

CONCLUSIONS

NTM infection is a unique entity in immunosuppressed with poor visual outcome. PCR forms a useful tool for rapid diagnosis and timely initiation of specific anti-tuberculosis therapy.

Induction of cystine-glutamate transporter xc- by human immunodeficiency virus type 1 transactivator protein tat in retinal pigment epithelium

PURPOSE

The transactivator protein Tat encoded by the human immunodeficiency virus-1 (HIV-1) genome reduces glutathione levels in mammalian cells. Because the retina contains large amounts of glutathione, a study was undertaken to determine the influence of Tat on glutathione levels, gamma-glutamyl transpeptidase activity, and the expression and activity of the cystine-glutamate transporter xc- in the human retinal pigment epithelial cell line ARPE-19 and in retina from Tat-transgenic mice.

METHODS

The transport function of xc- was measured as glutamate uptake in the absence of Na+. mRNA levels for xCT and 4F2hc, the two subunits of system xc-, were monitored by RT-PCR and Northern blot and protein levels by Western blot. The expression pattern of xCT and 4F2hc in the mouse retina was analyzed by immunofluorescence.

RESULTS

Expression of Tat in ARPE-19 cells led to a decrease in glutathione levels and an increase in gamma-glutamyl transpeptidase activity. The transport function of xc- was upregulated, and this increase was accompanied by increases in the levels of mRNAs for xCT and 4F2hc and in corresponding protein levels. The influence of Tat on the expression of xc- was independent of the cellular status of glutathione. Most of these findings were confirmed in the retina of Tat-transgenic mice.

CONCLUSIONS

Expression of HIV-1 Tat in the retina decreases glutathione levels and increases gamma-glutamyl transpeptidase activity. Tat also upregulates the expression of system xc-. Glutathione levels may be decreased and the expression of xc- enhanced in the retina of patients with HIV-1 infection, leading to oxidative stress and excitotoxicity.

Vasculopathies affecting the eye

The retinal arteries and veins may be involved in isolation or as the result of a systemic vasculitis. This article emphasizes neurologic diseases in which the ocular vasculature is affected.