There is a growing concern about sanctuaries of local human immunodeficiency virus (HIV) replication as it has already been documented for the central nervous system (CNS)(1). HIV might persist in these sanctuaries during antiretroviral treatment (ART) and theoretically cause the generation and dissemination of drug-resistant viruses. It has been found that detectable intraocular HIV viral load (VL) was higher in patients with the absence of retinal lesions, or ocular VL largely exceeded that of plasma(2). Among some patients with uveitis attributed to HIV, aqueous humor sequences had less genetic diversity compared to plasma, aqueous humor HIV sequences were compartmentalized from plasma(3). All these suggest the possibility of the existence of intraocular HIV repository.
The application of ART has effectively controlled the incidence of acquired immune deficiency syndrome (AIDS), and HIV-associated ocular complications have also decreased significantly. However, the latest data showed that 20%-30% patients still suffered from ocular complications, which mainly included opportunistic infections caused by immunodeficiency(4, 5). Our group found that cytomegalovirus retinitis (CMVR) accounted for the first place (about 10.6%), followed by the retinopathy induced by the invasion of HIV, which was associated with severe vision impairment (9.4%)(6).
So, we assessed the clinical characteristics and HIV VL of plasma and aqueous humor in 40 HIV-infected patients and attempted to analyze HIV dynamics across the blood–retinal barrier (BRB). Since the HIV patients suffer from high incidence of ocular complications, we would like to discuss the relevant risk factors and whether it’s associated with the persistence of ocular HIV.
Study Design
This is a retrospective study including data recorded from 57 HIV positive subjects for medical consultations and treatments in our institute between 2018 and 2021 due to blurred vision or black shadows. The study was approved by the institutional ethics committee of Huashan Hospital affiliated with Fudan University (protocol number: KY2021-837), and the treatment was performed under the tenets of the Declaration of Helsinki. The patients enrolled in the study signed the written informed consent for the publication of their data and examinations.
Paired blood and aqueous humor were evaluated for HIV VL. HIV VL was quantified in plasma and aqueous humor by COBAS TaqMan HIV-1 Test (Roche Molecular Systems, Inc., Branchburg, New Jersey, USA) with a detection limit of 20 copies/mL both in plasma and aqueous humor. The aqueous humor/plasma ratio of HIV-RNA was calculated, an aqueous humor/plasma ratio > 1 (indicating levels of HIV-RNA in aqueous humor higher than those in plasma) was labeled as a “discordance” between aqueous humor and plasma. Ocular “escape” was defined as detectable aqueous humor HIV VL in the setting of suppressed plasma VL.
Patient Characteristics
57 Patients were involved, mostly males (82.5%) with a median age of 44.3 years (IQR 34.0–53.0), females (17.5%) with a median age of 47.6 years (IQR 34.3–70.0), and the majority of them (96.4%) had acquired HIV infection through sexual intercourse. When patients were enrolled, median CD4+ T-lymphocyte level was 301 cells/µl (IQR, 183–410), and 33 (57.8%) patients were diagnosed with HIV-associated ocular complication, which included CMVR, acute retinal necrosis (ARN), immune restorative uveitis (IRU), ocular infection of Syphilis and Aeruginosa. Overall, 2 (3.5%) patients have not yet received any antiretroviral therapy, other patients were receiving an ART regimen with a median duration of 34.1 months (IQR, 8.0–36.0).
Viral Load
HIV VL on paired aqueous/plasma samples was available for 40 patients. Aqueous VL was detected in 22/40 patients (55%), plasma VL was detected in 22/40 patients (55%), and both can be detected in 14/40 (35%). Median aqueous and plasma HIV VL were 2.44 log10 cp/ml (IQR 1.30–3.60 log10 cp/ml) and 2.10 log10 cp/ml (IQR 1.30–2.74 log10 cp/ml), respectively. Aqueous VL was independent of CD4+ T-lymphocyte level (p = 0.28), plasma VL was negatively correlated with CD4+ T-lymphocyte levels (p = 0.009 and p < 0.05). Aqueous VL was negatively associated with ART duration (p = 0.02 and p < 0.05), plasma VL was independent of ART duration (p = 0.53).
An aqueous/plasma discordance was found in 19/40 (47.5%) patients, eight of whom (20%) had detectable aqueous VL despite a suppressed plasma VL (escape). The aqueous/plasma discordance was independent of CD4+ T-lymphocyte level (p = 0.19) and treatment time (p = 0.24).
Risk Factors For Hiv-associated Ocular Complications
The patients were divided into two groups according to whether they were diagnosed with HIV-related ocular complications. There were significant differences between the two groups in CD4+ T-lymphocyte levels (p = 0.012 and p < 0.05) and ART duration (p = 0.007 and p < 0.05). In patients with HIV-associated ocular involvement and those without, no differences were found in the plasma VL (p = 0.145), aqueous VL (p = 0.062) and aqueous/ plasma VL ratio (p = 0.75) at the time of ocular examination. (The detail is shown in Table 1.)
Statistics
Multiple variables per patient and different groups of patients were compared, including the aqueous humor and plasma HIV VL, age, sex, ART duration and CD4 + T-lymphocyte levels. Comparisons between groups were performed by means of Student’s t-test for continuous data and chi-square test for categorical data. The relationships between variables were evaluated with Pearson’s correlation analysis. Two-tailed p values < 0.05 were considered statistically significant. Our study was conducted with the approval of the medical ethical committee of Huashan Hospital, Fudan University. All patients were informed about these investigations and their consent was obtained.