Elucidating the effects of broadly neutralizing antibody treatment on neuroinflammation and CNS Persistence in SIV-ART macaques

Cognitive impairment persists even with highly effective antiretroviral therapy (ART) in people with HIV (PWH). Persistent neuroinflammation is one of many factors that contributes to ongoing cognitive impairment in virally suppressed (vs)PWH. However, there is a critical gap in understanding the underlying cause of neuroinflammation and, as a result, no available therapies to target it. Long-acting broadly neutralizing antibodies (bNAbs) are considered the next generation of therapy for PWH. Currently, there are 50+ trials that involve bNAbs. Despite this substantial effort, there are no funded NIH studies focusing on if bNAb therapy in combination with ART may reduce neuroinflammation and improve cognitive function. As the mechanism of action for bNAbs is the rapid neutralization of virus and clearance of infected cells via engagement of the immune system, a downstream effect of this therapy may be lower levels of inflammation, as is observed with other Ab therapies. We have evidence that HIV-specific antibodies (Ab) play a protective role in the CNS, and others have shown that bNAb therapy enhances host Ab immunity to HIV and simian immunodeficiency virus (SIV). Therefore, our central hypothesis is that bNAb therapy will reduce neuroinflammation in the CNS, by directly eliminating infected cells capable of trafficking to brain resulting in a smaller CNS reservoir, neutralizing virus within the CSF, and indirectly by reducing peripheral inflammation, resulting in improved cognition. To test our hypothesis, we will use the SIVmac251 rhesus macaque model of HIV and an SIV-specific bNAb (ITS103). The SIV-infected ART-suppressed NHP model will allow us to assess the effects of bNAbs on CNS inflammation, reservoir, and cognition. Additionally, this model will allow us to determine if bNAbs have a direct effect on the CNS or indirect effect through altering peripheral inflammation. AIM 1: Determine if bNAb therapy during ART initiation reduces neuroinflammation. To model ART-naïve PWH receiving bNAb therapy simultaneously with ART, we will treat SIV-infected macaques with ITS103 at the time of ART initiation. We will assess the effect of acute ITS103 therapy on 1) brain macrophage transcription, 2) CNS reservoir size, and 3) cognitive performance after 1 year of suppression compared to ART alone. AIM 2: Determine if bNAb therapy during chronic ART reduces neuroinflammation. To model vsPWH receiving bNAb therapy combined with ongoing ART, we will treat SIV-infected macaques with ITS103 after 36 weeks of ART suppression and assess the effect of chronic bNAb therapy on the same outcomes as in Aim 1. AIM 3: Determine if bNAbs have a direct or indirect effect on neuroinflammation. To determine if ITS103 plays a direct role in the CNS we will assess 1) ITS103 concentrations in the CSF, 2) viral decay rates in CSF, 3) central vs. peripheral inflammation and 4) plasma and CSF Ab neutralization capacity with and without bNAb therapy. Our in vivo study utilizing a native SIV and SIV-specific bNAb is highly innovative as it will be the first to study on the effects of bNAb therapy on neuroinflammation and evaluate if this is a viable treatment for PWH. Project Number: 1R01MH141671-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Mental Health (NIMH) | Principal Investigator: Rebecca Veenhuis | Institution: JOHNS HOPKINS UNIVERSITY, BALTIMORE, MD | Award Amount: $1,106,628 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZMH1 ERB-L (02)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11229308