CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

575

HIV-1 Infection and Alzheimer’s Disease Pathobiology in a Novel Humanized APP-Knock in Mouse Model Shaurav Bhattarai , Pravin Yeapuri, Jatin Machhi, Yaman Lu, Rana Kadry, Emma G. Foster, Krista L. Namminga, Emiko M. Waight, Chen Zhang, Prasanta Dash, Santhi Gorantla, Larisa Poluektova, Rodney L. Mosley, Howard E. Gendelman University of Nebraska Medical Center, Omaha, NE, USA Background: The prevalence of aged-associated Alzheimer's-like disease is increasing in people living with HIV. Disease mechanisms are linked to interactions between progressive HIV infection, neuroinflammation, CD4+ T cell depletion, and aggregation of misfolded proteins. Sustained viral replication in the brain and immune dysfunction accelerates neuroinflammation. Simultaneous HIV and Alzheimer's disease (AD)studies have been limited due to the lack of appropriate animal models. A relevant animal model would require human microglia and a robust adaptive immune system in an immune-deficient background amenable to human cell reconstitution. Methods: We created a novel humanized AD mouse using CRISPR-Cas9 technology to address the need for an appropriate animal model to study HIV and AD simultaneously. This was accomplished by knocking in (KI) human APPKM670,671NL, PS1M146V, or MAPTP301S in an immunodeficient NOG mouse (Fig 1A). The APP-KI mice were crossed with NOG/hIL34 [NOG/Tg (CMV-IL34], supporting the development of human microglia. This allows the reconstitution of a human innate and adaptive immune system in the brain and periphery (APP/NOG/hIL34 mice). APP-KI/NOG/hIL34 mice were reconstituted with human hematopoietic progenitor cells to evaluate progressive HIV-1 infection. Four month-old, humanized mice were infected with a macrophage-tropic HIV-1ADA at a tissue culture infectious dose (TCID 50 ) of 10e4/mice. Mice were sacrificed at four and eight weeks after viral infection. Results: After four weeks of infection, plasma viral load demonstrated productive HIV-1 infection with an average of plasma HIV-1 RNA levels of 8.96E+03 at 2 weeks and 2.82E+05 at 8 weeks after infection. HIV-1p24 was readily detected in the brain (Fig 1B). After four weeks, the insoluble amyloid burden in HIV-1 -infected mice was markedly increased compared to uninfected controls as determined by amyloid-beta42 (Aβ42) ELISA (Fig 1C). Immunofluorescence staining revealed co-localization of Aβ fibrils and human IBA1+ microglia. Similarly, IHC staining of the brain showed more reactive microglia in the HIV-infected mice compared to the control mice. Conclusion: We observed that HIV-1 infection accelerates AD pathology by increasing Aβ accumulation. Our results highlight, for the first time, the utility of this humanized CRISPR AD mouse model for evaluating the interconnections between progressive HIV infection and AD pathobiology.

576

Increased mtDNA Level in Neuron-Derived Extracellular Vesicles in African Americans With HIV Vladmir Berthaud , Waldemar Popik, Tarik Smith, Derek Wilus, Venkateswara R. Amara, Franklin Nouvet Meharry Medical College, Nashville, TN, USA Background: HIV-associated neurocognitive disorders (HAND) remain common among people with HIV (PWH). Cigarette smoking induces mitochondrial damage and is more prevalent among PWH. Mitochondrial DNA (mtDNA) content reduction often occurs before neuronal degeneration. Our objective was to determine the effect of smoking on mtDNA content in neuron-derived extracellular vesicles (NEVs) isolated from the peripheral blood of African Americans (AAs), according to smoking and HIV status. We hypothesized that smoking exacerbates neuronal mtDNA damage in virally suppressed AA PWH, leading to increased release of mtDNA in NEVs. Methods: Twenty-four AA men, aged 45-64, were recruited from Meharry outpatient clinics: HIV-negative non-smokers (NNS), HIV-negative smokers (NS), HIV-positive non-smokers (PNS), and HIV-positive smokers (PS). HIV-positive participants had plasma RNA ≤20 copies/ml. Blood plasma was obtained by centrifugation, and the total pool of EVs was isolated from 3 ml of plasma by ultracentrifugation. NEVs expressing neuron specific L1CAM antigen were isolated from a total pool of EVs. mtDNA content in NEVs was analyzed by qPCR using primer sets that amplify mtDNA's unique region (D-loop). The copy number of mtDNA amplicons was quantitated using a standard curve. Welch's One-way ANOVA was applied to determine differences in mean mtDNA content and multiple comparisons done with Games-Howell test, which considers heteroscedasticity. We used multiple linear regression and tested for interaction to determine the association between HIV and mtDNA content, adjusting for smoking status. Results: NEVs mtDNA content were heteroscedastic (P-Value < 0.001). We found significant pairwise differences among NEVs mtDNA groups: between NNS and PNS (P-Value = 0.022), NS and PNS (P-Value = 0.014), NNS and PS (P-Value = 0.006), and NS and PS (P-Value = 0.005). Smoking did not significantly contribute to the linear model. Significance was found in HIV status (P-Value = 0.006) and the interaction term between HIV and smoking status (P-Value = 0.011). Conclusion: We found a significant increase in mtDNA level in NEVs of AA PWH compared to HIV-negative counterparts. Smoking increased mtDNA levels in NEVs from AA PWH compared to non-smokers. mtDNA content in NEVs represents a potential biomarker for mitochondrial dysfunction that may precede neuronal damage in virally suppressed AA PWH.

Poster Abstracts

577

Cerebrospinal Fluid NfL Decreases After Initiation of ART, but Slower Than Inflammatory Biomarkers Linn Renborg , Aylin Yilmaz, Staffan Nilsson, Henrik Zetterberg, Kaj Blennow, Magnus Gisslén Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden Background: Persistent intrathecal immune activation and signs of neuronal disturbances are present in many HIV-infected individuals despite effective antiretroviral treatment (ART). We have studied the decay characteristics of neurofilament light (NfL) protein, a marker of neuronal injury, in cerebrospinal fluid (CSF) after initiation of ART in a large cohort of HIV-infected individuals. Methods: In this longitudinal study, we assessed the levels of NfL, and a panel of neuroinflammatory biomarkers, including YKL-40, sTREM-2, neopterin and GFAp, in consecutive archived CSF samples from 99 people with HIV (PWH) who had achieved viral suppression. Participants were followed from before treatment initiation and up to at least one year on ART. Comparison of means was performed using t-test and partial correlations were calculated adjusting for age.

CROI 2024 158