HIV-associated neurocognitive disorders: A review for NPs

Fentanyl dysregulates neuroinflammation and disrupts blood-brain barrier integrity in HIV-1 Tat transgenic mice

Opioid overdose deaths have dramatically increased by 781% from 1999 to 2021. In the setting of HIV, opioid drug abuse exacerbates neurotoxic effects of HIV in the brain, as opioids enhance viral replication, promote neuronal dysfunction and injury, and dysregulate an already compromised inflammatory response. Despite the rise in fentanyl abuse and the close association between opioid abuse and HIV infection, the interactive comorbidity between fentanyl abuse and HIV has yet to be examined in vivo. The HIV-1 Tat-transgenic mouse model was used to understand the interactive effects between fentanyl and HIV. Tat is an essential protein produced during HIV that drives the transcription of new virions and exerts neurotoxic effects within the brain. The Tat-transgenic mouse model uses a glial fibrillary acidic protein (GFAP)-driven tetracycline promoter which limits Tat production to the brain and this model is well used for examining mechanisms related to neuroHIV. After 7 days of fentanyl exposure, brains were harvested. Tight junction proteins, the vascular cell adhesion molecule, and platelet-derived growth factor receptor-β were measured to examine the integrity of the blood brain barrier. The immune response was assessed using a mouse-specific multiplex chemokine assay. For the first time in vivo, we demonstrate that fentanyl by itself can severely disrupt the blood-brain barrier and dysregulate the immune response. In addition, we reveal associations between inflammatory markers and tight junction proteins at the blood-brain barrier.

Neurocognitive Impairment in the Combined Antiretroviral Therapy Era in a Romanian Cohort of Young Adults with Chronic HIV Infection

HIV-associated neurocognitive disorders (HAND) continue to be reported even in patients with successful antiretroviral treatment. We investigated the prevalence of neurocognitive impairment and possible HIV-associated determinants of cognition in a Romanian cohort of young adults, parenterally infected with HIV during their first years of life. Two hundred fourteen treatment-experienced HIV-positive individuals [median age: 24 years, males: 48%, median duration on combined antiretroviral therapy (cART): 12 years] underwent standard immunologic and virological monitoring and antiretroviral resistance testing using pol gene sequencing in both plasma and, when available, cerebrospinal fluid (CSF) paired samples. Neurocognitive impairment was assessed using a comprehensive neuropsychological test battery, and a global deficit score (GDS) was calculated (cutoff ≥0.5). Cognitive impairment was detected in 35% of the study participants, without any association with sex, median age, CD4 cell count (actual or nadir), CSF and plasma viral load (actual or zenith), AIDS diagnosis, duration of HIV infection, and cART characteristics. Participants carrying resistant viruses tended to be more frequently cognitively impaired (p = 0.36), with a higher median GDS value (p = 0.06) compared with participants harboring wild-type HIV, although the figures did not reach statistical significance. No signs of virological compartmentalization were observed based on CSF versus plasma viral load and on the profile of pol sequences. A moderate rate of mild neurocognitive impairment is still present in young adults with chronic HIV infection acquired in early childhood despite successful cART, without any association with classic markers of HIV infection. New biomarkers reflecting persistent central nervous system inflammation and neuronal injury may be more relevant for the development of HAND.

Screening for HIV-Associated Neurocognitive Impairment: Relevance of Psychological Factors and Era of Commencement of Antiretroviral Therapy

Neurocognitive impairment (NCI) is common in people aging with HIV and can adversely affect health-related quality of life. However, early NCI may be largely asymptomatic and neurocognitive function is rarely assessed in the context of routine clinical care. In this study, we considered the utility of two assessment tools as screens for NCI in patients attending a community-based clinic (N = 58; mean age = 57 years): the Montreal Cognitive Assessment (MoCA) and a 3-item cognitive concerns questionnaire derived from the HIV Dementia Scale. Health-related quality of life and depression/anxiety were also measured. Indication of NCI using the MoCA was more prevalent compared to the 3-item questionnaire and was associated with the patients' initial antiretroviral therapy commencing between the years of 1997 and 2001, independently of age. Findings of the MoCA were not confounded by existing mood disorders, unlike the 3-item questionnaire. Therefore, we suggest implementing the MoCA as an initial screen for NCI.

HIV/neuroAIDS biomarkers

HIV infection often causes neurological symptoms including cognitive and motor dysfunction, which have been collectively termed HIV/neuroAIDS. Neuropsychological assessment and clinical symptoms have been the primary diagnostic criteria for HIV/neuroAIDS, even for the mild cognitive and motor disorder, the most prevalent form of HIV/neuroAIDS in the era of combination antiretroviral therapy. Those performance-based assessments and symptoms are generally descriptive and do not have the sensitivity and specificity to monitor the diagnosis, progression, and treatment response of the disease when compared to objective and quantitative laboratory-based biological markers, or biomarkers. In addition, effects of demographics and comorbidities such as substance abuse, psychiatric disease, nutritional deficiencies, and co-infection on HIV/neuroAIDS could be more readily determined using biomarkers than using neuropsychological assessment and clinical symptoms. Thus, there have been great efforts in identification of HIV/neuroAIDS biomarkers over the past two decades. The need for reliable biomarkers of HIV/neuroAIDS is expected to increase as the HIV-infected population ages and their vulnerability to neurodegenerative diseases, particularly Alzheimer's disease increases. Currently, three classes of HIV/neuroAIDS biomarkers are being pursued to establish objective laboratory-based definitions of HIV-associated neurologic injury: cerebrospinal fluid biomarkers, blood biomarkers, and neuroimaging biomarkers. In this review, we will focus on the current knowledge in the field of HIV/neuroAIDS biomarker discovery.