Cerebrospinal fluid extracellular vesicles and neurofilament light protein as biomarkers of central nervous system injury in HIV-infected patients on antiretroviral therapy

Abstract

Objective: The relationship of cerebrospinal fluid (CSF) extracellular vesicles to neurocognitive impairment (NCI) in HIV-infected individuals is unclear. Here, we characterize CSF extracellular vesicles and their association with central nervous system (CNS) injury related biomarkers [neurofilament light (NFL), S100B, neopterin] and NCI in HIV-positive individuals on combination antiretroviral therapy (cART). Design: A cross-sectional and longitudinal study of CSF samples from HIV-positive individuals on cART. Methods: NFL, S100B and neopterin were measured by ELISA in 190 CSF samples from 112 individuals (67 HIV-positive and 45 HIV-negative). CSF extracellular vesicles were isolated and characterized by electron microscopy, nanoparticle tracking analysis, immunoblotting for exosome markers (CD9, CD63, CD81, FLOT-1) and ELISA for HLA-DR. Results: HIV-positive individuals had median age 52 years, 67% with suppressed plasma viral load (< 50 copies/ml), median CD4 + nadir 66 cells/μl and CD4 + cell count 313 cells/μl. CSF NFL, S100B and neopterin levels were higher in HIV-positive vs. HIV-negative individuals, and nonsuppressed vs. suppressed HIV-positive individuals. Although CSF NFL and S100B levels were higher in NCI vs. unimpaired HIV-positive individuals ( P < 0.05), only NFL was associated with NCI in adjusted models ( P < 0.05). CSF extracellular vesicles were increased in HIV-positive vs. HIV-negative individuals, and NCI vs. unimpaired HIV-positive individuals ( P < 0.05), and correlated positively with NFL ( P < 0.001). HLA-DR was enriched in CSF extracellular vesicles from HIV-positive individuals with NCI ( P < 0.05), suggesting that myeloid cells are a potential source of CSF extracellular vesicles during HIV infection. Conclusion: Increased CSF extracellular vesicles correlate with neuronal injury biomarker NFL in cART-treated HIV-positive individuals with neurocognitive impairment, suggesting potential applications as novel biomarkers of CNS injury.

HIV-Associated Neurocognitive Impairment in the Modern ART Era: Are We Close to Discovering Reliable Biomarkers in the Setting of Virological Suppression?

“…However, the association between GDSs and CSF NFL has been observed mostly in individuals not receiving ART, in which plasma NFLs are higher compared to PWH receiving ART and usually decline over time after ART initiation (Andersson et al, 2006; Jessen Krut et al, 2014; Anderson et al, 2018). A trend towards higher CSF NFL was also seen in aviremic PWH with NCI compared to others (Edén et al, 2016) and, in a work including mostly ART-treated PWH (67 PWH of which 67% aviremic), CSF NFL levels were higher in PWH with NCI compared to unimpaired HIV-infected subjects ( p < 0.05; Guha et al, 2019). In the same study, CSF NFL was higher in NCI ( p = 0.009) and HAND ( p = 0.007) but not in unimpaired HIV-infected subjects compared to HIV-uninfected controls (Guha et al, 2019).…”

“…A trend towards higher CSF NFL was also seen in aviremic PWH with NCI compared to others (Edén et al, 2016) and, in a work including mostly ART-treated PWH (67 PWH of which 67% aviremic), CSF NFL levels were higher in PWH with NCI compared to unimpaired HIV-infected subjects ( p < 0.05; Guha et al, 2019). In the same study, CSF NFL was higher in NCI ( p = 0.009) and HAND ( p = 0.007) but not in unimpaired HIV-infected subjects compared to HIV-uninfected controls (Guha et al, 2019). In another interesting study, high levels of CSF NFL were consistently found in HAD subjects and in untreated asymptomatic PWH, especially those with lower counts of CD4+ T lymphocytes, suggesting a subclinical axonal injury also in neuroasymptomatic PWH and not on treatment (Jessen Krut et al, 2014).…”

“…In HIV-infected adults, higher plasma NFL concentration has been significantly associated with worse neuropsychological performance, after adjustment for possible confounding factors including age, CD4+ T cell count, and plasma HIV RNA levels (Anderson et al, 2018). High NFL concentration in CSF was found to be an independent biomarker of baseline NCI status in multivariable linear regression models adjusted for age, race, and plasma viral load (Guha et al, 2019). CSF NFL levels were also found to correlate with C1q concentrations in CSF in ART naïve PWH.…”

Blood Biomarkers for Detection of Brain Injury in COVID-19 Patients

“…Observational cohort study 178 elevations of BBs in CSF of tuberculous meningitis patients (GFAP, S100 calcium-binding protein [S100B], and neuronspecific enolase [NSE]), [172][173][174][175] HIV patients (NfL, GFAP, and S100B), [176][177][178][179][180] and cerebral malaria (S100B, NSE, tau proteins, and inflammatory protein markers). [181][182][183][184][185][186] Protein biomarkers of CNS damage have also been detected after a variety of acute injury modalities.…”

Extracellular Vesicles in Viral Infections of the Nervous System

“…In addition, increased numbers of CSF EVs have also been detected in HIV-positive individuals. An increase in concentrations of CSF EVs has been shown to correlate with an established neuronal injury biomarker (neurofilament light chain protein (NFL) as well as progression to HAND [ 186 ]. Furthermore, our group isolated neuronal-derived EVs (L1CAM+ EV) and found an increased presence of L1CAM+ neuronal-derived EVs both in the brain and serum of HIV-1 transgenic (Tg) rats, a model that results in the expression of HIV viral proteins but without active viral replication [ 187 ].…”