title: Cerebrospinal fluid cell-free mitochondrial DNA is associated with HIV replication, iron transport, and mild HIV-associated neurocognitive impairment.
abstract: Mitochondria are abundant organelles critical for energy metabolism and brain function. Mitochondrial DNA (mtDNA), released during cellular injury and as part of the innate immune response to viral pathogens, contains CpG motifs that act as TLR-9 ligands. We investigated relationships between cerebrospinal fluid (CSF) cell-free mtDNA levels and HIV viral load (VL), biomarkers of inflammation and iron transport, and neurocognitive (NC) function in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) cohort.
  
  
  
  We quantified cell-free mtDNA in CSF by droplet digital PCR in 332 CHARTER participants who underwent comprehensive neuropsychiatric evaluation. NC performance was assessed using the global deficit score (GDS) as either a continuous or a binary measure (GDS ≥ 0.5, impaired vs. GDS < 0.5, unimpaired). CSF, clinical, and biomarker data from the earliest available time point were analyzed. Cell-free mtDNA associations with CSF inflammation and iron-related biomarkers [CXCL10, IL-6, IL-8, TNF-a, transferrin (TF), ceruloplasmin (CP), and vascular endothelial growth factor (VEGF)], VL, and GDS were evaluated by multivariable regression.
  
  
  
  CSF cell-free mtDNA levels were significantly lower in participants with undetectable (vs. detectable) VL in either plasma (p < 0.001) or CSF (p < 0.001) and in those on antiretroviral therapy (ART; p < 0.001). Participants on ART with undetectable VL in both CSF and plasma had lower mtDNA levels than those with detectable VL in both compartments (p = 0.001). Higher mtDNA levels were observed in participants in the highest vs. lowest tertile (T3 vs. T1) of CSF CXCL10 (T3 vs. T1, p < 0.001) and TNF-a (T3 vs. T1, p < 0.05) in unadjusted analyses. MtDNA levels also correlated with CSF leukocyte count. After adjusting for CSF leukocyte count and VL, mtDNA levels were also associated with other inflammation- and iron-related biomarkers in CSF, including TF (T3 vs. T1, p < 0.05) and CP (T3 vs. T1, p < 0.05). With additional correction for ART use, mtDNA was also negatively associated with CSF VEGF (p < 0.05) and IL-6 (p = 0.05). We observed no associations of CSF mtDNA levels with age or GDS-defined NC impairment.
  
  
  
  CSF cell-free mtDNA levels were associated with HIV RNA and ART status, as well as with biomarkers of iron transport and VEGF, a growth factor with known effects on mitochondrial integrity and autophagy. CSF mtDNA may be a biomarker of iron dysregulation and/or neuroinflammation during HIV infection.
authors.affiliation: Department of Medicine, University of California-San Diego, San Diego, CA, USA. srmehta@ucsd.edu.|Department of Medicine, San Diego Veterans Affairs Medical Center, San Diego, CA, USA. srmehta@ucsd.edu.
authors.forename: Sanjay R
authors.initials: SR
authors.lastname: Mehta
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Josué
authors.initials: J
authors.lastname: Pérez-Santiago
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Vanderbilt University, Nashville, TN, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Hulgan
authors.affiliation: Division of Biostatistics, Washington University, St. Louis, MO, USA.
authors.forename: Tyler R C
authors.initials: TR
authors.lastname: Day
authors.affiliation: Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Barnholtz-Sloan
authors.affiliation: Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
authors.forename: Haley
authors.initials: H
authors.lastname: Gittleman
authors.affiliation: Department of Medicine, University of California-San Diego, San Diego, CA, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Letendre
authors.affiliation: Department of Neurology, University of California-San Diego, San Diego, CA, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Ellis
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Heaton
authors.affiliation: Department of Neurosurgery, Pennsylvania State/Hershey College of Medicine, Hershey, PA, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Patton
authors.affiliation: Department of Medicine, University of California-San Diego, San Diego, CA, USA.
authors.forename: Jesse D
authors.initials: JD
authors.lastname: Suben
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Franklin
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Debralee
authors.initials: D
authors.lastname: Rosario
authors.affiliation: Department of Neurology, Washington University, St. Louis, MO, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Clifford
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Ann C
authors.initials: AC
authors.lastname: Collier
authors.affiliation: Department of Neurology, University of Washington, Seattle, WA, USA.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Marra
authors.affiliation: Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Gelman
authors.affiliation: Department of Neurology, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: McArthur
authors.affiliation: Department of Medicine, University of California-San Diego, San Diego, CA, USA.
authors.forename: Allen
authors.initials: A
authors.lastname: McCutchan
authors.affiliation: Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Morgello
authors.affiliation: Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: David
authors.initials: D
authors.lastname: Simpson
authors.affiliation: Department of Neurosurgery, Pennsylvania State/Hershey College of Medicine, Hershey, PA, USA.
authors.forename: James
authors.initials: J
authors.lastname: Connor
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Grant
authors.affiliation: Genomic Medicine Institute/Lerner Research Institute Cleveland Clinic, Cleveland, OH, USA.|Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA.
authors.forename: Asha
authors.initials: A
authors.lastname: Kallianpur
mesh_terms: D015526:AIDS Dementia Complex / Q000134:cerebrospinal fluid* / Q000378:metabolism* / Q000821:virology*; D000328:Adult; D015415:Biomarkers / Q000134:cerebrospinal fluid; D000073888:Cell-Free Nucleic Acids / Q000134:cerebrospinal fluid*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004272:DNA, Mitochondrial / Q000134:cerebrospinal fluid*; D005260:Female; D006678:HIV; D006801:Humans; D007501:Iron / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019562:Viral Load; D014779:Virus Replication
chemical_list: D015415:Biomarkers; D000073888:Cell-Free Nucleic Acids; D004272:DNA, Mitochondrial; D007501:Iron
keywords: Cerebrospinal fluid; HIV; Inflammation; Iron; Mitochondrial DNA; Neurocognitive impairment