Journal Article

Elevated phospholipids and acylcarnitines C4 and C5 in cerebrospinal fluid distinguish viral CNS infections from autoimmune neuroinflammation

Waqas, Fakhar H., Skripuletz, Thomas, Pessler, Frank, Al-Mekhlafi, Amani, Krueger, Maike, Sühs, Kurt-Wolfram, Stangel, Martin, Klawonn, Frank, Akmatov, Manas K., Trebst, Corinna, Müller-Vahl, Kirsten

2023

Overview

Background Viral and autoimmune encephalitis may present with similar symptoms, but require different treatments. Thus, there is a need for biomarkers to improve diagnosis and understanding of pathogenesis. We hypothesized that virus-host cell interactions lead to different changes in central nervous system (CNS) metabolism than autoimmune processes and searched for metabolite biomarkers in cerebrospinal fluid (CSF) to distinguish between the two conditions. Methods We applied a targeted metabolomic/lipidomic analysis to CSF samples from patients with viral CNS infections (n = 34; due to herpes simplex virus [n = 9], varicella zoster virus [n = 15], enteroviruses [n = 10]), autoimmune neuroinflammation (n = 25; autoimmune anti-NMDA-receptor encephalitis [n = 8], multiple sclerosis [n = 17), and non-inflamed controls (n = 31; Gilles de la Tourette syndrome [n = 20], Bell’s palsy with normal CSF cell count [n = 11]). 85 metabolites passed quality screening and were evaluated as biomarkers. Standard diagnostic CSF parameters were assessed for comparison. Results Of the standard CSF parameters, the best biomarkers were: CSF cell count for viral infections vs. controls (area under the ROC curve, AUC = 0.93), Q-albumin for viral infections vs. autoimmune neuroinflammation (AUC = 0.86), and IgG index for autoimmune neuroinflammation vs. controls (AUC = 0.90). Concentrations of 2 metabolites differed significantly (p < 0.05) between autoimmune neuroinflammation and controls, with proline being the best biomarker (AUC = 0.77). In contrast, concentrations of 67 metabolites were significantly higher in viral infections than controls, with SM.C16.0 being the best biomarker (AUC = 0.94). Concentrations of 68 metabolites were significantly higher in viral infections than in autoimmune neuroinflammation, and the 10 most accurate metabolite biomarkers (AUC = 0.89–0.93) were substantially better than Q-albumin (AUC = 0.86). These biomarkers comprised six phosphatidylcholines (AUC = 0.89–0.92), two sphingomyelins (AUC = 0.89, 0.91), and acylcarnitines isobutyrylcarnitine (C4, AUC = 0.92) and isovalerylcarnitine (C5, AUC = 0.93). Elevated C4 and C5 concentrations suggested dysfunctional mitochondrial β-oxidation and correlated only moderately with CSF cell count (Spearman ρ  = 0.41 and 0.44), indicating that their increase is not primarily driven by inflammation. Conclusions Changes in CNS metabolism differ substantially between viral CNS infections and autoimmune neuroinflammation and reveal CSF metabolites as pathophysiologically relevant diagnostic biomarkers for the differentiation between the two conditions. In viral CNS infections, the observed higher concentrations of free phospholipids are consistent with disruption of host cell membranes, whereas the elevated short-chain acylcarnitines likely reflect compromised mitochondrial homeostasis and energy generation.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Albumin / Amino acids / Analysis / Autoimmune diseases / Autoimmunity / Bell's palsy / Biological markers / Biomarkers / Biomedical and Life Sciences / Biomedicine / Care and treatment / Cell interactions / Cell membrane / Cell membranes / Central nervous system / Cerebrospinal fluid / Chicken pox / Development and progression / Diagnostic tests / DNA sequencing / Encephalitis / Etiology / Fatty acid oxidation / Glutamic acid receptors (ionotropic) / Glycerol / Health aspects / Herpes simplex / Herpes viruses / Homeostasis / Immunoglobulin G / ImmunoVirology and ImmunoOncology / Infections / Inflammation / Leukocytes / Lipids / Measurement / Medicine/Public Health / Meningitis / Metabolites / Metabolomics / Multiple sclerosis / N-Methyl-D-aspartic acid receptors / Nucleotide sequencing / Pathogens / Phospholipids / Physiological aspects / Prognosis / Tourette syndrome / Tourette's syndrome / Varicella / Viruses