Reduced homovanillic acid, SDF-1α and SCGF-β levels in cerebrospinal fluid are related to depressive states in systemic lupus erythematosus

This study aimed to seek a new method of evaluation and surrogate markers for diffuse neuropsychiatric SLE (NPSLE).We enrolled 44 patients with SLE between 2017 and 2020 who fulfilled at least one of three specific inclusion criteria: high disease activity, abnormal findings (cerebrospinal fluid [CSF] examination, brain MRI, or electroencephalography), or history of neuropsychiatric illness. Psychiatric symptom rating scales (PSYRATS) were evaluated retrospectively. The primary end point was the PSYRATS positivity rate in SLE patients who had not been diagnosed with diffuse NPSLE.Based on the 1999 ACR classifications, 7 out of the 44 patients evaluated using PSYRATS had been diagnosed with diffuse NPSLE. PSYRATS positivity was seen in 13 out of 37 SLE patients (35.1%) who had not been diagnosed with diffuse NPSLE, and all these patients were positive for Montgomery-Åsberg Depression Rating Scale (MADRS), an indicator of depression state in PSYRATS. Additionally, in the 20 SLE patients exhibiting depression symptoms who were MADRS-positive, CSF concentrations of the neuroinflammatory markers homovanillic acid (HVA; P = 0.0400), stromal cell-derived factor-1α (SDF-1α; P = 0.0431) and stem cell growth factor-β (SCGF-1β; P = 0.0061) were significantly reduced compared with the 24 MADRS-negative SLE patients, and the levels of HVA, SDF-1α and SCGF-1β correlated with one another (P < 0.05).Many patients with active SLE have subclinical depression, and MADRS evaluation of neuropsychiatric symptoms is useful for detecting them. Additionally, the decrease in CSF levels of HVA, SDF-1 α and SCGF-1β reflects the same pathology, and these may serve as surrogate markers.