Cerebrospinal fluid cystatin C levels in patients with anti-NMDAR encephalitis and other neurological diseases.

BACKGROUND

Cystatin C has neuroprotective and immunomodulatory effects on the central nervous system. However, the role of cerebrospinal fluid (CSF) cystatin C in anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) remains unknown.

METHODS

In this study, CSF levels of cystatin C were determined in 73 patients with anti-NMDARE; 496 patients with other neurological diseases, comprising 108 with neuromyelitis optica, 77 with multiple sclerosis, 71 with schizophrenia, 68 with cryptococcus meningitis or meningoencephalitis, 43 with tuberculous meningitis or meningoencephalitis, 43 with bacterial meningitis or meningoencephalitis (BM), 35 with Guillain-Barré syndrome, 23 with spinal cord injury (SCI), 14 with amyotrophic lateral sclerosis (ALS), and 14 with idiopathic epilepsy; and 136 control patients with non-inflammatory diseases. The associations of CSF cystatin C with anti-NMDARE and its clinical parameters were evaluated.

RESULTS

CSF cystatin C levels were significantly lower in patients with anti-NMDARE than in patients with BM, SCI, and ALS, especially among those with poor functional status (modified Rankin Scale [mRS] ≥4). CSF cystatin C levels were also significantly lower in anti-NMDARE patients with poor functional status (mRS ≥4) than in those with good functional status (mRS <4). CSF cystatin C levels were significantly associated with mRS scores and CSF white blood cell counts in anti-NMDARE patients.

CONCLUSIONS

CSF levels of cystatin C are decreased in anti-NMDARE patients and negatively associated with disease severity.