CSF parvalbumin levels reflect interneuron loss linked with cortical pathology in multiple sclerosis.

INTRODUCTION AND METHODS: In order to verify whether parvalbumin (PVALB), a protein specifically expressed by GABAergic interneurons, could be a MS-specific marker of grey matter neurodegeneration, we performed neuropathology/molecular analysis of PVALB expression in motor cortex of 40 post-mortem progressive MS cases, with/without meningeal inflammation, and 10 control cases, in combination with cerebrospinal fluid (CSF) assessment. Analysis of CSF PVALB and neurofilaments (Nf-L) levels combined with physical/cognitive/3TMRI assessment was performed in 110 naïve MS patients and in 32 controls at time of diagnosis. RESULTS: PVALB gene expression was downregulated in MS (fold change = 3.7 ± 1.2, P < 0.001 compared to controls) reflecting the significant reduction of PVALB+ cell density in cortical lesions, to a greater extent in MS patients with high meningeal inflammation (51.8, P < 0.001). Likewise, post-mortem CSF-PVALB levels were higher in MS compared to controls (fold change = 196 ± 36, P < 0.001) and correlated with decreased PVALB+ cell density (r = -0.64, P < 0.001) and increased MHC-II+ microglia density (r = 0.74, P < 0.01), as well as with early age of onset (r = -0.69, P < 0.05), shorter time to wheelchair (r = -0.49, P < 0.05) and early age of death (r = -0.65, P < 0.01). Increased CSF-PVALB levels were detected in MS patients at diagnosis compared to controls (P = 0.002). Significant correlation was found between CSF-PVALB levels and cortical lesion number on MRI (R = 0.28, P = 0.006) and global cortical thickness (R = -0.46, P < 0.001), better than Nf-L levels. CSF-PVALB levels increased in MS patients with severe cognitive impairment (mean ± SEM:25.2 ± 7.5 ng/mL) compared to both cognitively normal (10.9 ± 2.4, P = 0.049) and mild cognitive impaired (10.1 ± 2.9, P = 0.024) patients. CONCLUSIONS: CSF-PVALB levels reflect loss of cortical interneurons in MS patients with more severe disease course and might represent an early, new MS-specific biomarker of cortical neurodegeneration, atrophy, and cognitive decline.

Immunochemical analysis of some proteins in cerebrospinal fluid and serum of patients with ischemic strokes.

Immunochemical studies of gamma gamma-neuron specific enolase (NSE), parvalbumin (PV), S-100 protein (S-100) and acidic fibrillary glial protein (GFAP) were studied in the cerebrospinal fluid and blood serum in 7 patients with ischemic cerebral stroke, aged 57 to 81 years. Cerebrospinal fluid and the first blood sample were taken on the first or second day of the disease. Further blood samples were taken once a week till the end of patients hospitalization, ending by patients discharge or death. Immunochemical identification of proteins under study were performed with Western-blotting technique. It was found that all proteins studied were present in both cerebrospinal fluid and blood serum on the first two days of the disease in small quantities. The blood content of both NSE and PV increased significantly during the first week of the disease. Both proteins disappeared from the blood serum between the second and fourth disease weeks. S-100 protein and GFAP contents in the blood reached significantly high level within the time interval between second and fifth disease weeks, and remained at a relatively high level till patients' death. In all cases computed tomography study and/or brain autopsy revealed extensive ischemic foci localized within areas supplied by the middle cerebral artery. No clear-cut correlation between extensiveness of the ischemic cerebral damage and the content of the proteins studied in both cerebrospinal fluid and blood serum was found. However, our data indicate that serial studies of the above proteins in patients with ischemic stroke may be useful in monitoring the progress of the disease, and occasionally in the prognosis at least in some cases.