Neurofilament light is a biomarker of brain involvement in lupus and primary Sjögren's syndrome.

BACKGROUND: To test the hypothesis that neurofilament light (NfL) in CSF is a biomarker of CNS involvement in patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS), we measured NfL in CSF from 52 patients with lupus and 54 with pSS and explored associations with clinical, structural, immunological and biochemical abnormalities. METHODS: In CSF, we measured NfL, anti-P antibodies, protein S100B and TWEAK by ELISA and anti-NR2 antibodies by electrochemiluminescence. Anti-phospholipid antibodies and routine immunological tests were performed in blood. IgG and albumin were measured in CSF and serum for assessment of the blood-brain barrier function (Q-albumin) and intrathecal IgG production (IgG index). Cerebral MRI and neuropsychological testing were performed. RESULTS: A multivariable regression model showed that increasing CSF anti-NR2 antibody levels were associated with increasing NfL levels in patients with SLE (B 1.27, 95% CI 0.88-1.65, p < 0.001). Age contributed significantly in the model (B 0.04, 95% CI 0.03-0.05, p < 0.001). Similar findings were observed in the pSS group. Adjusted for age and sex, no associations were found between NfL levels and any MRI data. In SLE patients, higher NfL concentrations were associated with impairments in psychomotor speed and motor function, and in pSS with motor dysfunction. These associations remained in multivariable regression models. CONCLUSIONS: Increased concentration of NfL in CSF is a marker of cerebral involvement in patients with SLE and pSS, is strongly associated with the presence of anti-NR2 antibodies, and correlates with cognitive impairment in several domains.

Association of hippocampal atrophy with cerebrospinal fluid antibodies against the NR2 subtype of the N-methyl-D-aspartate receptor in patients with systemic lupus erythematosus and patients with primary Sjögren's syndrome.

OBJECTIVE: Cognitive dysfunction is common in both systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (SS). Antibodies against the NR2 subtype of the N-methyl-D-aspartate receptor (anti-NR2 antibodies) cause hippocampal atrophy and cognitive impairment in mice and have been associated with memory impairment in both patients with SLE and patients with primary SS. In addition, a reduced volume of hippocampal gray matter has been demonstrated in both SLE and primary SS. This study was undertaken to investigate whether there is a connection between the presence of anti-NR2 antibodies and hippocampal atrophy in human diseases. METHODS: Fifty patients with SLE and 50 patients with primary SS underwent clinical examination and cerebral magnetic resonance imaging. Anti-NR2 antibodies in cerebrospinal fluid (CSF) were measured, and hippocampal gray matter volumes were compared between patients who were positive for and those who were negative for anti-NR2 antibodies. RESULTS: Patients with anti-NR2 antibodies in CSF had less hippocampal gray matter than patients without these antibodies. No other differences regarding gray matter volumes in other parts of the brain were identified. CONCLUSION: The present findings indicate that anti-NR2 antibodies in patients with SLE and primary SS cause neuronal death manifested as reduced hippocampal gray matter, as has been previously demonstrated in mice with autoimmune disease.

Memory dysfunction in primary Sjögren's syndrome is associated with anti-NR2 antibodies.

OBJECTIVE: Our understanding of the etiology and pathogenesis of neuropsychiatric involvement in primary Sjögren's syndrome (SS) is incomplete. In systemic lupus erythematosus, it has been reported that antibodies directed against N-methyl-D-aspartate receptor subtype NR2 (anti-NR2) interfere with memory and learning function, as well as mood. This has not been investigated in primary SS; however, the present study was undertaken to advance our understanding of neuropsychiatric involvement in this disease. METHODS: Sixty-six patients with primary SS and 66 age- and sex-matched healthy control subjects underwent clinical examination and neuropsychological evaluation. Anti-NR2 antibodies were measured in serum and cerebrospinal fluid. Hippocampus volume was estimated using software extensions to SPM5. RESULTS: Patients with primary SS had smaller hippocampi than healthy subjects (mean ± SD 8.15 ± 0.98 cm(3) versus 8.49 ± 0.88 cm(3); P = 0.01). In patients with primary SS, anti-NR2 antibodies in cerebrospinal fluid were associated with a worse performance in 8 of 10 memory and learning tests, and anti-NR2 antibodies in serum were associated with a worse performance in 6 of those same tests. In addition, a higher proportion of patients with depression than patients without depression had serum anti-NR2 antibody levels above the cutoff value. CONCLUSION: Results of this study indicate that anti-NR2 antibodies may represent one of the pathogenetic mechanisms for cognitive disturbances and mood disorders in patients with primary SS.

Migraine is frequent in patients with systemic lupus erythematosus: a case-control study.

INTRODUCTION: The objective of this study was to compare the prevalence of primary headaches in systemic lupus erythematosus (SLE) versus healthy subjects, and to determine whether headaches in SLE are associated with MRI- or cerebrospinal fluid (CSF) abnormalities. PATIENTS AND METHODS: The case-control study included MRI- and CSF investigations. Headache was classified according to the International Classification of Headache Disorders. Depression and fatigue were measured with Beck Depression Inventory (BDI) and Fatigue Severity Scale (FSS) respectively. RESULTS: Twenty-four out of 67 SLE patients and 13 out of 67 age- and gender matched healthy subjects had migraine (36% vs 19%, P = 0.03). Nine (13%) SLE patients had migraine with aura vs 4 (6%) in healthy subjects, P = 0.14. The prevalence of tension type headache was equal (60% in patients vs 58% in controls). There was no association between migraine and SLE disease activity, biochemical or immunological markers, cerebral white matter hyperintensities, interleukin-6 in CSF, impairment of the blood-brain barrier, or intrathecal immunoglobulin production. SLE patients had higher BDI- and FSS scores compared with healthy control subjects, and SLE patients with migraine had higher BDI scores than lupus patients without migraine. CONCLUSIONS: Migraine is more prevalent in SLE patients, associated with depression like in the general population, but not associated with disease activity or abnormalities detected on cerebral MRI, in CSF, or any SLE characteristics except from SLE photosensitivity. The inclusion of the migraine item in SLE disease activity instruments remains questionable.

Peripheral neuropathy in primary sjogren syndrome: a population-based study.

BACKGROUND: Neurological manifestations appear to be frequently involved in patients with primary Sjögren syndrome (PSS). OBJECTIVE: To investigate the involvement of the peripheral nervous system, including small-diameter nerve fibers, in an unselected cohort of patients who fulfilled the new international criteria for PSS. DESIGN: Cross-sectional study. SETTING: Stavanger University Hospital. Patients Sixty-two patients with PSS (mean +/- SD age, 57.1 +/- 14.6 years). INTERVENTIONS: Clinical neurologic examinations, conventional nerve conduction studies, and skin punch biopsies. MAIN OUTCOME MEASURES: Signs of large-diameter and small-diameter peripheral nerve fiber neuropathy as determined by clinical examination, nerve conduction studies, and densities of intraepidermal nerve fibers in skin punch biopsy specimens. RESULTS: Seventeen patients (27%) were diagnosed as having neuropathy after clinical examination. The results of nerve conduction studies were abnormal in 34 patients (55%): 19 patients (31%) had motor neuropathy, 8 (13%) had sensory neuropathy, and 7 (11%) had sensorimotor neuropathy. Two patients had intraepidermal nerve fiber densities less than 3.4 fibers per millimeter, fitting the morphologic criteria for small-diameter nerve fiber neuropathy. CONCLUSIONS: Peripheral neuropathy occurs in a large proportion of patients with PSS, in most cases as a subclinical demyelinating neuropathy. Small-diameter nerve fiber neuropathy is not a frequent finding in these patients.

Small-diameter nerve fiber neuropathy in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is an inflammatory, autoimmune, multiorgan disease often involving the central and peripheral nervous systems. OBJECTIVE: To determine whether there is a selective small-diameter nerve fiber neuropathy in patients with SLE. DESIGN: Cross-sectional study. SETTING: Stavanger University Hospital, Stavanger, Norway. Patients Sixty patients with SLE, aged 43.2 +/- 13.5 years (mean +/- SD). INTERVENTIONS: Skin biopsies, nerve conduction studies, and clinical neurologic examinations. MAIN OUTCOME MEASURES: Density of intraepidermal small-diameter nerve fibers in skin biopsy specimens and large-diameter nerve fiber function as determined by nerve conduction studies and clinical examinations. RESULTS: The mean density of intraepidermal small-diameter nerve fibers in patients with SLE was 7.5 +/- 3.8/mm. Eight patients (13%) had densities below reference values, consistent with small-diameter nerve fiber neuropathy, and results of nerve conduction studies were normal in 6 of them. Eleven patients (18%) had abnormal results of nerve conduction studies, reflecting large-diameter nerve fiber neuropathy, and 4 patients (7%) were classified by an experienced neurologist as having polyneuropathy after the clinical examination. CONCLUSIONS: An abnormal reduction in intraepidermal small-diameter nerve fiber densities is evident in some patients despite normal function of their larger nerve fibers. This adds further support to the theory that a pure small-diameter nerve fiber neuropathy may occur in SLE.