Neurofilament light in plasma is a potential biomarker of central nervous system involvement in systemic lupus erythematosus

BACKGROUND

Neuropsychiatric manifestations (NP) are common in systemic lupus erythematosus (SLE). However, the pathophysiological mechanisms are not completely understood. Neurofilament light protein (NfL) is part of the neuronal cytoskeleton. Increased NfL concentrations, reflecting neurodegeneration, is observed in cerebrospinal fluid (CSF) in several neurodegenerative and neuroinflammatory conditions. We aimed to explore if plasma NfL could serve as a biomarker for central nervous system (CNS) involvement in SLE.

METHODS

Sixty-seven patients with SLE underwent neurological examination; 52 underwent lumbar puncture, while 62 underwent cerebral magnetic resonance imaging (MRI). We measured selected auto-antibodies and other laboratory variables postulated to have roles in NP pathophysiology in the blood and/or CSF. We used SPM12 software for MRI voxel-based morphometry.

RESULTS

Age-adjusted linear regression analyses revealed increased plasma NfL concentrations with increasing creatinine (β = 0.01, p < 0.001) and Q-albumin (β = 0.07, p = 0.008). We observed higher plasma NfL concentrations in patients with a history of seizures (β = 0.57, p = 0.014), impaired motor function (β = 0.36, p = 0.008), increasing disease activity (β = 0.04, p = 0.008), and organ damage (β = 0.10, p = 0.002). Voxel-based morphometry suggested an association between increasing plasma NfL concentrations and the loss of cerebral white matter in the corpus callosum and hippocampal gray matter.

CONCLUSION

Increased plasma NfL concentrations were associated with some abnormal neurological, cognitive, and neuroimaging findings. However, plasma NfL was also influenced by other factors, such as damage accrual, creatinine, and Q-albumin, thereby obscuring the interpretation of how plasma NfL reflects CNS involvement. Taken together, NfL in CSF seems a better marker of neuronal injury than plasma NfL in patients with SLE.

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.

Electronic supplementary material

Supplementary information is available for this paper at 10.1007/s00415-020-10290-y.

The blood-brain barrier, TWEAK, and neuropsychiatric involvement in human systemic lupus erythematosus and primary Sjögren's syndrome

OBJECTIVE

A prevailing hypothesis for neuropsychiatric involvement in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome is that brain reactive autoantibodies enter the brain through a disrupted blood-brain barrier. Our aim was to investigate whether TNF-like weak inducer of apoptosis (TWEAK) plays a role in cerebral involvement in human SLE and primary Sjögren's syndrome, and whether an impaired blood-brain barrier is a prerequisite for neuropsychiatric manifestations.

METHODS

TWEAK was measured in the cerebrospinal fluid and serum and compared with markers of blood-brain barrier permeability (Q-albumin and MRI contrast-enhanced lesions) and S100B, an astrocyte activation marker in 50 SLE and 52 primary Sjögren's syndrome patients. Furthermore, we estimated the general intrathecal B-cell activation (IgG index), measured anti-NR2 antibodies in cerebrospinal fluid, and explored whether these variables were associated with neuropsychiatric manifestations.

RESULTS

No associations were found between TWEAK in the cerebrospinal fluid or serum and neuropsychiatric manifestations in SLE nor in primary Sjögren's syndrome patients. Furthermore, no associations were found between neuropsychiatric manifestations and indicators of blood-brain barrier integrity or astroglial activity. Anti-NR2 antibodies were associated with impaired visuospatial processing (odds ratio 4.9, P = 0.03) and motor functioning (odds ratio 6.0, P = 0.006).

CONCLUSION

No clinical neuropsychiatric manifestations could be attributed to impaired integrity of the blood-brain barrier, or to TWEAK levels in cerebrospinal fluid or serum in either patient group. The TWEAK concentration was considerably higher in the cerebrospinal fluid than in blood, which indicates intrathecal production. We hypothesize that increased TWEAK and S100B result from immunological stress caused by brain-reactive antibodies produced by brain residing immune cells.

Identification of a Sjögren's syndrome susceptibility locus at OAS1 that influences isoform switching, protein expression, and responsiveness to type I interferons

Sjögren's syndrome (SS) is a common, autoimmune exocrinopathy distinguished by keratoconjunctivitis sicca and xerostomia. Patients frequently develop serious complications including lymphoma, pulmonary dysfunction, neuropathy, vasculitis, and debilitating fatigue. Dysregulation of type I interferon (IFN) pathway is a prominent feature of SS and is correlated with increased autoantibody titers and disease severity. To identify genetic determinants of IFN pathway dysregulation in SS, we performed cis-expression quantitative trait locus (eQTL) analyses focusing on differentially expressed type I IFN-inducible transcripts identified through a transcriptome profiling study. Multiple cis-eQTLs were associated with transcript levels of 2'-5'-oligoadenylate synthetase 1 (OAS1) peaking at rs10774671 (PeQTL = 6.05 × 10-14). Association of rs10774671 with SS susceptibility was identified and confirmed through meta-analysis of two independent cohorts (Pmeta = 2.59 × 10-9; odds ratio = 0.75; 95% confidence interval = 0.66-0.86). The risk allele of rs10774671 shifts splicing of OAS1 from production of the p46 isoform to multiple alternative transcripts, including p42, p48, and p44. We found that the isoforms were differentially expressed within each genotype in controls and patients with and without autoantibodies. Furthermore, our results showed that the three alternatively spliced isoforms lacked translational response to type I IFN stimulation. The p48 and p44 isoforms also had impaired protein expression governed by the 3' end of the transcripts. The SS risk allele of rs10774671 has been shown by others to be associated with reduced OAS1 enzymatic activity and ability to clear viral infections, as well as reduced responsiveness to IFN treatment. Our results establish OAS1 as a risk locus for SS and support a potential role for defective viral clearance due to altered IFN response as a genetic pathophysiological basis of this complex autoimmune disease.

Migraine in patients with systemic lupus erythematosus is associated with reduced cerebral grey matter volume but not with measures of glial activation or anti-NR2 or anti-P antibodies

BACKGROUND AND PURPOSE

Migraine is frequent in patients with systemic lupus erythematosus (SLE), but the pathogenesis and pathophysiology are poorly understood. Migraine is assumed to be a consequence of abnormal neuronal excitability. Based on the hypothesis that the threshold for migraine is lower in SLE patients due to cerebral disturbances, whether structural abnormalities of the brain or relevant biomarkers are associated with headaches in SLE was investigated.

METHODS

Sixty-seven SLE patients and age- and gender-matched healthy subjects participated. Volumes of grey matter (GM) and white matter (WM) were estimated from cerebral magnetic resonance images with SPM8 software. Anti-NR2 and anti-P antibodies and protein S100B were measured in cerebrospinal fluid.

RESULTS

In regression analyses, larger GM volumes in SLE patients reduced the odds for headache in general [odds ratio (OR) 0.98, P = 0.048] and for migraine in particular (OR 0.95, P = 0.004). No localized loss of GM was observed. Larger WM volumes in patients increased the odds for migraine (OR 1.04, P = 0.007). These findings could not be confirmed in healthy subjects. Neither anti-NR2 and anti-P antibodies nor S100B were associated with headaches in SLE patients.

CONCLUSIONS

Systemic lupus erythematosus patients with migraine have a diffuse reduction in GM compared to patients without migraine. This finding was not observed in healthy subjects with migraine, and selected biomarkers did not indicate specific pathophysiological processes in the brain. These findings indicate that unknown pathogenic processes are responsible for the increased frequency of migraine in SLE patients.

Fatigue in Newly Diagnosed Inflammatory Bowel Disease

BACKGROUND AND AIMS

The present study investigated the prevalence and severity of fatigue in patients with newly diagnosed and untreated ulcerative colitis (UC) and Crohn's disease (CD) and examined relevant disease variables that may influence the severity of fatigue.

METHODS

Eighty-one patients with inflammatory bowel disease (IBD) (60 with UC and 21 with CD) were assessed for fatigue using two fatigue instruments: the Fatigue Severity Scale (FSS) and a fatigue visual analogue scale (fVAS). Cut-off for fatigue was defined as ≥4 for FSS and ≥50 for fVAS. Results were compared with fatigue scores from age-and gender-matched healthy individuals. Disease activity was assessed by symptom scores using the Mayo score in UC patients and the Harvey-Bradshaw index for CD patients, as well as C-reactive protein (CRP) and faecal calprotectin.

RESULTS

The prevalence of fatigue based on FSS and fVAS was 47 and 42%, respectively, in UC and 62 and 48% in CD. In multivariate regression models, disease activity markers were not associated with fatigue, while a significant relationship was found with age and depression for both fatigue measures.

CONCLUSIONS

Close to 50% of patients with IBD reported fatigue at the time of diagnosis. In newly diagnosed patients with active disease, the severity of fatigue was not associated with measures of disease activity.

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.

The IRF5-TNPO3 association with systemic lupus erythematosus has two components that other autoimmune disorders variably share

Exploiting genotyping, DNA sequencing, imputation and trans-ancestral mapping, we used Bayesian and frequentist approaches to model the IRF5-TNPO3 locus association, now implicated in two immunotherapies and seven autoimmune diseases. Specifically, in systemic lupus erythematosus (SLE), we resolved separate associations in the IRF5 promoter (all ancestries) and with an extended European haplotype. We captured 3230 IRF5-TNPO3 high-quality, common variants across 5 ethnicities in 8395 SLE cases and 7367 controls. The genetic effect from the IRF5 promoter can be explained by any one of four variants in 5.7 kb (P-valuemeta = 6 × 10(-49); OR = 1.38-1.97). The second genetic effect spanned an 85.5-kb, 24-variant haplotype that included the genes IRF5 and TNPO3 (P-valuesEU = 10(-27)-10(-32), OR = 1.7-1.81). Many variants at the IRF5 locus with previously assigned biological function are not members of either final credible set of potential causal variants identified herein. In addition to the known biologically functional variants, we demonstrated that the risk allele of rs4728142, a variant in the promoter among the lowest frequentist probability and highest Bayesian posterior probability, was correlated with IRF5 expression and differentially binds the transcription factor ZBTB3. Our analytical strategy provides a novel framework for future studies aimed at dissecting etiological genetic effects. Finally, both SLE elements of the statistical model appear to operate in Sjögren's syndrome and systemic sclerosis whereas only the IRF5-TNPO3 gene-spanning haplotype is associated with primary biliary cirrhosis, demonstrating the nuance of similarity and difference in autoimmune disease risk mechanisms at IRF5-TNPO3.

Loss of cerebral white matter in primary Sjögren's syndrome: a controlled volumetric magnetic resonance imaging study

BACKGROUND AND PURPOSE

Although brain involvement is common in primary Sjögren's syndrome (pSS), results from cerebral imaging studies are inconsistent. This study aimed to perform both voxel-wise and global brain volume analyses in a nearly population-based pSS cohort to explore whether the patients displayed any focal or diffuse volume differences compared with healthy subjects.

METHODS

Global grey matter (GM) and white matter (WM) volumes were measured and compared in 60 patients with pSS and 60 age- and gender-matched healthy subjects. Regression models were constructed with potential explanatory variables for GM and WM volumes. In the same groups, voxel-wise morphometric analyses were performed.

RESULTS

In analyses of global GM and WM, the patients had lower WM volumes than healthy subjects (540 ± 63 cm(3) vs. 564 ± 56 cm(3), P = 0.02), but no differences in GM. Voxel-wise analyses displayed no localized areas of GM or WM volume differences between pSS patients and healthy subjects.

CONCLUSION

Individuals with pSS have a diffuse reduction of cerebral WM but no localized loss of WM or GM. This indicates a general deleterious effect on WM due to pSS itself.

Variants at multiple loci implicated in both innate and adaptive immune responses are associated with Sjögren's syndrome

Sjögren’s syndrome is a common autoimmune disease (~0.7% of European Americans) typically presenting as keratoconjunctivitis sicca and xerostomia. In addition to strong association within the HLA region at 6p21 (P_meta=7.65×10⁻¹¹⁴), we establish associations with IRF5-TNPO3 (P_meta=2.73×10⁻¹⁹), STAT4 (P_meta=6.80×10⁻¹⁵), IL12A (P_meta =1.17×10⁻¹⁰), FAM167A-BLK (P_meta=4.97×10⁻¹⁰), DDX6-CXCR5 (P_meta=1.10×10⁻⁸), and TNIP1 (P_meta=3.30×10⁻⁸). Suggestive associations with P_meta<5×10⁻⁵ were observed with 29 regions including TNFAIP3, PTTG1, PRDM1, DGKQ, FCGR2A, IRAK1BP1, ITSN2, and PHIP amongst others. These results highlight the importance of genes involved in both innate and adaptive immunity in Sjögren’s syndrome.

A possible genetic association with chronic fatigue in primary Sjögren's syndrome: a candidate gene study

Fatigue is prevalent and disabling in primary Sjögren's syndrome (pSS). Results from studies in chronic fatigue syndrome (CFS) indicate that genetic variation may influence fatigue. The aim of this study was to investigate single nucleotide polymorphism (SNP) variations in pSS patients with high and low fatigue. A panel of 85 SNPs in 12 genes was selected based on previous studies in CFS. A total of 207 pSS patients and 376 healthy controls were genotyped. One-hundred and ninety-three patients and 70 SNPs in 11 genes were available for analysis after quality control. Patients were dichotomized based on fatigue visual analogue scale (VAS) scores, with VAS <50 denominated "low fatigue" (n = 53) and VAS ≥50 denominated "high fatigue" (n = 140). We detected signals of association with pSS for one SNP in SLC25A40 (unadjusted p = 0.007) and two SNPs in PKN1 (both p = 0.03) in our pSS case versus control analysis. The association with SLC25A40 was stronger when only pSS high fatigue patients were analysed versus controls (p = 0.002). One SNP in PKN1 displayed an association in the case-only analysis of pSS high fatigue versus pSS low fatigue (p = 0.005). This candidate gene study in pSS did reveal a trend for associations between genetic variation in candidate genes and fatigue. The results will need to be replicated. More research on genetic associations with fatigue is warranted, and future trials should include larger cohorts and multicentre collaborations with sharing of genetic material to increase the statistical power.

[Risk of infection through use of selective immunomodulating drugs for rheumatoid arthritis]

BACKGROUND

New drugs for rheumatoid arthritis (RA) have resulted in an improvement in patients' functioning and morbidity, but are linked with increased risk of infections. Traditional immunosuppressant drugs are often used in combination with anti-tumour necrosis factor-alpha (TNF-α) inhibitors or anti-CD20 (rituximab).

METHOD

The review is based on a search in PubMed and on the authors' own experience of treating infections in patients who receive immunosuppressant treatment.

RESULTS

Traditional immunomodulating treatment results in an increased risk of infection. The disease RA in itself increases the risk of infections. There is evidence of an increased incidence of infections with both extracellular bacteria and intracellular microorganisms such as mycobacteria, including Mycobacterium tuberculosis, and viruses in patients who are treated with TNF-α inhibitors. Patients who are about to start taking TNF-α inhibitors must therefore undergo a tuberculosis-risk assessment. Rituximab may increase the incidence of infection, but long-term observations are limited. Combination therapy involving different drugs that selectively modulate immune response is normally contraindicated because of the increased risk of infection.

INTERPRETATION

The benefit of TNF-α inhibitors and rituximab treatment for RA must be weighed up against the increased risk of infections. Symptoms, findings and laboratory test results pertaining to serious infections may be influenced by immunomodulation therapy and thereby make clinical assessment difficult.

Oxidative stress, as measured by protein oxidation, is increased in primary Sjøgren's syndrome

OBJECTIVE

Oxidative stress is an imbalance between the production of reactive oxygen species (ROS) and physiological antioxidant defences. It occurs frequently in conditions characterized by immune activation and inflammation. Plasma levels of oxidized end products have never been evaluated in primary Sjøgren's syndrome (pSS). The aim of this study was to investigate the level of oxidative stress in primary Sjøgren's syndrome. As a secondary outcome, the association between oxidative stress and fatigue was explored.

METHODS

A cross-sectional study of 26 pSS patients was carried out. Oxidative stress was assessed using two markers of protein oxidation, protein carbonyl (PC) and advanced oxidation protein products (AOPP). Reference values for the oxidative stress markers were obtained from 15 healthy subjects.

RESULTS

AOPP and PC levels were increased in the pSS patients compared to the healthy subjects. This is a novel finding. There were no associations between oxidative stress measures and fatigue in the patients.

CONCLUSIONS

Patients with pSS have increased levels of oxidative stress compared to healthy subjects.

Interleukin-1 inhibition and fatigue in primary Sjögren's syndrome--a double blind, randomised clinical trial

OBJECTIVES

Fatigue is a major cause of disability in primary Sjögren's syndrome (pSS). Fatigue has similarities with sickness behaviour in animals; the latter mediated by pro-inflammatory cytokines, in particular interleukin (IL)-1, acting on neuronal brain cells. We hypothesised that IL-1 inhibition might improve fatigue in pSS patients; thus, we examined the effects and safety of an IL-1 receptor antagonist (anakinra) on fatigue.

METHODS

Twenty-six pSS patients participated in a double-blind, placebo-controlled parallel group study. Patients were randomised to receive either anakinra or a placebo for four weeks. Fatigue was evaluated by a fatigue visual analogue scale and the Fatigue Severity Scale. The primary outcome measure was a group-wise comparison of the fatigue scores at week 4, adjusted for baseline values. Secondary outcome measures included evaluation of laboratory results and safety. The proportion of patients in each group who experienced a 50% reduction in fatigue was regarded as a post-hoc outcome. All outcomes were measured at week 4.

RESULTS

There was no significant difference between the groups in fatigue scores at week 4 compared to baseline after treatment with anakinra. However, six out of 12 patients on anakinra versus one out of 13 patients on the placebo reported a 50% reduction in fatigue VAS (p = 0.03). There were two serious adverse events in each group.

CONCLUSIONS

This randomised, double-blind, placebo-controlled trial of IL-1 blockade did not find a significant reduction in fatigue in pSS in its primary endpoint. A 50% reduction in fatigue was analysed post-hoc, and significantly more patients on the active drug than on placebo reached this endpoint. Although not supported by the primary endpoint, this may indicate that IL-1 inhibition influences fatigue in patients with pSS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00683345.

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 cere-brospinal fluid (CSF) abnormalitites.

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.

Fatigue in primary Sjögren's syndrome--a link to sickness behaviour in animals?

Interleukin-1beta (IL-1beta) is involved in the regulation of sickness behaviour in response to infection and inflammation in animals. Human fatigue can be considered an element of sickness behaviour and is a prominent and often disabling phenomenon in autoimmune diseases such as primary Sjögren's syndrome (PSS). The role of the IL-1 system in the fatigue of patients with PSS was explored. A cerebrospinal fluid (CSF) analysis of IL-1beta, IL-1Ra, and IL-1sRII was performed in 54 PSS patients and 53 control subjects. Fatigue was evaluated in the patients using the Fatigue Severity Scale (FSS) and a fatigue visual analogue scale (VAS); mood was evaluated using the Beck Depression Inventory (BDI). There were higher CSF levels of IL-1Ra pg/mL in PSS patients vs. controls (median 38.4: range 15.4-81.7 vs. 33.7: 7.3-163.1, p=0.026). Fatigue VAS scores were associated with increasing CSF levels of IL-1Ra in PSS patients (R(2)=0.11, p=0.015). In a subgroup analysis of the non-depressed PSS patients (N=37; 69%), the association between VAS scores and IL-1Ra was even stronger (R(2)=0.20, p=0.006). The positive association between VAS scores and IL-1Ra remained significant in a multiple regression analysis adjusting for age and BDI scores. Increased levels of IL-1Ra in the CSF are associated with increasing fatigue in PSS patients, indicating that the activated IL-1 system is a possible biological factor associated with fatigue.

Fatigue is associated with cerebral white matter hyperintensities in patients with systemic lupus erythematosus

BACKGROUND

Fatigue is a disabling phenomenon in many patients who have systemic lupus erythematosus (SLE). The pathophysiological processes are unknown, and no known biological disease factors influence the phenomenon. Because depressive mood is consistently associated with fatigue, and drug treatment for SLE does not ameliorate fatigue, a psychological explanation could be an alternative. In search of a somatic basis for fatigue, we looked for alternative markers of biologic activity associated with fatigue. Cerebral white matter hyperintensities (WMHs) represent biochemical changes of brain tissue and are frequently encountered in patients with SLE, and are associated with cognitive impairment in patients with multiple sclerosis. Presence of such an association between fatigue and WMHs in SLE would favour a biological axis to fatigue.

METHODS

A cross-sectional, case-control study with 62 unselected patients with SLE and 62 age- and gender-matched healthy subjects. Fatigue was evaluated using the Fatigue Severity Scale (FSS) and a fatigue visual analogue scale (VAS). WMHs were rated using Scheltens' method.

RESULTS

Greater fatigue and more WMHs appeared in patients with SLE versus healthy subjects. In the full group of patients (n = 62), fatigue VAS was associated with total WMH score (p = 0.009). In subgroup analysis of patients without clinical depression (n = 40), the association with total WMH remained (p = 0.035), whereas this was not the case in the depressed group (n = 18) (p = 0.211).

CONCLUSION

Increased cerebral WMH load is associated with increased fatigue, indicating a biological origin for some portion of fatigue in patients with SLE.

In vitro stability of insulin aspart in simulated continuous subcutaneous insulin infusion using a MiniMed 508 insulin pump

BACKGROUND

This study was designed to assess the stability and potency of insulin aspart under experimental circumstances simulating worst-case conditions during clinical use for continuous subcutaneous insulin infusion (CSII).

METHODS

The potency and stability of two batches of U100 insulin aspart, one recently manufactured and one nearing the end of shelf life, were evaluated after storage in a Medtronic (Northridge, CA) MiniMed 508 pump for up to 7 days at 37 +/- 2 degrees C. The pumps were placed on a vibrating platform (30 +/- 3 oscillations/min, 2 +/- 0.5 cm amplitude displacement) for 24 h/day to simulate movement by the pump user. The product remaining in the pump reservoir was tested at days 3, 4, and 7 and compared with control samples.

RESULTS

After 7 days of in-pump use, there was no significant reduction in potency of insulin aspart or difference from reference values with regards to pH, isoAsp(B28), desamido insulin aspart, insulin aspart-related impurities, or high-molecular-weight proteins. The concentration of phenol and m-cresol remained at levels sufficient to ensure preservative efficacy for both control and test samples. There was no evidence of fibrillation or precipitation.

CONCLUSIONS

The data indicate that storage in the plastic pump reservoir under temperature and vibration conditions simulating worst-case conditions during clinical use for CSII did not affect the stability or potency of insulin aspart significantly, and support an in-pump-use time of 7 days in the MiniMed 508 pump.

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.

Intraepidermal Nerve Fiber Densities in Chronic Inflammatory Autoimmune Diseases

BACKGROUND

Some patients with systemic lupus erythematosus have selective loss of small-diameter nerve fibers, while larger nerve fibers are unaffected.

OBJECTIVE

To determine intraepidermal nerve fiber densities in patients with different chronic inflammatory autoimmune diseases.

DESIGN

Cross-sectional study.

SETTING

Stavanger University Hospital, Stavanger, and Haukeland University Hospital, Haukeland, Norway.

PATIENTS

Sixty patients with systemic lupus erythematosus (SLE) (mean +/- SD age, 43.2 +/- 13.5 years), 61 patients with primary Sjögren syndrome (age, 57.1 +/- 14.7 years), and 52 patients with rheumatoid arthritis (age, 57.4 +/- 12.3 years) were compared with 106 healthy subjects (age, 49.0 +/- 19.6 years).

INTERVENTIONS

Skin biopsy specimens.

MAIN OUTCOME MEASURES

To evaluate small-diameter nerve fiber loss, intraepidermal nerve fiber densities were measured in skin punch biopsy specimens obtained from the distal part of the leg.

RESULTS

The mean +/- SD densities were 7.5 +/- 3.8 fibers/mm in patients with SLE, 9.2 +/- 3.8 fibers/mm in primary Sjögren syndrome, and 10.9 +/- 5.4 fibers/mm in rheumatoid arthritis vs 12.4 +/- 4.6 fibers/mm in healthy subjects. Densities were significantly less in patients with SLE vs patients with rheumatoid arthritis and vs healthy subjects (P<.001 for both), as well as in patients with primary Sjögren syndrome vs healthy subjects (P<.001). Eight patients (13%) with SLE, 2 patients (3%) with primary Sjögren syndrome, and 2 patients (4%) with rheumatoid arthritis had densities below the lower reference limit of 3.4 fibers/mm, consistent with small-diameter nerve fiber neuropathy.

CONCLUSION

The degree of loss of small-diameter nerve fibers differs among patients with these chronic inflammatory autoimmune diseases, likely reflecting differences in pathogenesis and organ affinity of the individual disease entities.

Neuropsychiatric symptoms in patients with multiple sclerosis

OBJECTIVE

To explore the range of psychiatric symptoms in patients with multiple sclerosis (MS) and their association with neurological disability.

METHOD

Patients diagnosed with MS during 1998-2000 in Rogaland and Hordaland counties, western Norway, were included. Psychiatric symptoms were assessed by the Neuropsychiatric Inventory (NPI). Patients with systemic lupus erythematosus (SLE) served as controls.

RESULTS

Eighty-six of 93 eligible MS patients were included, and 80% showed at least one psychiatric symptom. The most frequent symptoms were depression (59%), sleep disturbance (48%), irritability/emotional lability (42%), and apathy (31%). Depression was associated with higher disability score. MS patients showed significantly higher NPI irritability score (P = 0.002), appetite disturbance score (P < 0.001), and apathy score (P = 0.01) than SLE patients.

CONCLUSION

Neuropsychiatric symptoms occur frequently in patients with MS. Irritability and apathy are independent of disability and chronic disease and represent unique disease manifestations.

[Mycophenolate mofetil--a new therapeutic agent for chronic autoimmune diseases]

BACKGROUND

Mycophenolate mofetil is an immunosuppressive agent frequently used in regimens to prevent allograft rejection. In this review we focus on mycophenolate mofetil as a potential drug for chronic autoimmune diseases.

MATERIALS AND METHODS

We searched PubMed for relevant literature and present two case histories.

RESULTS AND INTERPRETATION

Treatment with mycophenolate mofetil is best documented in lupus nephritis. In this context, some studies have documented an effect equal to cyclophosphamide for induction treatment, and equal to azathioprine, and better than cyclophosphamide for remission maintenance. Mycophenolate mofetil is today an alternative, although experimental, agent for the treatment of certain autoimmune diseases when conventional drugs have failed or are not tolerated; in the future it may become more widely used for immunosuppression. To establish the role for mycophenolate mofetil, more prospective controlled multicentre studies are warranted.

Macromolecular prodrugs. XVI. Colon-targeted delivery--comparison of the rate of release of naproxen from dextran ester prodrugs in homogenates of various segments of the pig gastrointestinal (GI) tract

We have determined initial rates of naproxen formation from dextran-naproxen ester prodrugs incubated in homogenates of various segments of the pig GI tract. Drug liberation proceeded 15-17 times faster in cecum and colon homogenates than in aqueous pH 7.4 buffer or homogenates of the small intestine. The degree of conjugate substitution did not affect the liberation rates, whereas enhanced drug activation was observed with decreasing molecular size of the carrier dextran. During incubation in colon homogenates the average molecular weight of the dextran prodrugs decreased. The mechanism of drug activation from the prodrugs may therefore involve an initial depolymerization step of the dextran chains by dextranases secreted from bacteria in the pig colon. The generated small fragments then serve as substrates for esterases and other hydrolases.

Macromolecular prodrugs. XV. Colon-targeted delivery--bioavailability of naproxen from orally administered dextran-naproxen ester prodrugs varying in molecular size in the pig

The bioavailability of naproxen after oral administration of aqueous solutions of various dextran-naproxen ester prodrugs in pigs was determined. The dextran prodrugs employed ranged in molecular weight from 10,000 to 500,000. As calculated relative to an equivalent oral dose of parent naproxen, the absorption fractions of all the derivatives were close to 100%. Only small interindividual variation of naproxen bioavailability was observed. The naproxen plasma profiles for all the administered prodrugs exhibited a characteristic lag time of naproxen appearance in the blood (2-3 hr). Compared to administration of the prodrugs alone, coadministration of excess of the parent dextran further delayed the absorption of naproxen from the GI tract. The results of the present study demonstrate the potential of dextran prodrugs for colon site-specific delivery of drugs containing a carboxylic acid functional group.