Sophie Desplat-Jégo

TWEAK stimulation of astrocytes and the proinflammatory consequences

Astrocytes exert many active roles in brain homeostasis, potentially including the regulation of immune reactions. They possess a substantial aptitude for plasticity and, indeed, functional and phenotypic changes are frequently encountered in reactive gliosis observed in brain injuries. The significance of reactive astrocytes is still poorly defined, but it is clear that these cells are an important source of cytokines in inflamed brain. How tumor necrosis factor (TNF) and TNF‐receptor family members contribute to this reaction is an interesting issue that is currently being explored. It was previously shown that reactive astrocytes express high levels of Fas (CD95) and respond to Fas ligand (CD95L) by apoptosis or IL‐8 production. TWEAK (Apo‐3 ligand) is a recently identified member of the TNF family that is produced mainly by leukocytes that can infiltrate the inflamed brain and thus influence astrocyte behavior. Here we show that human astrocytes derived from different regions of the brain specifically bind TWEAK and are totally resistant to TWEAK mediated apoptosis. In addition, high amounts of IL‐8 and IL‐6 were secreted by astrocytes after TWEAK exposure. Finally, expression of cell surface molecules involved in the propagation and/or maintenance of brain inflammation was determined. TWEAK significantly increased ICAM‐1 expression on astrocytes, whereas no modification was detected in the expression of Fas, TNFRI, B7‐1, or MHC molecules. In conclusion, the proinflammatory effects induced by TWEAK on astrocytes in culture recapitulate many characteristics of reactive astrocytes observed in vivo, suggesting that TWEAK could play a significant role in brain inflammation. GLIA 32:102–107, 2000.

Lithostathine and pancreatitis-associated protein are involved in the very early stages of Alzheimer's disease

According to one of the theories formulated to explain the etiology of Alzheimers disease (AD), amylosis may reflect a specific inflammatory response. Two inflammatory proteins, lithostathine and PAP, were evidenced by immunohistochemistry in senile plaques and neurofibrillary tangles of patients with AD. In addition, lithostathine and PAP were significantly increased in the cerebrospinal fluid of patients with AD when compared to patients with multiple sclerosis, another inflammatory disease, and to normal control subjects. However, no correlation was observed with age of occurrence. Furthermore, lithostathine and PAP were increased even at the very early stages of AD, and their level remained elevated during the course of the AD unlike TNFalpha whose level, very high at very early stages, regularly decreased. Finally, if part of lithostathine and PAP are synthesized in the brain, a large part comes from serum by passage over the blood-brain barrier. These results indicate (i) the existence of an acute phase response followed by a chronic inflammation in AD, and (ii) that lithostathine and PAP are involved even at the first pre-clinical biochemical events of AD. In addition, because lithostathine undergoes an autolytic cleavage leading to its precipitation and the formation of fibrils, we believe that it may be involved in amyloidosis and tangles by allowing heterogeneous precipitation of other proteins.

Quantification of Immunoglobulin Free Light Chains in CerebroSpinal Fluid by Nephelometry

Oligoclonal free light chains (FLC) banding has been described in multiple sclerosis (MS) and should be correlated with disease activity. However, discrepancies between studies have been reported because of differences in methods. A new quantitative, rapid, and automated method using nephelometry is now available. Our objective was to investigate the interest of this method for the diagnosis and prognosis of MS. For this purpose, FLC index was determined in paired samples of CSF and serum from consecutive and unselected patients from the same department of neurology. We enrolled 89 patients (33 MS, 15 “possible MS”, and 41 controls) and correlated with IgG index, IgG oligoclonal banding, and clinical MS progression criteria. The main results were (1) FLC kappa index was more sensitive but less specific than IgG index for the diagnosis of MS, (2) two MS patients were negative for oligoclonal banding but exhibited a positive kappa index, (3) no relation between FLC kappa indices, MS clinical criteria, and disease progression was found. In conclusion, FLC kappa index should be considered as a useful complementary test for MS diagnosis. Its pronostic interest remains to be determined on a larger cohort of possible MS patients.

Evaluation of the BioPlex 2200 ANA screen for the detection of antinuclear antibodies and comparison with conventional methods

Abstract:  BioPlex 2200 multiplexed assays system is an automatic method allowing detection of antinuclear antibodies (ANA). The aim of our study was to evaluate the determination of 13 autoantibodies against chromatinic and nonchromatinic nuclear antigens by the BioPlex 2200 system and to compare the results achieved by this method to those obtained with our routinely used immunoassays. One thousand and four serum samples consecutively sent for ANA detection were routinely tested by indirect immunofluorescence (IIF) on HEp2 cells. Among them, 321 were also analyzed by dsDNA enzyme immunoassay (EliA) test and 657 by double immunodiffusion (DID) for extractable nuclear antigen (ENA) antibodies. All the sera were evaluated by the BioPlex 2200 ANA screen kit allowing simultaneous detection of antibodies against the following antigens: dsDNA, chromatin, SSA‐52 kDa, SSA‐60 kDa, SSB, Sm, Sm/RNP, RNP‐A, RNP‐68 kDa, Scl70, centromere B, Jo‐1, and P ribosomal proteins. The kappa coefficient between BioPlex 2200 and routine tests for detection of ANA on HEp2 cells, anti‐dsDNA, and anti‐ENA antibodies was, respectively, 0.31, 0.66, and 0.61. The comparison with our routine tests showed numerous discrepancies between IIF ANA screening and BioPlex but a good concordance for detection of anti‐dsDNA and anti‐ENA specificities. BioPlex 2200 system is a rapid and sensitive method for simultaneous quantitative detection of several autoantibodies. It is perfectly well adapted to determine ANA antigenic specificities of samples found positive using initial IIF screening. The capability of this multiplexed technology to analyze simultaneously 13 ANA autoantibodies leads to the rapid availability of an “autoimmune connective tissue disease serologic profile.”

TWEAK is expressed at the cell surface of monocytes during multiple sclerosis

The TNF superfamily ligand, TNF‐like weak inducer of apoptosis (TWEAK), regulates cellular responses ranging from proliferation to cell death in a manner highly dependent on the cell type and the microenvironmental context. We have shown previously that treatment of experimental autoimmune encephalomyelitis mice after the priming phase with neutralizing anti‐TWEAK antibodies results in a reduction in the severity of the disease and leukocyte infiltration. To further characterize TWEAK/fibroblast growth factor‐inducible 14‐kDa protein (Fn14) involvement during multiple sclerosis (MS), we evaluated in MS patients and controls: TWEAK and Fn14 expression on PBMC and soluble TWEAK concentration in serum and cerebrospinal fluid (CSF). Thirty‐six consecutive patients were enrolled, including 11 patients with relapsing‐remitting MS, 11 with a clinical isolated syndrome suggestive of MS (CISSMS), and 14 controls with non‐MS diseases. Intracellular TWEAK could be observed in lymphocytes and/or monocytes in all groups of patients. None of the 36 patients displayed TWEAK expression at the cell surface of lymphocytes. In contrast, 12 out of the 36 patients were positive for membrane TWEAK expression on their monocytes. Among these patients, eight were from the CISSMS group. Fn14 was not detected in PBMC. The soluble form of TWEAK is detectable in serum and CSF of patients, and TWEAK concentrations were not statistically different between the disease groups. We demonstrated for the first time that TWEAK is expressed at the cell surface of monocytes during MS, especially in the CISSMS group. Our results support the proposal that TWEAK could be a target for antibody therapy in MS.

TWEAK/Fn14 pathway modulates properties of a human microvascular endothelial cell model of blood brain barrier.

BackgroundThe TNF ligand family member TWEAK exists as membrane and soluble forms and is involved in the regulation of various human inflammatory pathologies, through binding to its main receptor, Fn14. We have shown that the soluble form of TWEAK has a pro-neuroinflammatory effect in an animal model of multiple sclerosis and we further demonstrated that blocking TWEAK activity during the recruitment phase of immune cells across the blood brain barrier (BBB) was protective in this model. It is now well established that endothelial cells in the periphery and astrocytes in the central nervous system (CNS) are targets of TWEAK. Moreover, it has been shown by others that, when injected into mice brains, TWEAK disrupts the architecture of the BBB and induces expression of matrix metalloproteinase-9 (MMP-9) in the brain. Nevertheless, the mechanisms involved in such conditions are complex and remain to be explored, especially because there is a lack of data concerning the TWEAK/Fn14 pathway in microvascular cerebral endothelial cells.MethodsIn this study, we used human cerebral microvascular endothelial cell (HCMEC) cultures as an in vitro model of the BBB to study the effects of soluble TWEAK on the properties and the integrity of the BBB model.ResultsWe showed that soluble TWEAK induces an inflammatory profile on HCMECs, especially by promoting secretion of cytokines, by modulating production and activation of MMP-9, and by expression of cell adhesion molecules. We also demonstrated that these effects of TWEAK are associated with increased permeability of the HCMEC monolayer in the in vitro BBB model.ConclusionsTaken together, the data suggest a role for soluble TWEAK in BBB inflammation and in the promotion of BBB interactions with immune cells. These results support the contention that the TWEAK/Fn14 pathway could contribute at least to the endothelial steps of neuroinflammation.

BioPlex™ 2200 multiplexed system: Simultaneous detection of anti-dsDNA and anti-chromatin antibodies in patients with systemic lupus erythematosus

Background. Antibodies for double-stranded DNA (anti-dsDNA) and chromatin represent specific markers of systemic lupus erythematosus (SLE). Aims. (1) To evaluate the analytical performance of a multiplexed bead assay (BioPlex™ 2200) for the simultaneous detection of anti-dsDNA and anti-chromatin antibodies, (2) to compare the results for anti-dsDNA with those obtained using Farr assay, and (3) to analyze the clinical relevance of these antibodies when applied to the follow-up of SLE patients with active nephritis. Patients and methods. Hundred and five clinically characterized SLE patients and 96 healthy blood donors sera were analyzed by BioPlex™ 2200. Results. Prevalence of these antibodies was significantly higher (p < 0.0001) in SLE patients than in controls (68 and 70% for anti-dsDNA and anti-chromatin, vs. 1% for both anti-dsDNA and anti-chromatin, respectively). If you consider a sample positive if either anti-dsDNA and/or anti-chromatin is positive, then the prevalence of these antibodies reached 78% (82/105) in SLE patients. For anti-dsDNA measurements, the kappa coefficient was 0.59 between BioPlex™ 2200 and Farr assay. Comparison between SLE patients with and without nephritis in a follow-up study showed that patients with active nephritis were associated with an increase of anti-dsDNA and anti-chromatin levels and a reduction of CH50, whereas no variation of antibody levels was observed in SLE patients without nephritis. Conclusion. Our results demonstrated a benefit of simultaneously measuring anti-dsDNA and anti-chromatin in SLE patients. The BioPlex™ 2200 achieved good analytical performances and proved to be a useful method for monitoring and diagnosing SLE.

Is TWEAK a Biomarker for Autoimmune/Chronic Inflammatory Diseases?

The TWEAK/Fn14 pathway is now well-known for its involvement in the modulation of inflammation in various human autoimmune/chronic inflammatory diseases (AICID) including lupus, rheumatoid arthritis, and multiple sclerosis. A panel of data is now available concerning TWEAK expression in tissues or biological fluids of patients suffering from AICID, suggesting that it could be a promising biological marker in these diseases. Evidences from several teams support the hypothesis that blocking TWEAK/Fn14 pathway is an attractive new therapeutic lead in such diseases and clinical trials with anti-TWEAK-blocking antibodies are in progress. In this mini-review we discuss the potential use of TWEAK quantification in AICD management in routine practice and highlight the challenge of standardizing data collection to better estimate the clinical utility of such a biological parameter.

NEUROPSYCHIATRIC SYMPTOMS IN THE ELDERLY: LET US NOT FORGET CELIAC DISEASE

To the Editor: Screening for thyroid disorders, especially hypothyroidism, is part of the recommended evaluation of the older patient suspected of dementia. 1 In populationbased studies, both high 2 and low 3 thyroid stimulating hormone (TSH) levels have been associated with an increased risk of dementia, whereas other studies 4,5 have found no relationship between TSH levels and cognitive function. In dementia prevalence studies 6 and clinic sample meta-analyses, 7,8 only a small number of patients with dementia was attributable to hypothyroidism. In one study, 9 nondemented patients with hypothyroidism were found to have lower mental status test scores, word fluency, and visuospatial and learning abilities than euthyroid controls. We analyzed TSH levels and diagnosis of Alzheimer’s disease (AD) in 829 consecutive referrals to the geriatric outpatient clinic of the Erasmus Medical Center. Patients were referred between 1987 and 1999 for a variety of reasons and underwent a comprehensive geriatric assessment. 10 The group consisted of 268 men (32.3%) and 561 women (67.7%), mean age 78.2 (range 60–98). AD was diagnosed in 344 patients (42.5%) who met the Diagnostic and Statistical Manual of Mental Disorders, Third Edition and National Institute of Neurological Disorders and Stroke—Alzheimer’s Disease and Related Disorders Associations criteria for the disease. TSH levels were determined using the RIAgnost (Behring-Werke, Marburg, Germany, from 1987 to July 1, 1991), the Amerlite (Amersham, Buckinghamshire, UK, from July 1, 1991 to July 1, 1992), and the Amerlite TSH-30 ultrasensitive assay 30 (an improved version of the Amerlite; Amersham, from July 1, 1992 onwards). The change to more-modern tests over the years did not influence the reference values of the TSH. We found no statistically significant differences in TSH levels between the AD patients and patients without any form of dementia (Table 1). Although hypoand hyperthyroidism have been associated with an increased risk of dementia, evidence of a causal link between the occurrence of dementia and thyroid disorders remains inconsistent. Thyroid disorders may cause subcortical symptoms. Because AD is classified as a cortical dementia, the question remains whether abnormal TSH levels are involved in the etiology of AD or whether they cause subcortical symptoms that play an additive role in the dementia symptomatology. Further prospective studies with a longer follow-up period are needed to specify the contribution of the thyroid disorder to the onset and the clinical characteristics of dementia, especially AD. In the meantime, we should continue to recognize and treat comorbid conditions in our Alzheimer patients. Quite apart from the consideration of total reversibility, there is the need to identify conditions that may cause “disease” to the patient or aggravate the dementia.

Targeting TNF and Its Family Members in Autoimmune/Inflammatory Disease

Tumor necrosis factor (TNF), a pleiotropic cytokine mainly produced by activated macrophages, modulates a wide range of biological functions in multiple tissues and organs. Besides its effects on tumor cell death, TNF is a key mediator of both acute and chronic inflammation. Since the description of TNF in the 1970s and through consideration of structural homologies, a total of 19 TNF-related cytokines have now been regrouped into a large family called the TNF ligand superfamily (TNFSF), whose members interact with TNF receptor superfamily (TNFRSF) members. More than 150,000 scientific publications (!) concerning TNF and its family members are available, demonstrating the strong interest of the scientific community in this molecule. Numerous studies implicating TNF family members in the pathophysiology of human autoimmune/inflammatory diseases have supported the emergence of TNF blocking agents developed for treatment of human disease, particularly over the last decade. These biotherapies, in the form of (I) chimeric, humanized, or human anti-TNF monoclonal antibodies or (II) fusion proteins involving a soluble TNF receptor, have been very successful in ameliorating disease signs and symptoms, especially in patients suffering from rheumatoid arthritis (RA) and Crohns disease. Nonetheless, several aspects of these beneficial effects remain enigmatic. Moreover, the modulatory factors influencing TNF production by macrophages are not all known. Nevertheless, it is expected that over the next few years we will witness an increasing number of diseases for which TNF-blockade therapy is indicated. In this special issue, eleven papers including research articles, review articles, and clinical studies provide new information and interesting discussion regarding current questions related to this hot topic. In the first group of articles, interesting data is presented about TNF-blocking therapies and modulation of TNF generation by macrophages. Y. Lv et al. studied the nonneuronal cholinergic system existing in macrophages and show in a murine monocyte/macrophage cell line that bacterial lipopolysaccharide (LPS) exposure enhances autocrine acetylcholine production associated with an attenuation of TNF release. In this same cell line, K. Borzecka et al. determined that, during high dose LPS stimulation, CD14 together with scavenger receptors is required for the binding of LPS but has a limited and dispensable contribution to TNF production. R. Cascao et al. recently identified gambogic acid as a simultaneous blocker of IL-1β and TNF secretion and described here a beneficial anti-inflammatory effect of gambogic acid in rat antigen-induced arthritis. Interestingly, F. R. Spinelli et al. show that blocking TNF biological effects during RA is associated with an increase of circulating endothelial progenitor cells, which might positively affect the endothelial function and may help in correcting the endothelial dysfunction observed in the disease. In the second group of articles, possible off-label uses of anti-TNF therapy in various disorders are discussed. Due to their low prevalence, discussion of the use of anti-TNF modalities in Behcets disease, sarcoidosis, and noninfectious uveitis in the review by D. Sanchez-Cano et al. was mainly based on case reports and case series. The clinical study of C. Garcia-De-Vicuna et al. supports the usefulness of adalimumab in the treatment of refractory uveitis associated with juvenile idiopathic arthritis. P.-A. Jarrot and G. Kaplanski review the use of anti-TNF therapy in vasculitis and conclude that, except for Behcets disease, this treatment has not shown significant efficacy. In their review article, A. Kumar et al. described how HIV infection is modulated by TNF and TNFR superfamily pathways and then discuss the emerging therapeutic options based on the modulation of TNF activity. The third group of articles tackle the topic of the management of anti-TNF therapy for its well-established indications. B. Morck et al. envision being able to reduce the drug costs in active HLA-B27 positive ankylosing spondylitis over time by reducing the infliximab dose and by extending the interval between infliximab doses. On the other hand, R. Altwegg and T. Vincent discuss the usefulness of monitoring serum trough levels and anti-drug antibodies in the optimization of anti-TNF therapies during inflammatory bowel disease. Lastly, Y. Aiba and M. Nakamura open a debate concerning a putative therapeutic role of TL1A/DR3 inhibition. They suggest that the modulation of this particular TNF/TNFR superfamily member interaction may be a potential therapeutic target in several autoimmune diseases including inflammatory bowel disease, RA, ankylosing spondylitis, and primary biliary cirrhosis. We hope that readers of the journal will find in this special issue not only accurate data and updated reviews on the targeting of TNF and its family members in autoimmune/inflammatory disease treatment, but also relevant questions that remain to be resolved including the extension of current therapeutic indications and the optimization of the anti-TNF therapies to find a better balance between cost and effectiveness. Sophie  Desplat-Jego Linda  Burkly Chaim  Putterman