[Diagnostic workup for polyneuropathy]. / Diagnostische Abklärung bei Polyneuropathie.

Polyneuropathy is a disease of the peripheral nervous system that usually results in distally emphasized, often symmetrical sensory and motor stimulation and deficits. These are often extremely painful. They can be divided into hereditary and acquired causes; inflammatory and infectious causes should be further differentiated among the acquired causes. A careful diagnostic workup is essential. Clinical signs and distribution patterns of symptoms can often already provide clues to the underlying aetiology. This review describes this workup, which in addition to the medical history and clinical examination always includes thorough laboratory diagnostics, electrophysiological examination and cerebrospinal fluid diagnostics. In individual cases, further diagnostic steps may be necessary in order to make the correct diagnosis.

Alemtuzumab as rescue therapy in a cohort of 50 relapsing-remitting MS patients with breakthrough disease on fingolimod: a multi-center observational study.

BACKGROUND: Relapsing-remitting multiple sclerosis (RRMS) requires efficient immunomodulatory treatment to reach "no evidence of disease activity" status at best. Alemtuzumab and fingolimod have proved to be efficient options in RRMS with active disease course. Yet, side effects and break-through disease may limit long-time treatment and necessitate switch of medication. Data on efficacy and safety of alemtuzumab following fingolimod treatment are limited, but useful for clinical practice. METHODS: Clinical and MRI data of 50 RRMS patients with a history of therapy switch from fingolimod to alemtuzumab were retrospectively analyzed. Data were acquired from nine large German MS Centers from 2013 to 2016 and analyzed using descriptive statistics. RESULTS: On average, patients with disease duration of 12.9 years and median EDSS of 3.0 at baseline switched to alemtuzumab after 68 weeks of fingolimod treatment. Thereafter, patients on alemtuzumab were followed for a mean of 64 weeks. The annualized relapse rate decreased from 2.2 in the year prior to 0.34 in the following year after switching to alemtuzumab and EDSS stabilized. In a subgroup of patients (n = 23), MRI data point to a reduction in enhancing (4.47 vs. 0.26) and new/enlarging T2 lesions (5.8 vs. 0.27) after treatment adjustment. Side effects were generally as expected from published data for alemtuzumab (autoimmunity 2/50, severe infections 1/50). One patient suffered combined lethal necrotizing leukoencephalopathy and hemolytic anemia. DISCUSSION: Therapy switch was highly effective in reducing clinical and MRI surrogates of disease activity and was mainly well tolerated within one year of follow-up. Hence, alemtuzumab constitutes a promising therapy in RRMS with refractory disease activity despite fingolimod treatment. Further studies are warranted to confirm these beneficial findings and to reveal safety concerns in the longer-term follow-up.

Design of TRUST, a non-interventional, multicenter, 3-year prospective study investigating an integrated patient management approach in patients with relapsing-remitting multiple sclerosis treated with natalizumab.

BACKGROUND: Natalizumab provides rapid and high-efficacy control of multiple sclerosis disease activity with long-term stabilization. However, the benefits of the drug are countered by a risk of developing progressive multifocal leukoencephalopathy in patients infected with the John Cunningham Virus. Close monitoring is required in patients with increased progressive multifocal leukoencephalopathy risk receiving natalizumab in the long-term for an optimal benefit-risk evaluation. Standardized high-quality monitoring procedures may provide a superior basis for individual benefit and risk evaluation and thus improve treatment decisions. The non-interventional study TRUST was designed to capture natalizumab effectiveness under real-life conditions and to examine alternate approaches for clinical assessments, magnetic resonance imaging monitoring and use of biomarkers for progressive multifocal leukoencephalopathy risk stratification. METHODS/DESIGN: TRUST is a non-interventional, multicenter, prospective cohort study conducted at approximately 200 German neurological centers. The study is intended to enroll 1260 relapsing-remitting multiple sclerosis patients with ongoing natalizumab therapy for at least 12 months. Patients will be followed for a period of 3 years, irrespective of treatment changes after study start. Data on clinical, subclinical and patient-centric outcomes will be documented in order to compare the effectiveness of continuous versus discontinued natalizumab treatment. Furthermore, the type and frequency of clinical, magnetic resonance imaging and biomarker assessments, reasons for continuation or discontinuation of therapy and the safety profile of natalizumab will be collected to explore the impact of a systematic patient management approach and its potential impact on patient outcome. Specifically, the role of biomarkers, the use of expert opinions, the impact of high-frequency magnetic resonance imaging assessment for early progressive multifocal leukoencephalopathy detection and the role of additional radiological and clinical expert advice will be explored. DISCUSSION: TRUST was initiated in spring 2014 and enrollment is anticipated to be completed by mid 2016. Annual interim analyses will deliver continuous information and transparency with regard to the patient cohorts and the completeness and quality of data as well as closely monitor any safety signals in the natalizumab-treated cohort. The study's results may provide insights into opportunities to improve the benefit-risk assessment in clinical practice and support treatment decisions.

The Correlation between the Virus- and Brain Antigen-Specific B Cell Response in the Blood of Patients with Multiple Sclerosis.

There is a largely divergent body of literature regarding the relationship between Epstein-Barr virus (EBV) infection and brain inflammation in multiple sclerosis (MS). Here, we tested MS patients during relapse (n = 11) and in remission (n = 19) in addition to n = 22 healthy controls to study the correlation between the EBV- and brain-specific B cell response in the blood by enzyme-linked immunospot (ELISPOT) and enzyme-linked immunosorbent assay (ELISA). Cytomegalovirus (CMV) was used as a control antigen tested in n = 16 MS patients during relapse and in n = 35 patients in remission. Over the course of the study, n = 16 patients were untreated, while n = 33 patients received immunomodulatory therapy. The data show that there was a moderate correlation between the frequencies of EBV- and brain-reactive B cells in MS patients in remission. In addition we could detect a correlation between the B cell response to EBV and disease activity. There was no evidence of an EBV reactivation. Interestingly, there was also a correlation between the frequencies of CMV- and brain-specific B cells in MS patients experiencing an acute relapse and an elevated B cell response to CMV was associated with higher disease activity. The trend remained when excluding seronegative subjects but was non-significant. These data underline that viral infections might impact the immunopathology of MS, but the exact link between the two entities remains subject of controversy.

Cerebrospinal fluid JC virus antibody index for diagnosis of natalizumab-associated progressive multifocal leukoencephalopathy.

OBJECTIVE: Progressive multifocal leukoencephalopathy (PML), caused by JC virus (JCV), can occur in patients receiving natalizumab for multiple sclerosis (MS). JCV detection by quantitative polymerase chain reaction (qPCR) in cerebrospinal fluid (CSF), or brain biopsy, is required for probable or definite diagnosis of PML. However, in some patients only low levels of JCV DNA (<100 copies/ml) are present in CSF, making the diagnosis challenging. Our objective was to assess the complementary value of a CSF JCV antibody index (AIJCV ) in the diagnosis of natalizumab-associated PML. METHODS: AIJCV was assessed in 37 cases of natalizumab-associated PML and 89 MS-patients treated with natalizumab without PML. Sera and CSF were tested in a capture enzyme-linked immunosorbent assay, using JCV-VP1 fused to glutathione S-transferase as antigen. Albumin levels and total immunoglobulin G concentration were determined by immunonephelometry, and the AIJCV was calculated as published. RESULTS: Twenty-six of 37 (70%) patients with natalizumab-associated PML exhibited an AIJCV > 1.5, whereas this was seen in none of the controls (p < 0.0001). At time of the first positive qPCR for JCV DNA, 11 of 20 (55%) patients with natalizumab-associated PML had an AIJCV > 1.5. JCV DNA levels of <100 copies/ml were seen in 14 (70%) of these 20 patients, of whom 8 (57%) demonstrated an AIJCV > 1.5. INTERPRETATION: Determination of the AIJCV could be an added tool in the diagnostic workup for PML and should be included in the case definition of natalizumab-associated PML.

A review of health effects of carbon disulfide in viscose industry and a proposal for an occupational exposure limit.

Occupational exposure limits (OELs) for carbon disulfide vary between 1 and 10 ppm worldwide. They are generally based on health effects observed in viscose industry. Publications after the mid-1970s are reviewed to determine whether there is a scientific justification for an OEL below 10 ppm. The exposure situation in viscose industry is governed by long exposure durations, high exposures in past decades, high peak exposures, former analytical procedures underestimating exposure, and shift work. Three approaches were used to define an OEL based on workplace data: (1) Division of a cumulative exposure index by lifetime exposure duration. This approach ignores the possible existence of a threshold and fails to differentiate between brief high and sustained low exposures. (2) Defining the NOEL/LOEL by mean exposure levels. With a wide range of exposures, effects observed at the mean are driven by high exposures underestimating the true NOEL. (3) Assessment of effects observed at workplaces complying with a predefined exposure limit. Without adverse effects at such a limit this should be the starting point to define the OEL. The most important health effects for carbon disulfide are coronary heart disease, coronary risk factors, retinal angiopathy, color discrimination, effects on peripheral nerves, psychophysiological effects, morphological and other central nervous system (CNS) effects, and fertility and hormonal effects. The data generally support an OEL of 10 ppm. Some uncertainties exist for effects on electrocardiogram (ECG), heart rate, retinal microaneurysms (in Japanese workers), peripheral nerve conduction velocities, some psychophysiological parameters, brain magnetic resonance imaging (MRI; hyperintensive spots), and hearing function. Further investigations on workers under defined long-term exposure conditions might help to come to a final conclusion. Finally, the reproductive capacity of female workers may not be adequately protected at exposures around 10 ppm.

Molecular ultrasound imaging of early vascular response in prostate tumors irradiated with carbon ions.

Individualized treatments with combination of radiotherapy and targeted drugs require knowledge about the behavior of molecular targets after irradiation. Angiogenic marker expression has been studied after conventional radiotherapy, but little is known about marker response to charged particles. For the very first time, we used molecular ultrasound imaging to intraindividually track changes in angiogenic marker expression after carbon ion irradiation in experimental tumors. Expression of intercellular adhesion molecule-1 (ICAM-1) and of alpha(v)beta(3)-integrin in subcutaneous AT-1 prostate cancers in rats treated with carbon ions (16 Gy) was studied using molecular ultrasound and immunohistochemistry. For this purpose, cyanoacrylate microbubbles were synthesized and linked to specific ligands. The accumulation of targeted microbubbles in tumors was quantified before and 36 hours after irradiation. In addition, tumor vascularization was analyzed using volumetric Doppler ultrasound. In tumors, the accumulation of targeted microbubbles was significantly higher than in nonspecific ones and could be inhibited competitively. Before irradiation, no difference in binding of alpha(v)beta(3)-integrin-specific or ICAM-1-specific microbubbles was observed in treated and untreated animals. After irradiation, however, treated animals showed a significantly higher binding of alpha(v)beta(3)-integrin-specific microbubbles and an enhanced binding of ICAM-1-specific microbubbles than untreated controls. In both groups, a decrease in vascularization occurred during tumor growth, but no significant difference was observed between irradiated and nonirradiated tumors. In conclusion, carbon ion irradiation upregulates ICAM-1 and alpha(v)beta(3)-integrin expression in tumor neovasculature. Molecular ultrasound can indicate the regulation of these markers and thus may help to identify the optimal drugs and time points in individualized therapy regimens.

Accelerated course of experimental autoimmune encephalomyelitis in PD-1-deficient central nervous system myelin mutants.

It is assumed that the onset and course of autoimmune inflammatory central nervous system (CNS) disorders (eg, multiple sclerosis) are influenced by factors that afflict immune regulation as well as CNS vulnerability. We challenged this concept experimentally by investigating how genetic alterations that affect myelin (primary oligodendrocyte damage in PLPtg mice) and/or T-cell regulation (deficiency of PD-1) influence both the onset and course of an experimental autoimmune CNS inflammatory disease [MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE)]. We observed that double pathology was associated with a significantly earlier onset of disease, a slight increase in the neurological score, an increase in the number of infiltrating cells, and enhanced axonal degeneration compared with wild-type mice and the respective, single mutant controls. Double-mutant PLPtg/PD-1(-/-) mice showed an increased production of interferon-gamma by CNS immune cells at the peak of disease. Neither PD-1 deficiency nor oligodendropathy led to detectable spread of antigenic MHC class I- or class II-restricted epitopes during EAE. However, absence of PD-1 clearly increased the propensity of T lymphocytes to expand, and the number of clonal expansions reliably reflected the severity of the EAE disease course. Our data show that the interplay between immune dysregulation and myelinopathy results in a stable exacerbation of actively induced autoimmune CNS inflammation, suggesting that the combination of several pathological issues contributes significantly to disease susceptibility or relapses in human disease.

PD-1 regulates neural damage in oligodendroglia-induced inflammation.

We investigated the impact of immune regulatory mechanisms involved in the modulation of the recently presented, CD8+ lymphocyte mediated immune response in a mouse model of oligodendropathy-induced inflammation (PLPtg-mutants). The focus was on the role of the co-inhibitory molecule PD-1, a CD28-related receptor expressed on activated T- and B-lymphocytes associated with immune homeostasis and autoimmunity. PLPtg/PD-1-deficient double mutants and the corresponding bone marrow chimeras were generated and analysed using immunohistochemistry, light- and electron microscopy, with particular emphasis on immune-cell number and neural damage. In addition, the immune cells in both the CNS and the peripheral immune system were investigated by IFN-gamma elispot assays and spectratype analysis. We found that mice with combined pathology exhibited significantly increased numbers of CD4+ and CD8+ T-lymphocytes in the CNS. Lack of PD-1 substantially aggravated the pathological phenotype of the PLPtg mutants compared to genuine PLPtg mutants, whereas the PD-1 deletion alone did not cause alterations in the CNS. CNS T-lymphocytes in PLPtg/PD-1-/- double mutants exhibited massive clonal expansions. Furthermore, PD-1 deficiency was associated with a significantly higher propensity of CNS but not peripheral CD8+ T-cells to secrete proinflammatory cytokines. PD-1 could be identified as a crucial player of tissue homeostasis and immune-mediated damage in a model of oligodendropathy-induced inflammation. Alterations of this regulatory pathway lead to overt neuroinflammation of high pathogenetic impact. Our finding may have implications for understanding the mechanisms leading to the high clinical variability of polygenic or even monogenic disorders of the nervous system.

Pharmacodynamics of streptavidin-coated cyanoacrylate microbubbles designed for molecular ultrasound imaging.

OBJECTIVES: To assess the pharmacodynamic behavior of cyanoacrylate, streptavidin-coated microbubbles (MBs) and to investigate their suitability for molecular ultrasound imaging. MATERIALS AND METHODS: Biodistribution of MBs was analyzed in tumor-bearing mice using gamma-counting, immunohistochemistry, flow cytometry, and ultrasound. Further, vascular endothelial growth factor receptor 2-antibody coupled MBs were used to image tumor neovasculature. RESULTS: After 1 minute >90% of MBs were cleared from the blood and pooled in the lungs, liver, and spleen. Subsequently, within 1 hour a decent reincrease of MB-concentration was observed in the blood. The remaining MBs were removed by liver and spleen macrophages. About 30% of the phagocytosed MBs were intact after 48 hours. Shell fragments were found in the kidneys only. No relevant MB-accumulation was observed in tumors. In contrast, vascular endothelial growth factor receptor 2-specific MBs accumulated significantly within the tumor vasculature (P < 0.05). CONCLUSIONS: The pharmacokinetic behavior of streptavidin-coated cyanoacrylate MBs has been studied. In this context, the low amount of MBs in tumors after >5 minutes is beneficial for specific targeting of angiogenesis.

Molecular profiling of angiogenesis with targeted ultrasound imaging: early assessment of antiangiogenic therapy effects.

Molecular ultrasound is capable of elucidating the expression of angiogenic markers in vivo. However, the capability of the method for volumetric "multitarget quantification" and for the assessment of antiangiogenic therapy response has rather been investigated. Therefore, we generated cyanoacrylate microbubbles linked to vascular endothelial growth factor receptor 2 (VEGFR2) and alphavbeta3 integrin binding ligands and quantified their accumulation in squamous cell carcinoma xenografts (HaCaT-ras-A-5RT3) in mice with the quantitative volumetric ultrasound scanning technique, sensitive particle acoustic quantification. Specificity of VEGFR2 and alphavbeta3 integrin binding microbubbles was shown, and changes in marker expression during matrix metalloproteinase inhibitor treatment were investigated. In tumors, accumulation of targeted microbubbles was significantly higher compared with nonspecific ones and could be inhibited competitively by addition of the free ligand in excess. Also, multimarker imaging could successfully be done during the same imaging session. Molecular ultrasound further indicated a significant increase of VEGFR2 and alphavbeta3 integrin expression during tumor growth and a considerable decrease in both marker densities after matrix metalloproteinase inhibitor treatment. Histologic data suggested that the increasing VEGFR2 and alphavbeta3 integrin concentrations in tumors during growth are related to an up-regulation of its expression by the endothelial cells, whereas its decrease under therapy is more related to the decreasing relative vessel density. In conclusion, targeted ultrasound appears feasible for the longitudinal molecular profiling of tumor angiogenesis and for the sensitive assessment of therapy effects in vivo.

Role of immune cells in animal models for inherited peripheral neuropathies.

Mice expressing half of the normal dose of protein zero (P0+/- mice) or completely deficient gap-junction protein connexin 32 -/- mice mimic demyelinating forms of inherited neuropathies, such as Charcot-Marie-Tooth (CMT) neuropathies type 1B and CMT type 1X, respectively. In both models, an almost normal myelin formation is observed during the first months of life, followed by a slowly progressing demyelinating neuropathy. In both models, there is a substantial increase of CD8+ T-lymphocytes and macrophages within the demyelinating nerves. Recently, this has also been observed in mice mildly overexpressing human peripheral myelin protein 22 kD mimicking the most common form of CMT, CMT type 1A. In all demyelinating models, the macrophages show close contacts with intact myelin sheaths or demyelinated axons, suggesting an active role of these cells in myelin degeneration. Additionally, fibroblast-like cells contact macrophages, suggesting a functional role of fibroblast-like cells in macrophage activation. By cross-breeding P0+/- and gap-junction protein connexin 32-/- mice with immunodeficient recombination activating gene-1-deficient mutants, a substantial alleviation of the demyelinating phenotype was observed. Similarly, cross-breeding of P0+/- mice with mutants with a defect in macrophage activation led to an alleviated phenotype as well. These findings demonstrate that the immune system is involved in the pathogenesis of demyelinating neuropathies. In contrast, in P0-/- mice, which display a compromised myelin compaction and axonal loss from onset, immune cells appear to have a neuroprotective effect because cross-breeding with recombination activating gene-1 mutants leads to an aggravation of axonopathic changes. In the present review, we discuss the influence of the immune system on inherited de- and dysmyelination regarding disease mechanisms and possible clinical implications.

Iron particles enhance visualization of experimental gliomas with high-resolution sonography.

BACKGROUND AND PURPOSE: Intraoperative MR imaging and sonography are used for navigation during neurosurgical procedures. The purpose of this experimental study was to evaluate the potential of high-resolution sonography using superparamagnetic iron oxide (SPIO) particles as a contrast medium to delineate brain tumors and to relate these findings with those of MR imaging. METHODS: C6 gliomas were implanted in 36 rats. Eleven days after tumor implantation, the animals underwent MR imaging with a 1.5-T MR imaging unit. Twelve animals received gadopentetate dimeglumine immediately before the MR examination, 12 animals were injected with SPIO particles 24 hours before MR imaging, and 12 animals received no contrast agent. Immediately after MR imaging, the animals were sacrificed and their brains were removed and placed in saline. Sonography was performed instantly after brain removal. Brains were embedded in paraffin, and sections were stained for iron with Perl's stain and for macrophages with ED-1 immunohistochemistry. RESULTS: At MR imaging, the tumors appeared hyperintense on T2-weighted and gadolinium-enhanced T1-weighted images. After application of SPIO particles, they became markedly hypointense on T2-weighted images and hypo- to hyperintense on T1-weighted images. On sonograms, gliomas were iso- to slightly hyperechoic to normal brain parenchyma on nonenhanced and on gadolinium-enhanced images. After application of SPIO particles, tumors became markedly hyperechoic and were distinctly demarcated from the surrounding brain tissue. CONCLUSION: SPIO particles improved the detection and demarcation of the experimental gliomas on sonograms, which may improve intraoperative neuronavigation with sonography.

Neuroprotective effect of the immune system in a mouse model of severe dysmyelinating hereditary neuropathy: enhanced axonal degeneration following disruption of the RAG-1 gene.

In mouse models of later onset forms of human hereditary demyelinating neuropathies, the immune system plays a crucial pathogenic role. Here, we investigated the influence of immune cells on early onset dysmyelination in mice homozygously deficient of the myelin component P0. In peripheral nerves of P0(-/-) mice, CD8+ T-lymphocytes increased with age. Macrophages peaked at 3 months followed by a substantial decline. They were mainly of hematogenous origin. To evaluate the functional role of immune cells, we cross-bred P0(-/-) mutants with RAG-1-deficient mice. At 3 months, the number of endoneurial macrophages did not differ from the macrophage number of immunocompetent myelin mutants, but the later decline of macrophages was not observed. Quantitative electron microscopy revealed that in plantar nerves of 6-month-old double mutants, significantly more axons had degenerated than in immunocompetent littermates. These data suggest a neuroprotective net effect of T-lymphocytes on axon survival in inherited, early onset dysmyelination.

The role of the polio virus receptor and the herpesvirus entry mediator B genes for the development of MS.

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system (CNS). Although the cause of MS is still uncertain, it is well accepted that both genetic and environmental factors are important for the development of disease. In this study, we focused on the Polio Virus Receptor (PVR) and Herpesvirus entry mediator B (HVEB) receptor genes, which are located on chromosome 19q13, a region previously linked to MS. Both receptors are expressed in the brain and immune system and play an important role for inter-cellular adhesion and entry of neurotropic viruses to the brain. We identified four new polymorphisms in the PVR gene, which were located in the promoter region and three different exons. All exonic polymorphisms altered the amino acid sequence of the receptor. No new polymorphisms were found in the HVEB gene, but we confirmed a previously identified intronic polymorphism. We analyzed the frequency of the polymorphisms by RFLP analysis in sporadic MS patients, MS families, and healthy controls and determined the surface expression of HVEB and PVR on peripheral blood monocytes. We did not find differences in the frequency of the polymorphisms or surface expression between MS patients and controls. Overall, our findings do not support a role of HVEB and PVR genes in the development of MS.

Bacterial infection of human hematopoietic stem cells induces monocytic differentiation.

Differentiation of hematopoietic stem cells (HSCs) can be influenced by different stimuli, including cytotoxic agents, certain cytokines, and contact with pathogens. Infection may result in dysregulation of these important progenitor cells and therefore interfere with the availability of blood cells. In this study we analyzed the effect of bacterial infection on HSCs concerning surface marker expression and cytokine release. Listeria monocytogenes and Yersinia enterocolitica accelerated maturation of hematopoietic progenitor cells along the myeloid lineage, as demonstrated by the upregulation of CD13, CD14, and costimulatory signals. By screening cytokine secretion, granulocyte-macrophage colony-stimulating factor, interleukin (IL)-6, IL-8, IL-10, IL-12, and tumor necrosis factor-alpha were found to be induced by bacterial infection. These data indicate that infection of HSCs with L. monocytogenes and Y. enterocolitica affects the differentiation of CD34(+) hematopoietic progenitors in vitro and may lead to secretion of cytokines that can influence the HSC differentiation capacity and immune response.

Origin of pathogenic macrophages and endoneurial fibroblast-like cells in an animal model of inherited neuropathy.

Macrophages have recently been shown to be critically involved in the pathogenesis of genetically determined demyelination in mice heterozygously deficient for P0 (P0(+-)). Since little is known about the origin of these cells, we created chimeric P0(+-) mice by transplanting bone marrow from green fluorescent protein (GFP)-transgenic mice into irradiated P0(+-) mice. When analyzing chimeric P0(+-) mice, we could determine two populations (GFP(+) and GFP(-)) of endoneurial macrophages that became phagocytic for myelin and increased in number. We found that both GFP(-) resident macrophages and GFP(+) macrophages proliferated in peripheral nerves of P0(+-) mice but not in nerves of chimeric or nonchimeric P0(++) mice. These findings demonstrate a so far poorly recognized role of resident endoneurial macrophages in demyelinating neuropathies. Surprisingly, we also found GFP(+) cells that unequivocally showed the morphological characteristics of fibroblasts. These blood-borne fibroblast-like cells express the common hematopoetic stem cell marker CD34 and might comprise another cell type of potential importance for immune regulation in hereditary demyelinating neuropathies.

Production of IL-12 and IL-18 in human dendritic cells upon infection by Listeria monocytogenes.

Dendritic cells (DCs) are major antigen-presenting cells of the immune system, which need to be activated in order to initiate an immune response. Here, we describe the immunostimulatory effects on human monocyte-derived DCs observed upon infection with Listeria monocytogenes or after treatment with listerial lipoteichoic acid (LTA) and lipopolysaccharide (LPS), respectively. All stimuli caused upregulation of costimulatory molecules, induced T-cell proliferative responses and secretion of cytokines in vitro. Infection of DCs with L. monocytogenes induced release of interleukin (IL)-12 and IL-18. In contrast treatment with purified listerial LTA yielded high levels of IL-18 release, but only minimal IL-12 production. Treatment of DCs with LPS conversely induced significant amounts of IL-12 production, but no IL-18. The release of both stimulating cytokines IL-12 and IL-18 upon infection with entire bacteria suggests that attenuated strains of L. monocytogenes may be a valuable tool for subunit vaccine delivery.

CTLA4 exon 1 dimorphism is associated with primary progressive multiple sclerosis.

The cytotoxic T-lymphocyte antigen 4 (CTLA4) is an important modifier of T-cell activation with down-regulatory properties upon B7 engagement. We investigated the association of the CTLA4 A/G dimorphism in exon 1 (+49) with disease susceptibility, disease course and severity. No differences in the allelic distribution of the G(49) allele between multiple sclerosis (MS) patients and the control group was found. However, the G(49) allele occurred in a significant higher percentage of patients with primary progressive MS compared to patients with bout onset of disease. The results suggest that dysregulation of CTLA4-driven down-regulation of T-cell function due a genetic dimorphism in exon 1 may be involved in the pathogenesis of different MS disease subtypes.