Neurotensin receptor type 2 protects B-cell chronic lymphocytic leukemia cells from apoptosis.

B-cell chronic lymphocytic leukemia (B-CLL) cells are resistant to apoptosis, and consequently accumulate to the detriment of normal B cells and patient immunity. Because current therapies fail to eradicate these apoptosis-resistant cells, it is essential to identify alternative survival pathways as novel targets for anticancer therapies. Overexpression of cell-surface G protein-coupled receptors drives cell transformation, and thus plays a critical role in malignancies. In this study, we identified neurotensin receptor 2 (NTSR2) as an essential driver of apoptosis resistance in B-CLL. NTSR2 was highly expressed in B-CLL cells, whereas expression of its natural ligand, neurotensin (NTS), was minimal in both B-CLL cells and patient plasma. Surprisingly, NTSR2 remained in a constitutively active phosphorylated state, caused not by a mutation-induced gain-of-function but rather by an interaction with the oncogenic tyrosine kinase receptor TrkB. Functional and biochemical characterization revealed that the NTSR2-TrkB interaction acts as a conditional oncogenic driver requiring the TrkB ligand brain-derived neurotrophic factor (BDNF), which unlike NTS is highly expressed in B-CLL cells. Together, NTSR2, TrkB and BDNF induce autocrine and/or paracrine survival pathways that are independent of mutation status and indolent or progressive disease course. The NTSR2-TrkB interaction activates survival signaling pathways, including the Src and AKT kinase pathways, as well as expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. When NTSR2 was downregulated, TrkB failed to protect B-CLL cells from a drastic decrease in viability via typical apoptotic cell death, reflected by DNA fragmentation and Annexin V presentation. Together, our findings demonstrate that the NTSR2-TrkB interaction plays a crucial role in B-CLL cell survival, suggesting that inhibition of NTSR2 represents a promising targeted strategy for treating B-CLL malignancy.

[Pathophysiology of primary Sjögren's syndrome]. / Physiopathologie du syndrome de Gougerot-Sjögren primitif.

Primary Sgögren's syndrome (SSP) is one of the most common connective tissue disorder with an estimated prevalence between 0.6 and 1.7% of the general population. Lymphocytic infiltration of salivary gland is easily accessible favoring the diagnosis, and clinical and fundamental research. However, while many advances have been obtained in the recent decades, the pathophysiology of SSP remains unclear combining environmental factors with genetic predisposition. A central role tends to be attributed to salivary gland epithelial cells, originally designated as "innocent bystanders" and to B cells through the intervention of survey factors like BAFF. New T cells subsets are also carefully studied, particularly natural T regulatory and Th17 cells. They could indeed represent new therapeutic targets.

Kinetics of chemically mediated neurodegeneration/neuroregeneration of mouse olfactory epithelium: monitoring by hyperlayer sedimentation field flow fractionation.

The increase in the incidence of neurodegenerative diseases linked to aging or injury needs to be addressed in research into neuroprotective or neuroregenerative therapies, and requires the development of specific biological models. To achieve this goal we propose (1) the use of the mouse olfactory epithelium as a biological support which specifically exhibits a regenerative or a self-renewing capacity and during the lifetime necessitates the presence of neural stem cells, and (2) the use of an intraperitoneal injection of 2,6-dichlorobenzonitrile (diclobenil) as a chemical inducer of neurodegeneration in olfactory epithelium by selectively killing mature cells. We developed a biological model to follow the processes of neurodegeneration (chemically induced) and neuroregeneration (self-renewal of olfactory epithelium). The purpose of this study was to develop a method to monitor quickly neurodegeneration/neuroregeneration processes in order to further screen protective and regenerative therapies. For this purpose, we used the sedimentation field flow fractionation elution of olfactory epithelium. We obtained specific elution profiles and retention parameters allowing the monitoring of the induction and kinetics of biological processes. The use of insulin-like growth factor 1α as a neuroprotective agent in an innovative nebulization protocol showed sedimentation field flow fractionation to be a simple, fast and low-cost method to monitor such a biological event on the scale of an entire organism.

[Small fibre neuropathy in primary Sjögren syndrome]. / Neuropathie des petites fibres au cours du syndrome de Sjögren primitif.

PURPOSE: About forty percent of the patients with primary Sjögren's syndrome (pSS) experience chronic neuropathic pain with normal electrodiagnostic studies. Two previous studies suggest that chronic neuropathic pain in pSS is due to small fiber neuropathy (SFN). Quantification of epidermal nerve fiber density after skin biopsy has been validated to diagnose small fiber neuropathy. METHODS: Skin biopsy was performed in 14 consecutive pSS patients (satisfying the american-european classification criteria) with chronic neuropathic pain and normal electrodiagnostic studies suggesting SFN. RESULTS: Fourteen female pSS patients exhibited chronic neuropathic pain [burning sensation (n=14), prickling (n=4), dysesthesia (n=8)] with paroxystic exacerbations (n=10) and allodynia (n=13), for a mean period of 18.4±12.4 months. Neuropathic pain involved mostly hands and feet (n=13), with a distal (n=9) and leg (n=4) predominant distribution. Neurological examination disclosed normal deep tendon responses and absence of motor weakness (n=14). Small fiber neuropathy was confirmed by skin biopsy in 13 cases. Epidermal nerve fiber density was decreased in distal [(n=12), mean 3.5±1.7 fibers/mm (N>6.9)] and proximal site of biopsy [(n=9), mean 7.04±2.63 fibers/mm (N>9.3)]. CONCLUSION: Small fiber neuropathy is commonly responsible of chronic neuropathic pain in pSS. Prevalence, physiopathology and neurological evolution of such neuropathies still remain unknown.

Immunological profile in primary Sjögren syndrome: clinical significance, prognosis and long-term evolution to other auto-immune disease.

OBJECTIVE: To study evolution of pSS immunological profile, impact on pSS activity and the long-term evolution of patients with atypical auto-antibodies in a bicentric cohort of patients with pSS (n=445, mean age 53.6+/-14years, mean follow-up 76.1+/-51months). RESULTS: 212 patients were SSA positive and 131 were both SSA and SSB positive. During follow-up, SSA antibodies disappear in 8 patients; 2 of them exhibit new systemic complications of pSS. 68 patients had cryoglobulinemia. 52 patients had other anti-nuclear antibodies (ANA) specificities: anti-RNP (n=12), anti-centromere (n=14), anti-DNA native (n=19), anti-Scl70 (n=3), anti-JO1 (n=3), anti-Sm (n=3) and anti-histone (n=1). Fourteen patients developed ANA-associated auto-immune disease during the follow-up: 5 polymyositis (mean apparition delay 78months), 6 systemic lupus erythematosus (mean occurrence delay 77months) and 2 systemic sclerosis (mean occurrence delay 133+/-64months). Among these 14 patients, only three presented atypical-ANA at pSS diagnosis. Cryoglobulinemia and anti-SSA and SSB antibodies at diagnosis were associated with new systemic involvements. IN CONCLUSION: Cryoglobulinemia and SSA/SSB positivity are associated with systemic activity after diagnosis in pSS. Although atypical ANA are found in 12% of the cases, long-term evolution to ANA associated auto-immune diseases concerned patients with active immunological profile and extra-glandular manifestations.

Development of a downscale sedimentation field flow fractionation device for biological event monitoring.

Classically described as a macroscale size-density based method, Sedimentation field flow fractionation (SdFFF) has been successfully used for cell sorting. The goal of this study was to develop a new SdFFF device for downscale applications, in particular for oncology research to rapidly monitor chemical biological event induction in a cell line. The development of a downscale SdFFF device required reduction of the separation channel volume. Taking advantage of a newly laboratory designed apparatus, channel volume was successfully decreased by reducing both length and breadth. To validate the apparatus and method, we used the well-known model of diosgenin dose-dependent induction of apoptosis or megakaryocytic differentiation in HEL cells. After a minute scale acquisition of a reference profile, the downscale device was able to perform fast, early, significant and reproducible monitoring of apoptosis and differentiation, two important biological mechanisms in the field of cancer research.

Analysis of relationship between cell cycle stage and apoptosis induction in K562 cells by sedimentation field-flow fractionation.

Recently, sedimentation field-flow fractionation (SdFFF) was used to study the specific kinetics of diosgenin-induced apoptosis in K562 cells. Here, we propose a new SdFFF cell separation application in the field of cancer research concerning the correlation between induction of a biological event (i.e. apoptosis) and cell status (i.e. cell cycle position). SdFFF isolated subpopulations depending on the cell cycle position allowing the study of apoptosis kinetics and extent. Results showed that cells in G0/G1 phases (F3 cells) underwent significant and earlier apoptosis than cells in the active part of the cell cycle (S/G2/M phases). Results shed light on the correlation between differences in apoptosis kinetics and cell cycle stage when exposure to the inducer began. SdFFF monitoring and size measurement also led to the description of different subpopulations demonstrating complex variations in density between fractions associated with differences in biological processes.

Brain-derived neurotrophic factor and nerve growth factor correlate with T-cell activation in primary Sjogren's syndrome.

OBJECTIVES: Identification of factors associated with disease activity and B and T cell activation is a challenge in primary Sjogren's syndrome (pSS). Neurotrophins (NTs), recently reported as B cell antiapoptotic, and T-cell activation factors seem to be implicated in autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). METHODS: Samples from 18 pSS patients and 12 control subjects were studied to determine serum levels of nerve-growth factor (NGF) and brain-derived neurotrophic factor (BDNF), and their relationships with T- and B-cell activation and disease activity. Peripheral blood mononuclear cells (PBMCs) from patients with pSS and controls were examined by flow cytometry for HLA-DR expression by activated T cells. B cell activation was evaluated by B cell activating factor (BAFF) serum levels measured by enzyme-linked immunosorbent assay (ELISA) and immunoglobulin (Ig) and free light chain (FLC) levels. RESULTS: Mean serum levels of BDNF in pSS patients were significantly higher than in healthy controls and correlated directly with disease activity. NGF levels were associated with the subgroup of patients with hypergammaglobulinaemia. The pSS group was characterized by peripheral CD4+ and CD8+ T cell activation that correlated positively with BDNF and NGF levels, respectively. CONCLUSION: NT levels are potential biomarkers for lymphocyte activation in pSS patients.

Study of diosgenin-induced apoptosis kinetics in K562 cells by Sedimentation Field Flow Fractionation.

Recently, the use of SdFFF in cancer research has been studied in order to better understand major phenomena implicated in cancer development and therapy: apoptosis and differentiation. In this report, we used SdFFF as a monitoring and cell separation tool to study the kinetics of apoptosis. Incubation of K562 cells with diosgenin, used as cellular model, led to a surprising apoptotic process occurring in two phases (after 24 and 48 h incubation), associated with specific p-ERK expression. Based on the capacity to sort apoptotic cells, results showed that SdFFF cell separation was an effective analytical tool to obtain different subpopulations regardless of the kinetics and extent of apoptosis. Results also showed that, after proper biological calibration of elution profiles, SdFFF can be used to monitor either the induction or the kinetics of a biological event.

Study of the phenotypic relationship in the IMR-32 human neuroblastoma cell line by sedimentation field flow fractionation.

Neuroblastoma (NB) is the most common childhood solid tumor. Although spontaneous regression can occur in patients <1-year old, 70% of patients over the age of 1 year have a high-risk and difficult-to-treat NB. Cell type heterogeneity is observed either in the morphological appearance of NB tumors or in cell lines isolated from tumor specimens. NB consists of two principal neoplastic cell types: i) neuroblastic or N-type (undifferentiated cells); and ii) stromal or S-type (differentiated cells). As NB cells seem to have the capacity to differentiate spontaneously in vivo and in vitro, their heterogeneity could affect treatment outcome, in particular the response to apoptosis induced by chemotherapy. Therefore, it is important to understand the underlying process governing changes in differentiation in order to improve treatment response and NB patient outcome and the neoplastic population in IMR-32 represented a good model for such a study. Results showed that this cell line was extremely heterogeneous and highly variable in its stage of differentiation and we demonstrated that sedimentation field flow fractionation (SdFFF) permitted the isolation of 2 N-phenotypes and contributed to the understanding of the IMR-32 cell population dynamics. The first N-phenotype forms a pool of quiescent undifferentiated cells while the second one was able to proliferate (incorporation of BrdU) and also give rise to adherent S-type cells (PSA-N-CAM+ and N-CAM+). The results could also suggest a close interaction between these different cellular phenotypes to create the IMR-32 cell lineage.

Increase of Fas-induced apoptosis by inhibition of extracellular phosphorylation of Fas receptor in Jurkat cell line.

Apoptosis signalling through the Fas pathway requires several steps of aggregation of the Fas receptor in the membrane, including aggregation that may occur in the absence of Fas ligand. Association of Fas domains is determinant to signal transmission following Fas ligand binding to a specific domain. The domains involved in Fas aggregation are located in its extracellular region and contain three potential protein kinase C-binding motifs. We therefore studied the possibility that phosphorylation of the extracellular region of Fas might be implicated in the regulation of Fas-mediated apoptosis. Inhibition experiments of extracellular phosphorylation were performed in human Jurkat T leukemia cells with K252b, an impermeant protein-kinase inhibitor. Extracellular phosphorylation of Fas receptor was related to ecto-kinase, as assessed by the [gamma-(32)P] ATP labelling of Fas-116 kDa aggregates, suppressed by K252b inhibitor which significantly increased the sensitivity to Fas-mediated apoptosis. Ecto-PKC involvement was demonstrated by bisindolylmaleimide VIII, a selective inhibitor of protein kinase C which significantly increased both Fas aggregation in the membrane and Fas-mediated apoptosis and by the addition of the PKC pseudo-substrate 19-36 which inhibited the phosphorylation of 116 kDa Fas aggregates. These data support a role for Fas phosphorylation in the decreased sensitivity to apoptosis in the Jurkat T leukemia cell line.

Modulation of Fas-induced apoptosis by p75 neurotrophin receptor in a human neuroblastoma cell line.

Fas and p75 neurotrophin receptors (p75(NTR)) are death receptors that alone induce apoptosis of SH-SY5Y neuroblastoma cell line respectively by Fas ligand or brain-derived neurotrophic factor (BDNF, a p75(NTR) ligand). We report on the modulation of Fas-mediated apoptosis by concomitant p75(NTR) activation. The exposure to both ligands suppressed the apoptotic effect. A co-localisation of Fas and p75(NTR) receptors was evidenced by co-capping and immunoprecipitation assays. Moreover, a caspase-8 inhibitor suppressed the protective effect of the concomitant BDNF and Fas ligand stimulation, suggesting that p75(NTR) and Fas receptors could share common signalling pathways.

[Polyradiculoneuritis and Campylobacter jejuni: clinical and physiopathological aspects]. / Polyradiculonévrites et Campylobacter jejuni: aspects cliniques et physiopathologiques.

Several explanations have been proposed to explain the relationship between axonal forms of acute auto-immune inflammatory polyradiculoneuritis and Campylobacter jejuni. The major hypothesis involving molecular imitation is based on the existence of common antigenic determinants (epitopes) in the lipopolysaccharides of the infectious agent and gangliosides, i.e. glycosphingolipides on the surface of the nervous system cells, especially peripheral nervous system cells. The purpose of this literature review is to improve understanding of the rather complex physiopathological mechanisms underlying Guillain-Barre syndrome.

Sedimentation field flow fractionation purification of immature neural cells from a human tumor neuroblastoma cell line.

The use of stem cells for therapeutic applications is now an important objective for the future. Stem cell preparation is difficult and time-consuming depending on the origin of cells. Sedimentation field flow fractionation (SdFFF) is an effective tool for cell separation, respecting integrity and viability. We used the human neuroblastic SH-SY5Y clone of the SK-N-SH cell line as a source of immature neural cells. Our results demonstrated that by using SdFFF cell sorter under strictly defined conditions, and immunological cell characterization, we are now able to provide, in less than 15 min, a sterile, viable, usable and purified immature neural cell fraction without inducting cell differentiation.

Expression of a functional Fas death receptor by human foetal motoneurons.

The expression of the apoptosis inducer Fas (CD95/APO-1) surface receptor by human foetal neurons was investigated in vitro and ex vivo. Immunofluorescence studies of brain and spinal cord cells in primary cultures and of cryosections obtained from 9- and 10-week-old human foetuses, respectively, showed that all Fas-expressing cells were motoneurons (5.3 and 4.2% of the neurons in brain or spinal cord cultures, respectively) on the basis of morphology, reactivity with the monoclonal antibody SMI-32, a mostly motoneuronal marker and acetylcholine esterase expression. Fas was undetectable on the other cell types in culture. The ability of Fas to induce apoptosis of cultured cells from both tissues was determined by using the terminal transferase (TdT)-mediated dUTP nick-end labelling (TUNEL) method combined with the same double-staining procedure. Under basal culture conditions, about 9% of cells, all glial fibrillary acidic protein-expressing astrocytes, were apoptotic. After a 48-h incubation with Fas ligand, mean 28.5% of brain motoneurons and 29.4% of spinal motoneurons underwent apoptosis, with an inhibition by Z-IETD-FMK, a caspase-8 inhibitor. Hence, Fas appears to be functional through a caspase-8-dependent pathway in a subpopulation of human foetal motoneurons.

Blood-cerebrospinal fluid barrier and intrathecal immunoglobulins compared to field diagnosis of central nervous system involvement in sleeping sickness.

Diagnosis of central nervous system (CNS) involvement in sleeping sickness is crucial in order to give an appropriate treatment regimen. Neurological symptoms occur late, therefore field diagnosis is based on white blood cell count, total protein concentration and presence of trypanosomes in cerebrospinal fluid (CSF). More sensitive and specific parameters are now available. Blood-CSF barrier (B-CSFB) dysfunction, intrathecal total and specific immunoglobulin synthesis were evaluated in 95 patients with and without obvious meningoencephalitis, and compared to field criteria.B-CSFB dysfunction is a rather late event in the course of CNS involvement and correlates with the presence of trypanosomes, neurological signs and intrathecal polyspecific and specific immune response. IgM intrathecal response and particularly IgM antibody index are early markers of CNS invasion. We showed that 29% of patients with CSF abnormalities but without trypanosome detection in the field had no neuro-immunological response. In contrast, patients with normal CSF according to field diagnosis showed an intrathecal immune response in 31% of the cases.Field diagnosis can therefore fail to determine neurological involvement but can also provide false positive results. Improved criteria including B-CSFB dysfunction and IgM detection are needed in order to provide an adapted treatment regimen.

[Non-simultaneous malignant lymphoma and antiphospholipid syndrome: 4 cases]. / Lymphomes malins et syndrome des antiphospholipides non simultanés: quatre observations.

OBJECTIVE: We report four cases of non-synchronous antiphospholipid syndrome (APS) and malignant lymphoma, which highlight the complex relationship that seems to exist between these illnesses. METHODS: In a retrospective study conducted in two departments (internal medicine and clinical hematology) of a university hospital, we collected all observations of patients with both APS and malignant lymphoma diagnosed throughout the past decade. RESULTS: An association of APS with malignant lymphoma was recorded in three female and one male patient, median age 42.5 years at the time of diagnosis of the first disease. In each case, the primary APS was diagnosed, with arterial thrombotic events in three cases and venous thrombotic events in one case. One patient had isolated IgG anticardiolipin antibody, whereas the others had a combination of IgG anticardiolipin antibody and lupus anticoagulant with or without IgG anti-beta 2 glycoprotein I antibody. One patient also had an acquired inhibitor to factor VIII:C and a chronic C virus hepatitis. The mean time apparently separating the two illnesses ranged from 18 months to 9 years, but in two cases the diagnosis of APS was delayed due to a progressive, atypical, neurological onset. In two instances, the APS took place at a distance from a cured malignant lymphoma (Hodgkin's disease and nodal large cell B-cell lymphoma), whilst in the others it preceded a B-cell lymphoma (nodal and cutaneous, small cells and primary hepatic, large cells). Treatment resulted in complete haematological response in both cases, with disappearance of anticardiolipin antibody and lupus anticoagulant in the latter following a double autologous peripheral blood stem cell transplantation. In addition, late carcinomas (breast, kidney, thyroid) were seen in two patients. CONCLUSIONS: Our data indicate that the diagnosis of a malignant lymphoma should be considered in patients with a primary APS and peripheral lymph node enlargement or unexplained constitutional symptoms. Conversely, a late onset of arterial or venous thrombotic diathesis after a malignant lymphoma may indicate not only late relapse of malignant lymphoma but also a subsequent APS.

[Risk factors for irreversible cerebral ischemia complications from Horton's disease: prospective study of 178 patients]. / Facteurs prédictifs de complications céphaliques ischémiques irréversibles au cours de la maladie de Horton: étude prospective sur 178 patients.

PURPOSE: To search for risk factors of developing irreversible cranial ischemic complications (ICIC) in patients with giant cell arteritis (GCA) and to explore whether two subsets of patients (high risk and low risk of developing ICIC) can be defined. METHODS: One-hundred seventy-eight consecutive patients with temporal arteritis (149 biopsy-proven) were diagnosed and followed up in a department of Internal Medicine between 1976 and 1999. The patients were separated into two groups, according to the presence or absence of ICIC, with comparison of 17 clinical and biological parameters prospectively recorded for each patient using a pre-established comprehensive questionnaire. RESULTS: ICIC occurred in 25 patients (14%), with amaurosis in 22 cases. Suggestive symptoms and/or signs of temporal arteritis were present in 92% of the patients, lasting 50 days (median) before the onset of ICIC. Forty-three patients (24%) complained of transient visual ischemic symptoms (TVIS), which preceded acute blindness in 11 cases. A multivariate logistic regression, from which 28 cases with upper limb artery involvement were excluded for technical reasons (no CCII in any case, thus predicting perfectly the lack of ischemic risk, P = 0.02), indicated that the only independent variables associated with the ischemic risk were: a history of TVIS (P = 0.05), the lack of signs of polymyalgia rheumatica (PMR; P = 0.02), lower blood levels of fibrinogen (P = 0.024) and higher mean blood platelets levels (P = 0.006). However, these five variables predicted only 30% of the variability of the model. Sensitivity, specificity, positive and negative predictive values of the model reached respectively 36, 96, 64 and 88%. Overall, 86% of the cases were correctly classified with respect to the ischemic risk. CONCLUSION: The rate of ICIC should be reduced by an earlier recognition of the usual signs of temporal arteritis. Several independent risk factors of ICIC have been identified. However, the logistic model failed to predict accurately the ischemic risk in 14% of the cases, indicating that as yet unrecognised factors probably exist that play a role in the occurrence of ICIC. Nevertheless, regarding the strong association between platelet levels and ICIC, patients with thrombocytosis should receive initially both corticosteroids and antiplatelet agents.