Marie-Odile Jauberteau

Role of Endogenous Brain-Derived Neurotrophic Factor and Sortilin in B Cell Survival

Brain-derived neurotrophic factor (BDNF), a major neuronal growth factor, is also known to exert an antiapoptotic effect in myeloma cells. Whereas BDNF secretion was described in B lymphocytes, the ability of B cells to produce sortilin, its transport protein, was not previously reported. We studied BDNF production and the expression of its receptors, tyrosine protein kinase receptor B and p75 neurotrophin receptor in the human pre-B, mature, and plasmacytic malignant B cell lines under normal and stress culture conditions (serum deprivation, Fas activation, or their combination). BDNF secretion was enhanced by serum deprivation and exerted an antiapoptotic effect, as demonstrated by neutralization experiments with antagonistic Ab. The precursor form, pro-BDNF, also secreted by B cells, decreases under stress conditions in contrast to BDNF production. Stress conditions induced the membranous expression of p75 neurotrophin receptor and tyrosine protein kinase receptor B, maximal in mature B cells, contrasting with the sequestration of both receptors in normal culture. By blocking Ab and small interfering RNA, we evidenced that BDNF production and its survival function are depending on sortilin, a protein regulating neurotrophin transport in neurons, which was not previously described in B cells. Therefore, in mature B cell lines, an autocrine BDNF production is up-regulated by stress culture conditions and exerts a modulation of apoptosis through the sortilin pathway. This could be of importance to elucidate certain drug resistances of malignant B cells. In addition, primary B lymphocytes contained sortilin and produced BDNF after mitogenic activation, which suggests that sortilin and BDNF might be implicated in the survival and activation of normal B cells also.

Articular manifestations in primary Sjögren’s syndrome: clinical significance and prognosis of 188 patients

OBJECTIVES Articular manifestations (AMs) occurred in approximately 30-60% of patients with primary SS (pSS). We conducted the current study to describe clinical presentation, specific treatment and to report clinical outcome of pSS patients with AM in a large bicentric French cohort. METHODS Clinical, biological and immunological features of 419 consecutive patients with pSS were recorded in order to describe the clinical and immunological course of pSS AM and to point out the impact of those rheumatological features on pSS evolution. RESULTS A total of 188 patients with pSS (172 women, 16 men) exhibited AM. They preceded sicca symptoms in 32, were simultaneous to pSS diagnosis in 98 and followed diagnosis in 59 patients. Clinical presentation was polyarticular and concerned mostly peripheral joints (synovitis, n = 66). Symptoms responded readily to symptomatic treatment in 45 cases (24%). DMARDs or immunosuppressive treatments were introduced in 133 patients: HCQ (n = 111), corticosteroid (n = 53), MTX (n = 12), SSZ (n = 6), AZA (n = 3), LEF (n = 1), etanercept (n = 1) and allochrysine (n = 1). Only one case of RA was diagnosed during the evolution. Statistical analysis identified clinical and biological factors associated with AM (P < or = 0.05): RP, muscular manifestations, renal involvement, peripheral neuropathy, cutaneous vasculitis, and positivity of RF, anti-SSB antibodies and cryoglobulinaemia. Patients with AM at diagnosis were characterized by a multisystemic involvement at the end of the follow-up period (P < 0.001). CONCLUSION Although AMs are frequent and usually mild in pSS, these manifestations are associated with a pluri-systemic involvement of pSS.

Sortilin mediates the release and transfer of exosomes in concert with two tyrosine kinase receptors

ABSTRACT The transfer of exosomes containing both genetic and protein materials is necessary for the control of the cancer cell microenvironment to promote tumor angiogenesis. The nature and function of proteins found in the exosomal cargo, and the mechanism of their action in membrane transport and related signaling events are not clearly understood. In this study, we demonstrate, in human lung cancer A549 cells, that the exosome release mechanism is closely linked to the multifaceted receptor sortilin (also called neurotensin receptor 3). Sortilin is already known to be important for cancer cell function. Here, we report for the first time its role in the assembly of a tyrosine kinase complex and subsequent exosome release. This new complex (termed the TES complex) is found in exosomes and results in the linkage of the two tyrosine kinase receptors TrkB (also known as NTRK2) and EGFR with sortilin. Using in vitro models, we demonstrate that this sortilin-containing complex exhibits a control on endothelial cells and angiogenesis activation through exosome transfer.

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.

Hallmarks in colorectal cancer: Angiogenesis and cancer stem-like cells

Carcinogenesis is a multistep process that requires the accumulation of various genetic and epigenetic aberrations to drive the progressive malignant transformation of normal human cells. Two major hallmarks of carcinogenesis that have been described are angiogenesis and the stem cell characteristic of limitless replicative potential. These properties have been targeted over the past decade in the development of therapeutic treatments for colorectal cancer (CRC), one of the most commonly diagnosed and lethal cancers worldwide. The treatment of solid tumor cancers such as CRC has been challenging due to the heterogeneity of the tumor itself and the chemoresistance of the malignant cells. Furthermore, the same microenvironment that maintains the pool of intestinal stem cells that contribute to the continuous renewal of the intestinal epithelia also provides the necessary conditions for proliferative growth of cancer stem-like cells. These cancer stem-like cells are responsible for the resistance to therapy and cancer recurrence, though they represent less than 2.5% of the tumor mass. The stromal environment surrounding the tumor cells, referred to as the tumor niche, also supports angiogenesis, which supplies the oxygen and nutrients needed for tumor development. Anti-angiogenic therapy, such as with bevacizumab, a monoclonal antibody against vascular-endothelial growth factor, significantly prolongs the survival of metastatic CRC patients. However, such treatments are not completely curative, and a large proportion of patient tumors retain chemoresistance or show recurrence. This article reviews the current knowledge regarding the molecular phenotype of CRC cancer cells, as well as discusses the mechanisms contributing to their maintenance. Future personalized therapeutic approaches that are based on the interaction of the carcinogenic hallmarks, namely angiogenic and proliferative attributes, could improve survival and decrease adverse effects induced by unnecessary chemotherapy.

Autophagy takes place in mutated p53 neuroblastoma cells in response to hypoxia mimetic CoCl2

Solid tumors like neuroblastoma exhibit hypoxic areas, which can lead both to cell death or aggressiveness increase. Hypoxia is a known stress able to induce stabilization of p53, implicated in cell fate regulation. Recently, p53 appeared to be involved in autophagy in an opposite manner, depending on its location: when nuclear, it enhanced transcription of pro-autophagic genes whereas when cytoplasmic, it inhibited the autophagic process. Today, we used cobalt chloride, a hypoxia mimetic that inhibits proteasomal HIF-1 degradation and generates reactive oxygen species (ROS). We focused on CoCl2-induced cell death in a DNA-binding mutated p53 neuroblastoma cell line (SKNBE(2c)). An autophagic signaling was evidenced by an increase of Beclin-1, ATG 5-12, and LC3-II expression whereas the p53(mut) presence decreased with CoCl2 time exposure. Activation of the pathway seemed to protect cells from ROS production and, at least in part, from death. The autophagic inhibitors activated the apoptotic signaling and the death was enhanced. To delineate the eventual implication of the p53(mut) in the autophagic process in response to hypoxia, we monitored signaling in p53(WT)SHSY5Y cells, after either shRNA-p53 down-regulation or transcriptional activity inhibition by pifithrin alpha. We did not detect autophagy neither with p53(wt) nor when p53 was lacking whereas such a response was effective with a mutated or inactivated p53. To conclude, mutated p53 in neuroblastoma cells could be linked with the switch between apoptotic response and cell death by autophagy in response to hypoxic mimetic stress.

Inflammasome activation restricts Legionella pneumophila replication in primary microglial cells through flagellin detection.

Microglial cells constitute the first line of defense of the central nervous system (CNS) against microbial invasion. Pathogens are detected thanks to an array of innate immune receptors termed pattern recognition receptors (PRRs). PRRs have been thoroughly characterized in bone marrow‐derived macrophages, but the PRRs repertoire and functionality in microglial cells remain largely unknown. Microglial cells express various Toll‐like Receptors and the Nod1/2 receptors. Recently, a novel innate immune signalling pathway, the inflammasome pathway has been uncovered. Inflammasome activation leads to caspase‐1 activation, release of the proinflammatory cytokines, IL‐1β and IL‐18 and cell death in a process termed pyroptosis. One inflammasome receptor, NLRP3, has been characterized in microglial cells and associated with response to infections and in the initiation of neuro‐degeneration in an Alzheimers disease model. Legionella pneumophila (L.pneumophila) is a flagellated bacterium replicating within macrophages. In bone marrow‐derived macrophages, L. pneumophila is detected in a flagellin‐dependent manner by the Naip5‐NLRC4 (Ipaf) inflammasome pathway. In this study, we decided to use L. pneumophila to investigate the presence and the functionality of this inflammasome in primary murine microglial cells. We show that microglial cells detect L. pneumophila infection in a flagellin‐dependent manner leading to caspase‐1‐mediated bacterial growth restriction, infected cell death and secretion of the proinflammatory cytokines IL‐1β and IL18. Overall, our data demonstrate that microglial cells have a functional Naip5‐NLRC4 inflammasome likely to be important to monitor and clear CNS infections by flagellated bacteria.

Label free biosensors for human cell characterization using radio and microwave frequencies

A novel micro biosensor concept functioning at microwave frequencies has been developed in order to study the intrinsic electrical parameters of human cells. This sensor is based on a resonant structure allowing a sensitive detection which associated to its microscopic size permits to work at the scale of one cell. The proposed bio-sensing method presents the advantage to be a label free method and allows potentially cell identification and discrimination. Hence, using a specific experimental protocol, tests performed have demonstrated the biosensor ability to differentiate at least two particular cell types.

Primary Sjögren's syndrome in men

Objective: To determine whether there were any clinical and biological differences between male and female patients with primary Sjögrens syndrome (pSS) in a large bicentric series of patient. Methods: We studied 419 consecutive patients (mean age at onset 53.6 years, mean disease outcome 73 months) with pSS according to American–European criteria, attending two different Departments of Internal Medicine in France. The 42 (9%) male patients in this cohort comprised the male group described in this study. Results: Extraglandular manifestations during the course of the disease were present in 37 (89%) of our male patients with pSS. The extraglandular manifestations were similar among the two groups except that the male patients showed a lower frequency of depression or asthaenia (5% vs. 20%, p = 0.014) compared with the females. A significantly greater percentage of women reported lymphopaenia (26% vs. 8%, p = 0.02) and leucopaenia (18% vs. 3%, p = 0.015) at onset, but thrombopaenia was more common in the male patients (21% vs. 6%, p = 0.001). Lymphoma development was slightly more common in the male patients, but with no statistical significance (10% vs. 3%, p = 0.06), and occurred earlier after the SS diagnosis (log rank test p = 0.04). Conclusion: Although pSS is typically a disease affecting women, clinicians should be aware that it may be diagnosed in male patients. Except for haematological presentation, we could not find any notable differences in clinical and immunological characteristics between male and female patients with pSS.

Monoclonal IgM reactive with several gangliosides in a chronic relapsing polyneuropathy

A possibly pathogenic serum monoclonal IgM lambda from a patient with chronic relapsing polyneuropathy was shown to react with the disialosyl-lactosyl residue (NeuAc alpha 2-8NeuAc alpha 2-3) -Gal beta 1-4Glc expressed by GD1b, GT1b, GQ1b, GD2 and GD3. A part of this epitope in terminal position in GM3, GD1a and LM1 was also recognized by the IgM lambda.