Fabrice Lalloué

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.

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.

Quantitative analysis of vascular colonisation and angio-conduction in porous silicon-substituted hydroxyapatite with various pore shapes in a chick chorioallantoic membrane (CAM) model

UNLABELLED The development of scaffolds for bone filling of large defects requires an understanding of angiogenesis and vascular guidance, which are crucial processes for bone formation and healing. There are few investigations on the ability of a scaffold to support blood vessel guidance and it this is of great importance because it relates to the quality and dispersion of the blood vessel network. This work reports an analysis of vascularisation of porous silicon-substituted hydroxyapatite (SiHA) bioceramics and the effects of pore shape on vascular guidance using an expedient ex ovo model, the chick embryo chorioallantoic membrane (CAM) assay. Image analysis of vascularised implants assessed the vascular density, fractal dimension and diameter of blood vessels at two different scales (the whole ceramic and pores alone) and was performed on model SiHA ceramics harbouring pores of various cross-sectional geometries (circles, square, rhombus, triangles and stars). SiHA is a biocompatible material which allows the conduction of blood vessels on its surface. The presence of pores did not influence angiogenesis related-parameters (arborisation, fractal dimension) but pore geometry affected the blood vessel guidance and angio-conductive potential (diameter and number of the blood vessels converging toward the pores). The measured angles of pore cross-section modulated the number and diameter of blood vessels converging to pores, with triangular pores appearing of particular interest. This result will be used for shaping ceramic scaffolds with specific porous architecture to promote vascular colonisation and osteointegration. STATEMENT OF SIGNIFICANCE An expedient and efficient method, using chick embryo chorioallantoic membrane (CAM) assays, has been set up to characterise quantitatively the angiogenesis and the vascular conduction in scaffolds. This approach complements the usual cell culture assays and could replace to a certain extent in vivo experiments. It was applied to silicon-substituted hydroxyapatite porous bioceramics with various pore shapes. The material was found to be biocompatible, allowing the conduction of blood vessels on its surface. The presence of pores does not influence the angiogenesis but the pore shape affects the blood vessel guidance and angio-conductive potential. Pores with triangular cross-section appear particularly attractive for the further design of scaffolds in order to promote their vascular colonisation and osteointegration and improve their performances.

Differential Expression of Neurotensin and Specific Receptors, NTSR1 and NTSR2, in Normal and Malignant Human B Lymphocytes

Neurotensin, a neuropeptide growth factor, and its two specific neurotensin receptors, NTSR1 and NTSR2, were shown to be expressed by human B cell lines. Another NTSR, sortilin, which is common to neurotensin and neurotrophins, was also detected as we have previously described. Neurotensin was functional in B cell lines; it induced their proliferation and inhibited apoptosis induced by serum deprivation or Fas activation. Quantitative study of gene expression in two malignant B cell diseases showed that NTSR2 was overexpressed, NTSR1 decreased, and neurotensin was unexpressed in B cell leukemia patient’s cells, as compared with healthy B cells. However, these expressions did not significantly change in large diffuse B cell lymphoma lymph nodes compared with benign ones. This study points out that neurotensin and its two specific receptors are expressed in human B lymphocytes. Such expressions were not described, and their relationship in B cell diseases, especially in chronic B cell leukemia, needs to be considered further in regard to these findings.

Brain‐derived neurotrophic factor and nerve growth factor correlate with T‐cell activation in primary Sjögren's syndrome

Objectives: Identification of factors associated with disease activity and B and T cell activation is a challenge in primary Sjögrens 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.

Microwave biosensors for identifying cancer cell aggressiveness grade

This paper illustrates the potential of microwave frequencies for biological analysis. Once penetrating inside biological cells, microwaves can interact with their intracellular content and inform on their safe or malignant state. This work demonstrates that their cancer grade (i.e. aggressiveness level) can also be identified by this way. Hence, based on permittivity measurements on three colon cancer cell lines loading RF resonators, the presented results show significant differences of electromagnetic signature in the cancer grade of analyzed cells. This sensing method appears very promising to develop new powerful tools for early cancer diagnostic.

The implications of sortilin/vps10p domain receptors in neurological and human diseases.

The neurotensin receptor-3 also known as sortilin is part of the new receptor family of vacuolar protein sorting 10 protein domain. Growing evidence show that the vacuolar protein sorting 10 protein domain family is implicated as a genetic risk factor for neurodegenerative diseases such as Alzheimers disease, frontotemporal lobar degeneration, and Parkinsons disease, in addition to links associated with type 2 diabetes mellitus, lysosomal disorders, cardiovascular disease and atherosclerosis. In fact, sortilin expression is elevated in many human cell lines controlling the trafficking and release of neurotrophins. Hence, not surprisingly the imbalance of neurotrophin signaling is implicated in several human diseases. The fine regulation of the growth factor, brain derived nerve factor by sortilin mediates both neuronal and tumor cell survival, whereas in Alzheimers disease sortilin mediated beta secretase-1 trafficking increases the cleavage of the beta-amyloid precursor protein. Perturbation of the autocrine/paracrine loop of neurotrophins in combination with the cell surface interaction of sortilin with neurotensin receptor 1 or 2 or tyrosine kinase receptor A or B are dramatically upregulated in both neurodegenerative diseases and cancer. In cardiovascular diseases, the circulatory low-density lipoprotein is closely correlated with sortilin expression in hepatocytes. Herein, this review discusses the multifaceted role played by sortilin and its interacting partners in human disease which could be interesting novel target(s) in drug discovery. Nevertheless, completely challenging the function of sortilin could prove unfavorable given the important universal role of sortilin plays in the body. Hence, metabolism disorders could be relieved with specific targeted therapeutic challenge of sortilin function.

p75 neurotrophin receptor and pro-BDNF promote cell survival and migration in clear cell renal cell carcinoma

p75NTR, a member of TNF receptor family, is the low affinity receptor common to several mature neurotrophins and the high affinity receptor for pro-neurotrophins. Brain-Derived Neurotrophic Factor (BDNF), a member of neurotrophin family has been described to play an important role in development and progression of several cancers, through its binding to a high affinity tyrosine kinase receptor B (TrkB) and/or p75NTR. However, the functions of these two receptors in renal cell carcinoma (RCC) have never been investigated. An overexpression of p75NTR, pro-BDNF, and to a lesser extent for TrkB and sortilin, was detected by immunohistochemistry in a cohort of 83 clear cell RCC tumors. p75NTR, mainly expressed in tumor tissues, was significantly associated with higher Fuhrman grade in multivariate analysis. In two derived-RCC lines, 786-O and ACHN cells, we demonstrated that pro-BDNF induced cell survival and migration, through p75NTR as provided by p75NTR RNA silencing or blocking anti-p75NTR antibody. This mechanism is independent of TrkB activation as demonstrated by k252a, a tyrosine kinase inhibitor for Trk neurotrophin receptors. Taken together, these data highlight for the first time an important role for p75NTR in renal cancer and indicate a putative novel target therapy in RCC.