T Lymphocyte Serotonin 5-HT7 Receptor Is Dysregulated in Natalizumab-Treated Multiple Sclerosis Patients.

Serotonin (5-HT) is known as a potent immune cell modulator in autoimmune diseases and should be protective in the pathogenesis of multiple sclerosis (MS). Nevertheless, there is limited knowledge about receptors involved in 5-HT effects as well as induced mechanisms. Among 5-HT receptors, the 5-HT7 receptor is able to activate naïve T cells and influence the inflammatory response; however, its involvement in the disease has never been studied so far. In this study, we collected blood sample from three groups: acute relapsing MS patients (ARMS), natalizumab-treated MS patients (NTZ), and control subjects. We investigated the 5-HT7 expression on circulating lymphocytes and evaluated the effects of its activation on cytokine production with peripheral blood mononuclear cell (PBMC) cultures. We found a significant increase in the 5-HT7 surface expression on T lymphocytes and on the different CD4+ T cell subsets exclusively in NTZ-treated patients. We also showed that the selective agonist 5-carboxamidotryptamine (5-CT)-induced 5-HT7R activation significantly promotes the production of IL-10, a potent immunosuppressive cytokine in PBMCs. This study provides for the first time a dysregulation of 5-HT7 expression in NTZ-MS patients and its ability to promote IL-10 release, suggesting its protective role. These findings strengthen the evidence that 5-HT7 may play a role in the immuno-protective mechanisms of NTZ in MS disease and could be considered as an interesting therapeutic target in MS.

Disturbed expression of autophagy genes in blood of Parkinson's disease patients.

Parkinson's disease (PD) is a common neurodegenerative disorder which affects dopaminergic neurons leading to alteration of numerous cellular pathways. Several reports highlight that PD disturbs also other cells than CNS neurons including PBMCs, which could lead, among other things, to dysfunctions of immune functions. Because autophagy could be altered in PD, a monocentric pilot study was performed to quantify the transcripts levels of several autophagy genes in blood cells. MAP1LC3B, GABARAP, GABARAPL1, GABARAPL2 and P62/SQSTM1 were found to be overexpressed in patients. On the contrary, transcripts for HSPA8 and GAPDH were both decreased. Expression of MAP1LC3B and GABARAP was able to successfully segregate PD patients from healthy controls. The accuracy of this segregation was substantially increased when combined expressions of MAP1LC3B and GAPDH or GABARAP and GAPDH were used as categorical variables. This pilot study suggests that autophagy genes expression is dysregulated in PD patients and may open new perspectives for the characterisation of prediction markers.

STING-dependent sensing of self-DNA drives silica-induced lung inflammation.

Silica particles induce lung inflammation and fibrosis. Here we show that stimulator of interferon genes (STING) is essential for silica-induced lung inflammation. In mice, silica induces lung cell death and self-dsDNA release in the bronchoalveolar space that activates STING pathway. Degradation of extracellular self-dsDNA by DNase I inhibits silica-induced STING activation and the downstream type I IFN response. Patients with silicosis have increased circulating dsDNA and CXCL10 in sputum, and patients with fibrotic interstitial lung disease display STING activation and CXCL10 in the lung. In vitro, while mitochondrial dsDNA is sensed by cGAS-STING in dendritic cells, in macrophages extracellular dsDNA activates STING independent of cGAS after silica exposure. These results reveal an essential function of STING-mediated self-dsDNA sensing after silica exposure, and identify DNase I as a potential therapy for silica-induced lung inflammation.

Dysregulation of apoptosis and autophagy gene expression in peripheral blood mononuclear cells of efficiently treated HIV-infected patients.

OBJECTIVE: We measure the transcript levels of the proapoptotic GALIG, antiapoptotic MCL1 genes and those of the autophagy genes BECN1, MAP1LC3B, ATG9a, P62/SQSTM1, GABARAP, GABARAPL1 and GABARAPL2 to define if mRNA alteration can characterize HIV-infected patients effectively treated with combined antiretroviral therapy (cART). DESIGN: Monocentric pilot study conducted on peripheral blood mononuclear cell (PBMC) of 40 uninfected donors and 27 HIV-positive patients effectively treated by cART for at least 8.4 years. METHODS: Transcripts of the various genes were quantified by reverse transcription (RT)-quantitative PCR (qPCR) and RT-droplet digital PCR and compared using the standard statistical Mann-Whitney U test and machine learning algorithms. RESULTS: A concomitant overexpression of GALIG and MCL1 is detected in PBMC of effectively cART-treated patients. Overexpression of MAP1LC3B and GABARAPL1 is also measured, whereas BECN1 is underexpressed. Finally, accurate classification (94.5%) of our PBMC samples as HIV-negative donors or HIV-positive cART-treated is obtained in three separate machine-learning algorithms with GABARAPL1 and ATG9a as input variables. CONCLUSION: cART-treated HIV patients display altered transcript levels for three genes of basal autophagy. Some of these alterations may appear contradictory: BECN1 and ATG9a, both key actors in the formation of mammalian autophagosome, exhibit decreased amount of transcripts, whereas mRNA from the ATG8 family increase. Given the known role of impaired basal autophagy in immune senescence and chronic inflammation, the functional significance of our findings should be explored in larger studies.

Interaction of Alpha-synuclein with Cytogaligin, a protein encoded by the proapoptotic gene GALIG.

GALIG, an internal gene to the human galectin-3 gene, encodes two distinct proteins, Mitogaligin and Cytogaligin through translation of a unique mRNA in two overlapping alternative reading frames. When overexpressed GALIG induces apoptosis. In cultured cells, Mitogaligin destabilizes mitochondria membranes through interaction with cardiolipin. Little is known regarding the role of Cytogaligin. This protein displays multiple subcellular localizations; cytosol, nucleus, and mitochondria. We illustrate here that Cytogaligin is also secreted in the extracellular medium. Cytogaligin is shown to interact with α-Synuclein, the major component of Lewy bodies in Parkinson's disease. Overexpression of Cytogaligin reduces α-Synuclein dimerization raising a possible role in the evolution of α-Synuclein aggregation, a key molecular event underlying the pathogenesis of Parkinson's disease.

Opposing Mcl-1, the GALIG proapoptotic gene is upregulated as neutrophils die and underexpressed in Acute Myeloid Leukemia cells.

GALIG gene expression induces apoptosis in cultured cells through a pathway still under investigation. It is highly expressed in leukocytes but weakly detectable in bone marrow, suggesting a role in the myeloid lineage homeostasis. We show here that GALIG-induced cell death is counteracted by the overexpression of MCL-1, a pro-survival member of the Bcl2 family. Moreover, during spontaneous neutrophil apoptosis, a substantial increase in GALIG gene expression is observed: GALIG still opposes MCL-1. Finally, in bone marrow and peripheral blood cells from patients with Acute Myeloid Leukemia type 2, the level of GALIG transcripts is massively down-regulated when compared to their normal counterparts, while MCL-1 is expressed to the same extent. These data suggest that GALIG could be a key player in the cell death pathway involved in leukocytes homeostasis and myeloid malignancies.

The mitogaligin protein is addressed to the nucleus via a non-classical localization signal.

Mitogaligin, a protein encoded by galig, an internal cytotoxic gene of the galectin-3 locus, is mostly a mitochondrial protein. Mitochondrial targeting is due to an already identified mitochondrial localization signal. Interaction of mitogaligin with mitochondria leads to cytochrome c cytosolic leakage and ultimately to cell death. We have previously pointed out that mitogaligin can also be directed to the nucleus when the mitochondrial addressing signal is inactivated, indicating a possible dual intracellular localization of the protein. When expressed in the nucleus, mitogaligin exhibits also apoptotic properties leading to cell death. In this report, we show that nuclear addressing of mitogaligin depends on a sequence differing from classical signals containing basic, lysine or proline-tyrosine rich residues. The signal consists of a long sequence of amino acids residues based on a series of a short repetitive degenerated sequence.

Multiple reprobing of Western blots after inactivation of peroxidase activity by its substrate, hydrogen peroxide.

Sequential detections of different proteins on Western blot save time and precious samples. The main problem concerning reprobing is that stripping buffers can unbind both the antibody and the tested antigen. An original reprobing method has been set up based on horseradish peroxidase (HRP) inhibition after enhanced chemiluminescence detection. Instead of removing previously fixed antibodies as common stripping buffers do, the HRP activity linked to the secondary antibody is irreversibly inhibited by excess of hydrogen peroxide. A 15-min incubation allows one to perform at least five different sequential detections without losing significant amounts of blotted proteins.

Apoptotic activity of a nuclear form of mitogaligin, a cell death protein.

Galig, an internal gene to the galectin-3 gene, encodes two proteins and induces cell death in human cells. Mitogaligin, one of these proteins, contains a mitochondrial targeting sequence and promotes the release of cytochrome c into the cytosol. Here, we show that mitogaligin can also localize to nucleus. The nuclear form of mitogaligin induced cell death through a pathway exhibiting typical properties of apoptosis. These observations indicate for the first time that mitogaligin expresses cytotoxic properties not only when addressed to mitochondria but also when targeted to the nucleus.

Destabilization of membranes containing cardiolipin or its precursors by peptides derived from mitogaligin, a cell death protein.

Galig, a gene embedded within the galectin-3 gene, induces cell death when transfected in human cells. This death is associated with cell shrinkage, nuclei condensation, and aggregation of mitochondria. Galig contains two different overlapping open reading frames encoding two unrelated proteins. Previous observations have shown that one of these proteins, named mitogaligin, binds to mitochondria and promotes the release of cytochrome c. However, the mechanism of action of this cytotoxic protein remains still obscure. The present study provides evidence that synthetic peptides enclosing the mitochondrial localization signal of mitogaligin bind to anionic biological membranes leading to membrane destabilization, aggregation, and content leakage of mitochondria or liposomes. This binding to anionic phospholipids is the most efficient when cardiolipin, a specific phospholipid of mitochondria, is inserted in the membranes. Thus, cardiolipin may constitute a target of choice for mitogaligin sorting and membrane destabilization activity.

A paediatric vaccination vector based on live attenuated measles vaccine.

Live attenuated RNA viruses make highly efficient vaccines. Among them, measles virus (MV) vaccine has been given to a very large number of children and shown to be highly effective and safe. MV vaccine induces a life-long immunity after a single or two low-dose injections. It is easily produced on a large scale in most countries and can be distributed at low cost. Reversion to pathogenicity has never been observed with this vaccine. Because of all these characteristics, MV vaccine might be a very promising vector to immunise children against both measles and other infectious agents, such as HIV or flaviviruses, in the developing world. In this article, we describe recent data that we obtained showing the capacity of recombinant Schwarz MVs to express proteins from human immunodeficiency or West Nile viruses, and to induce specific immune responses able, in the case of West Nile virus, to protect from an experimental challenge.

A single injection of recombinant measles virus vaccines expressing human immunodeficiency virus (HIV) type 1 clade B envelope glycoproteins induces neutralizing antibodies and cellular immune responses to HIV.

The anchored and secreted forms of the human immunodeficiency virus type 1 (HIV-1) 89.6 envelope glycoprotein, either complete or after deletion of the V3 loop, were expressed in a cloned attenuated measles virus (MV) vector. The recombinant viruses grew as efficiently as the parental virus and expressed high levels of the HIV protein. Expression was stable during serial passages. The immunogenicity of these recombinant vectors was tested in mice susceptible to MV and in macaques. High titers of antibodies to both MV and HIV-Env were obtained after a single injection in susceptible mice. These antibodies neutralized homologous SHIV89.6p virus, as well as several heterologous HIV-1 primary isolates. A gp160 mutant in which the V3 loop was deleted induced antibodies that neutralized heterologous viruses more efficiently than antibodies induced by the native envelope protein. A high level of CD8+ and CD4+ cells specific for HIV gp120 was also detected in MV-susceptible mice. Furthermore, recombinant MV was able to raise immune responses against HIV in mice and macaques with a preexisting anti-MV immunity. Therefore, recombinant MV vaccines inducing anti-HIV neutralizing antibodies and specific T lymphocytes responses deserve to be tested as a candidate AIDS vaccine.

A molecularly cloned Schwarz strain of measles virus vaccine induces strong immune responses in macaques and transgenic mice.

Live attenuated RNA viruses make highly efficient vaccines. Among them, measles virus (MV) vaccine has been given to a very large number of children and has been shown to be highly efficacious and safe. Therefore, this vaccine might be a very promising vector to immunize children against both measles and other infectious agents, such as human immunodeficiency virus. A vector was previously derived from the Edmonston B strain of MV, a vaccine strain abandoned 25 years ago. Sequence analysis revealed that the genome of this vector diverges from Edmonston B by 10 amino acid substitutions not related to any Edmonston subgroup. Here we describe an infectious cDNA for the Schwarz/Moraten strain, a widely used MV vaccine. This cDNA was constructed from a batch of commercial vaccine. The extremities of the cDNA were engineered in order to maximize virus yield during rescue. A previously described helper cell-based rescue system was adapted by cocultivating transfected cells on primary chicken embryo fibroblasts, the cells used to produce the Schwarz/Moraten vaccine. After two passages the sequence of the rescued virus was identical to that of the cDNA and of the published Schwarz/Moraten sequence. Two additional transcription units were introduced in the cDNA for cloning foreign genetic material. The immunogenicity of rescued virus was studied in macaques and in mice transgenic for the CD46 MV receptor. Antibody titers and T-cell responses (ELISpot) in animals inoculated with low doses of rescued virus were identical to those obtained with commercial Schwarz MV vaccine. In contrast, the immunogenicity of the previously described Edmonston B strain-derived MV clone was much lower. This new molecular clone will allow for the production of MV vaccine without having to rely on seed stocks. The additional transcription units allow expressing heterologous antigens, thereby providing polyvalent vaccines based on an approved, safe, and efficient MV vaccine strain that is used worldwide.