Impact of bone marrow-derived mesenchymal stromal cells on experimental xenogeneic graft-versus-host disease

in Cytotherapy (2013), 15(3), 267-279

Background aims. Graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation caused by donor T cells reacting against host tissues. Previous ... [more ▼]

Background aims. Graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation caused by donor T cells reacting against host tissues. Previous studies have suggested that mesenchymal stromal cells (MSCs) could exert potent immunosuppressive effects. Methods. The ability of human bone marrow derived MSCs to prevent xenogeneic GVHD in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice and in NOD/SCID/interleukin-2Rg(null) (NSG) mice transplanted with human peripheral blood mononuclear cells (PBMCs) was assessed. Results. Injection of 200 106 human PBMCs intraperitoneally (IP) into sub-lethally (3.0 Gy) irradiated NOD/SCID mice also given anti-asialo GM1 antibodies IP 1 day prior and 8 days after transplantation induced lethal xenogeneic GVHD in all tested mice. Co-injection of 2 106 MSCs IP on day 0 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. Similarly, injection of 30 106 human PBMCs IP into sub-lethally (2.5 Gy) irradiated NSG mice induced a lethal xenogeneic GVHD in all tested mice. Injection of 3 106 MSCs IP on days 0, 7, 14 and 21 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. Conclusions. Injection of MSCs did not prevent xenogeneic GVHD in these two humanized mice models. [less ▲]

An Improved Protocol for Efficient Engraftment in NOD/ LTSZ-SCIDIL-2RcNULL Mice Allows HIV Replication and Development of Anti-HIV Immune Responses

in PLoS ONE (2012), 7(6), 38491

Cord blood hematopoietic progenitor cells (CB-HPCs) transplanted immunodeficient NOD/LtsZ-scidIL2Rcnull (NSG) and NOD/SCID/IL2Rcnull (NOG) mice need efficient human cell engraftment for long-term HIV-1 ... [more ▼]

Cord blood hematopoietic progenitor cells (CB-HPCs) transplanted immunodeficient NOD/LtsZ-scidIL2Rcnull (NSG) and NOD/SCID/IL2Rcnull (NOG) mice need efficient human cell engraftment for long-term HIV-1 replication studies. Total body irradiation (TBI) is a classical myeloablation regimen used to improve engraftment levels of human cells in these humanized mice. Some recent reports suggest the use of busulfan as a myeloablation regimen to transplant HPCs in neonatal and adult NSG mice. In the present study, we further ameliorated the busulfan myeloablation regimen with fresh CB-CD34+cell transplantation in 3–4 week old NSG mice. In this CB-CD34+transplanted NSG mice engraftment efficiency of human CD45+cell is over 90% in peripheral blood. Optimal engraftment promoted early and increased CD3+T cell levels, with better lymphoid tissue development and prolonged human cell chimerism over 300 days. These humanized NSG mice have shown long-lasting viremia after HIV-1JRCSF and HIV-1Bal inoculation through intravenous and rectal routes. We also saw a gradual decline of the CD4+T cell count, widespread immune activation, up-regulation of inflammation marker and microbial translocation after HIV-1 infection. Humanized NSG mice reconstituted according to our new protocol produced, moderate cellular and humoral immune responses to HIV-1 postinfection. We believe that NSG mice reconstituted according to our easy to use protocol will provide a better in vivo model for HIV-1 replication and anti-HIV-1 therapy trials. [less ▲]

Mice with Disrupted Type I Protein Kinase A Anchoring in T Cells Resist Retrovirus-Induced Immunodeficiency

in Journal of Immunology (2011), 186(9), 5119-30

Type I protein kinase A (PKA) is targeted to the TCR-proximal signaling machinery by the A-kinase anchoring protein ezrin and negatively regulates T cell immune function through activation of the C ... [more ▼]

Type I protein kinase A (PKA) is targeted to the TCR-proximal signaling machinery by the A-kinase anchoring protein ezrin and negatively regulates T cell immune function through activation of the C-terminal Src kinase. RI anchoring disruptor (RIAD) is a high-affinity competitor peptide that specifically displaces type I PKA from A-kinase anchoring proteins. In this study, we disrupted type I PKA anchoring in peripheral T cells by expressing a soluble ezrin fragment with RIAD inserted in place of the endogenous A-kinase binding domain under the lck distal promoter in mice. Peripheral T cells from mice expressing the RIAD fusion protein (RIAD-transgenic mice) displayed augmented basal and TCR-activated signaling, enhanced T cell responsiveness assessed as IL-2 secretion, and reduced sensitivity to PGE2- and cAMP-mediated inhibition of T cell function. Hyperactivation of the cAMP–type I PKA pathway is involved in the T cell dysfunction of HIV infection, as well as murine AIDS, a disease model induced by infection of C57BL/6 mice with LP-BM5, a mixture of attenuated murine leukemia viruses. LP-BM5–infected RIADtransgenic mice resist progression of murine AIDS and have improved viral control. This underscores the cAMP–type I PKA pathway in T cells as a putative target for therapeutic intervention in immunodeficiency diseases. [less ▲]

SHIP-1 inhibits CD95/APO-1/Fas-induced apoptosis in primary T lymphocytes and T leukemic cells by promoting CD95 glycosylation independently of its phosphatase activity

in Leukemia : Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K (2010)

SHIP-1 functions as a negative regulator of immune responses by hydrolyzing phosphatidylinositol-3,4,5-triphosphate generated by PI 3-kinase activity. As a result, SHIP-1 deficiency in mice results in ... [more ▼]

SHIP-1 functions as a negative regulator of immune responses by hydrolyzing phosphatidylinositol-3,4,5-triphosphate generated by PI 3-kinase activity. As a result, SHIP-1 deficiency in mice results in myeloproliferation and B cell lymphoma. On the other hand, SHIP-1 deficient mice have a reduced T cell population, but the underlying mechanisms are unknown. In this work, we hypothesized that SHIP-1 plays anti-apoptotic functions in T cells upon stimulation of the death receptor CD95/APO-1/Fas. Using primary T cells from SHIP-1-/- mice and T leukemic cell lines, we report here that SHIP-1 is a potent inhibitor of CD95-induced death. We observed that a small fraction of the SHIP-1 pool is localized to the endoplasmic reticulum where it promotes CD95 glycosylation. This post-translational modification requires an intact SH2 domain of SHIP-1, but is independent of its phosphatase activity. The glycosylated CD95 fails to oligomerize upon stimulation, resulting in impaired DISC formation and downstream apoptotic cascade. These results uncover an unanticipated inhibitory function for SHIP-1 and emphasize the role of glycosylation in the regulation of CD95 signaling in T cells. This work may also provide a new basis for therapeutic strategies using compounds inducing apoptosis through the CD95 pathway on SHIP-1 negative leukemic T cells. [less ▲]

Elongator controls the migration and differentiation of cortical neurons through acetylation of a tubulin

in Cell (2009), 136

The generation of cortical projection neurons relies on the coordination of radial migration with branching. Here we report that the multi-subunit histone acetyltransferase Elongator complex, which ... [more ▼]

The generation of cortical projection neurons relies on the coordination of radial migration with branching. Here we report that the multi-subunit histone acetyltransferase Elongator complex, which contributes to transcript elongation, also regulates the maturation of projection neurons. Indeed, silencing of its scaffold (Elp1) or catalytic subunit (Elp3) cell-autonomously delays the migration and impairs the branching of projection neurons. Strikingly, neurons defective in Elongator show reduced levels of acetylated alpha tubulin. A direct reduction of alpha tubulin acetylation leads to comparable defects in cortical neurons and suggests that alpha tubulin is a target of Elp3. This is further supported by the demonstration that Elp3 promotes acetylation and counteracts HDAC6-mediated deacetylation of this substrate in vitro. Our results uncover alpha tubulin as a target of the Elongator complex and suggest that a tight regulation of its acetylation underlies the maturation of cortical projection neurons. [less ▲]

KCTD5, a putative substrate adaptor for cullin3 ubiquitin ligases

in FEBS Journal (2008), 275(15), 3900-3910

Potassium channel tetramerization domain (KCTD) proteins contain a bric-a-brac, tramtrak and broad complex (BTB) domain that is most similar to the tetramerization domain (T1) of voltage-gated potassium ... [more ▼]

Potassium channel tetramerization domain (KCTD) proteins contain a bric-a-brac, tramtrak and broad complex (BTB) domain that is most similar to the tetramerization domain (T1) of voltage-gated potassium channels. Some BTB-domain-containing proteins have been shown recently to participate as substrate-specific adaptors in multimeric cullin E3 ligase reactions by recruiting proteins for ubiquitination and subsequent degradation by the proteasome. Twenty-two KCTD proteins have been found in the human genome, but their functions are largely unknown. In this study, we have characterized KCTD5, a new KCTD protein found in the cytosol of cultured cell lines. The expression of KCTD5 was upregulated post-transcriptionally in peripheral blood lymphocytes stimulated through the T-cell receptor. KCTD5 interacted specifically with cullin3, bound ubiquitinated proteins, and formed oligomers through its BTB domain. Analysis of the interaction with cullin3 showed that, in addition to the BTB domain, some amino acids in the N-terminus of KCTD5 are required for binding to cullin3. These findings suggest that KCTD5 is a substrate-specific adaptor for cullin3-based E3 ligases. [less ▲]

Cervix carcinoma is associated with an up-regulation and nuclear localization of the dual-specificity protein phosphatase VHR.

in BMC Cancer (2008), 8

BACKGROUND: The 21-kDa Vaccinia virus VH1-related (VHR) dual-specific protein phosphatase (encoded by the DUSP3 gene) plays a critical role in cell cycle progression and is itself regulated during the ... [more ▼]

BACKGROUND: The 21-kDa Vaccinia virus VH1-related (VHR) dual-specific protein phosphatase (encoded by the DUSP3 gene) plays a critical role in cell cycle progression and is itself regulated during the cell cycle. We have previously demonstrated using RNA interference that cells lacking VHR arrest in the G1 and G2 phases of the cell cycle and show signs of beginning of cell senescence. METHODS: In this report, we evaluated successfully the expression levels of VHR protein in 62 hysterectomy or conization specimens showing the various (pre) neoplastic cervical epithelial lesions and 35 additional cases of hysterectomy performed for non-cervical pathologies, from patients under 50 years of age. We used a tissue microarray and IHC technique to evaluate the expression of the VHR phosphatase. Immunofluorescence staining under confocal microscopy, Western blotting and RT-PCR methods were used to investigate the localization and expression levels of VHR. RESULTS: We report that VHR is upregulated in (pre) neoplastic lesions (squamous intraepithelial lesions; SILs) of the uterine cervix mainly in high grade SIL (H-SIL) compared to normal exocervix. In the invasive cancer, VHR is also highly expressed with nuclear localization in the majority of cells compared to normal tissue where VHR is always in the cytoplasm. We also report that this phosphatase is highly expressed in several cervix cancer cell lines such as HeLa, SiHa, CaSki, C33 and HT3 compared to primary keratinocytes. The immunofluorescence technique under confocal microscopy shows that VHR has a cytoplasmic localization in primary keratinocytes, while it localizes in both cytoplasm and nucleus of the cancer cell lines investigated. We report that the up-regulation of this phosphatase is mainly due to its post-translational stabilization in the cancer cell lines compared to primary keratinocytes rather than increases in the transcription of DUSP3 locus. CONCLUSION: These results together suggest that VHR can be considered as a new marker for cancer progression in cervix carcinoma and potential new target for anticancer therapy. [less ▲]

A role for the transcriptional complex elongator in cell migration and spreading

Poster (2007, March)

Downregulation of CD94/NKG2A inhibitory receptors on CD8+ T cells in HIV infection is more pronounced in subjects with detected viral load than in their aviraemic counterparts.

in Retrovirology (2007), 4

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small ... [more ▼]

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small fraction of activated CD8+ T lymphocytes. Abnormal upregulation of the CD94/NKG2A inhibitory NKR on cytotoxic T cells (CTLs) could be responsible for a failure of immunosurveillance in cancer or HIV infection. In this study, CD94/NKG2A receptor expression on CD8+ T lymphocytes and NK cells was assessed in 46 HIV-1-infected patients (24 viraemic, 22 aviraemic) and 10 healthy volunteers. The percentage of CD8+ T lymphocytes expressing the CD94/NKG2A inhibitory heterodimer was very significantly decreased in HIV-1-infected patients in comparison with non-infected controls. Within the HIV infected patients, the proportion of CD8+ T lymphocytes and NK cells expressing CD94/NKG2A was higher in subjects with undetectable viral loads in comparison with their viraemic counterparts. No significant difference was detected in the proportion of CD8+ T lymphocytes expressing the activatory CD94/NKG2C heterodimer between the HIV-1 infected patients and the healthy donors, nor between the vireamic and avireamic HIV-1 infected patients. In conclusion, chronic stimulation with HIV antigens in viraemic patients leads to a decreased rather than increased CD94/NKG2A expression on CD8+ T lymphocytes and NK cells. [less ▲]

Loss of the VHR dual-specific phosphatase causes cell-cycle arrest and senescence

in Nature Cell Biology (2006), 8(5), 524-178

Protein tyrosine phosphatases regulate important processes in eukaryotic cells and have critical functions in many human diseases including diabetes to cancer(1-3). Here, we report that the human Vaccinia ... [more ▼]

Protein tyrosine phosphatases regulate important processes in eukaryotic cells and have critical functions in many human diseases including diabetes to cancer(1-3). Here, we report that the human Vaccinia H1-related (VHR) dual-specific protein tyrosine phosphatase regulates cell-cycle progression and is itself modulated during the cell cycle. Using RNA interference (RNAi), we demonstrate that cells lacking VHR arrest at the G1-S and G2-M transitions of the cell cycle and show the initial signs of senescence, such as flattening, spreading, appearance of autophagosomes, beta-galactosidase staining and decreased telomerase activity. In agreement with this notion, cells lacking VHR were found to upregulate p21(Cip-Waf1), whereas they downregulated the expression of genes for cell-cycle regulators, DNA replication, transcription and mRNA processing. Loss of VHR also caused a several-fold increase in serum-induced activation of its substrates, the mitogen-activated protein ( MAP) kinases Jnk and Erk. VHR-induced cell-cycle arrest was dependent on this hyperactivation of Jnk and Erk, and was reversed by Jnk and Erk inhibition or knock-down. We conclude that VHR is required for cell-cycle progression as it modulates MAP kinase activation in a cell-cycle phase-dependent manner. [less ▲]