The therapeutic effects of gingival mesenchymal stem cells and their exosomes in a chimeric model of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis is a chronic systemic autoimmune disease that involves transformation of the lining of synovial joints into an invasive and destructive tissue. Synovial fibroblasts become transformed, invading and destroying the bone and cartilage of the affected joint(s). Due to the significant role these cells play in the progression of the disease process, developing a therapeutic strategy to target and inhibit their invasive destructive nature could help patients who are afflicted with this debilitating disease. Gingival-derived mesenchymal stem cells are known to possess immunomodulatory properties and have been studied extensively as potential cell-based therapeutics for several autoimmune disorders.

METHODS

A chimeric human/mouse model of synovitis was created by surgically implanting SCID mice with a piece of human articular cartilage surrounded by RASF. Mice were injected once with either GMSC or GMSCExo at 5-7 days post-implantation. Histology and IHC were used to assess RASF invasion of the cartilage. Flow cytometry was used to understand the homing ability of GMSC in vivo and the incidence of apoptosis of RASF in vitro.

RESULTS

We demonstrate that both GMSC and GMSCExo are potent inhibitors of the deleterious effects of RASF. Both treatments were effective in inhibiting the invasive destructive properties of RASF as well as the potential for these cells to migrate to secondary locations and attack the cartilage. GMSC home to the site of the implant and induce programmed cell death of the RASF.

CONCLUSIONS

Our results indicate that both GMSC and GMSCExo can block the pathological effects of RASF in this chimeric model of RA. A single dose of either GMSC or GMSCExo can inhibit the deleterious effects of RASF. These treatments can also block the invasive migration of the RASF, suggesting that they can inhibit the spread of RA to other joints. Because the gingival tissue is harvested with little difficulty, relatively small amounts of tissue are required to expand the cells, the simple in vitro expansion process, and the increasing technological advances in the production of therapeutic exosomes, we believe that GMSCExo are excellent candidates as a potential therapeutic for RA.

Therapeutic Effects of Gingival Mesenchymal Stem Cells and Their Exosomes in a Chimeric Model of Rheumatoid Arthritis

Background

Rheumatoid arthritis is a chronic systemic autoimmune disease that involves transformation of the lining of synovial joints into an invasive and destructive tissue. Synovial fibroblasts become transformed, invading and destroying bone and cartilage of the affected joint(s). Due to the significant role these cells play in the progression of the disease process, developing a therapeutic strategy to target and inhibit their invasive destructive nature could help patients who are affiicted with this debilitating disease. Gingival-derived mesenchymal stem cells are known to possess immunomodulatory properties and have been studied extensively as potential cell-based therapeutics for several autoimmune disorders.

Methods

A chimeric human/mouse model of synovitis was created by surgically implanting SCID mice with a piece of human articular cartilage surrounded by RASF. Mice were injected once with either GMSC or GMSCExo at 5-7 days post-implantation. Histology and IHC were used to assess RASF invasion of the cartilage. Flow cytometry was used to understand the homing ability of GMSC in vivo and the incidence of apoptosis of RASF in vitro.

Results

We demonstrate that both GMSC and GMSCExo are potent inhibitors of the deleterious effects of RASF. Both treatments were effective in inhibiting the invasive destructive properties of RASF as well as the potential of these cells to migrate to secondary locations and attack the cartilage. GMSC home to the site of the implant and induce programmed cell death of the RASF.

Conclusions

Our results indicate that both GMSC and GMSCExo can block the pathological effects of RASF in this chimeric model of RA. A single dose of either GMSC or GMSCExo can inhibit the deleterious effects of RASF. These treatments can also block the invasive migration of the RASF, suggesting that they can inhibit the spread of RA to other joints. Because the gingival tissue is harvested with little difficulty, relatively small amounts of tissue are required to expand the cells, the simple in vitro expansion process, and the increasing technological advances in the production of therapeutic exosomes, we believe that GMSCExo are excellent candidates as a potential therapeutic for RA.

Managing Spatial Selections With Contextual Snapshots

Spatial selections are a ubiquitous concept in visualization. By localizing particular features, they can be analysed and compared in different views. However, the semantics of such selections often depend on specific parameter settings and it can be difficult to reconstruct them without additional information. In this paper, we present the concept of contextual snapshots as an effective means for managing spatial selections in visualized data. The selections are automatically associated with the context in which they have been created. Contextual snapshots can also be used as the basis for interactive integrated and linked views, which enable in-place investigation and comparison of multiple visual representations of data. Our approach is implemented as a flexible toolkit with well-defined interfaces for integration into existing systems. We demonstrate the power and generality of our techniques by applying them to several distinct scenarios such as the visualization of simulation data, the analysis of historical documents and the display of anatomical data.

Flow-based combinatorial antibody profiling: an integrated approach to cell characterization

BD FACS™ CAP (CAP = combinatorial antibody profile) is a screening tool for rapid characterization of human cell surface protein expression profiles using semi-automated high-throughput flow cytometry. The current configuration consists of 229 directly conjugated antibodies arrayed in a 96-well plate as three-color cocktails, which enables the characterization of each of the 229 individual surface markers. Each individual cell type of interest is analyzed on the 96-well screening plates and the data are acquired on a flow cytometer equipped with a high-throughput sampler. The expression level of each marker for each cell type is then calculated using semiautomated custom flow cytometry software. The process of characterizing these surface markers in a highly efficient manner using BD FACS™ CAP is enabled by automated liquid handling for staining, automated flow cytometry for data acquisition, and standardized algorithms for automated data analysis.

Fast firing of tiles containing paper mill sludge, glass cullet and clay

The paper describes results obtained in the development of a previous research. We study here, in fast firing, the sintering behaviour and measure some properties of tiles containing a mixture of 60 wt% of paper mill sludge and 40 wt% of glass cullet. The behaviour of this material is compared to those displayed by materials obtained by the same mixture added with 10, 20 and 30 wt% of a natural red clay. In parallel, the same properties are measured also on a reference blend, which is presently used to produce commercial tiles. We show that powders containing 60 wt% of paper sludge and 40 wt% of glass cullet to which 30 wt% of clay is added give rise to materials that display a stable sintering process and have good hardness and strength and therefore could be used for the industrial production of tiles.

Distinct functions for the transcription factor Foxo1 at various stages of B cell differentiation

The Foxo transcription factors (Foxo1, Foxo3, Foxo4) modulate cell fate decisions in diverse systems. Here we show that Foxo1-dependent gene expression was critical at multiple stages of B cell differentiation. Early deletion of Foxo1 caused a severe block at the pro-B cell stage, due to a failure to express interleukin 7 receptor α (IL-7Rα). Foxo1 inactivation in late pro-B cells resulted in an arrest at the pre-B cell stage due to a reduction in Rag1 and Rag2 expression. Deletion of Foxo1 in peripheral B cells led to fewer lymph node B cells due to reduced L-selectin expression, and failed class switch recombination due to impaired Aicda upregulation. Thus, Foxo1 regulates a transcriptional program that is essential for early B cell development and peripheral B cell function.

Production and characterization of sintered ceramics from paper mill sludge and glass cullet

Three different types of paper mill sludge were first incinerated and then attrition milled separately or mixed with glass cullet in varying proportions to obtain powders of different compositions. These powders were then dried, sieved, uniaxially pressed into samples and air sintered. Fired samples were characterized by density, water absorption, shrinkage on firing, strength, hardness and fracture toughness measurements; SEM and X-ray diffractions were also carried out to investigate microstructure and phase composition. Some sintered samples displayed fairly good physical and mechanical properties as a consequence of their low residual porosity and fine microstructure.

Lipid raft targeting of hematopoietic protein tyrosine phosphatase by protein kinase C theta-mediated phosphorylation

Protein kinase C theta (PKC theta) is unique among PKC isozymes in its translocation to the center of the immune synapse in T cells and its unique downstream signaling. Here we show that the hematopoietic protein tyrosine phosphatase (HePTP) also accumulates in the immune synapse in a PKC theta-dependent manner upon antigen recognition by T cells and is phosphorylated by PKC theta at Ser-225, which is required for lipid raft translocation. Immune synapse translocation was completely absent in antigen-specific T cells from PKC theta-/- mice. In intact T cells, HePTP-S225A enhanced T-cell receptor (TCR)-induced NFAT/AP-1 transactivation, while the acidic substitution mutant was as efficient as wild-type HePTP. We conclude that HePTP is phosphorylated in the immune synapse by PKC theta and thereby targeted to lipid rafts to temper TCR signaling. This represents a novel mechanism for the active immune synapse recruitment and activation of a phosphatase in TCR signaling.

Multi-walled carbon nanotubes induce T lymphocyte apoptosis

Carbon nanotubes are a man-made form of carbon that did not exist in our environment until very recently. Due to their unique chemical, physical, optical, and magnetic properties, carbon nanotubes have found many uses in industrial products and in the field of nanotechnology, including in nanomedicine. However, very little is yet known about the toxicity of carbon nanotubes. Here, we compare the toxicity of pristine and oxidized multi-walled carbon nanotubes on human T cells and find that the latter are more toxic and induce massive loss of cell viability through programmed cell death at doses of 400 microg/ml, which corresponds to approximately 10 million carbon nanotubes per cell. Pristine, hydrophobic, carbon nanotubes were less toxic and a 10-fold lower concentration of either carbon nanotube type were not nearly as toxic. Our results suggest that carbon nanotubes indeed can be very toxic at sufficiently high concentrations and that careful toxicity studies need to be undertaken particularly in conjunction with nanomedical applications of carbon nanotubes.

Yersinia Phosphatase Induces Mitochondrially Dependent Apoptosis of T Cells

To evade the immune system, the etiologic agent of plague, Yersinia pestis, injects an exceptionally active tyrosine phosphatase called YopH into host cells using a type III secretion system. We recently reported that YopH acutely inhibits T cell antigen receptor signaling by dephosphorylating the Lck tyrosine kinase. Here, we show that prolonged presence of YopH in primary T cells or Jurkat T leukemia cells causes apoptosis, detected by annexin V binding, mitochondrial breakdown, caspase activation, and internucleosomal fragmentation. YopH also causes cell death when expressed in HeLa cells, and this cell death was inhibited by YopH-specific small molecule inhibitors. Cell death induced by YopH was also prevented by caspase inhibition or co-expression of Bcl-xL. We conclude that YopH not only paralyzes T cells acutely, but also ensures that the cells will not recover to induce a protective immune response but instead undergo mitochondrially regulated programmed cell death.

Inhibition of Yersinia tyrosine phosphatase by furanyl salicylate compounds

To avoid detection and targeting by the immune system, the plague-causing bacterium Yersinia pestis uses a type III secretion system to deliver a set of inhibitory proteins into the cytoplasm of immune cells. One of these proteins is an exceptionally active tyrosine phosphatase termed YopH, which paralyzes lymphocytes and macrophages by dephosphorylating critical tyrosine kinases and signal transduction molecules. Because Y. pestis strains lacking YopH are avirulent, we set out to develop small molecule inhibitors for YopH. We used a novel and cost-effective approach, in which leads from a chemical library screening were analyzed and computationally docked into the crystal structure of YopH. This resulted in the identification of a series of novel YopH inhibitors with nanomolar Ki values, as well as the structural basis for inhibition. Our inhibitors lack the polar phosphate-mimicking moiety of rationally designed tyrosine phosphatase inhibitors, and they readily entered live cells and rescued them from YopH-induced tyrosine dephosphorylation, signaling paralysis, and cell death. These inhibitors may become useful for treating the lethal infection by Y. pestis.

Control of vesicle fusion by a tyrosine phosphatase

The tyrosine phosphatase PTP-MEG2 is targeted by its amino-terminal Sec14p homology domain to the membrane of secretory vesicles. There it regulates vesicle size by promoting homotypic vesicle fusion by a mechanism that requires its catalytic activity. Here, we identify N-ethylmaleimide-sensitive factor (NSF), a key regulator of vesicle fusion, as a substrate for PTP-MEG2. PTP-MEG2 reduced the phosphotyrosine content of NSF and co-localized with NSF and syntaxin 6 in intact cells. Furthermore, endogenous PTP-MEG2 co-immunoprecipitated with endogenous NSF. Phosphorylation of NSF at Tyr 83, as well as an acidic substitution at the same site, increased its ATPase activity and prevented alphaSNAP binding. Conversely, expression of a Y83F mutant of NSF caused spontaneous fusion events. Our results suggest that the molecular mechanism by which PTP-MEG2 promotes secretory vesicle fusion involves the local release of NSF from a tyrosine-phosphorylated, inactive state. This represents a novel mechanism for localized regulation of NSF and the first demonstrated role for a protein tyrosine phosphatase in the regulated secretory pathway.

Protein tyrosine phosphatases in T cell physiology

The molecular mechanisms of signal transduction have been the focus of intense research during the last decade. In T cells, much of the work has centered on protein tyrosine kinase-mediated signaling from the TCR and cytokine receptors, while the study of protein tyrosine phosphatases has lagged behind. Nevertheless, it has now become clear that many protein tyrosine phosphatases play equally important roles in T cell physiology and that no kinase-regulated system would work without the counterbalancing participation of phosphatases. In fact, we have learned that many processes are regulated primarily on the phosphatase side. This minireview summarizes the current state-of-the art in our understanding of the regulation and biology of protein tyrosine phosphatases in T lymphocyte physiology.

Lck dephosphorylation at Tyr-394 and inhibition of T cell antigen receptor signaling by Yersinia phosphatase YopH

A key virulence factor for Yersinia pestis, the etiologic agent of plague, is the tyrosine phosphatase YopH, which the bacterium injects into host cells. We report that treatment of human T lymphocytes with a recombinant membrane-permeable YopH resulted in severe reduction in intracellular tyrosine phosphorylation and inhibition of T cell activation. The primary signal transducer for the T cell antigen receptor, the Lck tyrosine kinase, was specifically precipitated by a substrate-trapping YopH mutant, and Lck was dephosphorylated at its positive regulatory site, Tyr-394, in cells containing active YopH. By turning off Lck, YopH blocks T cell antigen receptor signaling at its very first step, effectively preventing the development of a protective immune response against this lethal bacterium.

The fungal biocontrol agent Coniothyrium minitans: production by solid-state fermentation, application and marketing

Biological control agents (BCAs) are potential alternatives for the chemical fungicides presently used in agriculture to fight plant diseases. Coniothyrium minitans is an example of a promising fungal BCA. It is a naturally occurring parasite of the fungus Sclerotinia sclerotiorum, a wide-spread pathogen which substantially reduces the yield of many crops. This review describes, exemplified by C. minitans, the studies that need to be carried out before a fungal BCA is successfully introduced into the market. The main aspects considered are the biology of C. minitans, the development of a product by mass production of spores using solid-state fermentation technology, its biocontrol activity and marketing of the final product.