Tumor Rejection Induced by CD70-mediated Quantitative and Qualitative Effects on Effector CD8+ T Cell Formation

In vivo priming of antigen-specific CD8(+) T cells results in their expansion and differentiation into effector T cells followed by contraction into a memory T cell population that can be maintained for life. Recent evidence suggests that after initial antigenic stimulation, the magnitude and kinetics of the CD8(+) T cell response are programmed. However, it is unclear to what extent CD8(+) T cell instruction in vivo is modulated by costimulatory signals. Here, we demonstrate that constitutive ligation of the tumor necrosis factor receptor family member CD27 by its ligand CD70 quantitatively augments CD8(+) T cell responses to influenza virus infection and EL-4 tumor challenge in vivo by incrementing initial expansion and maintaining higher numbers of antigen-specific T cells in the memory phase. Concomitantly, the quality of antigen-specific T cells improved as evidenced by increased interferon (IFN)-γ production and a greater cytotoxic potential on a per cell basis. As an apparent consequence, the superior effector T cell formation induced by CD70 protected against a lethal dose of poorly immunogenic EL4 tumor cells in a CD8(+) T cell– and IFN-γ–dependent manner. Thus, CD70 costimulation enhances both the expansion and per cell activity of antigen-specific CD8(+) T cells

CD27-CD70 interactions sensitise naive CD4+ T cells for IL-12-induced Th1 cell development

Stimulation of CD27, a member of the tumour necrosis factor receptor family, by its ligand CD70 induces expansion of IFNgamma secreting CD4+ and CD8+ T cells in vivo. We here analysed the mechanisms through which CD27 mediates this effect. CD27 co-stimulation induced cell division but did not directly instruct naive CD4+ T cells to differentiate into IFNgamma-producing Th1 cells. Rather, in concert with signals delivered through the TCR-CD3 complex, CD27 co-stimulation enhanced the Th1-specific transcription factor T-bet and caused up-regulation of the IL-12Rbeta2 chain. Consequently, CD27-costimulated T cells yielded vast numbers of IFNgamma-secreting cells in response to IL-12. Additionally, CD27 ligation induced a strong up-regulation of Bcl-xL, but not of related anti-apoptotic molecules. Thus, CD27-CD70 interactions may promote Th1 formation by permitting naive T cells to respond to differentiation signals and by promoting survival of activated effector T cell

Introduction of Specific 3D Micromorphologies in Collagen Scaffolds Using Odd and Even Dicarboxylic Acids

The construction of scaffolds and subsequent incorporation of cells and biologics have been widely investigated to regenerate damaged tissues. Scaffolds act as a template to guide tissue formation, and their characteristics have a considerable impact on the regenerative process. Whereas many technologies exist to induce specific two-dimensional (2D) morphologies into biomaterials, the introduction of three-dimensional (3D) micromorphologies into individual pore walls of scaffolds produced from biological molecules such as collagen poses a challenge. We here report the use of dicarboxylic acids to induce specific micromorphologies in collagen scaffolds and evaluate their effect on cellular migration and differentiation. Insoluble type I collagen fibrils were suspended in monocarboxylic and dicarboxylic acids of different concentrations, and unidirectional and random pore scaffolds were constructed by freezing and lyophilization. The application of various acids and concentrations resulted in variations in 3D micromorphologies, including wall structure, wall thickness, and pore size. The use of dicarboxylic acids resulted in acid-specific micromorphologies, whereas monocarboxylic acids did not. Dicarboxylic acids with an odd or even number of C-atoms resulted in frayed/fibrillar or smooth wall structures, respectively, with varying appearances. The formation of micromorphologies was concentration-dependent. In vitro analysis indicated the cytocompatibility of scaffolds, and micromorphology-related cell behavior was indicated by enhanced myosin staining and myosin heavy chain gene expression for C2C12 myoblasts cultured on scaffolds with frayedlike micromorphologies compared to those with smooth micromorphologies. In conclusion, porous collagen scaffolds with various intrawall 3D micromorphologies can be constructed by application of dicarboxylic acids, superimposing the second level of morphology to the overall scaffold structure. Acid crystal formation is key to the specific micromorphologies observed and can be explained by the odd/even theory for dicarboxylic acids. Scaffolds with a 3D micrometer-defined topography may be used as a screening platform to select optimal substrates for the regeneration of specific tissues

Introduction of Specific 3D Micromorphologies in Collagen Scaffolds Using Odd and Even Dicarboxylic Acids

The construction of scaffolds and subsequent incorporation of cells and biologics have been widely investigated to regenerate damaged tissues. Scaffolds act as a template to guide tissue formation, and their characteristics have a considerable impact on the regenerative process. Whereas many technologies exist to induce specific two-dimensional (2D) morphologies into biomaterials, the introduction of three-dimensional (3D) micromorphologies into individual pore walls of scaffolds produced from biological molecules such as collagen poses a challenge. We here report the use of dicarboxylic acids to induce specific micromorphologies in collagen scaffolds and evaluate their effect on cellular migration and differentiation. Insoluble type I collagen fibrils were suspended in monocarboxylic and dicarboxylic acids of different concentrations, and unidirectional and random pore scaffolds were constructed by freezing and lyophilization. The application of various acids and concentrations resulted in variations in 3D micromorphologies, including wall structure, wall thickness, and pore size. The use of dicarboxylic acids resulted in acid-specific micromorphologies, whereas monocarboxylic acids did not. Dicarboxylic acids with an odd or even number of C-atoms resulted in frayed/fibrillar or smooth wall structures, respectively, with varying appearances. The formation of micromorphologies was concentration-dependent. In vitro analysis indicated the cytocompatibility of scaffolds, and micromorphology-related cell behavior was indicated by enhanced myosin staining and myosin heavy chain gene expression for C2C12 myoblasts cultured on scaffolds with frayedlike micromorphologies compared to those with smooth micromorphologies. In conclusion, porous collagen scaffolds with various intrawall 3D micromorphologies can be constructed by application of dicarboxylic acids, superimposing the second level of morphology to the overall scaffold structure. Acid crystal formation is key to the specific micromorphologies observed and can be explained by the odd/even theory for dicarboxylic acids. Scaffolds with a 3D micrometer-defined topography may be used as a screening platform to select optimal substrates for the regeneration of specific tissues

Introduction of Specific 3D Micromorphologies in Collagen Scaffolds Using Odd and Even Dicarboxylic Acids

Contains fulltext : 217569.pdf (publisher's version ) (Open Access

CD40 stimulation of B-cell chronic lymphocytic leukaemia cells enhances the anti-apoptotic profile, but also Bid expression and cells remain susceptible to autologous cytotoxic T-lymphocyte attack

To enhance the poor antigen-presenting capacity of B-cell chronic lymphocytic leukaemia (B-CLL), CD40 triggering has been considered as an active immunotherapy. However, CD40 stimulation also has an anti-apoptotic effect and may further impair the dysregulated response of B-CLL to apoptotic stimuli. Therefore, we measured the expression of virtually all regulators of apoptosis before and after CD40 stimulation. These findings were correlated with sensitivity for chemotherapy- and death-receptor-induced apoptosis and T-cell-mediated killing. CD40 stimulation enhanced the constitutive anti-apoptotic profile of B-CLL cells by upregulation of Bcl-xL and Bfl-1 and downregulation of the BH3-only protein Harakiri. Unexpectedly, the BH3-only protein Bid was strongly induced. Functionally, CD40-stimulated B-CLL cells became resistant to drug-induced apoptosis and, despite upregulation of CD95 and Bid, were not sensitive to CD95L. In contrast, autologous T cell killing, triggered by loading CLL cells with viral (CMV) peptides, was very efficient both before and after CD40 stimulation. Upon CTL interaction, CLL targets underwent mitochondrial depolarization and caspase-3 activation. Thus, despite an increased anti-apoptotic profile, CD40 triggered B-CLL cells remain excellent targets for resident cytotoxic T cells. These data support therapeutic exploitation of CD40 stimulation in B-CLL, provided that a strong CTL component is induce

A salt-based method to adapt stiffness and biodegradability of porous collagen scaffolds

Contains fulltext : 213621.pdf (publisher's version ) (Open Access

Immune activation modulates hematopoiesis through interactions between CD27 and CD70

The differentiation of hematopoietic stem cells into mature blood cell lineages is tightly regulated. Here we report that CD27, which is expressed on stem and early progenitor cells in bone marrow, can be important in this process. Deletion of CD27 increased the myeloid colony - forming potential of stem and early progenitor cells and enhanced B lymphoid reconstitutive capacity in competitive transplantation experiments. Conversely, stimulation of CD27(+) progenitor cells with CD70, the unique ligand for CD27, inhibited colony-forming potential in vitro and lymphocyte outgrowth in vivo. As CD70 is expressed only on activated immune cells, we suggest that CD27 triggering on early progenitor cells provides a negative feedback signal to leukocyte differentiation during immune activation