Granulocytes mediates the Fas-L-associated apoptosis during lung metastasis of melanoma that determines the metastatic behaviour

The survival of tumour cells in a new tissue environment is crucial for tumour metastasis. Factors contributing to the death of tumour cells during metastasis are not completely understood. In murine melanoma model, activation of Fas (CD95, APO-1) signal in tumour cells reduces their lung metastasis potential, which may be associated with an induction of apoptosis in tumours. To elucidate the cellular mechanism, we used a Fas-ligand (Fas-L) specific ribozyme (Fas-Lribozyme) to suppress the expression of Fas-L but not Fas or TNF-α in B16F10 melanoma cells. The Fas-Lribozyme-carrying cells grew slightly faster in vitro with better viability than controls. Suppression of Fas-L in B16F10 melanoma cells by Fas-Lribozyme enhanced lung metastasis of the cells in C57BL/6 mice, and that was correlated with reductions in both apoptotic tumour cells and granulocytic infiltration. Mice depleted of granulocytes, but not CD4+ and CD8+ cells, showed a greatly elevated susceptibility to lung metastasis. Moreover, apoptosis in tumour cells was significantly reduced in granulocyte-depleted mice during the course of tumour formation. Taken together, our findings indicate that Fas-L-associated apoptosis in tumour cells determines the metastasis behaviour of melanoma in the lung and this apoptosis is primarily mediated by the cytotoxicity of recruited granulocytes

Eradication of Disseminated Lymphomas with CpG-DNA Activated T Helper Type Cells from Nontransgenic Mice.

Various evidence suggests that adoptive transfer of polyclonal, tumor-specific, IFN-γ-producing CD4+ T cells [T helper type 1 (Th1) cells] should be highly efficient for tumor immune therapy. However, this approach could not be tested because very few MHC class II-restricted tumor peptides have been defined. Here we show that stimulation of freshly isolated T helper cells with syngeneic tumor cells and antigen-presenting cells in the presence of immunostimulatory CpG DNA allows the generation of large numbers of strongly polarized, tumor-specific Th1 cells within 3 weeks of culture, even when T helper cells were derived from tumor-bearing mice. A single injection of 0.5 × 106 A20-specific Th1 cells even eradicated disseminated A20 lymphomas and provided lifelong protection without inducing autoimmune disease. The therapy was largely independent of CD8+ cells but required IFN-γ and CD40-CD40L interactions, suggesting that tumor-specific Th1 cells eradicate established tumors by activating proinflammatory macrophages

Glucose kinase-dependent catabolite repression in Staphylococcus xylosus.

By transposon Tn917 mutagenesis, 16 mutants of Staphylococcus xylosus were isolated that showed higher levels of beta-galactosidase activity in the presence of glucose than the wild-type strain. The transposons were found to reside in three adjacent locations in the genome of S. xylosus. The nucleotide sequence of the chromosomal fragment affected by the Tn917 insertions yielded an open reading frame encoding a protein with a size of 328 amino acids with a high level of similarity to glucose kinase from Streptomyces coelicolor. Weaker similarity was also found to bacterial fructokinases and xylose repressors of gram-positive bacteria. The gene was designated glkA. Immediately downstream of glkA, two open reading frames were present whose deduced gene products showed no obvious similarity to known proteins. Measurements of catabolic enzyme activities in the mutant strains grown in the presence or absence of sugars established the pleiotropic nature of the mutations. Besides beta-galactosidase activity, which had been used to detect the mutants, six other tested enzymes were partially relieved from repression by glucose. Reduction of fructose-mediated catabolite repression was observed for some of the enzyme activities. Glucose transport and ATP-dependent phosphorylation of HPr, the phosphocarrier of the phosphoenolpyruvate:carbohydrate phosphotransferase system involved in catabolite repression in gram-positive bacteria, were not affected. The cloned glkA gene fully restored catabolite repression in the mutant strains in trans. Loss of GlkA function is thus responsible for the partial relief from catabolite repression. Glucose kinase activity in the mutants reached about 75% of the wild-type level, indicating the presence of another enzyme in S. xylosus. However, the cloned gene complemented an Escherichia coli strain in glucose kinase. Therefore, the glkA gene encodes a glucose kinase that participates in catabolite repression in S. xylosus

Natural killer cells activated by MHC class ILow targets prime dentritic cells to induce protective CD8 T cells responses.

AbstractConserved molecular patterns derived from pathogenic microorganisms prime antigen-presenting dendritic cells (DC) to induce adaptive T cell responses. In contrast, virus-infected or tumor cells that express low levels of major histocompatibility complex (MHC) class I activate natural killer (NK) cells for direct killing. It is unknown whether NK cell recognition of MHC class Ilow targets can also induce adaptive T cell responses. Here, we show that MHC class Ilow targets initiate a cascade of immune responses, starting with the immediate activation of NK cells. The activated NK cells then prime DC to produce IL-12 and to induce highly protective CD8 T cell memory responses. Therefore, sensing of MHC class Ilow targets by NK cells can link innate and adaptive immunity to induce protective T cell responses and may alarm the immune system during early infection with noncytopathic viruses

IL-4 instructs TH1 responses and resistance to Leishmania major in susceptible BALB/c mice.

Immunity to infection with intracellular pathogens is regulated by interleukin 12 (IL-12), which mediates protective T helper type 1 (TH1) responses, or IL-4, which induces TH2 cells and susceptibility. Paradoxically, we show here that when present during the initial activation of dendritic cells (DCs) by infectious agents, IL-4 instructed DCs to produce IL-12 and promote TH1 development. This TH1 response established resistance to Leishmania major in susceptible BALB/c mice. When present later, during the period of T cell priming, IL-4 induced TH2 differentiation and progressive leishmaniasis in resistant mice. Because immune responses developed via the consecutive activation of DCs and then T cells, the contrasting effects of IL-4 on DC development and T cell differentiation led to immune responses that had opposing functional phenotypes