IL-12 controls cytotoxicity of a novel subset of self-antigen-specific human CD28+ cytolytic T cells.

Activated CD8 T cells develop cytotoxicity against autologous cells bearing foreign Ags and self/tumor Ags. However, self-specific cytolysis needs to be kept under control to avoid overwhelming immunopathology. After peptide vaccination of melanoma patients, we studied molecular and functional properties of T cell subsets specific for the self/tumor Ag Melan-A/MART-1. Ex vivo analysis revealed three Ag-specific effector memory (EM) populations, as follows: CD28-negative EM (EM28(-)) T cells strongly expressing granzyme/perforin, and two EM28(+) subsets, one with high and the other with low level expression of these cytotoxic proteins. For further functional characterization, we generated 117 stable CD8 T cell clones by ex vivo flow cytometry-based sorting of these subsets. All EM28(-)-derived clones lysed target cells with high efficacy. In contrast, EM28(+)-derived clones were heterogenous, and could be classified in two groups, one with high and the other with low killing capacity, correlating with granzyme/perforin expression. High and low killer phenotypes remained surprisingly stable for several months. However, strongly increased granzyme expression and cytotoxicity were observed after exposure to IL-12. Thus, the data reveal a newly identified subset of CD28(+) conditional killer T cells. Because CD28 can mediate strong costimulatory signals, tight cytotoxicity control, as shown in this study through IL-12, may be particularly important for subsets of T cells expressing CD28.

Increased neuroendocrine cells in resected metastases compared to primary colorectal adenocarcinomas.

Neuroendocrine differentiation has been described in rectal adenocarcinomas receiving neoadjuvant therapy prior to radical surgery, but its clinical relevance is controversial and no data are currently available in colorectal carcinoma metastases as compared to primary tumors. The presence of chromogranin A positive tumor cells was investigated by means of immunohistochemistry on surgical specimens from 54 primary colorectal carcinomas and their corresponding metastases, resected at diagnosis or during tumor progression. In 47 patients, tumor metastases were resected 1 month to 12 years after chemotherapy and/or radiotherapy, while in the remaining seven patients no additional therapy after primary surgery was performed. In primary tumors, neuroendocrine differentiation was found in 12/54 cases (22.2%) as compared to 25/54 metastatic lesions (46.3%; p?=?0.01). The presence of neuroendocrine phenotype was not correlated with any clinical pathological parameter nor with a different proliferation index. However, patients having neuroendocrine cells in the primary tumor had a significantly shorter survival from the time of metastatic spread than those having not (33.3 vs. 55.5 months; p?=?0.04). In summary, our data show that colorectal carcinoma metastases contain a higher percentage of neuroendocrine differentiated cells as compared to their corresponding primaries, a finding possibly related to the influence of chemotherapy in neuroendocrine differentiation during colorectal carcinoma progression.

Interaction of Leukocyte Elastase Inhibitor/L-DNase II with BCL-2 and BAX

Leukocyte Elastase Inhibitor (LEI, also called serpin B1) is a protein involved in apoptosis among other physiological processes. We have previously shown that upon cleavage by its cognate protease, LEI is transformed into L-DNase II, a protein with a pro-apoptotic activity. The caspase independent apoptotic pathway, in which L-DNase II is the final effector, interacts with other pro-apoptotic molecules like Poly-ADP-Ribose polymerase (PARP) or Apoptosis Inducing Factor (AIF). The screening of LEI/L-DNase II interactions showed a possible interaction with several members of the BCL-2 family of proteins which are known to have a central role in the regulation of caspase dependent cell death. In this study, we investigated the regulation of LEI/L-DNase II pathway by two members of this family of proteins: BAX and BCL-2, which have opposite effects on cell survival. We show that, in both BHK and HeLa cells, LEI/L-DNase II can interact with BCL-2 and BAX in apoptotic and non-apoptotic conditions. These proteins which are usually thought to be anti-apoptotic and pro-apoptotic respectively, both inhibit the L-DNase II pro-apoptotic activity. These results give further insight in the regulation of caspase-independent pathways and highlight the involvement of the intracellular environment of a given protein in the determinism of its function. They also add a link between caspase-dependent and independent pathways of apoptosis.

Combined simulation and mutagenesis analyses reveal the involvement of key residues for peroxisome proliferator-activated receptor alpha helix 12 dynamic behavior.

The dynamic properties of helix 12 in the ligand binding domain of nuclear receptors are a major determinant of AF-2 domain activity. We investigated the molecular and structural basis of helix 12 mobility, as well as the involvement of individual residues with regard to peroxisome proliferator-activated receptor alpha (PPARalpha) constitutive and ligand-dependent transcriptional activity. Functional assays of the activity of PPARalpha helix 12 mutants were combined with free energy molecular dynamics simulations. The agreement between the results from these approaches allows us to make robust claims concerning the mechanisms that govern helix 12 functions. Our data support a model in which PPARalpha helix 12 transiently adopts a relatively stable active conformation even in the absence of a ligand. This conformation provides the interface for the recruitment of a coactivator and results in constitutive activity. The receptor agonists stabilize this conformation and increase PPARalpha transcription activation potential. Finally, we disclose important functions of residues in PPARalpha AF-2, which determine the positioning of helix 12 in the active conformation in the absence of a ligand. Substitution of these residues suppresses PPARalpha constitutive activity, without changing PPARalpha ligand-dependent activation potential.

A study of personality in children aged 8-12 years: Comparing self- and partents' ratings

This study was designed to investigate personality development with children aged 8 to 12. For this purpose, Children's self-perceptions were compared to parent's ratings. 506 children and their parents completed a selection of 38 questions from the Hierarchical Personality Inventory for Children (HiPIC). Results showed an age-related increase in the structural congruence of children's ratings compared to parents' ratings and a highly significant increase in the reliabilities of both parents' and children's assessments. The mean correlation between the children's self-descriptions and parents' ratings were higher for Conscientiousness and Imagination than for Extraversion, Benevolence and Emotional Stability and significantly increased with the children's age. Mean-levels decreased with age for Imagination in parents' ratings and for Benevolence, Conscientiousness, and Imagination, in children's ratings. This study showed that personality development from 8 to 12 years goes along with an increase in the agreement between the children's self-perceptions and the parents' perceptions of the children's personality.