CD4CD8αα Lymphocytes, A Novel Human Regulatory T Cell Subset Induced by Colonic Bacteria and Deficient in Patients with Inflammatory Bowel Disease

It has become evident that bacteria in our gut affect health and disease, but less is known about how they do this. Recent studies in mice showed that gut Clostridium bacteria and their metabolites can activate regulatory T cells (Treg) that in turn mediate tolerance to signals that would ordinarily cause inflammation. In this study we identify a subset of human T lymphocytes, designated CD4CD8αα T cells that are present in the surface lining of the colon and in the blood. We demonstrate Treg activity and show these cells to be activated by microbiota; we identify F. prausnitzii, a core Clostridium strain of the human gut microbiota, as a major inducer of these Treg cells. Interestingly, there are fewer F. prausnitzii in individuals suffering from inflammatory bowel disease (IBD), and accordingly the CD4CD8αα T cells are decreased in the blood and gut of patients with IBD. We argue that CD4CD8αα colonic Treg probably help control or prevent IBD. These data open the road to new diagnostic and therapeutic strategies for the management of IBD and provide new tools to address the impact of the intestinal microbiota on the human immune system

Enhancement of metastatic ability by ectopic expression of ST6GalNAcI on a gastric cancer cell line in a mouse model

ST6GalNAcI is a sialyltransferase responsible for the synthesis of sialyl Tn (sTn) antigen which is expressed in a variety of adenocarcinomas including gastric cancer especially in advanced cases, but the roles of ST6GalNAcI and sTn in cancer progression are largely unknown. We generated sTn-expressing human gastric cancer cells by ectopic expression of ST6GalNAcI to evaluate metastatic ability of these cells and prognostic effect of ST6GalNAcI and sTn in a mouse model, and identified sTn carrier proteins to gain insight into the function of ST6GalNAcI and sTn in gastric cancer progression. A green fluorescent protein-tagged human gastric cancer cell line was transfected with ST6GalNAcI to produce sTn-expressing cells, which were transplanted into nude mice. STn-positive gastric cancer cells showed higher intraperitoneal metastatic ability in comparison with sTn-negative control, resulting in shortened survival time of the mice, which was mitigated by anti-sTn antibody administration. Then, sTn-carrying proteins were immunoprecipitated from culture supernatants and lysates of these cells, and identified MUC1 and CD44 as major sTn carriers. It was confirmed that MUC1 carries sTn also in human advanced gastric cancer tissues. Identification of sTn carrier proteins will help understand mechanisms of metastatic phenotype acquisition of gastric cancer cells by ST6GalNAcI and sTn

A novel transcriptional activator originating from an upstream promoter in human growth hormone gene

Transcription of the human growth hormone gene can start in vitro and in vivo 197 base pairs upstream from the cap site of growth hormone mRNA (Courtois, S. J., Lafontaine, D., and Rousseau, G. G. (1992) J. Biol. Chem. 267, 19736-19743). We have now characterized the mRNA that originates from this optional promoter and have found that it occurs in human hypophysis and placenta but not in 10 other tissues. This mRNA contains an open reading frame for a protein of 107 residues that shares sequence similarity with three domains of hepatic nuclear factor-1alpha. With antibodies directed against a peptide corresponding to the C terminus of this protein, immunoreactive material was detected in a subset of cells of the adenohypophysis. When fused to the DNA-binding domain of the yeast transcription factor GAL4, the protein stimulated transcription from a GAL4-sensitive reporter gene in transiently transfected pituitary and placental cells

PBMC are as good a source of tumor-reactive T lymphocytes as TIL after selection by Melan-A/A2 multimer immunomagnetic sorting.: Immunomagnetic sort of Melan-A specific T cells from TIL and PBMC

International audienceChoosing a reliable source of tumor-specific T lymphocytes and an efficient method to isolate these cells still remains a critical issue in adoptive cellular therapy (ACT). In this study, we assessed the capacity of MHC/peptide based immunomagnetic sorting followed by polyclonal T cell expansion to derive pure polyclonal and tumor-reactive Melan-A specific T cell populations from melanoma patient's PBMC and TIL. We first demonstrated that this approach was extremely efficient and reproducible. We then used this procedure to compare PBMC and TIL-derived cells from three melanoma patients in terms of avidity for Melan-A A27L analog, Melan-A(26-35)and Melan-A(27-35), tumor reactivity (lysis and cytokine production) and repertoire. Regardless of their origin, i.e., fresh PBMC, peptide stimulated PBMC or TIL, all sorted populations (from the three patients) were cytotoxic against HLA-A2+ melanoma cell lines expressing Melan-A. Although some variability in peptide avidity, lytic activity and cytokine production was observed between populations of different origins in a given patient, it differed from one patient to another and thus no correlation could be drawn between T cell source and reactivity. Analysis of Vbeta usage within the sorted populations showed the recurrence of Vbeta3 and Vbeta14 subfamilies in the three patients but differences in the rest of the Melan-A repertoire. In addition, in two patients, we observed major repertoire differences between populations sorted from the three sources. We especially documented that in vitro peptide stimulation of PBMC, used to facilitate the sort by enriching in specific T lymphocytes, could significantly alter their repertoire and reactivity towards tumor cells. We conclude that PBMC which are easily obtained from all melanoma patients, can be as good a source as TIL to derive high amounts of tumor-reactive Melan-A specific T cells, with this selection/amplification procedure. However, the conditions of peptide stimulation should be improved to prevent a possible loss of reactive clonotypes