Escape from suppression: tumor-specific effector cells outcompete regulatory T cells following stem-cell transplantation

Immune reconstitution of autologous hematopoietic stem-cell transplant recipients with the progeny of mature T cells in the graft leads to profound changes in the emerging functional T-cell repertoire. In the steady state, the host is frequently tolerant to tumor antigens, reflecting dominant suppression of naive and effector T cells by regulatory T cells (T(regs)). We examined the relative frequency and function of these 3 components within the tumor-specific T-cell compartment during immune reconstitution. Grafts from tumor-bearing donors exerted a significant antitumor effect in irradiated, syngeneic tumor-bearing recipients. This was associated with dramatic clonal expansion and interferon-gamma (IFNgamma) production by previously tolerant tumor-specific T cells. While donor-derived T(regs) expanded in recipients, they did not inhibit the antigen-driven expansion of effector T cells in the early posttransplantation period. Indeed, the repopulation of tumor-specific effector T cells significantly exceeded that of T(regs), the expansion of which was limited by IL-2 availability. Although the intrinsic suppressive capacity of T(regs) remained intact, their diminished frequency was insufficient to suppress effector cell function. These findings provide an explanation for the reversal of tolerance leading to tumor rejection in transplant recipients and likely contribute to the efficacy of adoptive T-cell therapies in lymphopenic hosts.     

ATM gene mutations in former uranium miners of SDAG Wismut: a pilot study

Ataxia-telangiectasia is an autosomal recessive disease characterized by neurological and immunological symptoms, radiosensitivity and cancer predisposition. Heterozygous carriers of an ataxia-telangiectasia gene mutation are predisposed to epithelial cancers. We initiated a study to elucidate the frequency and clinical relevance of ATM gene mutations in former uranium miners exposed to high levels of radiation from radon and its decay products. Former uranium miners with Schneeberg lung cancer (n=48), former uranium miners suffering from silicosis (n=60) and uranium miners without occupational lung disorders (n=102) were investigated for nine mutations in the ATM gene. One gastric and one prostate cancer occurred in the group of miners without occupational lung diseases. Mutation analyses for S707P, IVS10-6Tright curved arrow G, 2250Gright curved arrow A, E1978X, R2443X, 3801delG, S49C and D2625E-A2626P were performed using genomic DNA obtained from peripheral blood samples. Three ATM gene alterations (S707P, S49C or IVS10-6Tright curved arrow G) were observed. Of all cancer patients, 8.0% were heterozygous, but only 1.9% of the non-cancer controls were [OR=4.6; 95% confidence interval (CI), 0.8-26.8]. In this pilot study a major role of six ATM gene mutations could not be revealed for cancer predisposition in former uranium miners. The results leave the possibility of a moderate risk associated with more subtle ATM gene alterations.     

The Stoichiometric Production of IL-2 and IFN-γ mRNA Defines Memory T Cells That Can Self-Renew After Adoptive Transfer in Humans

Adoptive immunotherapy using ex vivo-expanded tumor-reactive lymphocytes can mediate durable cancer regression in selected melanoma patients. Analyses of these trials have associated the in vivo engraftment ability of the transferred cells with their antitumor efficacy. Thus, there is intensive clinical interest in the prospective isolation of tumor-specific T cells that can reliably persist after transfer. Animal studies have suggested that central memory CD8(+) T cells (T(CM)) have divergent capabilities including effector differentiation to target antigen and stem cell-like self-renewal that enable long-term survival after adoptive transfer. We sought to isolate human melanoma-specific T(CM) to define their in vivo fate and function after autologous therapeutic transfer to metastatic patients. To facilitate the high-throughput identification of these rare cells from patients, we report that T(CM) have a defined stoichiometric production of interleukin-2 (IL-2) and interferon-γ (IFN-γ) mRNA after antigen stimulation. Melanoma-specific T cells screened for high relative IL-2 production had a T(CM) phenotype and superior in vitro proliferative capacity compared to cells with low IL-2 production. To investigate in vivo effector function and self-renewal capability, we allowed melanoma-specific T(CM) to undergo in vitro expansion and differentiation into lytic effector clones and then adoptively transferred them back into their hosts. These clones targeted skin melanocytes in all five patients and persisted long term and reacquired parental T(CM) attributes in four patients after transfer. These findings demonstrate the favorable engraftment fitness for human T(CM)-derived clones, but further efforts to improve their antitumor efficacy are still necessary.     

Detecting Biochemical Changes in the Rodent Cervix During Pregnancy Using Raman Spectroscopy

The goal of this research is to determine whether Raman spectroscopy (RS), an optical method that probes the vibrational modes of tissue components, can be used in vivo to study changes in the mouse cervix during pregnancy. If successful, such a tool could be used to detect cervical changes due to pregnancy, both normal and abnormal, in animal models and humans. For this study, Raman spectra were acquired before, during and after a 19-day mouse gestational period. In some cases, after Raman data was obtained, cervices were excised for structural testing and histological staining for collagen and smooth muscle. Various peaks of the Raman spectra, such as the areas corresponding to fatty acid content and collagen organization, changed as the cervix became softer in preparation for labor and delivery. These findings correspond to the increase in compliance of the tissue and the collagen disorganization visualized with the histological staining. The results of this study suggest that non-invasive RS can be used to study cervical changes during pregnancy, labor and delivery and can possibly predict preterm delivery before overt clinical manifestations, potentially lead to more effective preventive and therapeutic interventions.     

Indian hedgehog, but not histidine decarboxylase or amphiregulin, is a progesterone-regulated uterine gene in hamsters

Implantation occurs only in the progesterone (P4)-primed uterus in the majority of species, but little effort has been given to identify P4-mediated molecules in these species. Using hamsters as a model for P4-dependent implantation and three well-known uterine receptivity-associated P4-regulated genes, Indian hedgehog (Ihh), histidine decarboxylase (Hdc), and amphiregulin (Areg), in mice that require ovarian estrogen for uterine receptivity and implantation, our strategy aimed to determine whether P4 regulates uterine expression of these genes in hamsters and whether the event- and cell-specific uterine expression patterns of these genes during the periimplantation period in hamsters follow similarly with their patterns in mice. We report here that P4-mediated Ihh signaling is important for uterine receptivity and implantation in hamsters because uterine epithelial Ihh expression was regulated by P4 and its expression patterns during the periimplantation period of hamsters closely follow its pattern in mice. In contrast, we noted no hormonal regulation of Hdc and Areg in the hamster uterus. However, this did not diminish their importance in hamsters because their expression patterns and functions are event and cell specific during the periimplantation period: whereas Hdc was expressed exclusively in d 4 uterine glands and regulated by the blastocyst, Areg was expressed on the decidual area adjacent to the embryo from d 5 onward and involved in stromal cell proliferation. We conclude that similarities and dissimilarities exist in uterine expression pattern of implantation-related genes, including hormonal regulation and their event-specific importance.     

Implantation and decidualization defects in prolactin receptor (PRLR)-deficient mice are mediated by ovarian but not uterine PRLR

PRL and its homologs accomplish their biological effects through the PRL receptor (PRLR). We evaluated the expression and function of PRLR in the embryo and uterus during the periimplantation period because PRLR deficiency results in implantation failure. In wild-type mice, PRLR expression was localized to undecidualized stromal cells in the antimesometrial border on days 6-8 of pregnancy. A small population of PRLR-expressing cells was observed adjacent to the ectoplacental cone in the mesometrial stroma. Low levels of PRLR expression were also detected in the developing embryo on days 6-8. To determine the significance of PRLR expression in this distribution, we examined implantation and decidualization in PRLR-/- mice. Progesterone (P4) administration rescued infertility in PRLR-/- mice from the periimplantation period to midgestation. Artificially induced decidualization was absent in pseudopregnant PRLR-/- mice but was identical to wild-type in P4-treated PRLR-/- mice. Furthermore, wild-type and P4-treated PRLR-/- mice had similar expression of the implantation-specific genes, LIF, amphiregulin, HB-EGF, COX-1, COX-2, PPARdelta, Hoxa-10, cyclin-D3, VEGF, and its receptors, Flk-1 and neuropilin-1. Together, these results show that luteal P4 production via ovarian PRLR signaling is required for implantation and early pregnancy. The function of uterine PRLR remains unclear. However, the eventual loss of pregnancy in P4-treated PRLR-/- mice suggests that uterine PRLR may be essential for the support of late gestation.