Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is expressed by in vitro activated natural killer (NK) cells, but the relevance of this observation to the biological function of NK ...cells has been unclear. Herein, we have demonstrated the in vivo induction of mouse TRAIL expression on various tissue NK cells and correlated NK cell activation with TRAIL-mediated antimetastatic function in vivo. Expression of TRAIL was only constitutive on a subset of liver NK cells, and innate NK cell control of Renca carcinoma hepatic metastases in the liver was partially TRAIL dependent. Administration of therapeutic doses of interleukin (IL)-12, a powerful inducer of interferon (IFN)-gamma production by NK cells and NKT cells, upregulated TRAIL expression on liver, spleen, and lung NK cells, and IL-12 suppressed metastases in both liver and lung in a TRAIL-dependent fashion. By contrast, alpha-galactosylceramide (alpha-GalCer), a powerful inducer of NKT cell IFN-gamma and IL-4 secretion, suppressed both liver and lung metastases but only stimulated NK cell TRAIL-mediated function in the liver. TRAIL expression was not detected on NK cells from IFN-gamma-deficient mice and TRAIL-mediated antimetastatic effects of IL-12 and alpha-GalCer were strictly IFN-gamma dependent. These results indicated that TRAIL induction on NK cells plays a critical role in IFN-gamma-mediated antimetastatic effects of IL-12 and alpha-GalCer.
Abstract Background Several previous studies have reported both an association between selective serotonin reuptake inhibitors (SSRI) and decreased bone mineral density and increased fractures, but ...no previous studies have specifically evaluated bone health in young adults who have a history of SSRI use. Objective The purpose was to characterize the effect SSRI use in early adulthood on bone mineral density. Methods A cross-sectional study was conducted on subjects who voluntarily responded to recruitment methods for the study. Young adults aged 18 to 25 years who were currently or had previously taken an SSRI for a minimum of 3 consecutive months were included in the study. A subject interview was conducted on each patient to collect background information. Each subject’s calcaneal bone mineral density was then measured with an ultrasonometer. Results Complete data were collected on 51 subjects. The median duration of SSRI use was 24 ± 54 months. A significant negative correlation was observed between SSRI duration and calcaneal ultrasound T-score ( r = –0.53, P < 0.001) which was unchanged in depressed subjects. Subjects on continuous SSRIs for >24 months had a significantly lower median T-score (0.30 ± 0.93) than subjects taking SSRIs for ≤24 months (0.90 ± 0.81; P = 0.0010). Conclusions In this young relatively healthy population who were following most of the recommendations to improve bone health, a significant negative correlation was observed between the duration of SSRI use and bone mineral density. Subjects who were on SSRIs for longer than 24 months had a significantly lower T-score. Further large scale longitudinal studies are needed in this younger population to determine the effects of chronic SSRI use on bone health.
Systemic administration of IL-12 and intermittent doses of IL-2 induce complete regression of metastatic murine renal carcinoma. Here, we show that overt tumor regression induced by IL-12/pulse IL-2 ...is preceded by recruitment of CD8(+) T cells, vascular injury, disrupted tumor neovascularization, and apoptosis of both endothelial and tumor cells. The IL-12/IL-2 combination synergistically enhances cell surface FasL expression on CD8(+) T lymphocytes in vitro and induces Fas and FasL expression within tumors via an IFN-gamma-dependent mechanism in vivo. This therapy also inhibits tumor neovascularization and induces tumor regression by mechanisms that depend critically on endogenous IFN-gamma production and an intact Fas/FasL pathway. The ability of IL-12/pulse IL-2 to induce rapid destruction of tumor-associated endothelial cells and regression of established metastatic tumors is ablated in mice with a dysregulated Fas/FasL pathway. The common, critical role for endogenous IFN-gamma and the Fas/FasL pathway in early antiangiogenic effects and in antitumor responses suggests that early, cytokine-driven innate immune mechanisms and CD8(+) T cell-mediated responses are interdependent. Definition of critical early molecular events engaged by IL-12/IL-2 may provide new perspective into optimal therapeutic engagement of a productive host-antitumor immune response.
IL-13 and IL-4 have similar biological activities and are characteristic of cytokines expressed by Th2 cells. In contrast, IL-12 and IL-18 have been shown to be strong cofactors for Th1 cell ...development. In this study, we found strong induction of IL-13 mRNA and protein by IL-2 + IL-18 in NK and T cells. In contrast, IL-12 did not enhance the IL-13 production induced by IL-2 alone. Moreover, IL-13 mRNA and protein expression induced by IL-2 + IL-18 in purified NK and T cells obtained from IFN-gamma knockout (-/-) mice were greater than seen in purified cells from normal controls. In contrast, IL-10 production induced by IL-2 and/or IL-12 was not significantly different in IFN-gamma (-/-) mice and normal controls. These results suggest IL-13 expression induced by IL-2 + IL-18 may be regulated by IFN-gamma in vivo, while IL-10 expression may be IFN-gamma-independent. Thus, depending upon the cell type, IL-18 may act as a strong coinducer of Th1 or Th2 cytokines. Our findings suggest that IL-12 and IL-18 have different roles in the regulation of gene expression in NK and T cells.
Graft-versus-host disease (GVHD), in which immunocompetent donor cells attack the host, remains a major cause of morbidity after allogeneic bone marrow transplantation (BMT). To understand the role ...of cytokines in the pathobiology of GVHD, we used cytokine knockout (KO) mice as a source of donor T cells. Two different MHC-disparate strain combinations were examined: BALB/c (H2(d)) donors into lethally irradiated C57BL/6 (H2(b)) recipients or C57BL/6 (H2(b)) donors into B10.BR (H2(k)) recipients. Donor cells were from mice in which either the interferon-gamma (IFN-gamma) or the IL-4 gene was selectively disrupted to understand the role of these cytokines in acute GVHD. In both strain combinations the same pattern was noted with regard to GVHD onset and morbidity. All mice exhibited the classic signs of acute GVHD: weight loss with skin, gut, and liver pathology resulting in morbidity and mortality. Surprisingly, donor cells obtained from mice lacking IFN-gamma gave rise to accelerated morbidity from GVHD when compared with cells from wild-type control donors. Similar results were obtained using normal donors when neutralizing antibodies to IFN-gamma were administered immediately after the BMT. These results suggest that IFN-gamma plays a role in protection from acute GVHD. In marked contrast, cells obtained from IL-4 KO mice resulted in protection from GVHD compared with control donors. Splenocytes from IFN KO mice stimulated with a mitogen proliferated to a significantly greater extent and produced more IL-2 compared with splenocytes obtained from IL-4 KO or control mice. Additionally, there was increased IL-2 production in the spleens of mice undergoing GVHD using IFN-gamma KO donors. These results therefore indicate, with regard to the TH1/ TH2 cytokine paradigm, the absence of a TH1-type cytokine can be deleterious in acute GVHD, whereas absence of a TH2 cytokine can be protective.
NKT and NK cells are important immune regulatory cells. The only efficient means to selectively stimulate NKT cells in vivo is alpha-galactosylceramide (alphaGalCer). However, alphaGalCer effectively ...stimulates and then diminishes the number of detectable NKT cells. It also exhibits a potent, indirect ability to activate NK cells. We have now discovered another ceramide compound, beta-galactosylceramide (betaGalCer) (C12), that efficiently diminishes the number of detectable mouse NKT cells in vivo without inducing significant cytokine expression or activation of NK cells. Binding studies using CD1d tetramers loaded with betaGalCer (C12) demonstrated significant but lower intensity binding to NKT cells when compared with alphaGalCer, but both ceramides were equally efficient in reducing the number of NKT cells. However, betaGalCer (C12), in contrast to alphaGalCer, failed to increase NK cell size, number, and cytolytic activity. Also in contrast to alphaGalCer, betaGalCer (C12) is a poor inducer of IFN-gamma, TNF-alpha, GM-CSF, and IL-4 gene expression. These qualitative differences in NKT perturbation/NK activation have important implications for delineating the unique in vivo roles of NKT vs NK cells. Thus, alphaGalCer (which triggers NKT cells and activates NK cells) efficiently increases the resistance to allogeneic bone marrow transplantation while betaGalCer (C12) (which triggers NKT cells but does not activate NK cells) fails to enhance bone marrow graft rejection. Our results show betaGalCer (C12) can effectively discriminate between NKT- and NK-mediated responses in vivo. These results indicate the use of different TCR-binding ceramides can provide a unique approach for understanding the intricate immunoregulatory contributions of these two cell types.
Background: Interleukin 2 (IL-2) and interleukin 12 (IL-12) are potent immunoregulatory cytokines that exhibit antitumor activity. Preliminary evidence suggests that combined administration of IL-2 ...and IL-12 may yield greater antitumor activity than that observed with either agent alone. Purpose: We evaluated the ability of combination regimens of IL-2 and IL-12 to induce regression of established primary and metastatic murine renal carcinoma (Renca) tumors. Methods: BALB/c mice were given either subcutaneous or intrarenal injections of 105 Renca cells; tumor cell injections were given to 10–12 mice for each treatment group. Mice bearing subcutaneous primary tumors were treated with chronic IL-2 (300 000 IU given on a daily basis) or pulse IL-2 (300 000 IU given twice daily one day per week) alone, IL-12 alone (0.5 μg given on a daily basis), or IL-12 in combination with either chronic or pulse IL-2. Mice with metastatic tumors (arising from intrarenal implants; animals were nephrectomized to remove the primary tumors) were treated with IL-12 plus or minus pulse IL-2; in these experiments, IL-12 was given at doses of either 0.5 or 1.0 μg. In most experiments, treatment was continued for at least 3 weeks. Two-sided statistical tests were used to evaluate the data. Results: Most mice with subcutaneous Renca tumors treated with the combination of IL-12 and chronic IL-2 died of treatment-related toxic effects within 7–14 days. In contrast, treatment with IL-12 plus pulse IL-2 was well tolerated, and six of 10 mice experienced complete tumor regression; none of the mice treated with either IL-12 alone or pulse IL-2 alone experienced a curative response. Seven of eight and nine of nine mice with metastatic tumors experienced complete tumor regression after treatment with 0.5 μg IL-12 plus pulse IL-2 or 1.0 μg IL-12 plus pulse IL-2, respectively; two of 12 mice treated with pulse IL-2 alone and 10% or less of mice treated with IL-12 alone were cured of metastatic tumors (with 0.5 μg IL-12, none of 10 mice; with 1.0 μg IL-12, one of 10 mice). Five of 10 mice with metastatic tumors treated with a short-course regimen of IL-12 and pulse IL-2 (two pulses of IL-2 flanking 5 days of 0.5 μg IL-12) experienced complete tumor regression, while only one of the 12 mice treated with IL-2 alone and none of the mice treated with IL-12 alone experienced complete tumor regression. Virtually all curative response frequencies obtained with IL-12 and pulse IL-2 combination regimens differed significantly (P<.05) from those obtained with corresponding single-agent treatments. Conclusions: IL-12 administered in combination with pulse IL-2 induced rapid and complete regression of primary and metastatic Renca tumors and displayed greater antitumor activity than that observed with either IL-12 or IL-2 alone. J Natl Cancer Inst 1996; 88:38–43
A model of immune evasion mediated by tumors expressing constitutively activated Stat3 was recently proposed in
Nature Medicine by Wang et al., suggesting opportunities for a new therapeutic approach ...for cancer.
Kidney cancer is a devastating disease; however, biological therapies have achieved some limited success. The murine renal cancer Renca has been used as a model for developing new preclinical ...approaches to the treatment of renal cell carcinoma. Successful cytokine-based approaches require CD8(+) T cells, but the exact mechanisms by which T cells mediate therapeutic benefit have not been completely identified. After successful biological therapy of Renca in BALB/c mice, we generated CTLs in vitro using mixed lymphocyte tumor cultures. These CTL mediated tumor-specific H-2K(d)-restricted lysis and production of IFN-gamma, TNF-alpha, and Fas ligand (FasL) in response to Renca. CTL used both granule- and FasL-mediated mechanisms to lyse Renca, although granule-mediated killing was the predominant lytic mechanism in vitro. The cytokines IFN-gamma and TNF-alpha increased the sensitivity of Renca cells to CTL lysis by both granule- and FasL-mediated death pathways. Adoptive transfer of these anti-Renca CTL into tumor-bearing mice cured most mice of established experimental pulmonary metastases, and successfully treated mice were immune to tumor rechallenge. Interestingly, we were able to establish Renca-specific CTL from mice gene targeted for perforin (pfp(-/-)) mice. Although these pfp(-/-) CTL showed reduced cytotoxic activity against Renca, their IFN-gamma production in the presence of Renca targets was equivalent to that of wild-type CTL, and adoptive transfer of pfp(-/-) CTL was as efficient as wild-type CTL in causing regression of established Renca pulmonary metastases. Therefore, although granule-mediated killing is of paramount importance for CTL-mediated lysis in vitro, some major in vivo effector mechanisms clearly are independent of perforin.
IL‐18 is considered to be a strong cofactor for CD4+ T helper 1 (Th1) cell induction. We have recently reported that IL‐18 can induce IL‐13 production in both NK cells and T cells in synergy with ...IL‐2 but not IL‐12, suggesting IL‐18 can induce Th1 and Th2 cytokines when accompanied by the appropriate first signals for T cells. We have now found that IL‐18 can act as a cofactor to induce IL‐4, IL‐10 and IL‐13 as well as IFN‐γ production in T cells in the presence of anti‐CD3 monoclonal antibodies (mAb). IL‐18 can rapidly induce CD40 ligand (CD154) mRNA and surface expression on CD4+ but not CD8+ T cells. The administration of IL‐18 alone in vivo significantly increased serum IgE levels in C57BL/6 (B6) and B6 IL‐4 knockout mice. Furthermore, the administration of IL‐18 plus IL‐2 induced approximately 70‐fold and 10‐fold higher serum levels of IgE and IgG1 than seen in control B6 mice, respectively. IgE and IgG1 induction in B6 mice by administration of IL‐18 plus IL‐2 was eliminated by the pretreatment of mice with anti‐CD4 or anti‐CD154, but not anti‐CD8 or anti‐NK1.1 mAb. These results suggest that IL‐18 can induce Th2 cytokines and CD154 expression, and can contribute to CD4+ T cell‐dependent, IL‐4‐independent IgE production.
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