The Receptor for Advanced Glycation Endproducts [RAGE] is an evolutionarily recent member of the immunoglobulin super-family, encoded in the Class III region of the major histocompatability complex. RAGE is highly expressed only in the lung at readily measurable levels but increases quickly at sites of inflammation, largely on inflammatory and epithelial cells. It is found either as a membrane-bound or soluble protein that is markedly upregulated by stress in epithelial cells, thereby regulating their metabolism and enhancing their central barrier functionality. Activation and upregulation of RAGE by its ligands leads to enhanced survival. Perpetual signaling through RAGEinduced survival pathways in the setting of limited nutrients or oxygenation results in enhanced autophagy, diminished apoptosis, and (with ATP depletion) necrosis. This results in chronic inflammation and in many instances is the setting in which epithelial malignancies arise. RAGE and its isoforms sit in a pivotal role, regulating metabolism, inflammation, and epithelial survival in the setting of stress. Understanding the molecular structure and function of it and its ligands in the setting of inflammation is critically important in understanding the role of this receptor in tumor biology.
Cancer vaccination may be our best and most benign option for preventing or treating metastatic cancer. However, breakthroughs are hampered by immune suppression in the tumor microenvironment (TME). In this study, we analyzed whether cyclic di-guanylate (c-di-GMP), a ligand for stimulator of interferon genes (STING), could overcome immune suppression and improve vaccination against metastatic breast cancer. Mice with metastatic breast cancer (4T1 model) were therapeutically immunized with an attenuated Listeria monocytogenes (LM)-based vaccine, expressing tumor-associated antigen Mage-b (LM-Mb), followed by multiple low doses of c-di-GMP (0.01 nmol). This resulted in a striking and near elimination of all metastases. Experiments revealed that c-di-GMP targets myeloid-derived suppressor cells (MDSC) and tumor cells. Low doses of c-di-GMP significantly increased the production of IL-12 by MDSCs, in correlation with improved T-cell responses to Mage-b, while high dose of c-di-GMP (range 15–150 nmol) activated caspase-3 in the 4T1 tumor cells and killed the tumor cells directly. Based on these results we tested one administration of high dose c-di-GMP (150 nmol) followed by repeated administrations of low dose c-di-GMP (0.01 nmol) in the 4T1 model, and found equal efficacy compared to the combination of LM-Mb and c-di-GMP. This correlated with a mechanism of improved CD8 T-cell responses to tumor-associated antigens (TAA) Mage-b and Survivin, most likely through cross-presentation of these TAAs from c-di-GMP-killed 4T1 tumor cells, and through c-di-GMP-activated TAA-specific T cells. Our results demonstrate that activation of STING-dependent pathways by c-di-GMP is highly attractive for cancer immunotherapy.
Success of cancer vaccination is strongly hampered by immune suppression in the tumor microenvironment (TME). Interleukin (IL)-6 is particularly and highly produced by triple-negative breast cancer (TNBC) cells, and has been considered as an important contributor to immune suppression in the TME. Therefore, we hypothesized that IL-6 reduction may improve efficacy of vaccination against TNBC cancer through improved T-cell responses. To prove this hypothesis, we investigated the effect of curcumin, an inhibitor of IL-6 production, on vaccination of a highly attenuated Listeria monocytogenes (Listeriaat), encoding tumor-associated antigens (TAA) Mage-b in a TNBC model 4T1. Two therapeutic vaccination strategies with Listeriaat-Mage-b and curcumin were tested. The first immunization strategy involved all Listeriaat-Mage-b vaccinations and curcumin after tumor development. As curcumin has been consumed all over the world, the second immunization strategy involved curcumin before and all therapeutic vaccinations with Listeriaat-Mage-b after tumor development. Here, we demonstrate that curcumin significantly improves therapeutic efficacy of Listeriaat-Mage-b with both immunization strategies particularly against metastases in a TNBC model (4T1). The combination therapy was slightly but significantly more effective against the metastases when curcumin was administered before compared to after tumor development. With curcumin before tumor development in the combination therapy, the production of IL-6 was significantly decreased and IL-12 increased by myeloid-derived suppressor cells (MDSC), in correlation with improved CD4 and CD8 T-cell responses in blood. Our study suggests that curcumin improves the efficacy of Listeriaat-Mage-b vaccine against metastases in TNBC model 4T1 through reversal of tumor-induced immune suppression.This study is focused on improving cancer vaccination by reducing immune suppression. Here we demonstrate that curcumin improves vaccine efficacy of Listeria-Mage-b by converting myeloid-derived suppressor cells into an immune stimulating phenotype, that is, through reducing IL-6 and increasing IL-12 production, in correlation with improved T cell responses and a dramatic reduction in the number of metastases. The novel results of this study may be a platform for improvement of other cancer vaccines by curcumin.
Purpose: We evaluated the impact of varicocele grade on the response to varicocelectomy or spermatic vein embolization. Materials and Methods: We systematically reviewed the published English language literature to identify studies on changes in semen quality and pregnancy outcomes after varicocele treatment, stratified by varicocele grade. Descriptive statistics and continuous random effects models were used to study the impact of varicocele grade and the surgical approach on the response to treatment. Result heterogeneity among studies was analyzed using the I 2 statistic. Quality assessment of nonrandomized studies was done with the Newcastle-Ottawa Scale. Publication bias was analyzed using funnel plots and the Egger test. Results: We identified 20 studies describing the outcome of varicocele treatment stratified by varicocele grade in a total of 2,001 infertile men with varicocele. A microsurgical approach (inguinal, subinguinal and/or Palomo) was used in 11 of the 20 studies (55%). Varicocele treatment was associated with improvements in sperm concentration and overall motility in patients with all grades of varicocele. Semen quality improvements were directly related to varicocele grade. The mean sperm concentration improvement in men with grades 1, 2, 2-3 and 3 varicoceles were 5.5, 8.9, 12.7 and 16.0 million sperm per ml, respectively. The mean improvement in the percent of overall motility in men with grades 1, 2, 2-3 and 3 varicoceles was 9.6%, 10.6%, 10.8% and 17.7%, respectively. Pregnancy outcomes were assessed but could not be analyzed systematically due to the lack of adequate published data. Conclusions: Mean improvements in the sperm concentration and the percent of overall motility after treatment of grade 1 varicocele were statistically significant but small in magnitude. In contrast, mean improvements in the sperm concentration and the percent of overall motility after treatment of grade 2-3 varicoceles were greater and highly likely to be clinically significant. Incorporating varicocele grade into shared decision making discussions with affected couples may improve the ability to select patients who are the best candidates for treatment.
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