Project description:Natural killer (NK) cells contribute to immunosurveillance and first-line defense in the control of tumor growth and metastasis diffusion. NKEVs are constitutively secreted, are biologically active, reflect the protein and genetic repertoire of their originating cells and exert anti-tumor activity in vitro and in vivo. NKEVs from tumor-conditioned NK cells interact with naïve NK cells promoting their cytotoxic activity. In cancer NK cells exhibit profound defects in degranulation ability, a status probably reflected by their NKEVs. Hence, NKEVs could contribute to improve cancer therapy by interacting with tumor and/or immune cells at the same time sensing the actual NK cell status in cancer patients. Here we investigated the role of NKEVs in stimulating the immune system and developed an immune enzymatic test (NKExoELISA) to sense the systemic NK cell status by measuring plasma NK-derived exosomes through combined capture of exosomes, expressing typical EV (tsg101) and NK cell (CD56) markers. We analyzed by LC-MS/MS the protein content from NKEVs evaluating proteins differentially expressed in exosomes (NKExo), vescicles (NKMV) and total cell extract (Tot extr) from parental NK cells. Proteomic data confirmed the presence of many EV markers and detected several proteins involved in immune response, cell adhesion and complement biological processes.
Project description:In this study we have compared the proteomic profile of extracellular vesicles (EVs) prepared from primary, human NK cells or the human NK cell lines NK-92 and KHYG-1 cultured for 48hrs in serum-free conditions. EVs were harvested from cells either under resting conditions (culture in IL-15) or upon activation (combination of IL-12, IL-15, and IL-18). In addition, primary NK cells were activated in the presence of anti-CD16-coated beads, and EVs harvested after 48hrs. The aim was to compare their ability to target and kill a variety of tumor cell line-derived spheroids
Project description:Neuroblastomas are tumors of the developing peripheral sympathetic nervous system, which originates from the neural crest. Twenty percent of neuroblastomas show amplification of the MYCN oncogene, which correlates with poor prognosis. The MYCN transcription factor can activate and repress gene expression. To broaden our insight in the spectrum of genes down-regulated by MYCN, we generated gene expression profiles of the neuroblastoma cell lines SHEP-21N and SKNAS-NmycER, in which MYCN activity can be regulated. In this study, we show that MYCN suppresses the expression of Dickkopf-1 (DKK1) in both cell lines. DKK1 is a potent inhibitor of the wnt/beta-catenin signalling cascade, which is known to function in neural crest cell migration. We generated a DKK1 inducible cell line, IMR32-DKK1, which showed impaired proliferation upon DKK1 expression. Surprisingly, DKK1 expression did not inhibit the canonical wnt/beta-catenin signalling, suggesting a role of DKK1 in an alternative route of the wnt pathway. Gene expression profiling of two IMR32-DKK1 clones showed that only a few genes, amongst which SYNPO2, were up-regulated by DKK1. SYNPO2 encodes an actin-binding protein and was previously found to inhibit proliferation and invasiveness of prostate cancer cells. These results suggest that MYCN might stimulate cell proliferation by inhibiting the expression of DKK1. DKK1 might exert part of its growth suppressive effect by induction of SYNPO2 expression. Keywords: DKK1, MYCN, neuroblastoma, Dickkopf
Project description:GM-CSF is involved in immune complex (IC)-mediated arthritis. However, little is known about what is the cellular source of GM-CSF and how it is regulated during IC-mediated inflammation. Using novel GM-CSF reporter mice, we show that NK cells produce GM-CSF during an IC-mediated model of inflammatory arthritis. NK cells promoted STIA in a GM-CSF-dependent manner, as deletion of NK cells and selective removal of GM-CSF production by NK cells abrogated disease. Furthermore, we show that myeloid cell activation by GM-CSF is restrained by induction of JAK/STAT checkpoint inhibitor cytokine-inducible SH2-containing protein, CIS. Myeloid cells from CIS-deficient mice had exaggerated responses to GM-CSF, and these mice develop exacerbated STIA. Our data suggest that tissue NK cells may amplify joint inflammation in arthritis via GM-CSF production and thus represent a novel target in IC-mediated pathology. Endogenous CIS provides a key brake on signaling through the GM-CSF receptor and strategies that boost its function may provide an alternative anti-inflammatory approach.
Project description:Cancer associated fibroblasts (CAFs) are one of the most abundant components of the breast tumor microenvironment (TME) and major contributors to immune modulation in the TME. CAFs are well known to regulate the activity of diverse types of immune cells including T cells, macrophages and dendritic cells, however little is known about their interaction with Natural killer (NK) cells. NK cells constitute an important arm of anti-tumor immunity, yet the regulation of NK cell activity by CAFs in solid tumors is poorly understood. Here we find, using mouse models of cancer and ex-vivo cocultures, that immunosuppressive CAF subsets severely inhibit NK cell cytotoxicity towards cancer cells. We unravel the mechanism by which this suppression occurs, through CAF-mediated downregulation of the NK-surface receptors, Natural Killer Group 2D (NKG2D) and DNAX Accessory Molecule-1 (DNAM-1). Ligands for these receptors are known to be expressed by cancer cells and minimally expressed in healthy tissue. Here we find that CAFs also upregulate ligands for NKG2D and DNAM-1. Ligand-receptor engagement between NK cells and CAFs leads to CAF cytolysis, which in turn diminishes the expression of NKG2D and DNAM-1 on NK cells via a negative feedback loop, and promotes cancer escape from NK cell surveillance. These results reveal a CAF-mediated immunosuppressive mechanism with implications for treatment of solid tumors.
Project description:Infection with oncogenic human papillomavirus (HPV) is a major cause for the development of cervical cancer, which is mainly driven by the expression of the HPV E6 and E7 oncoproteins. We uncovered that the concentration levels of the putative tumor suppressor Dickkopf-1 (Dkk1) are restricted in cervical cancer cells by HPV E6 expression due to the E6-mediated proteolytic degradation of p53, which is a transcriptional regulator of Dkk1. Moreover, we found that Dkk1 is critically involved in the pro-apoptotic Cisplatin response of these cells, as Dkk1 repression was associated with an increased resistance towards the chemotherapeutic compound. This could be of high relevance for cervical cancer treatments, which usually involve Cisplatin for standard care. Although Dkk1 is a major antagonist of the canonical Wnt signaling, the differential response towards Cisplatin observed in Dkk1-depleted cells was not associated to an activation of this pathway. To elucidate alternative underlying mechanisms, we performed Affymetrix Gene Expression analyses comparing the transcriptome of Cisplatin-treated parental HeLa to CRISPR/Cas9-generated Dkk1 knockout (KO) HeLa cells. These revealed that Dkk1 depletion is linked to an impairment of the pro-apoptotic JNK/AP-1 pathway in cervical cancer cells, suggesting that Dkk1 drives Cisplatin-mediated apoptosis via activation of this signaling hub.
Project description:The co-infection of hepatitis B (HBV) patients with the hepatitis D virus (HDV) causes the most severe form of viral hepatitis and thus drastically worsens the course of the disease. Therapy options for HBV/HDV patients are still limited. Here, we investigated the potential of natural killer (NK) cells that are crucial drivers of the innate immune response against viruses to target HDV-infected hepatocytes. We established in vitro co-culture models using HDV-infected hepatoma cell lines and human peripheral blood NK cells. We determined NK cell activation by flow cytometry, transcriptome analysis, bead-based cytokine immunoassays, and NK cell-mediated effects on T cells by flow cytometry. We validated the mechanisms using CRISPR/Cas9-mediated gene deletions. Moreover, we assessed the frequencies and phenotype of NK cells in peripheral blood of HBV and HDV superinfected patients. Upon co-culture with HDV-infected hepatic cell lines, NK cells upregulated activation markers, interferon-stimulated genes (ISGs) including the death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), produced interferon (IFN)-gamma and eliminated HDV-infected cells via the TRAIL-TRAIL-R2 axis. We identified IFN-beta released by HDV-infected cells as an important enhancer of NK cell activity. In line with our in vitro data, we observed activation of peripheral blood NK cells from HBV/HDV co-infected, but not HBV mono-infected patients. Our data demonstrate NK cell activation in HDV infection and their potential to eliminate HDV-infected hepatoma cells via the TRAIL/TRAIL-R2 axis which implies a high relevance of NK cells for the design of novel anti-viral therapies.
Project description:Dickkopf 1 (DKK1) could promote tumor progression by suppressing immunity. Therefore, we investigated whether DKK1 influence prognosis and sensitivity to PD-1 blockade in colorectal cancers (CRCs) with defective DNA mismatch repair genes (dMMR) or microsatellite instability (MSI). We found that elevated DKK1 expression was associated with recurrence and dismissed CD8+ T cell infiltrations, and patients with high serum DKK1 had poor anti-PD-1 response. RNA interference or neutralization of DKK1 in CRCs enhanced CD8+ T cell cytotoxicity, and down-regulation of T-bet and E2F1 following GSK3β activation was detected in DKK1-treated CD8+ T cells. In organoid-lymphocyte co-culture model, apoptosis proportions were elevated after individual neutralization of both PD-1 and DKK1, and the combined neutralization resulted in further increases. In conclusion, DKK1 suppresses tumor immunity in dMMR/MSI CRCs by inactivating CD8+ T cells through GSK3β/E2F1/T-bet axis. DKK1 neutralization may improve the sensitivity to PD-1 blockade in dMMR/MSI CRCs.