Cell-mediated Activity Research Articles

The metabolic basis of resistance to Adoptive T Cell Therapy (ACT) in patients with solid tumors

Abstract Adoptive T cell therapy (ACT) has produced impressive responses in a subset of patients with advanced malignancies. However, majority of patients still failed to respond. Thus, there is an urgent need to understand the resistant mechanisms in non-responders and develop more effective ACT strategies. Here, we employed two independent and unbiased approaches to identify novel molecular determinants of immune resistance. We generated gene expression profiles on an immune resistant melanoma cell line to identify alternative immunosuppressive mechanisms. In addition, we utilized a new high-throughput shRNA screening platform developed by our group to functionally interrogate immune resistance in patient-derived melanoma cells. Results from both analyses implicated tumor-associated glycolysis as a critical pathway that enables tumor cells to evade T cell-mediated antitumor activity. By using samples from melanoma and non-small cell lung cancer patients, we showed that increased expression of glycolysis-related genes is associated with poor T cell infiltration of tumors. Moreover, we found that increasing tumor glycolysis impaired T cell killing of melanoma cells, while inhibiting glycolysis restored T cell-mediated apoptosis of tumor cells. More importantly, from two non-overlapping ACT-treated patient cohorts, we discovered that tumor glycolytic activity in patients who experienced disease progression following ACT was significantly higher compared to those patients who were responsive to therapy. Taken together, our results demonstrate that tumor glycolytic metabolism is associated with the efficacy of ACT and identify glycolysis as a candidate target for combinatorial therapeutic intervention.

Tradeoffs between immune function and childhood growth among Amazonian forager-horticulturalists

Immune function is an energetically costly physiological activity that potentially diverts calories away from less immediately essential life tasks. Among developing organisms, the allocation of energy toward immune function may lead to tradeoffs with physical growth, particularly in high-pathogen, low-resource environments. The present study tests this hypothesis across diverse timeframes, branches of immunity, and conditions of energy availability among humans. Using a prospective mixed-longitudinal design, we collected anthropometric and blood immune biomarker data from 261 Amazonian forager-horticulturalist Shuar children (age 4-11 y old). This strategy provided baseline measures of participant stature, s.c. body fat, and humoral and cell-mediated immune activity as well as subsample longitudinal measures of linear growth (1 wk, 3 mo, 20 mo) and acute inflammation. Multilevel analyses demonstrate consistent negative effects of immune function on growth, with children experiencing up to 49% growth reduction during periods of mildly elevated immune activity. The direct energetic nature of these relationships is indicated by (i) the manifestation of biomarker-specific negative immune effects only when examining growth over timeframes capturing active competition for energetic resources, (ii) the exaggerated impact of particularly costly inflammation on growth, and (iii) the ability of children with greater levels of body fat (i.e., energy reserves) to completely avoid the growth-inhibiting effects of acute inflammation. These findings provide evidence for immunologically and temporally diverse body fat-dependent tradeoffs between immune function and growth during childhood. We discuss the implications of this work for understanding human developmental energetics and the biological mechanisms regulating variation in human ontogeny, life history, and health.

Abstract P3-05-04: An IL-15 superagonist enhances antibody-dependent cell-mediated cytotoxicity against breast cancer cells regardless of FCGR3A (CD16) genotype and rescues NK cell from TGF-β1-induced immunosuppression

Abstract It has been reported that the Natural killer (NK) cell with FCGR3A (CD16a) V genotype is associated with enhanced clinical response to IgG1 monoclonal Ab (mAb) therapy such as trastuzumab, rituximab and cetuximab (1,2), suggesting a role of antibody-dependent cell-mediated cytotoxicity (ADCC) induced by NK cells. NK cells express three types of polymorphism of CD16; FcγRIIIa-158 VV, VF, FF, which are derived from the genotype of FCGR3A. It is a clinical challenge to improve the outcome in patients with FCGR3A 158FF genotype whose NK cells have lower affinity to mAb and mediate poor ADCC activity. The IL-15 superagonist/IL-15Rα-Fc fusion complex (ALT-803) activates the IL-15 receptor on CD8 T cells and NK cells, inducing their expansion, cytotoxity, and ADCC against B cell lymphoma (3, 4, 5). Here, we examined the effect of ALT803 on NK cell-mediated ADCC activity by the the anti-HER2 IgG1 mAb trastuzumab in HER2+ cell lines (SKBR3, BT474, MDA-MB-453). In addition, we used the anti-epidermal growth factor receptor(EGFR) IgG1 mAb cetuximab in EGFR positive TNBC cell lines (MDA-MB-231, SUM149, BT549). Finally, we examined the anti-PD-L1 IgG1 mAb avelumab was used for PD-L1 positive breast cancer cell lines (MDA-MB-231, BT549). Trastuzumab, cetuximab, and avelumab all significantly increased NK cell-induced lysis via ADCC. ALT803 significantly further increased both NK induced lysis and ADCC activity in all the cell lines. There was a significant positive correlation for the mean of ADCC lysis induced by NK cells from three FF (21%), three VF (33%), three VV (45%) donors. ALT803 significantly increased the mean of ADCC lysis by NK cells from all donors of each genotype to the same extent. ALT803 increased the expression of NK cell-activating receptors and cytotoxic granules regardless of the genotype of NK cell FCGR3A in terms VV, VF, or FF. We further examined the potential of ALT803 for NK cell-cytotoxicity suppressed by TGF-β1 which is one of the main barriers to immunity in the tumor microenvionment (TME). NK cells treated with TGF-β1 showed lower expression of activating receptors and cytotoxic granules, culminating in decreased lysis of MDA-MB231. ALT803 inhibited TGF-β1 from down-regulating the expression of NK cell-activating receptors and cytotoxic granules, and from suppressing the cytotoxicity of NK cells to MDA-MB231. In conclusion, the IL-15 superagonist ALT803 can potentially increase the clinical benefit of ADCC-based mAb therapy for breast cancer patients, regardless of the genotype of FCGR3A. Moreover, ALT803 prevented NK cell-cytotoxity from TGF-β1-induced suppression, providing a rationale for ALT803 therapy to overcome TME-mediated immunosuppression. References (1) Gavin et. al. JAMA Oncol.2017;3(3) (2) Musolino et. al. J Clin Oncol.2008;26(33) (3) Xu et. al. Cancer Res.2013;73(10) (4) Kim et. al. Oncotarget.2016;7(13) (5) Rosario et. al. Clin. Cancer Res. 2016; 22(3) Citation Format: Fujii R, Wong HC, Schlom J, Hodge JW. An IL-15 superagonist enhances antibody-dependent cell-mediated cytotoxicity against breast cancer cells regardless of FCGR3A (CD16) genotype and rescues NK cell from TGF-β1-induced immunosuppression [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-04.

Sestrin2 and sestrin3 suppress NK-92 cell-mediated cytotoxic activity on ovarian cancer cells through AMPK and mTORC1 signaling.

Ovarian cancer is one of the major cancer types. NK-92 cell line, which has consistently and reproducibly high anti-tumor cytotoxicity, may be used for immunotherapy against ovarian cancer. Understanding the mechanisms that regulate the anti-tumor activity of NK-92 cells is important for developing novel therapeutic strategies. In the current study, using an ovarian cancer xenograft mouse model, we identified the up-regulation of sestrin2 (SESN2) and sestrin3 (SESN3) in intratumoral NK-92 cells. Lentivirus-transduced NK-92 cells, which overexpressed SESN2 or SESN3 after doxycycline treatment, exhibited less expression of activating receptors, perforin and granzyme B. Overexpression of SESN2 and SESN3 impaired tumoricidal effect of NK-92 cells both in vitro and in vivo. Furthermore, overexpression of SESN2 and SESN3 inhibited mTORC1 signaling while promoting AMPK signaling in NK-92 cells. Taken together, our data highlights the crucial effects of SESN2 and SESN3 on NK-92 cell-mediated anti-ovarian cancer activity. This study might be valuable for designing a novel therapeutic strategy for ovarian cancer.

Antitumor and antimetastatic activities of pectic polysaccharides isolated from persimmon leaves mediated by enhanced natural killer cell activity

To investigate the antitumor and antimetastatic activities of pectic polysaccharides isolated from persimmon leaves, three polysaccharides (PLE-0, -I, and -II) were prepared. Based on IL-6 cytokine production, PLE-II was selected for further analysis. PLE-II significantly increased IL-6 and IL-12 production in peritoneal macrophages. Moreover, the antitumor and antimetastatic activities of PLE-II were mediated by the activation of natural killer (NK) cells. Depletion of NK cells abolished its antimetastasis activity, thus confirming the role of NK cells in mediating the antimetastatic effect. To determine the commercial potential of PLE, the crude polysaccharide, PLE-0, was administered orally to mice, and its antitumor and antimetastatic activities were evaluated. PLE-0 also induced NK cell-mediated tumoricidal activity and inhibited tumor metastasis in mice in a dose-dependent manner. These data suggest that both PLE-0 and PLE-II have antitumor and antimetastatic activities, and PLE-0 could potentially be used in functional foods and nutraceuticals for cancer prevention.

Harnessing co-stimulatory TNF receptors for cancer immunotherapy: Current approaches and future opportunities

Co-stimulatory tumor necrosis factor receptors (TNFRs) can sculpt the responsiveness of T cells recognizing tumor-associated antigens. For this reason, agonist antibodies targeting CD137, CD357, CD134 and CD27 have received considerable attention for their therapeutic utility in enhancing anti-tumor immune responses, particularly in combination with other immuno-modulatory antibodies targeting co-inhibitory pathways in T cells. The design of therapeutic antibodies that optimally engage and activate co-stimulatory TNFRs presents an important challenge of how to promote effective anti-tumor immunity while avoiding serious immune-related adverse events. Here we review our current understanding of the expression, signaling and structural features of CD137, CD357, CD134 and CD27, and how this may inform the design of pharmacologically active immuno-modulatory antibodies targeting these receptors. This includes the integration of our emerging knowledge of the role of Fcγ receptors (FcγRs) in facilitating antibody-mediated receptor clustering and forward signaling, as well as promoting immune effector cell-mediated activities. Finally, we bring our current preclinical and clinical knowledge of co-stimulatory TNFR antibodies into the context of opportunities for next generation molecules with improved pharmacologic properties.

Abstract B44: Selective stimulation of RIG-I with a novel synthetic RNA induces strong anti-tumor immunity in mouse tumor models

Abstract We describe a novel immunotherapy approach in which a natural viral defense system is harnessed to stimulate anti-tumor immunity. Cancer immunotherapy has revolutionized oncology in recent years, yet many tumors become resistant or do not respond to current treatments such as checkpoint inhibitors. Stimulation of the innate immune system opens a new therapeutic strategy that could be combined effectively with other immunotherapeutic regimens. The ubiquitously expressed cytosolic RNA receptor retinoic acid inducible gene I (RIG-I) recognizes double-stranded RNA bearing a 5'-triphosphate. RIG-I plays a prominent role in antiviral defense. Its activation induces apoptosis preferentially in tumor cells and simultaneously activates the innate immune system via type I interferon (IFN) signaling. We developed an optimized, fully synthetic oligonucleotide, designated RGT100, which is a RIG-I selective ligand. RGT100 activates the RIG-I pathway leading to the induction of cytokines, including IFN-α and IFN-β. The treatment of tumor-bearing mice with RGT100 induced potent anti-tumor activity against large established B16 melanoma and CT26 colon carcinoma tumors. RGT100 also was efficacious in a spontaneous melanoma model. Histological and flow cytometric analysis of the tumors revealed infiltration and activation of immune cells after RGT100 treatment. RGT100 induced a strong and durable type I IFN response in tumors. Treatment of subcutaneous tumors by intratumor injection led to efficacy of both the treated tumors as well as untreated contralateral tumors. Furthermore, systemic delivery of RGT100 was efficacious against both local subcutaneous B16 melanoma as well as lung metastases. Data support both rapid natural killer (NK) cell-mediated and long-term T cell-mediated anti-tumor activities. Depletion of NK cells blocked the immediate anti-tumor activity of RGT100. In summary, Rigontec's RIG-I-selective ligand RGT100 shows strong anti-tumor activity in several clinically relevant mouse tumor models, while bearing an advantageous safety profile. RGT100 is rapidly progressing toward clinical evaluation in cancer patients. This agent will be evaluated both for single-agent activity as well as in combination with checkpoint inhibitors. Citation Format: Jim Barsoum, Marcel Renn, Christine Schuberth, Christopher Jakobs, Anna Schwickart, Martin Schlee, Jasper van den Boorn, Gunther Hartmann. Selective stimulation of RIG-I with a novel synthetic RNA induces strong anti-tumor immunity in mouse tumor models. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B44.

Young and old rats have different strategies of metabolic adaptation to Cu-induced liver fibrosis

We investigated the role of pro- and antioxidant and immune systems in age-related adaptive reactions to chronic exposure to toxicants (copper ions). For this purpose, we administered multiple doses of copper sulfate to younger and older rats in order to induce liver fibrosis and then measured the parameters of proand antioxidant and immune systems and physiological indices. It was found that Cu-induced liver fibrosis was accompanied by oxidative stress and a significant reduction in cell-mediated immune activity. If oxidative stress was eliminated by the administration of exogenous antioxidants (mix factor), the physical capacity, body weight, and content of red blood cells in rats with fibrosis was recovered. The parameters of cell-mediated immune response recovered more effectively in older animals than in younger ones. The metabolic strategies of adaptation to toxic exposure were different in younger and older animals.

Combination of a Novel HDAC 6 Inhibitor ACY-241 with Anti-PD-L1 Antibody Enhances Anti-Tumor Immunity and Cytotoxicity in Multiple Myeloma

Introduction Histone deacetylases (HDACs) are attractive therapeutic targets, and selective HDAC inhibitors (HDACi), alone or in combination with other anti-cancer agents are useful treatment strategies in multiple myeloma (MM). HDACs are also involved in immune regulation in hematological malignancies. For example, blockade of HDACs upregulate immunecheckpoints such as PD-1 ligand (PD-L1). Furthermore, combination of HDACi with PD-1/PD-L1 checkpoint blockade significantly improves immunotherapy in a murine B16F10 model [Woods et al, Cancer Immunol Res. 2015; 3:1375-85]. Here we utilized an orally bioavalable HDAC6 selective inhibitor ACY-241 currently under clinical trials to examine whether combination of ACY-241 with anti-PD-L1 antibody enhances anti-MM immunity. For these studies, we utilized our previously published co-culture models of immune effector cells (plasmacytoid dendritic cells, pDCs, T cells, NK cells) and MM cells (Chauhan et al, Cancer Cell 2009, 16:309-323; Ray et al, Leukemia 2015, 29:1441-1444). Specifically, in MM we have shown that: 1) PD-1 is highly expressed on T and NK cells, and both pDCs and MM cells express PD-L1; 2) MM-pDCs confer T- and NK cell immune suppression via PD-L1/PD-1 immune checkpoints and 3) blockade of PD-L1-PD-1 signaling axis by anti-PD-L1 Ab generates MM-specific CD8+ CTL activity, as well as enhances NK-cell-mediated MM cell cytolytic activity. We here examined whether combination of ACY-241 with anti-PD-L1 Ab increases anti-tumor immunity and cytotoxicity in MM.Methods Minimally cytotoxic concentrations of ACY-241 (0.1-0.2 µM) or anti-PD-L1 Ab (5 µg/ml) were utilized to assess immune function. In T cell proliferation assay, MM patient pDCs were co-cultured with autologous T cells (pDC:T ratio; 1:10) in the presence of ACY-241, anti-PD-L1 Ab, or a combination of ACY-241 and anti-PD-L1 Ab for 5 days; proliferation was then quantified using CellTrace Violet proliferation kit for flow cytometry. CTL activity assays MM CD8+ T cells were cultured with autologous pDCs (1:10 pDC/T ratio) with ACY-241, anti-PD-L1 Ab, or both for 5 days; cells were then washed to remove drug, and pre-stained target MM cells (20:1 E/T ratio) were then added for another 2-3 days, followed by quantification of viable MM cells using FACS. NK-cell mediated cytotoxicity was assessed using flow-based CFSE-stained target lysis assays, as well as degranulation assay quantifying cell surface CD107a. Statistical parameters were calculated using GraphPad Prism.Results. 1) Treatment of RPMI-8226, U266, and MM.1S cells with ACY-241 increases PD-L1 expression; and blockade of PD-L1 using anti-PD-L1 Ab increases the anti-MM activity of ACY-241. 2) Combination of ACY-241 and anti-PDL1 Ab enhances MM-patient pDC-induced NK cell-mediated cytolytic activities against allogenic MM cells (p < 0.008; 2-5 fold increase for combination versus anti-PD-L1 Ab alone). NK cell mediated lysis was insignificant in the absence of pDCs. 3) ACY-241, anti-PD-L1 Ab or their combination, activates patient BM-CD8+T cells in autologous pDCs/T cell co-cultures. Importantly, combination of ACY-241 and anti-PD-L1 Ab triggers a more robust allogenic and autologous MM-specific CD8+ CTL activity than anti-PD-L1 Ab alone (1.5-2.0 fold increase in combination regimen vs anti-PD-L1 Ab; p = 0.01). 4) Treatment of pDC-T cell cocultures with ACY-241 plus anti-PD-L1 Ab enhanced cytotoxic activity of CD8+ T cells against HLA-A2+ U266 cells (1.5-2 fold in combinations vs anti-PD-L1 Ab; p = 0.003). 5) In concert with above findings, ACY-241 plus anti-PD-L1 Ab increases CD107a expression in NK and CD8+T cells (CD107a+ NK: 5 fold; p = 0.003; CD107a+ CD8+T: 5 fold; p= 0.001; vs anti-PD-L1 Ab alone). Finally, 6) pDC-mediated CD8+ CTL activity was also confirmed using HLA-A2+ HCT116 colon cancer cells (~2 fold loss in viability in combination vs anti-PD-L1 Ab; p = 0.006)Conclusions The combination of HDAC6 inhibitor ACY-241 and anti-PD-L1 Ab enhances pDC-induced T and NK cell-mediated cytolytic acitvities in MM. Our study provides the basis for combining ACY-241 with anti-PD-L1 Ab to restore immune function, and enhance MM cytotoxicity, and improve patient outcome in MM. DisclosuresHideshima:Acetylon: Consultancy; C4 Therapeutics: Equity Ownership. Chauhan:C4 Therapeutics: Equity Ownership; Epicent Rx: Consultancy; Oncopeptide AB: Consultancy; Stemline Therapeutics, Inc.: Consultancy. Anderson:Celgene Corporation: Consultancy; Millennium Pharmaceuticals: Consultancy; Novartis AG: Consultancy; Bristol-Myers Squibb:: Consultancy; Oncopep: Other: Scientific Founder; Acetylon: Other: Scientific Founder.

Infections with Plasmodium falciparum during pregnancy affect VAR2CSA DBL-5 domain-specific T cell cytokine responses.

BackgroundCurrent knowledge of human immunological responses to pregnancy-associated malaria-specific Plasmodium falciparum protein VAR2CSA concerns almost exclusively B cell-driven antibody-mediated activity. Knowledge of VAR2CSA-specific T cell-mediated activity is minimal by comparison, with only a single published report of a study investigating VAR2CSA-derived peptide-specific T cell responses. The study described here represents an attempt to redress this balance.MethodsWithin the framework of a cohort study of 1037 pregnant Beninese, sub-groups were selected on the basis of the documented presence/absence of infection with P. falciparum and conducted detailed immunological assessments both at inclusion into the study and at delivery. Peripheral blood mononuclear cells were isolated, stimulated in vitro, and VAR2CSA DBL-5 domain-specific, IFN-γ-secreting T-cell frequencies and cytokine responses were quantified using flow cytometric techniques. Multivariate analyses were used to determine primarily whether the T cell-mediated DBL5-specific activity measured was associated with infection by P. falciparum adjusted for gravidity, anaemia and other cofactors.ResultsInfections with P. falciparum detected at inclusion were associated with enhanced non-specific TNF responses, whilst diminished non-specific and DBL-5-specific IL-10 responses were associated with infections detected at delivery. Infections during pregnancy led to enhanced non-specific and DBL-5-specific IFN-γ responses detectable at delivery but to concomitantly lower DBL-5-specific CD8+ IFN-γ responses. Prospective assessments indicated that non-specific pro-inflammatory responses detectable at inclusion in the study were associated with the occurrence of infections subsequently during pregnancy.ConclusionsThe findings represent a first step in elucidating the quantity and quality of cellular immunological responses to VAR2CSA, which will help in the development of the primary vaccine candidate for prevention of pregnancy-associated malaria.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1525-x) contains supplementary material, which is available to authorized users.

Overexpression of LLT1 (OCIL, CLEC2D) on prostate cancer cells inhibits NK cell-mediated killing through LLT1-NKRP1A (CD161) interaction.

Prostate cancer is the most common type of cancer diagnosed and the second leading cause of cancer-related death in American men. Natural Killer (NK) cells are the first line of defense against cancer and infections. NK cell function is regulated by a delicate balance between signals received through activating and inhibitory receptors. Previously, we identified Lectin-like transcript-1 (LLT1/OCIL/CLEC2D) as a counter-receptor for the NK cell inhibitory receptor NKRP1A (CD161). Interaction of LLT1 expressed on target cells with NKRP1A inhibits NK cell activation. In this study, we have found that LLT1 was overexpressed on prostate cancer cell lines (DU145, LNCaP, 22Rv1 and PC3) and in primary prostate cancer tissues both at the mRNA and protein level. We further showed that LLT1 is retained intracellularly in normal prostate cells with minimal cell surface expression. Blocking LLT1 interaction with NKRP1A by anti-LLT1 mAb on prostate cancer cells increased the NK-mediated cytotoxicity of prostate cancer cells. The results indicate that prostate cancer cells may evade immune attack by NK cells by expressing LLT1 to inhibit NK cell-mediated cytolytic activity through LLT1-NKRP1A interaction. Blocking LLT1-NKRP1A interaction will make prostate cancer cells susceptible to killing by NK cells and therefore may be a new therapeutic option for treatment of prostate cancer.

OR24 Recipient FCGR3A-158V homozygous genotype is associated with an increased risk of chronic lung allograft dysfunction

Aim Chronic lung allograft dysfunction (CLAD) is a major obstacle in the long-term success of lung transplantation. Recipient natural killer (NK) cells substantially influence the immune response to the allografts. NK cells can respond to allograft via three distinct mechanisms: missing-self, induced-self, and antibody dependent cell cytotoxicity (ADCC). NK cell ADCC is regulated by CD16 (FcRIIIa), a low-affinity cell-surface receptor for the Fc portion of IgG antibodies. CD16 is encoded byFCGR3A, which carries a functional single nucleotide polymorphism that substitutes phenylalanine (F) for valine (V) at residue 158. Despite identical levels of CD16 expression, 158V homozygotes have higher binding affinity for IgG compared with 158F homozygotes. We hypothesized that the recipients carrying high binding FCGR3A-158V variants would have worse outcome compared to the weakly binding FCGR3A-158F carriers. Methods We developed a melting curve based q-PCR method to analyze FCGR3A-V158F variants in a cohort of 252 lung transplant recipients. CLAD was determined by date of FEV1 or FVC drop to Results Numbers of recipients with FCGR3A-158 FF, VV, and VF genotypes are 107 (42%), 30 (12%) and 115 (46%), respectively. CLAD-free survival was shorter in the 158VV group (3.0 median years) than the 158FF group (6.0 median years, HR 1.6, 95% CI 1.0-2.7, P = 0.05) and VF group (5.3 median years, ns) (Figure). Conclusions We observed an association between theFCGR3A-158 VV genotype and worse CLAD-free survival. Recipients with this genotype would presumably have more NK cell-mediated ADCC activity and could be at increased risk of graft dysfunction in the context of donor-specific antibodies. Mechanistic studies and validation in other cohorts will be needed to determine the significance of this finding to lung transplant outcomes. Download : Download high-res image (64KB) Download : Download full-size image

Intracellular haemolytic agents of Heterocapsa circularisquama exhibit toxic effects on H. circularisquama cells themselves and suppress both cell-mediated haemolytic activity and toxicity to rotifers (Brachionus plicatilis)

A harmful dinoflagellate, Heterocapsa circularisquama, is highly toxic to shellfish and the zooplankton rotifer Brachionus plicatilis. A previous study found that H. circularisquama has both light-dependent and -independent haemolytic agents, which might be responsible for its toxicity. Detailed analysis of the haemolytic activity of H. circularisquama suggested that light-independent haemolytic activity was mediated mainly through intact cells, whereas light-dependent haemolytic activity was mediated by intracellular agents which can be discharged from ruptured cells. Because H. circularisquama showed similar toxicity to rotifers regardless of the light conditions, and because ultrasonic ruptured H. circularisquama cells showed no significant toxicity to rotifers, it was suggested that live cell-mediated light-independent haemolytic activity is a major factor responsible for the observed toxicity to rotifers. Interestingly, the ultrasonic-ruptured cells of H. circularisquama suppressed their own lethal effect on the rotifers. Analysis of samples of the cell contents (supernatant) and cell fragments (precipitate) prepared from the ruptured H. circularisquama cells indicated that the cell contents contain inhibitors for the light-independent cell-mediated haemolytic activity, toxins affecting H. circularisquama cells themselves, as well as light-dependent haemolytic agents. Ethanol extract prepared from H. circularisquama, which is supposed to contain a porphyrin derivative that displays photosensitising haemolytic activity, showed potent toxicity to Chattonella marina, Chattonella antiqua, and Karenia mikimotoi, as well as to H. circularisquama at the concentration range at which no significant toxicity to rotifers was observed. Analysis on a column of Sephadex LH-20 revealed that light-dependent haemolytic activity and inhibitory activity on cell-mediated light-independent haemolytic activity existed in two separate fractions (f-2 and f-3), suggesting that both activities might be derived from common compounds. Our results suggest that the photosensitising haemolytic toxin discharged from ruptured H. circularisquama cells has a relatively broad spectrum of phytoplankton toxicity, and that physical collapse of H. circularisquama cells can lead not only to the disappearance of its own toxicity, but also to mitigation of the effects of other HABs.

“Universal Flu Vaccine”: Can NK Cell-mediated ADCC Tip the Scales?

“Universal Flu Vaccine”: Can NK Cell-mediated ADCC Tip the Scales?

Reducing liver metastases of colon cancer in the context of extensive and minor surgeries through β-adrenoceptors blockade and COX2 inhibition

Liver metastases are a major cause of colorectal cancer death, and the perioperative period is believed to critically affect the metastatic process. Here we tested whether blocking excess release of catecholamines and prostaglandins during surgical procedures of different extent can reduce experimental liver metastasis of the syngeneic CT26 colon cancer in female and male BALB/c mice. Animals were either treated with the beta-blocker, propranolol, the COX-2 inhibitor, etodolac, both drugs, or vehicle. The role of NK cells in controlling CT26 hepatic metastasis and in mediating the effect of the drugs was assessed by in vivo depletion or stimulation of NK cells, using anti-asialo GM1 or CpG-C, respectively. Surgical extent was manipulated by adding laparotomy to small incision, extending surgical duration, and enabling hypothermia. The results indicated that combined administration of propranolol and etodolac, but neither drug alone, significantly improved host resistance to metastasis. These beneficial effects occurred in both minor and extensive surgeries, in both sexes, and in two tumor inoculation approaches. NK cell-mediated anti-CT26 activity is involved in mediating the beneficial effects of the drugs. Specifically, CpG-C treatment, known to profoundly activate mice marginating-hepatic NK cytotoxicity, reduced CT26 hepatic metastases; and NK-depletion increased metastases and prevented the beneficial effects of the drugs. Overall, given prevalent perioperative psychological and physiological stress responses in patients, and ample prostaglandin release by colorectal tumors and injured tissue, propranolol and etodolac could be tested clinically in laparoscopic and open colorectal surgeries, attempting to reduce patients’ metastatic disease.

Sialic acid removal from dendritic cells improves antigen cross-presentation and boosts anti-tumor immune responses.

Dendritic cells (DCs) hold promise for anti-cancer immunotherapy. However, clinically, their efficiency is limited and novel strategies to improve DC-mediated anti-tumor responses are needed. Human DCs display high content of sialic acids, which inhibits their maturation and co-stimulation capacity. Here, we aimed to understand whether exogenous desialylation of DCs improves their anti-tumor immunity. Compared to fully sialylated DCs, desialylated human DCs loaded with tumor-antigens showed enhanced ability to induce autologous T cells to proliferate, to secrete Th1 cytokines, and to specifically induce tumor cell apoptosis. Desialylated DCs showed an increased expression of MHC-I and -II, co-stimulatory molecules and an augmented secretion of IL-12. Desialylated HLA-A*02:01 DCs pulsed with gp100 peptides displayed enhanced peptide presentation through MHC-I, resulting in higher activation ofgp100280–288 specific CD8+ cytotoxic T cells. Desialylated murine DCs also exhibited increased MHC and co-stimulatory molecules and higher antigen cross-presentation via MHC-I. These DCs showed higher ability to activate antigen-specific CD4+ and CD8+ T cells, and to specifically induce tumor cell apoptosis. Collectively, our data demonstrates that desialylation improves DCs' ability to elicit T cell-mediated anti-tumor activity, due to increased MHC-I expression and higher antigen presentation via MHC-I. Sialidase treatment of DCs may represent a technology to improve the efficacy of antigen loaded-DC-based vaccines for anti-cancer immunotherapy.

NK Cell-Dependent Growth Inhibition of Lewis Lung Cancer by Yu-Ping-Feng, an Ancient Chinese Herbal Formula.

Little is known about Yu-Ping-Feng (YPF), a typical Chinese herbal decoction, for its antitumor efficacy in non-small-cell lung cancer (NSCLC). Here, we found that YPF significantly inhibited the growth of Lewis lung cancer, prolonged the survival of tumor-bearing mice, promoted NK cell tumor infiltration, increased the population of NK cells in spleen, and enhanced NK cell-mediated killing activity. The growth suppression of tumors by YPF was significantly reversed by the depletion of NK cells. Furthermore, we found that YPF significantly downregulated the expression of TGF-β, indoleamine 2,3-dioxygenase, and IL-10 in tumor microenvironment. These results demonstrated that YPF has a NK cell-dependent inhibitory effect on Lewis lung cancer.

Serum relaxin levels in subjects with multiple sclerosis.

Multiple Sclerosis is an inflammatory, auto-immune, neurodegenerative disease of the central nervous system. The disease has a prevalence of approx 1:700 with at least 2.5 million cases worldwide. It is the leading, non-trauma cause of physical disability among young and mid- dle-aged adults. Recently developed therapies do reduce disease activity but only modestly, with all of the available agents producing significant side effects that reduce compliance, and/ or serious risk for adverse events. Relaxin has been long-recognized to play a critical role in pregnancy. Recent investigations have revealed that relaxin may be an important regulator of inflammation and immune processes. This is due to the ability of relaxin to promote the pro- duction of glucocorticoid receptors, increase serum levels of the adrenocorticotropic hormone and inhibiting cell-mediated pro-inflammatory activity by stimulation of the peroxisome prolif- erator-activated receptor gamma. This study found serum relaxin levels to be elevated in sub- jects with multiple sclerosis. Production of relaxin is down regulated by a negative feedback loop through its own receptor binding. Decreased receptor binding may contribute to the high- er level of relaxin seen in these patients and may lead to dysregulation of the inflammatory and immune pathways.

Immunomodulatory activity of aqueous extract of Nyctanthes arbor-tristis flowers with particular reference to splenocytes proliferation and cytokines induction.

Objectives:To investigate the immunomodulatory activity of aqueous extract of Nyctanthes arbor-tristis flowers (NAFE) with particular reference to splenocytes proliferation and induction of cytokines.Materials and Methods:Antibody titer was determined by tube agglutination and indirect ELISA assay in four groups of mice-control, antigen alone, and NAFE-treated (400 and 800 mg/kg for 21 days) after immunization with Salmonella antigen while cellular immunity was studied in three groups of rats (control and NAFE-treated - 400 and 800 mg/kg) following DNCB application. Splenocytes from untreated and NAFE-treated rats were stimulated using concanavalin-A (Con-A) and optical density (OD) and stimulation index were determined. Splenocytes from control rats were also treated in vitro with NAFE (50–1600 μg/ml) and Con-A to determine the effect on splenocytes proliferation. Interleukin-2 (IL-2) and IL-6 levels in splenocytes supernatant from control and NAFE-treated rats and following in vitro treatment of splenocytes with NAFE (50–1600 μg/ml) were determined using ELISA kits.Results:Marked to a significant increase in antibody titer by both the methods in NAFE-treated mice and a significant increase in skin thickness in rats after challenge with DNCB, respectively suggested humoral and cell-mediated immunostimulant potential of NAFE. Significant increase in OD and stimulation index following e x vivo and in vitro exposure of splenocytes and sensitization with Con-A and significant elevation in IL-2 and IL-6 levels in splenocytes supernantant was also observed after their ex vivo and in vitro exposure to NAFE.Conclusion:Humoral and cell-mediated immunostimulant activity of NAFE seems to be mediated through splenocytes proliferation and increased production of cytokines, especially IL-2 and IL-6.

NK cell-based cancer immunotherapy: from basic biology to clinical application.

Natural killer (NK) cells, which recognize and kill target cells independent of antigen specificity and major histocompatibility complex (MHC) matching, play pivotal roles in immune defence against tumors. However, tumor cells often acquire the ability to escape NK cell-mediated immune surveillance. Thus, understanding mechanisms underlying regulation of NK cell phenotype and function within the tumor environment is instrumental for designing new approaches to improve the current cell-based immunotherapy. In this review, we elaborate the main biological features and molecular mechanisms of NK cells that pertain to regulation of NK cell-mediated anti-tumor activity. We further overview current clinical approaches regarding NK cell-based cancer therapy, including cytokine infusion, adoptive transfer of autologous or allogeneic NK cells, applications of chimeric antigen receptor (CAR)-expressing NK cells and adoptive transfer of memory-like NK cells. With these promising clinical outcomes and fuller understanding the basic questions raised in this review, we foresee that NK cell-based approaches may hold great potential for future cancer immunotherapy.