In vivo anti- and pro-tumour activities of the TLR2 ligand FSL-1

TLR ligands as Th1 inducers have been investigated as potential anti-tumour agents. However, few attempts have been made to investigate the anti-tumour activity of TLR ligands as Th2 inducers. This study, therefore, was carried out to determine whether the TLR2 ligand FSL-1 as a Th2 inducers affects the growth of a QRsP tumour, a fibrosarcoma derived from the C57BL/6 (TLR2^+/+) mouse in vivo. Tumour volumes in TLR2^+/+ mice immunized with both FSL-1 and tumour-associated antigens were significantly smaller than those in control mice. Immunization with both FSL-1 and tumour-associated antigens increased the survival rate of TLR2^+/+ mice. However, surprisingly, immunization with FSL-1 alone significantly enhanced the growth of tumour. Both anti- and pro-tumour activities of FSL-1 were not observed in TLR2^−/− mice. Immunization of both FSL-1 and tumour-associated antigens induced tumour-associated antigen-specific cytolytic T cells, antibody-dependent cell-mediated cytotoxicity of natural killer cells by production of the tumour-specific antibodies, tumour lysis by complement activation and reduction of the number of regulatory T cells in the draining lymph node. Immunization with FSL-1 alone increased the number of regulatory T cells in the draining lymph node, and in vivo administration of anti-CD25 antibody into mice abrogated the pro-tumour activity of FSL-1, suggesting that regulatory T cells are involved in the pro-tumour activity.This study demonstrated that FSL-1 exhibited TLR2-mediated anti- and pro-tumour activities when immunized with and without tumour-associated antigens, respectively.     

A novel aza-anthrapyrazole blocks the progression of experimental autoimmune encephalomyelitis after the priming of autoimmunity

Mitoxantrone is one of the few FDA-approved drugs available to treat rapidly progressing forms of multiple sclerosis; however, its utilization is compromised by a cardiotoxic potential and the risk of mitoxantrone-induced leukemia. BBR3378, a novel aza-anthrapyrazole, is structurally similar to mitoxantrone, but lacks the ring hydroxyls that may contribute to cardiotoxicity. Here, we investigated the therapeutic activity of BBR3378 in a C57BL/6 mouse model of multiple sclerosis. Mice given BBR3378, before or after the priming and expansion of MOG-specific responses, were protected from ascending paralysis. Strikingly, two doses of BBR3378 given a week after EAE induction were sufficient to provide significant protection from clinical symptoms and reduce MOG-specific proinflammatory T cell cytokine production, and serum IgG responses. Furthermore, while mitoxantrone is associated with persistent lymphopenia and cardiotoxicity, no such outcomes were detected in BBR3378-treated mice. Our findings show that BBR3378 can ameliorate encephalitogenic mechanisms in EAE and antagonize underlying autoimmune mechanisms.     

Putting the parts together: Combining in vitro methods to test for skin sensitizing potentials

Allergic contact dermatitis is a common skin disease and is elicited by repeated skin contact with an allergen. In the regulatory context, currently only data from animal experiments are acceptable to assess the skin sensitizing potential of substances. Animal welfare and EU Cosmetic Directive/Regulation call for the implementation of animal-free alternatives for safety assessments. The mechanisms that trigger skin sensitization are complex and various steps are involved. Therefore, a single in vitro method may not be able to accurately assess this endpoint. Non-animal methods are being developed and validated and can be used for testing strategies that ensure a reliable prediction of skin sensitization potentials. In this study, the predictivities of four in vitro assays, one in chemico and one in silico method addressing three different steps in the development of skin sensitization were assessed using 54 test substances of known sensitizing potential. The predictivity of single tests and combinations of these assays were compared. These data were used to develop an in vitro testing scheme and prediction model for the detection of skin sensitizers based on protein reactivity, activation of the Keap-1/Nrf2 signaling pathway and dendritic cell activation.     

Lupeol protects against acetaminophen-induced oxidative stress and cell death in rat primary hepatocytes

Drug induced hepatotoxicity is a major problem where phytochemicals hold promise for its abrogation. This study was carried out to explore cytoprotective potential of lupeol, a triterpene, against acetaminophen (AAP)-induced toxicity in rat hepatocytes. AAP exposure significantly (p < 0.05) reduced cell viability, disturbed Bcl-2 family pro/anti-apoptotic protein balance, increased ROS production and altered redox homeostasis. It also induced mitochondria-mediated hepatocellular injury by significant mitochondrial depolarization, caspase-9/3 activation and subsequent DNA fragmentation. Our results suggest that lupeol pre-treatment effectively restored antioxidant enzyme levels, decreased lipid peroxidation, inhibited ROS generation and depolarization of mitochondria. Lupeol also attenuated mitochondria-mediated signaling pathway and DNA damage as evident from TUNEL assay and cell cycle studies leading to prevention of cytotoxicity. This study confirms the efficacy of lupeol, a food derived antioxidant, in abrogating ROS generation, maintaining redox balance and providing significant protection against mitochondria-mediated cell death during AAP-induced toxicity.     

Positive virtual crossmatch with negative flow crossmatch results in two cases

Pre-transplant (Tx) presence of HLA antibodies (HLA-Ab) especially donor specific antibodies (DSA) has been correlated with post-Tx rejection. While crossmatch (XM) is the specific method to identify DSA, logistical reasons prevent performing a prospective XM in all transplants. In such cases DSA as identified by solid-phase assay (SPA) are being used to perform a virtual crossmatch (VXM). We present two cases, a heart-lung transplant and a kidney transplant, for which testing detected a presumptive DSA with discordant results: a negative flow cytometric crossmatch (FXM) and a positive VXM using SPA. The subsequent investigation determined the antibody, in both cases, was presumably directed against an epitope of a HLA-B*44 antigen found on the single antigen beads (SAB) used in the SPA but not against the native form on the donor lymphocytes used in the FXM. Manufacturing of SAB beads results in denaturation of epitopes, majority of which are removed from the final product, but residual amount is present on the final product. Denaturation of majority of antigen epitopes on single antigen beads did not remove the activity of the recipient's antibodies but it did diminish the activity of positive control serum. This indicates denaturation of some of the HLA-B*44 antigen during manufacturing of the SAB may have lead to the reactivity. Antibody mediated rejection does not appear to be associated with the titer of this antibody to denatured antigen in the first case and so clinical relevance of such antibodies is unclear. Subsequently a second case of discordant FXM and VXM was identified in a potential kidney transplant patient who went on to an uneventful transplant. In this case, lymphocytes from the donor were positively shown to express HLA-B*44:02 using known anti- HLA-B*44:02 control serum. Platelets identified as HLA-B*44:02 could adsorb the anti-HLA-B*44:02 from the control serum activity but not from that of the recipient's anti- HLA-B 44 antibody adding evidence that this antibody should best be classified as a false positive finding. The presence of such an antibody if misidentified may result in unnecessary therapy being instituted or the inappropriate denial of an organ for transplantation.     

Suppression of dendritic cells' maturation and functions by daidzein, a phytoestrogen

Isoflavones are ubiquitous compounds in foods and in the environment in general. Daidzein and genistein, the best known of isoflavones, are structurally similar to 17β-estradiol and known to exert estrogenic effects. They also evidence a broad variety of biological properties, including antioxidant, anti-carcinogenic, anti-atherogenic and anti-osteoporotic activities. Previously, daidzein was reported to increase the phagocytic activity of peritoneal macrophages and splenocyte proliferation, and to inhibit nitric oxide (NO) production in macrophages. However, its potential impacts on immune response in dendritic cells (DCs), antigen-presenting cells that link innate and adaptive immunity, have yet to be clearly elucidated. In this study, we evaluated the effects of isoflavones on the maturation and activation of DCs. Isoflavones (formononetin, daidzein, equol, biochanin A, genistein) were found to differentially affect the expression of CD86, a costimulatory molecule, on lipopolysaccharide (LPS)-stimulated DCs. In particular, daidzein significantly and dose-dependently inhibited the expression levels of maturation-associated cell surface markers including CD40, costimulatory molecules (CD80, CD86), and major histocompatibility complex class II (I-A^b) molecule on LPS-stimulated DCs. Daidzein also suppressed pro-inflammatory cytokine production such as IL-12p40, IL-6 and TNF-α, whereas it didn't affect IL-10 and IL-1β expression. Furthermore, daidzein enhanced endocytosis and inhibited the allo-stimulatory ability of LPS-stimulated DCs on T cells, indicating that daidzein treatment can inhibit the functional maturation of DCs. These results demonstrate that daidzein may exhibit immunosuppressive activity by inhibiting the maturation and activation of DCs.     

Anthracycline treatment of the human monocytic leukemia cell line THP-1 increases phosphatidylserine exposure and tissue factor activity

Introduction

Cancer associated thrombosis is a well-recognized phenomenon that results in considerable patient morbidity and mortality. Malignancy conveys an increased risk for thrombosis and chemotherapy further elevates this risk. The pathophysiological mechanisms underlying this process remain poorly defined.

Materials and Methods

A human acute monocytic leukemia cell line (THP-1) was treated with commonly used anthracycline chemotherapeutics at concentrations similar to those found in the plasma of cancer patients. Cells were analyzed for tissue factor (TF) mRNA, protein, and activity. Microparticle (MP) TF activity was also measured. Phosphatidylserine (PS) exposure on cells and MPs was analyzed by flow cytometry. PS levels on MPs was also evaluated in an annexin V capture assay.

Results

Anthracycline treatment of THP-1 cells resulted in a concentration-dependent increase in cellular TF activity without a change in TF protein, which was associated with increased PS exposure on the cell surface and apoptosis. The increase in TF activity was abolished by annexin V or lactadherin indicating that PS exposure was required. Anthracycline treatment of THP-1 cells also increased the number of TF-positive MPs.

Conclusion

Treatment of THP-1 cells with anthracyclines induces apoptosis and increases cellular TF activity. The increased activity required an increase in exposure of PS. Additionally, anthracyclines increase the release of TF-positive MPs from THP-1 cells. We propose that the increase in cellular TF activity in circulating leukemic cells, combined with increased numbers of TF-positive MPs, may contribute to thrombosis in cancer patients receiving chemotherapy.