TNF-derived peptides inhibit tumour growth and metastasis through cytolytic effects on tumour lymphatics

Tumour necrosis factor (TNF) is a multi-functional cytokine with profound and diverse effects on physiology and pathology. Identifying the molecular determinants underlying the functions and pathogenic effects of TNF is key to understanding its mechanisms of action and identifying new therapeutic opportunities based on this important molecule. Previously, we showed that some evolutionarily conserved peptides derived from TNF could induce cell death (e.g. apoptosis and/or necrosis), a feature of immune defence mechanisms shared by many vertebrates. In this study, we demonstrated that necrosis-inducing peptide P16 kills human glioblastoma cancer cells and primary human hepatoma or renal cancer cells isolated from patients who had not responded to standard treatments. Importantly, we show that the necrosis-inducing peptide P1516 significantly improves survival by inhibiting tumour metastasis in a 4T1 breast cancer syngeneic graft mouse model. Because the lymphatic system is an important metastatic route in many cancers, we also tested the effect of TNF-derived peptides on monolayers of primary human lymphatic endothelial cells (hDLEC) and found that they increased junctional permeability by inducing cytoskeletal reorganization, gap junction formation and cell death. Transmission electron microscopy imaging evidence, structural analysis and in-vitro liposome leakage experiments strongly suggest that this killing is due to the cytolytic nature of these peptides. P1516 provides another example of a pro-cytotoxic TNF peptide that probably functions as a cryptic necrotic factor released by TNF degradation. Its ability to inhibit tumour metastasis and improve survival may form the basis of a novel approach to cancer therapy.     

Pro- and anti-inflammatory cytokine production by autoimmune T cells against preproinsulin in HLA-DRB1*04, DQ8 Type 1 diabetes

Aims/hypothesis Preproinsulin is a target T cell autoantigen in human Type 1 diabetes. This study analyses the phenotype and epitope recognition of preproinsulin reactive T cells in subjects with a high genetic risk of diabetes [HLA-DRB1*04, DQ8 with Ab+ (autoantibody-positive) or without islet autoantibodies (control subjects)], and in HLA-matched diabetic patients.Methods A preproinsulin peptide library approach was used to screen for cytokine profiles and epitope specificities in human peripheral blood lymphocytes, and CD4⁺CD45RA^– and CD4⁺CD45RA⁺ T cell subfractions, representing memory and naive and recently primed T cells respectively.Results In CD4⁺ T cell subsets we identified immunodominant epitopes and cytokine production patterns that differed profoundly between patients, Ab+ subjects and non-diabetic HLA-matched control subjects. In Ab+ subjects, a C-peptide epitope C13–29 and insulin B-chain epitope B11–27 were preferentially recognised, whereas insulin-treated Type 1 diabetic patients reacted to native insulin and B-chain epitope B1–16. In peripheral blood lymphocytes of Ab+ subjects, an increase in T helper (Th) 1 (IFN, IL-2) and Th2 (IL-4) cytokines was detectable, wheras in CD45RA⁺ and CD45RA^– subsets, IL-4 and IL-10 phenotypes dominated, compatible with the contribution of non-CD4 cells to IFN content. In insulin-treated Type 1 diabetic patients, naive and recently primed CD4⁺ cells were characterised by increasd IFN, TNF, and IL-5.Conclusions/interpretation Our data show that T cell reactivity to preproinsulin in CD45RA subsets is Th2-dominant in Ab+ subjects, challenging the Th1 paradigm in Type 1 diabetes. Characteristic immunodominant epitopes and cytokine patterns distinguish diabetic patients and Ab+ subjects from HLA-matched healthy individuals. This could prove useful in monitoring of T-cell immunity in clinical diabetes intervention trials.Abbreviations PPI Preproinsulin - PBMC peripheral blood mononuclear cells - Th T helper cells - Ab+ autoantibody-positive - ICA islet cell antibodies - IA-2A islet thyrosine phosphatase - SI stimulation index - Tr T regulatory cells W. Karges and B.O. Boehm contributed equally to this article     

抗人红细胞血型糖蛋白A非多态性表位单克隆抗体的制备和鉴定

目的制备抗人红细胞血型糖蛋白A(Glycophorin A,GPA)非多态性表位单克隆抗体并鉴定其特性。方法用小鼠B淋巴细胞杂交瘤技术获得分泌单抗-GPA非多态性表位的杂交瘤细胞株;鉴定抗体特异性和亚型;通过和各种酶处理细胞的反应确定单抗结合抗原位点的特性。结果得到的2株抗-GPA非多态性表位的单克隆细胞株Q6D7和Q7C9,均属IgG1亚类、Kappa型轻链,所针对的抗原位点均抗胰蛋白酶、胰凝乳蛋白酶处理,对无花果酶、木瓜酶、唾液酸酶敏感。结论制备获得2株抗-GPA非多态性表位单克隆抗体。     

Epitope load identifies kidney transplant recipients at risk of allosensitization following minimization of immunosuppression

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