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Recombinant murine (rm) TNF-alpha but not recombinant human (rh) TNF-alpha induces the proliferation of murine thymocytes in the presence of a comitogenic stimulus. This effect does not appear to be due to the production of significant levels of IL-1, IL-2, or IL-4. although not directly mitogenic (i.e., in the absence of PHA-P) for thymocytes, rmTNF-alpha amplifies the direct mitogenic signals from hIL-1 and rhIL-2 but not rmIL-4. In the presence of PHA-P, thymocytes stimulated with hIL-1, rhIL-2, and rmIL-4 produced significant amounts of TNF-alpha. Although rhTNF-alpha does not induce a proliferative response, it will competitively inhibit the proliferative response of thymocytes to rmTNF-alpha. These data suggest a critical role for TNF-alpha in the intrathymic proliferation of developing T cells.

Background: Innate and adaptive immune responses are pivotal in atherosclerosis, but their association with early-stage atherosclerosis in humans is incompletely understood. In this regard, untreated children with familial hypercholesterolaemia may serve as a human model to investigate the effect of elevated low-density lipoprotein (LDL)-cholesterol.Objectives: We aimed to study the immunological and inflammatory pathways involved in early atherosclerosis by examining mRNA molecules in peripheral blood mononuclear cells (PBMCs) from children with FH.Methods: We analysed the level of 587 immune-related mRNA molecules using state-of-the-art Nanostring technology in PBMCs from children with (n = 30) and without (n = 21) FH, and from FH children before and after statin therapy (n = 10).Results: 176 genes (30%) were differentially expressed between the FH and healthy children at P < 0.05. Compared to healthy children, the dysregulated pathways in FH children included the following: T cells (18/19); B cells (5/6); tumour necrosis factor super family (TNFSF) (6/8); cell growth, proliferation and differentiation (5/7); interleukins (5/9); toll-like receptors (2/5); apoptosis (3/7) and antigen presentation (1/7), where the ratio denotes higher expressed genes to total number of genes. Statin therapy reversed expression of thirteen of these mRNAs in FH children.Conclusion: FH children display higher PBMC expression of immune-related genes mapped to several pathways, including T and B cells, and TNFSF than healthy children. Our results suggest that LDL-C plays an important role in modulating expression of different immune-related genes, and novel data on the involvement of these pathways in the early atherosclerosis may represent future therapeutic targets for prevention of atherosclerotic progression. [ABSTRACT FROM AUTHOR]

Summary: There is a close cross‐talk between complement, Toll‐like receptors (TLRs) and coagulation. The role of the central complement component 5 (C5) in physiological and pathophysiological hemostasis has not, however, been fully elucidated. This study examined the effects of C5 in normal hemostasis and in Escherichia coli‐induced coagulation and tissue factor (TF) up‐regulation. Fresh whole blood obtained from six healthy donors and one C5‐deficient individual (C5D) was anti‐coagulated with the thrombin inhibitor lepirudin. Blood was incubated with or without E. coli in the presence of the C5 inhibitor eculizumab, a blocking anti‐CD14 monoclonal antibody (anti‐CD14) or the TLR‐4 inhibitor eritoran. C5D blood was reconstituted with purified human C5. TF mRNA was measured by quantitative polymerase chain reaction (qPCR) and monocyte TF and CD11b surface expression by flow cytometry. Prothrombin fragment 1+2 (PTF1·2) in plasma and microparticles exposing TF (TF‐MP) was measured by enzyme‐linked immunosorbent assay (ELISA). Coagulation kinetics were analyzed by rotational thromboelastometry and platelet function by PFA‐200. Normal blood with eculizumab as well as C5D blood with or without reconstitution with C5 displayed completely normal biochemical hemostatic patterns. In contrast, E. coli‐induced TF mRNA and TF‐MP were significantly reduced by C5 inhibition. C5 inhibition combined with anti‐CD14 or eritoran completely inhibited the E. coli‐induced monocyte TF, TF‐MP and plasma PTF1·2. Addition of C5a alone did not induce TF expression on monocytes. In conclusion, C5 showed no impact on physiological hemostasis, but substantially contributed to E. coli‐induced procoagulant events, which were abolished by the combined inhibition of C5 and CD14 or TLR‐4. Effect of eculizumab, anti‐CD14 or the TLR‐4 inhibitor eritoran on Escherichia coli (E. coli)‐induced monocyte tissue factor (TF) surface expression (a), tissue factor function in plasma microparticles (TF‐MP) (b) and prothrombin fragment 1+2 (PTF1·2) levels in plasma (c). Inhibition of C5 using eculizumab reduced the E. coli‐induced TF‐MP level. C5 inhibition combined with anti‐CD14 or eritoran completely inhibited the E. coli‐induced monocyte TF, TF‐MP and plasma PTF1·2. [ABSTRACT FROM AUTHOR]