Background-T cells play an important role during the immune response that accompanies atherosclerosis. To date, the role for interleukin (IL)-17A in atherogenesis is not well defined. Here, we tested the hypothesis that atherosclerosisprone conditions induce the differentiation of IL-17A-producing T cells, which in turn promote atherosclerosis. Methods and Results-IL-17A was found to be elevated in the plasma and tissues of apolipoprotein E-deficient (Apoe A therosclerosis is the leading cause of cardiovascular disease worldwide. Defined as chronic inflammation of the artery wall, its progression from fatty streaks to more complex lesions and plaque rupture involves a complicated interplay between many different cell types and cytokine networks. Both innate and adaptive immune responses have been shown to regulate local and systemic inflammation during atherogenesis. 1,2 T cells are found within the adventitia of normal/noninflamed vessels as a result of a constitutive T-cell homing into the aorta. 3 Atherosclerosis-prone conditions accelerate T-cell recruitment into the aorta of apolipoprotein E-deficient (Apoe Ϫ/Ϫ ) mice in both the early and advanced stages of atherosclerosis. 3 The majority of aortic T cells are T-cell receptor ␣␤ ϩ CD4 ϩ cells, with few CD8 ϩ and ␥␦ ϩ T cells present. 1,4 Of the CD4 ϩ T cells, T helper 1 (Th1) cells predominate over T helper 2 (Th2) cells during early lesion formation and respond with an elevated production of interferon (IFN)-␥ and interleukin (IL)-6. In the later stages of the disease, a switch to a Th2 response and IL-4 production is evident in the atherosclerotic lesions of Apoe Ϫ/Ϫ mice. 5 Clinical Perspective on p 1755IL-17A is a member of the IL-17 family, which includes IL-17A, IL-17B, IL-17C, IL-17D, IL-17E, and IL-17F. 6 Many lymphocyte subsets secrete IL-17A in response to cytokine or monoclonal antibody stimulation, including CD4 ϩ ␣␤ ϩ (Th17 cells) CD8 ϩ , CD4 Ϫ CD8 Ϫ ␣␤ low , natural killer T cells, and ␥␦ ϩ T cells. 7 The expression of IL-17A is low under normal/noninflamed conditions, in which ␥␦ ϩ T cells are the largest IL-17A-producing T-cell subset. 6 In several murine models of autoimmune diseases, including multiple sclerosis, inflammatory bowel disease, and arthritis, serum IL-17A levels are elevated, and the T helper 17 (Th17) cell population is expanded and plays a highly pathogenic role. 8 Conversely, IL-17A is a protective cytokine in host responses against extracellular pathogens through the induction of proinflammatory cytokines such as IL-6, tumor

We examined the hypothesis that stromal fibroblasts modulate the ability of endothelial cells (EC) to recruit lymphocytes in a site-specific manner. PBL were perfused over HUVEC that had been cultured with fibroblasts isolated from the inflamed synovium or the skin of patients with rheumatoid arthritis or osteoarthritis, or from normal synovium, with or without exposure to the inflammatory cytokines TNF-α+IFN-γ. Fibroblasts from inflamed synovium, but no others, caused unstimulated HUVEC to bind flowing lymphocytes. This adhesion was supported by α4β1-VCAM-1 interaction and stabilised by activation of PBL through CXCR4–CXCL12. Antibody neutralisation of IL-6 during co-culture effectively abolished the ability of EC to bind lymphocytes. Cytokine-stimulated EC supported high levels of lymphocyte adhesion, through the presentation of VCAM-1, E-selectin and chemokine(s) acting through CXCR3. Interestingly, co-culture with dermal fibroblasts caused a marked reduction in cytokine-induced adhesion, while synovial fibroblasts had variable effects depending on their source. In the dermal co-cultures, neutralisation of IL-6 or TGF-β caused partial recovery of cytokine-induced lymphocyte adhesion; this was complete when both were neutralised. Exogenous IL-6 was also found to inhibit response to TNF-α+IFN-γ. Normal stromal fibroblasts appear to regulate the cytokine-sensitivity of vascular endothelium, while fibroblasts associated with chronic inflammation bypass this and develop a directly inflammatory phenotype. Actions of IL-6 might be pro-inflammatory or anti-inflammatory, depending on the local milieu.

Key Points• EBV infection leads to PRMT5 overexpression and global epigenetic changes that are essential to drive B-lymphocyte transformation.• Highly selective PRMT5 inhibitors represent a novel, first-in-class drug that restores critical regulatory checkpoints in lymphoma cells.Epigenetic events that are essential drivers of lymphocyte transformation remain incompletely characterized. We used models of Epstein-Barr virus (EBV)-induced B-cell transformation to document the relevance of protein arginine methyltransferase 5 (PRMT5) to regulation of epigenetic-repressive marks during lymphomagenesis. EBV 1 lymphomas and transformed cell lines exhibited abundant expression of PRMT5, a type II PRMT enzyme that promotes transcriptional silencing of target genes by methylating arginine residues on histone tails. PRMT5 expression was limited to EBV-transformed cells, not resting or activated B lymphocytes, validating it as an ideal therapeutic target. We developed a first-in-class, small-molecule PRMT5 inhibitor that blocked EBV-driven B-lymphocyte transformation and survival while leaving normal B cells unaffected. Inhibition of PRMT5 led to lost recruitment of a PRMT5/p65/HDAC3-repressive complex on the miR96 promoter, restored miR96 expression, and PRMT5 downregulation. RNA-sequencing and chromatin immunoprecipitation experiments identified several tumor suppressor genes, including the protein tyrosine phosphatase gene PTPROt, which became silenced during EBV-driven B-cell transformation. Enhanced PTPROt expression following PRMT5 inhibition led to dephosphorylation of kinases that regulate B-cell receptor signaling. We conclude that PRMT5 is critical to EBV-driven B-cell transformation and maintenance of the malignant phenotype, and that PRMT5 inhibition shows promise as a novel therapeutic approach for B-cell lymphomas. (Blood. 2015;125(16):2530-2543

Recent data indicate that transforming growth factor-beta1 (TGF-beta1) can act to promote tumour progression in the late stages of carcinogenesis. The mechanism by which this occurs is unknown although a ligand-induced epithelial-mesenchymal transition (EMT) is thought to be important. In this study, we demonstrate that active Ras is required for TGF-beta1-induced EMT in human keratinocytes and that epidermal growth factor (EGF) can substitute for mutant Ras. EMT was reversed by the removal of TGF-beta1. Under conditions of TGF-beta1-induced EMT, cells were growth inhibited by the ligand resulting in G1 arrest. In cells containing normal Ras, TGF-beta1-activated ERK and p38 mitogen-activated protein kinases (MAPKs), and levels of activation were further increased by co-treatment with EGF. Inhibition of MAPK pathways and Smad2/3 signalling blocked the induction of EMT by TGF-beta1. Further, inhibition of the AP-1 transcriptional complex by [6]-Gingerol, or by the ectopic expression of JDP2, blocked TGF-beta1-induced EMT and conversely, stimulation of AP-1 by 12-O-tetradecanoylphorbol 13-acetate (TPA) substituted for EGF in the induction of EMT by TGF-beta1 in cells containing normal Ras. The presence of oncogenic Ras, the treatment of cells with EGF, or the treatment of cells with TPA to activate AP-1, potentiated TGF-beta1-induced Smad-dependent transcription, an effect that was attenuated by the inhibition of MAPKs and AP-1. The results demonstrate that active Ras and TGF-beta1 co-operate to reversibly induce EMT in human keratinocytes by mechanisms that involve MAPKs, Smad2/3 and AP-1. Further we demonstrate that MAPK/AP-1 signalling enhances Smad transcriptional activity under conditions associated with TGF-beta1-induced EMT.

Chromosome Conformation Capture, or 3C, is a pioneering method for investigating the three-dimensional structure of chromatin. 3C is used to analyze long-range looping interactions between any pair of selected genomic loci. Most 3C studies focus on defined genomic regions of interest that can be up to several hundred Kb in size. The method has become widely adopted and has been modified to increase throughput to allow unbiased genome-wide analysis. These large-scale adaptations are presented in other articles in this issue of Methods. Here we describe the 3C procedure in detail, including the appropriate use of the technology, the experimental set-up, an optimized protocol and troubleshooting guide, and considerations for data analysis. The protocol described here contains previously unpublished improvements, which save time and reduce labor. We pay special attention to primer design, appropriate controls and data analysis. We include notes and discussion based on our extensive experience to help researchers understand the principles of 3C-based techniques and to avoid common pitfalls and mistakes. This paper represents a complete resource and detailed guide for anyone who desires to perform 3C.

Objective. Rheumatoid arthritis (RA) is classically thought of as a Th1, T lymphocyte-driven disease of the adaptive immune system. However, cells of the innate immune system, including neutrophils, are prevalent within the diseased joint, and accumulate in large numbers. This study was undertaken to determine whether cells of the rheumatoid stromal microenvironment could establish an inflammatory environment in which endothelial cells are conditioned in a diseasespecific manner to support neutrophil recruitment.Methods. Human umbilical vein endothelial cells (ECs) and fibroblasts isolated from the synovium or skin of RA patients were established in coculture on opposite sides of porous transwell filters. After 24 hours of EC conditioning, the membranes were incorporated into a parallel-plate, flow-based adhesion assay and levels of neutrophil adhesion to ECs were measured.Results. ECs cocultured with synovial, but not skin, fibroblasts could recruit neutrophils in a manner that was dependent on the number of fibroblasts. Antibody blockade of P-selectin or E-selectin reduced neutrophil adhesion, and an antibody against CD18 (the ␤2 integrin) abolished adhesion. Blockade of CXCR2, but not CXCR1, also greatly inhibited neutrophil recruitment. Interleukin-6 (IL-6) was detectable in coculture supernatants, and both IL-6 and neutrophil adhesion were reduced in a dose-dependent manner by hydrocortisone added to cocultures. Antibody blockade of IL-6 also effectively abolished neutrophil adhesion.Conclusion. Synovial fibroblasts from the rheumatoid joint play an important role in regulating the recruitment of inflammatory leukocytes during active disease. This process may depend on a previously unsuspected route of IL-6-mediated crosstalk between fibroblasts and endothelial cells.

Three-dimensional genome structure plays an important role in gene regulation. Globally, chromosomes are organized into active and inactive compartments while, at the gene level, looping interactions connect promoters to regulatory elements. Topologically associating domains (TADs), typically several hundred kilobases in size, form an intermediate level of organization. Major questions include how TADs are formed and how they are related to looping interactions between genes and regulatory elements. Here we performed a focused 5C analysis of a 2.8 Mb chromosome 7 region surrounding CFTR in a panel of cell types. We find that the same TAD boundaries are present in all cell types, indicating that TADs represent a universal chromosome architecture. Furthermore, we find that these TAD boundaries are present irrespective of the expression and looping of genes located between them. In contrast, looping interactions between promoters and regulatory elements are cell-type specific and occur mostly within TADs. This is exemplified by the CFTR promoter that in different cell types interacts with distinct sets of distal cell-type-specific regulatory elements that are all located within the same TAD. Finally, we find that long-range associations between loci located in different TADs are also detected, but these display much lower interaction frequencies than looping interactions within TADs. Interestingly, interactions between TADs are also highly cell-type-specific and often involve loci clustered around TAD boundaries. These data point to key roles of invariant TAD boundaries in constraining as well as mediating cell-type-specific long-range interactions and gene regulation.

The proinflammatory cytokine IL-17A, mainly produced by specialized T cells, plays an important homeostatic role in regulating neutrophil production and blood neutrophil counts. This review will assemble and discuss the evidence for this function of IL-17A-producing cells, which are collectively called neutrophil-regulatory T cells or Tn cells. IL-17A-producing lymphocytes are most abundant in the mesenteric lymph node, where they account for 0.15% of all lymphocytes. About 60% of the Tn cells are gammadelta T cells, about 25% NKTlike cells, and less than 15% are CD4 T cells. These latter cells are also known as T-17 or ThIL-17 cells, a subset of Tn cells that also plays an important role in autoimmune diseases. IL-17A produced by Tn cells regulates the production of G-CSF, which in turn promotes the proliferation of promyelocytes and maturation of neutrophils. This homeostatic mechanism plays an important role in normal physiology and in host defense against bacterial infections. This review is aimed at highlighting the important role of IL-17A-producing T cells at the interface between the adaptive and innate immune system.