David Gibson

Biomarkers in rheumatology, now and in the future

This review examines the biomarker development process by using rheumatic disorders as the disease model for discussion. We evaluate the current role of biomarkers in the practice of rheumatology and discuss their likely role in the future. We define the essential components of the biomarker development pipeline and discuss the issue of fitness for purpose, i.e. what the biomarker(s) might offer in a clinical setting. As a component of this review we also highlight several emerging technologies that are beginning to provide practical solutions to support biomarker validation. In the process, we highlight some scenarios where additional biomarkers would add considerable value to clinical practice, and we review appropriate methods for each. We also emphasize some important but infrequently discussed considerations, including the need for protein variant verification. Ultimately, the adroit application of the methods of proteomics will transform the practice rheumatology and allow personalized clinical practice to become a reality.

DNA methylation profiling in inflammatory bowel disease provides new insights into disease pathogenesis

BACKGROUND AND AIMS Inflammatory bowel diseases (IBDs) are heterogeneous disorders with complex aetiology. Quantitative genetic studies suggest that only a small proportion of the disease variance observed in IBD is accounted for by genetic variation, indicating a potential role for differential epigenetic regulation in disease aetiology. The aim of this study was to assess genome-wide DNA methylation changes specifically associated with ulcerative colitis (UC), Crohns disease (CD) and IBD activity. METHODS DNA methylation was quantified in peripheral blood mononuclear cells (PBMCs) from 149 IBD cases (61 UC, 88 CD) and 39 controls using the Infinium HumanMethylation450 BeadChip. Technical and functional validation was performed using pyrosequencing and the real-time polymerase chain reaction. Cross-tissue replication of the top differentially methylated positions (DMPs) was tested in colonic mucosa tissue samples obtained from paediatric IBD cases and controls. RESULTS A total of 3196 probes were differentially methylated between CD cases and controls, while 1481 probes were differentially methylated between UC cases and controls. There was considerable (45%) overlap between UC and CD DMPs. The top-ranked IBD-associated PBMC differentially methylated region (promoter region of TRIM39-RPP2) was also significantly hypomethylated in colonic mucosa from paediatric UC patients. In addition, we confirmed TRAF6 hypermethylation using pyrosequencing and found reduced TRAF6 gene expression in PBMCs of IBD patients. CONCLUSIONS Our data provide new insights into differential epigenetic regulation of genes and molecular pathways, which may contribute to the pathogenesis and activity of IBD.

Validation of Protein Biomarkers to Advance the Management of Autoimmune Disorders

Despite the anticipated boom stemming from proteomic investigations, the rate at whichnovel protein biomarkers are introduced into clinical practice has remained static over thepast 20 years. The reality is that approaches to both discover and validate proteinbiomarkers remain inadequate, and consequently, many areas of medicine, including thebroad field of autoimmune disorders, remain deprived of the tools essential for the optimalmanagement of patients. Most importantly, there is a huge backlog of candidate biomarkersthat are yet to undergo thorough investigation and validation to assess their clinical utility.A recent assessment of the situation has estimated that although many tens of thousands ofpublications claim biomarker discoveries, there are roughly only 100 routinely used inclinical practice (Poste, 2011).This chapter reviews the potential applications of protein biomarkers to manageautoimmune diseases with a special focus on the transition from the biomarker discoverythrough to validation phases using proteomic strategies. We emphasize the importance ofcareful review of the discovery data, the critical roles of protein isoform verification, and theessential features of targeted and thorough validation. Ultimately, when these factors areappropriately considered and implemented, we are optimistic that autoimmune disorderscan be transformed by omics technologies and personalized practice can become a reality.

Sa1761 Anti-TNF Therapy Switches on CD39+ FoxP3 Tregs in Association With Symptomatic and Endoscopic Remission in IBD

BACKGROUND & AIMS: Interferon gamma (IFNγ) responses and distinct CD8+ T cell transcriptional signatures can be linked to clinical manifestations of inflammatory bowl disease (IBD). CD39 is an ectonucleotidase and is typically associated with CD4+ T regulatory memory cells, which have the capacity to generate immunosuppressive adenosine. However, immunomodulatory effects of CD39 expression on CD8+ T cells, as in IBD, remain unknown. METHODS:CD39+CD8+ T cells were purified from peripheral blood (PB) and lamina propria (LP) of patients with Crohns disease. Phenotypic features and functions of CD39+CD8+ T cells were assessed by flow cytometry and immunoblotting. RESULTS: CD39 expressing CD8+ T cells of patients with Crohns disease are IFNγ-producing cells, and exhibited type 1 CD8+ T cell (Tc1) properties. CD3 and CD28-mediated synergistic stimulation of CD8+ T cells augment CD39 expression, boost reactive oxygen species (ROS) generation, and increase IFNγ production. CD39+CD8+ T cells preferentially express CD28, and exhibit robust ROS-JNK/NFkB signals and IFNγ production. Decreases in ROSmediated by inhibitors of NADPH oxidases (NOX) or knockdown of gp91phox (NOX2) in CD8+ T cells abrogate effects of TCR ligation, and decrease both CD39 expression and IFNγ production. Curiously, CD39+CD8+ T cells inhibit IFNγ production by CD39-CD8+ T cells via generation of adenosine, which is operational via the paracrine expression of Adenosine 2A (ADORA2A) receptor. CONCLUSIONS: CD8+ Tc1 cells express CD39, which is further boosted by cell activation and ROS, which in turn limit IFNg responses by these cells. Strategies to regulate ROS signal cascades and adenosine-mediated effects might have therapeutic potential in the treatment of Crohns disease.