Summarizing techniques that combine three non-parametric scores to detect disease-associated 2-way SNP-SNP interactions

Identifying susceptibility genes that influence complex diseases is extremely difficult because loci often influence the disease state through genetic interactions. Numerous approaches to detect disease-associated SNP-SNP interactions have been developed, but none consistently generates high-quality results under different disease scenarios. Using summarizing techniques to combine a number of existing methods may provide a solution to this problem. Here we used three popular non-parametric methods—Gini, absolute probability difference (APD), and entropy—to develop two novel summary scores, namely principle component score (PCS) and Z-sum score (ZSS), with which to predict disease-associated genetic interactions. We used a simulation study to compare performance of the non-parametric scores, the summary scores, the scaled-sum score (SSS; used in polymorphism interaction analysis (PIA)), and the multifactor dimensionality reduction (MDR). The non-parametric methods achieved high power, but no non-parametric method outperformed all others under a variety of epistatic scenarios. PCS and ZSS, however, outperformed MDR. PCS, ZSS and SSS displayed controlled type-I-errors (< 0.05) compared to GS, APDS, ES (> 0.05). A real data study using the genetic-analysis-workshop 16 (GAW 16) rheumatoid arthritis dataset identified a number of interesting SNP-SNP interactions.     

In Vivo Optical Imaging of Brain Tumors and Arthritis Using Fluorescent SapC-DOPS Nanovesicles

We describe a multi-angle rotational optical imaging (MAROI) system for in vivo monitoring of physiopathological processes labeled with a fluorescent marker. Mouse models (brain tumor and arthritis) were used to evaluate the usefulness of this method. Saposin C (SapC)-dioleoylphosphatidylserine (DOPS) nanovesicles tagged with CellVue Maroon (CVM) fluorophore were administered intravenously. Animals were then placed in the rotational holder (MARS) of the in vivo imaging system. Images were acquired in 10° steps over 380°. A rectangular region of interest (ROI) was placed across the full image width at the model disease site. Within the ROI, and for every image, mean fluorescence intensity was computed after background subtraction. In the mouse models studied, the labeled nanovesicles were taken up in both the orthotopic and transgenic brain tumors, and in the arthritic sites (toes and ankles). Curve analysis of the multi angle image ROIs determined the angle with the highest signal. Thus, the optimal angle for imaging each disease site was characterized. The MAROI method applied to imaging of fluorescent compounds is a noninvasive, economical, and precise tool for in vivo quantitative analysis of the disease states in the described mouse models.     

类风湿性关节炎治疗药物进展

类风湿性关节炎是常见的自身免疫性疾病,可引起关节肿痛、畸形以及不同程度的残疾,影响了患者的生活质量。随着对发病机制的深入研究,出现了越来越多的治疗类风湿性关节炎的药物,依据发展的时间及原理,共分为五代:第一代是非甾体类抗炎药物;第二代是糖皮质激素;第三代是改变病情药(慢作用抗风湿药);第四代是以α肿瘤坏死因子(TNF-α)抑制剂为主的早期生物制剂;第五代为直接针对T细胞发生作用的新型生物制剂。其中第四代和第五代的生物制剂是近年来治疗类风湿性关节炎的新型药物,与传统药物相比体现了明显的优势,具有广泛的应用前景。本文对类风湿性关节炎的发病机制进行简要阐述,重点对类风湿性关节炎治疗药物的新进展进行综述。     

CD4~+CD25~+Treg细胞在类风湿关节炎中的研究进展

调节性T细胞(Tregs)是近年来发现的一群具有免疫调节作用的CD4+T细胞亚群,如Th3、Tr1细胞等。因其能够产生多种具有免疫抑制作用的细胞因子而发挥其免疫负调节作用,不但在维持机体自身耐受方面发挥重要作用,在预防自身免疫性疾病方面也占据重要位置。其中CD4+CD25+Treg因其具有独特的作用方式及功能特征,而被学者广泛关注。近年来,关于CD4+CD25+Treg在类风湿关节炎(rheumatoid arthritis,RA)发病机制中的作用以及在RA治疗方面的应用也越来越受到人们的关注,认为其数目减少或功能失调与RA发病密切相关。RA是一种以关节破坏为主要表现的慢性炎症性疾病,病理早期主要表现为毛细血管生成,滑膜增生,后期主要表现为炎性细胞浸润,血管翳形成,并出现关节软骨以及骨的破坏,最终导致关节畸形及功能障碍。本文现将CD4+CD25+Treg与RA的研究进展做一综述。     

Enforced Expression of Roquin Protein in T Cells Exacerbates the Incidence and Severity of Experimental Arthritis

To investigate the role of Roquin, a RING-type ubiquitin ligase family member, we used transgenic mice with enforced Roquin expression in T cells, with collagen-induced arthritis (CIA). Wild-type (WT) and Roquin transgenic (Tg) mice were immunized with bovine type II collagen (CII). Arthritis severity was evaluated by clinical score; histopathologic CIA severity; proinflammatory and anti-inflammatory cytokine levels; anti-CII antibody levels; and populations of Th1, Th2, germinal center B cells, and follicular helper T cells in CIA. T cell proliferation in vitro and cytokine levels were determined to assess the response to CII. Roquin Tg mice developed more severe CIA and joint destruction compared with WT mice. Production of TNF-α, IFN-γ, IL-6, and pathogenic anti-collagen CII-specific IgG and IgG2a antibodies was increased in Roquin Tg mice. In addition, in vitro T cell assays showed increased proliferation and proinflammatory cytokine production in response to CII as a result of enforced Roquin expression in T cells. Furthermore, the Th1/Th2 balance was altered by an increased Th1 and decreased Th2 population. These findings suggest that overexpression of Roquin exacerbates the development of CIA and that enforced expression of Roquin in T cells may promote autoimmune diseases such as CIA.     

Flow cytometric analysis of phospho-p38 mitogen-activated kinase (MAPK): p38 MAPK does not mediate the effect of adalimumab on peripheral T cell cytokine production in rheumatoid arthritis

Background: The therapeutic effect of TNFα inhibition in rheumatoid arthritis (RA) is accompanied by an altered peripheral T cell cytokine profile, but the underlying mechanisms are not well known. In CD4+ T cells, TNF signalling includes the p38 MAP kinase (MAPK) pathway, which is also involved in proliferation and production of IL-4 and IFNγ. Methods: Phosphorylation of p38 MAPK was analysed flow cytometrically in peripheral blood mononuclear cells (PBMC) from healthy individuals and RA patients before and after adalimumab therapy. Cytokine production by CD3/CD28-stimulated PBMC was measured in the supernatant. Results: Despite a transient activation of p38 MAPK in response to cellular stress from the cell separation, a significant decrease of spontaneous p38 MAPK phosphorylation was observed after adalimumab, compared to RA patients with active disease. Brief stimulation with TNFα/IL-1β significantly activated p38 MAPK after but not before adalimumab therapy. In CD3/CD28-stimulated PBMC, significantly less p38 MAPK activation and increased IFNγ production were observed after adalimumab therapy. Conclusion: In rheumatoid arthritis, adalimumab therapy decreases the phosphorylation of p38 MAPK except for its response to TNF/IL-1, while enhancing the production of IFNγ. This suggests that p38 MAPK is not directly involved in the effect of TNF inhibition on cytokine production.     

Small interfering RNA targeting CD81 ameliorated arthritis in rats

CD81 belongs to a family of cell-surface protein (tetraspanin) known as one of the up-regulated elements in rheumatoid arthritis synoviocytes. In this study, the therapeutic effect of small interfering RNA targeting CD81 (siCD81) was examined by in vivo electroporation method. Treatment with siCD81 significantly ameliorated paw swelling of collagen-induced arthritic (CIA) rats. In histological examination, hypertrophy of synovium, bone erosion, and degeneration of articular cartilage were milder in rats treated with siCD81 than in the control group and the non-specific siRNA group. Expression of synoviolin, a rheumatoid regulator, was suppressed by siCD81. Thus, therapeutic intervention by targeting CD81 may be used in the treatment of rheumatoid arthritis.     

Temporospatial expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in mouse antigen-induced arthritis

Several lines of evidence speak for an important role of matrix metalloproteinases (MMPs) in the development of progressive joint destruction. To better understand the role of MMPs and their tissue inhibitors (TIMPs) in this process, we have used the antigen-induced arthritis model to study the temporospatial expression of several MMPs and TIMPs during the progression of arthritis. Arthritis was induced by a single intra-articular injection of methylated bovine serum albumin (mBSA) into one or both knee joints of adult mice previously immunised against mBSA. Samples were collected at 3, 7, 21 and 42 days after induction of arthritis for histology and RNA extraction, and analysed by Northern hybridisation, histochemistry and immunohistochemistry for production of several MMPs and TIMPs −1, −2 and −3. A systematic analysis of MMP and TIMP mRNA levels in mouse knee joints demonstrated a general upregulation of both MMPs and TIMPs during progression of arthritis. Upregulation of MMP-9, −13 and −14 coincided with the advancement of cartilage degeneration, but the expression patterns of MMP-9 and −13 also followed the course of synovial inflammation. TIMPs were steadily upregulated throughout the examination period. Immunohistochemical localisation of MMPs and TIMPs suggested the synovium to be the major source of MMP and TIMP production in arthritis, although articular cartilage chondrocytes also showed an increased production of both MMPs and TIMPs.     

T-cell recognition of differentially tolerated epitopes of cartilage proteoglycan aggrecan in arthritis

Proteoglycan (PG) aggrecan, a major macromolecular component of cartilage, is highly immunogenic; it induces arthritis in genetically susceptible BALB/c mice. The present study maps the T-cell epitope repertoire of cartilage PG by identifying a total of 27 distinct T-cell epitopes. An epitope hierarchy, accounting for the different effector functions of PG-specific T cells, and determinant spreading, has been found. T-cell responses to four epitopes were associated with arthritis induction. Some of the T-cell epitopes were full T-cell activators, whereas a number of subdominant and cryptic epitopes proved to be partial activators in vitro, inducing either cytokine secretion or T-cell proliferation, but not both. A few T-cell epitopes of the core protein of cartilage PG were clearly recognized by T cells in PG-immunized arthritic animals, but the corresponding peptides did not induce T-cell responses when injected into naive BALB/c mice; thus these T-cell epitopes were designated as "conditionally immunogenic."