Objective: To evaluate the possible role of activation‐induced, T cell–derived, and chemokine‐related cytokine (ATAC)/lymphotactin (Lptn) in the pathogenesis of rheumatoid arthritis (RA).Methods: ATAC/Lptn levels in serum and synovial fluid samples were measured by sandwich enzyme‐linked immunosorbent assay. Expression of messenger RNA for ATAC/Lptn in synovial tissues was analyzed by reverse transcription–polymerase chain reaction (PCR) and by in situ hybridization, and was quantitated by real‐time PCR. The phenotype of peripheral blood mononuclear cells (PBMCs) expressing ATAC/Lptn was analyzed by intracellular cytokine staining and flow cytometry.Results: Levels of ATAC/Lptn were similar in sera and synovial fluids from RA patients (n = 20) and osteoarthritis controls (n = 15). In phorbol myristate acetate/ionomycin–stimulated PBMCs, ATAC/Lptn expression was detected in CD8+ T cells and in a significantly increased proportion of CD4+,CD28− T cells from RA patients as compared with healthy controls. In synovial tissues, ATAC/Lptn was predominantly localized in CD3+ T cells in the sublining layer. Lymphocytes, synovial macrophages, and, unexpectedly, fibroblast‐like synoviocytes (FLS) were identified as major target cells for ATAC/Lptn in RA synovium, as determined by analysis of the ATAC/Lptn receptor XCR1. In vitro, ATAC/Lptn stimulation of FLS resulted in a marked down‐regulation of matrix metalloproteinase 2 production.Conclusion: These data indicate that in RA synovium, ATAC/Lptn is mainly produced by T cells. Considering its function as a lymphocyte‐specific chemoattractant, ATAC/Lptn might be a key modulator for T cell trafficking in the pathogenesis of RA. In addition, functional studies suggest that ATAC/Lptn may exert additional immunomodulatory effects in RA.

Introduction: The introduction of tumor necrosis factor-alpha (TNF-α) antagonists has substantially improved patient’s clinical outcome in rheumatoid arthritis (RA). However, nearly 20% to 40% of RA patients do not respond to anti-TNF-α treatment strategies. To identify valid predictors of TNF-α antagonist response in RA, serum proteome profiles from responders (R) and non-responders (NR) to etanercept, a soluble recombinant TNF-α receptor/IgG Fc fusion protein receptor, were compared in a prospective cohort study. Methods: In this clinical study 50 RA patients with inadequate response to conventional DMARDs were included and treated with etanercept. The primary efficacy endpoint was response according to the European League against Rheumatism (EULAR) improvement criteria. Serum samples collected prior to initiation and after six months of etanercept therapy were cleared of the most abundant major proteins by immunoaffinity chromatography. After separation by two-dimensional differential gel electrophoresis (2D-DIGE) and identification by mass spectrometry (MS) data were validated by Western blot analysis. Results: After six months of etanercept treatment 62% (n = 31) of RA patients achieved response. Haptoglobin-α1 (Hp-α1) and -α2 (Hp-α2) and vitamin D-binding protein (VDBP) were found to be significantly upregulated in responder sera (P ≤0.02) at study entry. In contrast, apolipoprotein C-III (ApoC-III) showed significantly higher levels in non-responders (P = 0.0162). At study end ApoA-II, Hp-α1, Hp-α2 and VDBP were identified to be expressed at significantly higher levels (P <0.05) in responder sera. Conclusions: By application of clinical proteomics in immunodepleted sera we could identify and validate for the first time Hp-α1, -α2, VDBP and ApoC-III as potential biomarkers for prediction of etanercept drug response in RA.

Statins, such as atorvastatin (ATV), are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors known to exert lipid-lowering but also anti-inflammatory, effects. In this study, we analysed the in vitro effects of ATV on peripheral blood mononuclear cells (PBMCs) and fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA), a chronic inflammatory joint disease. PBMCs isolated from 25 RA patients and 20 healthy blood donors were stimulated in vitro with 0.1 microM ATV for 24 h. PBMC cultures were analysed for cell surface markers to characterize T-cell subtypes (CD4, CD8, CD69, HLA-DR) by flow cytometry and for T helper cell type 1 (Th1) and type 2 (Th2) cytokines [interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-10] in culture supernatants by enzyme-linked immunosorbent assay (ELISA). Furthermore, RNA isolated from ATV-stimulated RA-FLS pre- and post-ATV stimulation was analysed by microarray and quantitative reverse transcription polymerase chain reaction (RT-PCR). Flow cytometric analysis of T-cell subsets revealed no significant differences for CD4, CD8, CD69, and HLA-DR surface marker expression of PBMCs in RA patients and healthy controls after ATV stimulation. However, the proportion of IFN-gamma expressing CD4+ T cells and the IFN-gamma cytokine concentrations in culture supernatants were significantly reduced in T-cell cultures from RA patients. In ATV-stimulated FLS a significant downregulation of proinflammatory cytokine (IL-6) and chemokine (IL-8) expression was detected (p<0.001). Our study demonstrates a marked in vitro anti-inflammatory activity of ATV in RA including a systemic effect on a pathogenic CD4+ T-cell population (Th1) and a local effect on FLS. These findings may provide a scientific rationale for statins as add-on therapy in RA.

Cadherins represent a family of calcium‐dependent cell adhesion molecules with an important regulatory function for maintenance of tissue architecture. Alterations of cadherin expression have been demonstrated in the development and progression of different epithelial tumors. In renal cell carcinoma (RCC), the majority of tumors express N‐cadherin and cadherin‐6. Screening a series of 16 RCC cell lines for the expression of different novel type II cadherins by RT‐PCR revealed a complex pattern of cadherin expression: cadherins 6 and 14 were expressed in most of the RCC cell lines, whereas cadherins 11, 12 and 13 could not be detected at all. Interestingly, cadherin‐8, previously shown in mice to be restricted to the CNS and thymus during development, was detected by RT‐PCR, immunofluorescence and in situ hybridization in 4 of 16 RCC cell lines as well as in paraffin sections of the corresponding human RCC biopsies. In normal renal tissue, however, cadherin‐8 could be detected only during the early stages of kidney development. These results suggest that alterations of type II cadherin expression may play a role in RCC development. In particular, cadherin‐8 may be involved in both kidney morphogenesis as well as tumorigenesis in some types of RCC.