Alteration of the cellular response to interleukin-1 beta by SV40 large T antigen in rheumatoid synovial fibroblasts

CC and CXC chemokines play key roles in the development of polyomaviruses related pathological conditions

It has been reported that polyomaviruses are the microbes which can be a cause of several human pathological conditions including cancers, nephropathy, progressive multifocal leukoencephalopathy and gynaecological disease. Although investigators proposed some mechanisms used by the viruses to induce the disorders, the roles played by chemokines in the pathogenesis of polyomaviruses infections are yet to be clarified. This review article investigated recent studies regarding the roles played by chemokines in the pathogenesis of the polyomaviruses infections. The research in the literature revealed that CXC chemokines, including CXCL1, CXCL5, CXCL8, CXCL9, CXCL10, CXCL11, CXCL12 and CXCL16, significantly participate in the pathogenesis of polyomaviruses. CC chemokines, such as CCL2, CCL5 and CCL20 also participate in the induction of the pathological conditions. Therefore, it appears that CXC chemokines may be considered as the strategic factors involved in the pathogenesis of polyomaviruses.

Evaluation of SV40-transformed synovial fibroblasts in the study of rheumatoid arthritis pathogenesis

The SV40 T antigen has been used to generate immortalized cells from rheumatoid arthritis (RA) synovial fibroblasts (RASFs) that are commonly used in lieu of primary RASFs. In the current study, we investigated the effect of stimulation by tissue necrosis factor alpha (TNF-α) and interleukin 17 (IL-17) on primary and immortalized RASFs in order to gauge the appropriateness of the use of immortalized RASFs, the MH7A cell line, in the study of RA pathogenesis. Changes in the levels of secretion and expression of 8 proteins associated with RA upon stimulation were assessed by multiplex immunoassay. IL-17 stimulation had a minimal impact on protein secretion and expression for primary and immortalized cells. Basic fibroblast growth factor (FGF-2) was not detectable for the primary cells but was detectable for the immortalized cells. In contrast, monocyte chemoattractant protein 1 (MCP-1) was detectable for primary cells but was undetectable for immortalized cells. In general, protein expression and secretion by cells stimulated with TNF-α were significantly increased. For primary cells, several proteins were below the limit of detection for unstimulated cells and cells stimulated with IL-17, while levels for TNF-α-stimulated cells were within the detectable range. For the same proteins, expression was observed for immortalized cells, regardless of stimulation, suggestive of constitutive activation of the NF-κB signaling pathway. The current study therefore provides strong evidence that immortalized and primary RASFs differ in regard to protein expression and secretion and therefore may not be appropriate for use in the study of RA pathogenesis.

Key regulatory molecules of cartilage destruction in rheumatoid arthritis: an in vitro study

Background

Rheumatoid arthritis (RA) is a chronic, inflammatory and systemic autoimmune disease that leads to progressive cartilage destruction. Advances in the treatment of RA-related destruction of cartilage require profound insights into the molecular mechanisms involved in cartilage degradation. Until now, comprehensive data about the molecular RA-related dysfunction of chondrocytes have been limited. Hence, the objective of this study was to establish a standardized in vitro model to profile the key regulatory molecules of RA-related destruction of cartilage that are expressed by human chondrocytes.

Methods

Human chondrocytes were cultured three-dimensionally for 14 days in alginate beads and subsequently stimulated for 48 hours with supernatants from SV40 T-antigen immortalized human synovial fibroblasts (SF) derived from a normal donor (NDSF) and from a patient with RA (RASF), respectively. To identify RA-related factors released from SF, supernatants of RASF and NDSF were analyzed with antibody-based protein membrane arrays. Stimulated cartilage-like cultures were used for subsequent gene expression profiling with oligonucleotide microarrays. Affymetrix GeneChip Operating Software and Robust Multi-array Analysis (RMA) were used to identify differentially expressed genes. Expression of selected genes was verified by real-time RT-PCR.

Results

Antibody-based protein membrane arrays of synovial fibroblast supernatants identified RA-related soluble mediators (IL-6, CCL2, CXCL1–3, CXCL8) released from RASF. Genome-wide microarray analysis of RASF-stimulated chondrocytes disclosed a distinct expression profile related to cartilage destruction involving marker genes of inflammation (adenosine A2A receptor, cyclooxygenase-2), the NF-κB signaling pathway (toll-like receptor 2, spermine synthase, receptor-interacting serine-threonine kinase 2), cytokines/chemokines and receptors (CXCL1–3, CXCL8, CCL20, CXCR4, IL-1β, IL-6), cartilage degradation (matrix metalloproteinase (MMP)-10, MMP-12) and suppressed matrix synthesis (cartilage oligomeric matrix protein, chondroitin sulfate proteoglycan 2).

Conclusion

Differential transcriptome profiling of stimulated human chondrocytes revealed a disturbed catabolic–anabolic homeostasis of chondrocyte function and disclosed relevant pharmacological target genes of cartilage destruction. This study provides comprehensive insight into molecular regulatory processes induced in human chondrocytes during RA-related destruction of cartilage. The established model may serve as a human in vitro disease model of RA-related destruction of cartilage and may help to elucidate the molecular effects of anti-rheumatic drugs on human chondrocyte gene expression.

Interleukin-1beta stimulates interleukin-8 production and gene expression in synovial cells from human temporomandibular joint

PURPOSE

The aims of the present study were to isolate and characterize cultured synovial cells from human temporomandibular joint (TMJ) specimens and to investigate the effect of interleukin (IL)-1beta on IL-8 production and gene expression in those cells.

MATERIALS AND METHODS

Synovial cells (HTS cells) were isolated from TMJ synovial tissues using an outgrowth method and then primary cultured. The cells were examined for cell-specific markers of fibroblast, macrophage, and dendritic cells using immunocytochemistry. HTS cells were then treated with IL-1beta, and amounts of IL-8 were measured by enzyme-linked immunosorbent assay. IL-8 production and expression were also investigated using immunocytochemistry and a reverse transcription-polymerase chain reaction method.

RESULTS

HTS cells were positive for the fibroblast-specific markers, such as vimentin and propyl 4-hydroxylase. The macrophage or dendritic cell markers and HLA class II antigen were negative. Furthermore, IL-1beta enhanced IL-8 production in HTS cells in a time- and dose-dependent manner and stimulated IL-8 gene expression.

CONCLUSIONS

HTS cells may provide important advantages for studies of the cellular and molecular mechanisms in the TMJ. In addition, we found that IL-1beta stimulated IL-8 production through an increase in IL-8 gene expression in HTS cells, which may be associated with the increase of infiltrating inflammatory cells seen in the synovial membrane of TMJ disorders.

Role of nuclear factor kappaB in synovial inflammation

The evaluation of molecular pathways has revealed novel insights into the pathophysiology of rheumatoid arthritis in the last several years. Gene transcription factors such as nuclear factor kB (NFkB) are activated by extracellular signals or cell-to-cell interactions that are converted into intracellular activation signals through receptor molecules located in the cell membrane. The number of known genes being translated after NFkB activation is increasing steadily. These genes includes cytokines, chemokines, growth factors, cellular ligands, and adhesion molecules. Because many of these genes are part of the pathogenesis of RA, there is considerable interest in the evaluation of the synovium-specific effects of NFkB to unveil its potential for future therapeutic strategies. The goal is to evolve these strategies from the therapies that have a wide spectrum of effects and side effects into rheumatoid arthritis-specific therapies designed to inhibit distinct molecular pathways within the synovium.

Induction of nitric oxide production by bovine mammary epithelial cells and blood leukocytes

A recent study from our laboratory has shown that significant amounts of nitric oxide are released by somatic cells recovered during endotoxin-induced mastitis. The present study was undertaken to investigate which cell type(s) among milk somatic cell population can produce nitric oxide under inflammatory conditions. Nitric oxide release from mammary epithelial cell lines and from bovine neutrophils and monocytes extracted from blood was measured in response to cytokines and Escherichia coli lipopolysaccharides. An epithelial cell line isolated from bovine mammary gland, FbE cells, was found to release nitric oxide after exposure to interleukin-1beta. This nitric oxide production was completely abolished by addition of L-N6-(1-iminoethyl) lysine, a potent inducible nitric oxide synthase inhibitor. Bovine monocytes produced nitric oxide in response to recombinant bovine interferon-gamma alone or in combination with E. coli lipopolysaccharides. In these cells, nitric oxide release was reduced by the addition of inducible nitric oxide synthase inhibitors L-N6-(1-iminoethyl) lysine and aminoguanidine. Lipopolysaccharides and recombinant bovine interferon-gamma increased nitric oxide synthase mRNA in neutrophils, but nitric oxide release could not be detected under any of the experimental conditions used. These results show that bovine epithelial cells and mononuclear phagocytes produce nitric oxide under inflammatory conditions and suggest that these cell populations are responsible for nitric oxide release observed during mastitis.

Activation of synoviocytes

The evaluation of molecular pathways has revealed various novel insights into rheumatoid arthritis pathophysiology during the past year. In addition, there is an increasing tendency toward analysis not merely of a single mechanism but rather of data addressing a substantial part of the cascade of events leading to cellular activation. Because synovial fibroblasts are key cells involved in joint destruction, this review outlines the events that trigger or inhibit the crucial pathways leading to their aggressive behavior. Major topics include cellular and humoral interactions (frequently modulated by cytokines), intracellular signaling and upregulation of gene transcription, and the deleterious effects on articular homeostasis.

Involvement of Thioredoxin in Rheumatoid Arthritis: Its Costimulatory Roles in the TNF-α-Induced Production of IL-6 and IL-8 from Cultured Synovial Fibroblasts

Thioredoxin (TRX) is a cellular reducing catalyst induced by oxidative stress and is involved in the redox regulation of transcription factors such as NF-κB. We found that the serum TRX concentration was elevated in patients with rheumatoid arthritis (RA) as compared with values from healthy individuals and patients with osteoarthritis (33.6 ± 35.1 vs 11.8 ± 6.6 ng/ml, p < 0.01). Moreover, the TRX concentration in the synovial fluid (SF) was much more elevated in RA patients than in osteoarthritis patients (103.4 ± 53.3 vs 24.6 ± 17.4 ng/ml, p < 0.001). Multiple regression analysis revealed that the serum C-reactive protein value was better correlated with the linear combination of SF TNF-α and SF TRX values than with SF TNF-α alone, suggesting that TRX might play a subsidiary role in the rheumatoid inflammation. We thus examined the effect of TRX on the TNF-α-induced IL-6 and IL-8 production using rheumatoid synovial fibroblast cultures. The extents of IL-6 and IL-8 production in response to TNF-α were greatly augmented by TRX as compared with TNF-α alone. TRX alone did not have such effects. We also found that TRX appeared to accelerate the nuclear translocation of NF-κB, a major transcriptional regulator for production of IL-6 and IL-8 on stimulation with TNF-α. Consistent with these findings, the IκBα phosphorylation at Ser32 and its subsequent degradation in response to TNF-α was facilitated by TRX. These findings indicate that the elevated TRX concentration in SF of RA patients might be involved in the aggravation of rheumatoid inflammation by augmenting the NF-κB activation pathway.