Characteristics of human rheumatoid synovial and normal blood dendritic cells. Retention of class II major histocompatibility complex antigens and accessory function after short-term culture

Identification of Diagnostic Biomarkers, Immune Infiltration Characteristics, and Potential Compounds in Rheumatoid Arthritis

Aims

This study is aimed at investigating the pathogenesis of rheumatoid arthritis (RA) by identifying key biomarkers, associated immune infiltration, and small-molecule compounds using bioinformatic analysis.

Methods

Six datasets were obtained from the Gene Expression Omnibus database, and the batch effect was adjusted. Functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyse differentially expressed genes (DEGs). Furthermore, candidate small-molecule drugs associated with RA were selected from the Connectivity Map (CMap) database. The least absolute shrinkage and selection operator regression, support vector machine recursive feature elimination, and multivariate logistic regression analyses were performed on DEGs to screen for RA diagnostic markers. The receiver operating characteristic curve, concordance index, and GiViTi calibration band were the metrics used to assess the diagnostic markers of RA identified in this analysis. The single-sample gene set enrichment analysis was performed to calculate the scores of infiltrating immune cells and evaluate the activities of immune-related pathways. Finally, the correlation between screening markers and RA diagnosis was determined.

Results

A total of 227 DEGs were identified. Functional enrichment analysis and KEGG revealed that DEGs were enriched by the immune response. CMap analysis identified 11 small-molecule compounds with therapeutic potential for RA. In gene expression, the activities of 13 immune cells and 12 immune-related pathways significantly differed between patients with RA and healthy controls. DPYSL3 and SPP1 had the potential to diagnose RA. SPP1 expression was positively correlated with DPYSL3 in 11 immune cells and 10 immune-related pathways.

Conclusion

This study comprehensively analysed DEGs and immune infiltration and screened for potential diagnostic markers and small-molecule compounds of RA.

Enumeration and phenotypical analysis of distinct dendritic cell subsets in psoriatic arthritis and rheumatoid arthritis

Dendritic cells (DCs) comprise heterogeneous subsets of professional antigen-presenting cells, linking innate and adaptive immunity. Analysis of DC subsets has been hampered by a lack of specific DC markers and reliable quantitation assays. We characterised the immunophenotype and functional characteristics of psoriatic arthritis (PsA)-derived and rheumatoid arthritis (RA)-derived myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to evaluate their potential role in arthritis. Circulating peripheral blood (PB) pDC numbers were significantly reduced in PsA patients (P = 0.0098) and RA patients (P = 0.0194), and mDCs were significantly reduced in RA patients (P = 0.0086) compared with healthy controls. The number of circulating mDCs in RA PB was significantly inversely correlated to C-reactive protein (P = 0.021). The phenotype of both DC subsets in PsA PB and RA PB was immature as compared with healthy controls. Moreover, CD62L expression was significantly decreased on both mDCs (PsA, P = 0.0122; RA, P = 0.0371) and pDCs (PsA, P = 0.0373; RA, P = 0.0367) in PB. Both mDCs and pDCs were present in PsA synovial fluid (SF) and RA SF, with the mDC:pDC ratio significantly exceeding that in matched PB (PsA SF, P = 0.0453; RA SF, P = 0.0082). pDCs isolated from RA SF and PsA SF displayed an immature phenotype comparable with PB pDCs. RA and PsA SF mDCs, however, displayed a more mature phenotype (increased expression of CD80, CD83 and CD86) compared with PB mDCs. Functional analysis revealed that both SF DC subsets matured following toll-like receptor stimulation. pDCs from PB and SF produced interferon alpha and tumour necrosis factor alpha on TLR9 stimulation, but only SF pDCs produced IL-10. Similarly, mDCs from PB and SF produced similar tumour necrosis factor alpha levels to TLR2 agonism, whereas SF mDCs produced more IL-10 than PB controls. Circulating DC subset numbers are reduced in RA PB and PsA PB with reduced CD62L expression. Maturation is incomplete in the inflamed synovial compartment. Immature DCs in SF may contribute to the perpetuation of inflammation via sampling of the inflamed synovial environment, and in situ presentation of arthritogenic antigen.

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.

Complement receptors in HIV infection

The complement system plays an important role in the antimicrobial defense of the organism. Its components recognize a large variety of pathogens and target them for destruction, either directly by formation of a membrane attack complex or indirectly by recruiting phagocytic cells. In addition, it has several functions in cell activation, clearance of immune complexes, control of inflammatory reactions, chemotaxis and autoimmunity. For mediation of all these tasks of the complement system, complement receptor molecules on the cell surface play a key role. Current knowledge on structure, function, signal transduction and associated molecules is briefly summarized here. The role of complement receptors for human immunodeficiency virus (HIV)-associated pathogenesis is ambiguous and varies depending on cell type. On the one hand, complement receptors support the infected host to manage HIV infection and to defend itself, at least partially, against viral spreading throughout the organism. Such complement receptor-mediated supporting mechanisms are activation of immune cells and lysis of viral particles and infected host cells. On the other hand, HIV employs complement receptors to intrude more easily into various cell types, to become localized into lymph follicles and to activate viral replication in latently infected cells. This review summarizes the complex interaction of virus and complement receptors in HIV infection for different cell types.

Lymphoid and non-lymphoid cells in the adenoid of children with otitis media with effusion: a comparative study

We characterized on immuno- and enzymecytochemical level the lymphoid and non-lymphoid cells in the adenoid of children with upper respiratory tract infections (URI) and otitis media with effusion (OME) and compared these with the adenoid of children with URI without OME and with the adenoid of 'healthy' children and adults. Besides macrophages and dendritic cells we also showed the presence of MHC class II positive, ciliated, epithelial cells. These non-lymphoid cells were present in all adenoids. However, their number was less than 1% of all cells. We found no difference in lymphocyte subsets from children with URI + OME compared with those from children with URI alone. These two groups showed a significant decrease of CD8-positive (suppressor/cytotoxic) cells and a slight increase in CD22-positive B cells in comparison to 'healthy' children. No difference was found in percentages of CD4-positive (helper/inducer) cells. The localization of the lymphoid subsets in adenoids of children with URI and/or OME did not differ from those of 'healthy' children and adults.

Dendritic cells in human blood and synovial exudates

Dendritic cells from human blood and synovial exudates are distinct from other leukocytes and are homogeneous by several criteria. Morphologically, their most prominent feature is numerous veils. Phenotypically, dendritic cells lack the surface antigens that identify monocytes, T cells, B cells, and NK cells. Human dendritic cells strongly express class I and class II MHC products, and have a distinct array of integrin and adhesin molecules. In many systems, dendritic cells are potent stimulators of T cell function. In the allogeneic mixed leukocyte reaction, for example, dendritic cells are 30-100 times more efficient than other cells in presenting transplantation antigens, for the induction of DNA synthesis, cytokine release, and generation of cytotoxic T cells. In addition, dendritic cells can induce the long-term clonal growth of T lymphocytes. Although dendritic cells are a minor subpopulation in human blood, new isolation protocols are available that permit efficient isolation and enrichment to > 90%.

Increased expression of HLA-DQ antigens by interstitial cells and endothelium in the synovial membrane of rheumatoid arthritis patients compared with reactive arthritis patients

We investigated cellular phenotypes and expression of class II major histocompatibility complex antigens on endothelium and cellular infiltrates in synovium from patients with rheumatoid arthritis (RA) or reactive arthritis, using an indirect immunoperoxidase technique. The RA specimens showed synovial lining layer hypertrophy and several focal accumulations of lymphocytes, both of which were absent in the reactive arthritis synovium. The percentage of cells expressing monocyte/macrophage markers was significantly higher in RA specimens. The percentages of cells expressing B and T cell markers were similar in both diseases. There was no significant difference in the expression of HLA-DR or DP by endothelium in the 2 diseases, but a marked increase in expression of HLA-DQ by endothelium was observed in the RA synovium versus that from patients with reactive arthritis. This overexpression of HLA-DQ was also seen in the interstitial cells of RA patients compared with reactive arthritis patients. In the reactive arthritis synovium, a significant population of cells (30%) was noted to be HLA-DR positive, and negative for macrophage and lymphocyte markers. Some of these cells had a dendritic morphology. The coexpression of HLA-DQ and HLA-DR may play an important role in antigen presentation and disease chronicity in RA.

Inflammatory synovial T cells in different activity subgroups of patients with rheumatoid arthritis and juvenile rheumatoid arthritis

Mononuclear cells were eluted from synovial membranes of 39 patients with rheumatoid arthritis and 12 patients with juvenile rheumatoid arthritis. A considerable cell loss, about 50% or more, was seen during the various isolation steps. The CD4/CD8 ratio just after enzyme treatment (stage I) was significantly higher than at later stages, i.e. after removal of adherent cells (stage II, p less than 0.05) and after Isopaque Ficoll gradient centrifugation (stage III, p less than 0.01). This indicates a selective loss of CD4+ cells during isolation. In addition, stages I and II had higher CD4/CD8 ratios than peripheral blood of normal controls (p less than 0.01 and p less than 0.03), but not significantly higher than in peripheral blood of patients (p greater than 0.05). The CD4/CD8 ratio in eluted synovial membrane cells did not differ between patients with high and patients with low disease activity (p greater than 0.05). No correlation was found between any of the CD4/CD8 ratios and individual disease activity variables. Furthermore, a laboratory activity index and a disease outcome index were determined for each patient and no correlation was found between these indices and the CD4/CD8 ratios.

Rheumatoid lymphoid dendritic cells--characteristics and functions

Dendritic cells have been isolated from peripheral blood and inflamed synovial tissue and synovial fluid of patients with rheumatoid arthritis and from normal peripheral blood. Synovial and blood dendritic cells are strongly positive for CD45 and MHC class II antigens, and lack almost all other mononuclear cell markers. Thus, in most respects they have the same characteristics as lymphoid dendritic cells in mice. Synovial and blood dendritic cells are very potent accessory cells for T lymphocyte responses, and much more effective than monocytes. Synovial dendritic cells also spontaneously produce interleukin 1. The accessory function is inhibited by an antibody to interleukin 1. Synovial dendritic cells may thus be critical for starting and perpetuating the chronic inflammation seen in rheumatoid arthritis.

B lymphocytes, B cell clones and rheumatoid factor antibodies in rheumatoid inflammation

This report focuses on the B lymphocytes and plasma cells in rheumatoid inflammation, and discusses the major autoantibodies in the pathogenetic mechanisms, i.e. the rheumatoid factor (RF) antibodies. We describe ways of raising human hybridomas that produce RF antibodies in rheumatoid arthritis (RA) in order to elucidate how these antibodies differ from the RF antibodies that are part of the normal immune response in man and animals, and from those in diseases other than RA, e.g. in M-components seen in mixed cryoglobulinaemia and in Waldenström's macroglobulinaemia. The preliminary results of these studies are presented and discussed.