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Summary: Arthritis is a common clinical feature of systemic lupus erythematosus (SLE) and is usually non‐erosive, as opposed to rheumatoid arthritis (RA). While RA synovial pathology has been extensively studied, little is known about the pathophysiology of lupus arthritis. Here, we aimed to explore the cytokine and cellular compartments in synovial fluids of SLE patients with arthritic manifestations. Acellular synovial fluid and paired serum samples from SLE patients (n = 17) were analyzed with cytokine bead array for T helper‐associated cytokines. From two SLE patients, synovial fluid mononuclear cells (SFMC) could also be captured and were analyzed by multiparameter flow cytometry to dissect T cell, B cell, monocyte and dendritic cell phenotypes. SLE‐derived SFMC were further stimulated in vitro to measure their capacity for producing interferon (IFN)‐γ and interleukin (IL)‐17A. All patients fulfilled the ACR 1982 classification criteria for SLE. Clinical records were reviewed to exclude the presence of co‐morbidities such as osteoarthritis or overlap with RA. IL‐17A and IL‐6 levels were high in SLE synovial fluid. A clear subset of the synovial CD4+ T cells expressed CCR6+, a marker associated with T helper type 17 (Th17) cells. IL‐17A‐production was validated among CD4+CCR6+ T cells following in‐vitro stimulation. Furthermore, a strong IFN‐γ production was observed in both CD4+ and CD8+ cells. Our study shows high IL‐17A and IL‐6 levels in synovial fluids of patients with lupus arthritis. The Th17 pathway has been implicated in several aspects of SLE disease pathogenesis and our data also point to Th17 involvement for lupus arthritis. [ABSTRACT FROM AUTHOR]

Objectives: To examine whether signs of an active human cytomegalovirus (HCMV) infection are present in affected joints of patients with rheumatoid arthritis (RA). Method: Polymorphonuclear leucocytes (PMNLs) were obtained from synovial fluid (SF) of 17 RA patients and were analysed for HCMV-pp65 and HCMV-immediate early (IE) proteins using the antigenemia assay. Peripheral blood (PB) and SF obtained from these 17 patients and from 17 additional RA patients (n = 34) were tested for HCMV-IE and pp150 DNA with Taqman polymerase chain reaction. Plasma samples from the patients were analysed for HCMV-immunoglobulin M (IgM) and immunoglobulin G (IgG) by enzyme-linked immunosorbent assay and compared to 71 healthy gender-matched blood donors. Results: HCMV-pp65 protein was detected in 65% of synovial PMNL samples, but in only 18% of PMNLs from PB. In contrast, HCMV IE protein was not found in any of the analysed PMNL samples. On the DNA level, HCMV-IE and pp150 DNA was detected in SF of 13/32 (41%) and 14/23 (61%) of RA patients, respectively. HCMV-IE and pp150 DNA was also found in 24/33 (73%) and in 16/24 (67%) of PB samples obtained from RA patients, respectively. HCMV IgG seroprevalence was 76% in RA patients as well as in healthy controls, while only one RA patient was positive for specific IgM. Conclusions: HCMV pp65 antigen was found in PMNLs from SF of RA patients, indicating an active infection in the affected joint. Future studies are needed to determine whether HCMV infection can aggravate the inflammatory process in these patients. [ABSTRACT FROM AUTHOR]

Background: Rituximab (RTX) is being used increasingly in anti-neutrophil cytoplasmatic antibody (ANCA)-associated vasculitis (AAV). Late-onset neutropenia (LON) and risks of infections have been observed following RTX therapy in rheumatological diseases including granulomatosis with polyangiitis (GPA) but data on microscopic polyangiitis (MPA) are lacking.Method: We studied the occurrence of LON in 59 AAV (47 GPA/12 MPA) patients treated with RTX. Patient charts were retrospectively reviewed for the occurrence of LON and clinical data were extracted and included in the analysis.Results: Seven of the total 59 patients (11.9%) developed LON after a median time of 86 days (range 56-168 days) since their latest RTX treatment. Of these seven LON patients, 5/47 (10.6%) had a diagnosis of GPA and 2/12 (16.7%) of MPA. Three of the patients developed LON after the first RTX treatment and four had received repeated courses. Five LON patients developed infectious symptoms. Six of the patients were hospitalized. Retreatment with RTX was given in three cases without further LON episodes.Conclusions: LON is a potentially severe side-effect of RTX occurring in both GPA and MPA and may develop after both single and repeated treatment courses. As infections are commonly seen, the condition requires an increased awareness. No predisposing factors for LON were identified. [ABSTRACT FROM AUTHOR]

Proinflammatory CD4+ CD28null T cells are frequently found in the circulation of patients with rheumatoid arthritis ( RA), but are less common in the rheumatic joint. In the present study, we sought to identify functional differences between CD4+ CD28null T cells from blood and synovial fluid in comparison with conventional CD28-expressing CD4+ T cells. Forty-four patients with RA, displaying a distinct CD4+ CD28null T cell population in blood, were recruited for this study; the methylation status of the IFNG locus was examined in isolated T cell subsets, and intracellular cytokine production ( IFN- γ, TNF, IL-17) and chemokine receptor expression ( CXCR3, CCR6 and CCR7) were assessed by flow cytometry on T cells from the two compartments. Circulating CD4+ CD28null T cells were significantly more hypomethylated in the CNS-1 region of the IFNG locus than conventional CD4+ CD28+ T cells and produced higher levels of both IFN- γ and TNF after TCR cross-linking. CD4+ CD28null T cells from the site of inflammation expressed significantly more CXCR3 and CCR6 compared to their counterparts in blood. While IL-17A production could hardly be detected in CD4+ CD28null cells from the blood, a significant production was observed in CD4+ CD28null T cells from synovial fluid. CD4+ CD28null T cells were not only found to differ from conventional CD4+ CD28+ T cells in the circulation, but we could also demonstrate that synovial CD4+ CD28null T cells showed additional effector functions ( IL-17 coproduction) as compared to the same subset in peripheral blood, suggesting an active role for these cells in the perpetuation of inflammation in the subset of patients having a CD28null population. [ABSTRACT FROM AUTHOR]

Many genetic variants associate with the risk of developing rheumatoid arthritis (RA); however, their functional roles are largely unknown. Here, we aimed to investigate whether the RA-associated serotonin receptor 2A (HTR2A) haplotype affects T-cell and monocyte functions. Patients with established RA (n=379) were genotyped for two single-nucleotide polymorphisms (SNPs) in the HTR2A locus, rs6314 and rs1328674, to define presence of the risk haplotype for each individual. Patients with and without the RA-associated TC haplotype were selected and T-cell and monocyte function was monitored following in vitro stimulations with staphylococcal enterotoxin B and lipopolysaccharide (LPS) using multiparameter flow cytometry. Within the cohort, 44 patients were heterozygous for the TC haplotype (11.6%) while none were homozygous. Upon stimulation, T cells from TC-carrier patients produced more proinflammatory cytokines (tumor necrosis factor alpha (TNF-α), interleukin-17 (IL-17) and interferon gamma (IFN-γ)) and monocytes produced higher levels of TNF-α compared with patients carrying the non-TC haplotype (P<0.05 and 0.01, respectively). Such cytokine production could be inhibited in the presence of the selective 5-HT2 receptor agonist (2,5-Dimethoxy-4-iodoamphetamine, DOI); interestingly, this effect was more pronounced in TC carriers. Our data demonstrate that association of RA with a distinct serotonin receptor haplotype has functional impact by affecting the immunological phenotype of T cells and monocytes. [ABSTRACT FROM AUTHOR]

Regulatory T cells have recently been implicated in a number of human diseases, including rheumatoid arthritis. To investigate whether the presence of CD25+CD4+ regulatory T cells is a general finding in arthritic joints, synovial fluid of patients with different rheumatic diseases such as undifferentiated arthritides, systemic rheumatic diseases and reactive arthritis were investigated for the presence of such cells. In 95% of the patients, a higher frequency of CD25brightCD4+ T cells was found in synovial fluid as compared with peripheral blood. Both in vitro suppression experiments and FOXP3 mRNA analysis confirmed these cells to be natural regulatory T cells. Together with our previous data, we conclude that arthritic joints, irrespective of precise diagnosis and disease duration, are enriched with natural regulatory T cells. These results suggest that suppressor cells migrate to and/or multiply at the sites of inflammation as part of the immune responses' effort to combat injurious inflammation. [ABSTRACT FROM AUTHOR]

CD4+ T cells lacking the costimulatory molecule CD28 have been described both in elderly individuals and in chronic inflammatory disorders, one being rheumatoid arthritis (RA). We, in this study, provide a comprehensive characterization of cell surface markers on and function of such CD28nullCD4+ T cells, as well as correlations with clinical parameters. We conclude that of all surface markers associated with these cells, only CD57 and CD11b are expressed on the majority of them. This CD28null population occurred in one-third of patients with RA and was independent of clinical characteristics. The population was persistent and expanded in peripheral blood, but was excluded from the joint in most patients. Functionally, CD28nullCD4+ T cells were potent effector memory cells with regard to their proliferation and cytokine-secretion profiles. This capacity correlated with a hitherto unpublished surface phenotype, the cells being uniformly CCR7– and CD43high. Moreover, a new terminally differentiated CD45RA+CCR7– population of CD4+ T cells was identified. We would like to suggest that in the unbalanced immune system of patients with autoimmune disease and chronic infection an expanded CD28nullCD4+ T-cell population able to secrete high levels of cytokines is likely to contribute to disease manifestations. [ABSTRACT FROM AUTHOR]

Collagen type II (CII) induced arthritis (CIA) in mice is an experimental model for rheumatoid arthritis. Induction with non-self (e.g. human) CII induces severe arthritis whereas the mice are less susceptible to induction with self CII (i.e. mouse). To analyse whether an autoimmune response to human CII can develop and is pathogenic the authors have established transgenic mice expressing human CII in cartilage and backcrossed them into two different gene backgrounds susceptible to CIA (DBA/1 and C3H.Q). The transgenic human CII expression was restricted to cartilage and did not disturb cartilage morphology or lead to chondrodystrophy. In addition, development of stress-induced arthritis was not affected by the transgene. The cartilage specific expression of human CII reduced, but did not eliminate, the susceptibility to CIA irrespective of the species source (human, bovine, chick, rat) of CII used for immunization. A common denominator between these heterologous CII in comparison with mouse CII is the previously defined CII 256-270 epitope. An expression level dependent T-cell tolerance was seen in this epitope as well as to the entire CII. However, all human transgenic mouse lines could still mount significant autoreactive T- and B-cell responses. Approximately 10% of the transgenic mice developed arthritis after immunization with human CII. These findings show, therefore, that cartilage-located human CII induce tolerance but can nevertheless be a target for development of arthritis. [ABSTRACT FROM AUTHOR]