Immune Complex-mediated Arthritis Research Articles

Collagen Autoantibodies and Their Relationship to CCP Antibodies and Rheumatoid Factor in the Progression of Early Rheumatoid Arthritis.

Serum autoantibodies to cyclic citrullinated peptides (anti-CCP) and rheumatoid factor (RF) are important markers for diagnosis and prognosis of rheumatoid arthritis (RA), but their autoantigens are not cartilage-specific. Autoantibodies to joint-specific type II collagen (CII) also occur in RA, and monoclonal antibodies of similar specificity induce collagen antibody-induced arthritis in animals, but their role in RA is uncertain. We utilized an enzyme-linked immunosorbent assay (ELISA) with the CB10 peptide of CII to compare the frequency of autoantibodies with those of anti-CCP and RF in stored sera from a prospective study of 82 patients with early RA to examine the outcome, defined as remission (n = 23), persisting non-erosive arthritis (n = 27), or erosions (n = 32). Initial frequencies of anti-CB10, anti-CCP and RF were 76%, 54%, and 57% in RA, and 4%, 0%, and 9% in 136 controls. The frequency of anti-CB10 was unrelated to outcome, but anti-CCP and RF increased with increasing severity, and the number of autoantibodies mirrored the severity. We suggest RA is an immune complex-mediated arthritis in which the three antibodies interact, with anti-CII inducing localized cartilage damage and inflammation resulting in citrullination of joint proteins, neoepitope formation, and a strong anti-CCP response in genetically-susceptible subjects, all amplified and modified by RF.

CD55 deposited on synovial collagen fibers protects from immune complex-mediated arthritis.

IntroductionCD55, a glycosylphosphatidylinositol-anchored, complement-regulating protein (decay-accelerating factor), is expressed by fibroblast-like synoviocytes (FLS) with high local abundance in the intimal lining layer. We here explored the basis and consequences of this uncommon presence.MethodsSynovial tissue, primary FLS cultures, and three-dimensional FLS micromasses were analyzed. CD55 expression was assessed by quantitative polymerase chain reaction (PCR), in situ hybridization, flow cytometry, and immunohistochemistry. Reticular fibers were visualized by Gomori staining and colocalization of CD55 with extracellular matrix (ECM) proteins by confocal microscopy. Membrane-bound CD55 was released from synovial tissue with phospholipase C. Functional consequences of CD55 expression were studied in the K/BxN serum transfer model of arthritis using mice that in addition to CD55 also lack FcγRIIB (CD32), increasing susceptibility for immune complex-mediated pathology.ResultsAbundant CD55 expression seen in FLS of the intimal lining layer was associated with linearly oriented reticular fibers and was resistant to phospholipase C treatment. Expression of CD55 colocalized with collagen type I and III as well as with complement C3. A comparable distribution of CD55 was established in three-dimensional micromasses after ≥3 weeks of culture together with the ECM. CD55 deficiency did not enhance K/BxN serum-induced arthritis, but further exaggerated disease activity in Fcgr2b−/− mice.ConclusionsCD55 is produced by FLS and deposited on the local collagen fiber meshwork, where it protects the synovial tissue against immune complex-mediated arthritis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0518-4) contains supplementary material, which is available to authorized users.

SAT0572 The Effect of Interleukin-4 on Mechanical Stress-Induced Protease Expressions by Human Chondrocytes

BackgroundWe previously reported that runt-related transcription factor 2 (RUNX-2) has an important role in regulation of mechanical stress-induced expression of ADAMTS aggrecanases in chondrocytes. Interleukin-4 (IL-4) is an anti-inflammatory cytokine,...

Bcl-2 overexpression ameliorates immune complex-mediated arthritis by altering FcγRIIb expression and monocyte homeostasis

RA is a chronic autoimmune disease characterized by accumulation of inflammatory cells within synovial joints. RA is associated with a failure of apoptosis of infiltrating leukocytes, thought to be a result of overexpression of prosurvival Bcl-2 proteins. Overexpression of Bcl-2 in hematopoietic cells can result in spontaneous autoimmunity. We therefore hypothesized that increased Bcl-2 in the hematopoietic compartment would reduce apoptosis and thereby, exacerbate inflammatory arthritis. Paradoxically, we found that overexpression of Bcl-2 in mice (vav-bcl-2) markedly reduced pathology in antibody-dependent models of RA (CIA and K/BxN serum transfer arthritis). No such protection was observed in a model of CD4(+) T cell-dependent, B cell-independent arthritis (mBSA/IL-1-induced arthritis). In CIA, vav-bcl-2 Tg mice had lower antibody production to CII, which might explain reduced disease. However, Bcl-2 overexpression also reduced passive K/BxN serum transfer arthritis. Overexpression of Bcl-2 caused a monocytosis, with preferential expansion of Ly6C(lo) monocytes and increased expression of the inhibitory receptor for IgG, FcγRIIb, on leukocytes. Skewing of the myeloid cell population, increases in FcγRIIb, and reduced arthritis were independent of the hypergammaglobulinemia found in vav-bcl-2 Tg mice. These data reveal selective effects of the Bcl-2-regulated apoptotic pathway on monocyte differentiation and the expression of FcRs critical for regulation of antibody/immune complex-mediated disease.

Differential MHC Class II Presentation of a Pathogenic Autoantigen during Health and Disease

Glucose-6-phosphate isomerase (GPI) is the target autoantigen recognized by KRN T cells in the K/BxN model of rheumatoid arthritis. T cell reactivity to this ubiquitous Ag results in the recruitment of anti-GPI B cells and subsequent immune complex-mediated arthritis. Because all APCs have the capacity to process and present this autoantigen, it is unclear why systemic autoimmunity with polyclonal B cell activation does not ensue. To this end, we examined how GPI is presented by B cells relative to other immunologically relevant APCs such as dendritic cells (DCs) and macrophages in the steady state, during different phases of arthritis development, and after TLR stimulation. Although all APCs can process and present the GPI:I-A(g7) complex, they do so with different efficiencies. DCs are the most potent at baseline and become progressively more potent with disease development correlating with immune complex uptake. Interestingly, in vivo and in vitro maturation of DCs did not enhance GPI presentation, suggesting that DCs use mechanisms to regulate the presentation of self-peptides. Non-GPI-specific B cells are the weakest APCs (100-fold less potent than DCs) and fail to productively engage KRN T cells at steady state and during arthritis. However, the ability to stimulate KRN T cells is strongly enhanced in B cells after TLR ligation and provides a mechanism whereby polyclonal B cells may be activated in the wake of an acute infection.

Local IL-13 gene transfer prior to immune-complex arthritis inhibits chondrocyte death and matrix-metalloproteinase-mediated cartilage matrix degradation despite enhanced joint inflammation

During immune-complex-mediated arthritis (ICA), severe cartilage destruction is mediated by Fcγ receptors (FcγRs) (mainly FcγRI), cytokines (e.g. IL-1), and enzymes (matrix metalloproteinases (MMPs)). IL-13, a T helper 2 (Th2) cytokine abundantly found in synovial fluid of patients with rheumatoid arthritis, has been shown to reduce joint inflammation and bone destruction during experimental arthritis. However, the effect on severe cartilage destruction has not been studied in detail. We have now investigated the role of IL-13 in chondrocyte death and MMP-mediated cartilage damage during ICA. IL-13 was locally overexpressed in knee joints after injection of an adenovirus encoding IL-13 (AxCAhIL-13), 1 day before the onset of arthritis; injection of AxCANI (an empty adenoviral construct) was used as a control. IL-13 significantly increased the amount of inflammatory cells in the synovial lining and the joint cavity, by 30% to 60% at day 3 after the onset of ICA. Despite the enhanced inflammatory response, chondrocyte death was diminished by two-thirds at days 3 and 7. The mRNA level of FcγRI, a receptor shown to be crucial in the induction of chondrocyte death, was significantly down-regulated in synovium. Furthermore, MMP-mediated cartilage damage, measured as neoepitope (VDIPEN) expression using immunolocalization, was halved. In contrast, mRNA levels of MMP-3, -9, -12, and -13 were significantly higher and IL-1 protein, which induces production of latent MMPs, was increased fivefold by IL-13. This study demonstrates that IL-13 overexpression during ICA diminished both chondrocyte death and MMP-mediated VDIPEN expression, even though joint inflammation was enhanced.

FcγRI Up-Regulation Induced by Local Adenoviral-Mediated Interferon-γ Production Aggravates Chondrocyte Death during Immune Complex-Mediated Arthritis

Using various FcgammaR-deficient mice, we have obtained suggestive evidence that FcgammaRI on macrophages is responsible for severe cartilage destruction during arthritis mediated by immune complexes (ICs). This role of FcgammaRI is pronounced in the presence of activated Th1 cells and a likely Th1 cell-derived cytokine mediating up-regulation of FcgammaRI expression is interferon (IFN)-gamma. We now investigated whether local overexpression of IFN-gamma using an adenoviral vector is able to elevate cartilage destruction during experimental immune complex-mediated arthritis (ICA) and to what extent this process is FcgammaRI-mediated. IFN-gamma overexpression during ICA had no significant effect on the total cell mass infiltrating the knee joint. However, a higher percentage of macrophages expressing markers for a proinflammatory phenotype was found and these macrophages were situated in close proximity of the cartilage surface. Interestingly, cartilage destruction as studied by matrix metalloproteinase (MMP)-mediated proteoglycan damage (VDIPEN expression), chondrocyte death, and erosion was significantly increased. This effect of IFN-gamma was only found in the presence of ICs, as IFN-gamma overexpression during zymosan-induced arthritis, which is not IC-dependent, did not lead to severe cartilage destruction. These results imply a crucial role for ICs and the IgG-binding receptors in the aggravation of cartilage damage by IFN-gamma. Local overexpression of IFN-gamma induced increased FcgammaRI mRNA levels in synovium. To study whether this up-regulation of FcgammaRI mediates aggravation of cartilage destruction, ICA was raised in FcgammaRI(-/-) and their wild-type controls. IFN-gamma resulted in elevated VDIPEN expression, which was still present in FcgammaRI(-/-). Of great interest, chondrocyte death remained low in FcgammaRI(-/-). These results indicate that IFN-gamma overexpression deteriorates cartilage destruction in the presence of ICs and that FcgammaRI is crucial in the development of chondrocyte death.

FcγRI up-regulation induced by local adenoviral-mediated IFN-γ production aggravates chondrocyte death during immune-complex-mediated arthritis

Using various FcγR-deficient mice, we have obtained suggestive evidence that FcγRI on macrophages is responsible for severe cartilage destruction during arthritis mediated by immune complexes (ICs) and Th1 cells. In contrast, in arthritis mediated solely by ICs, FcγRIII seems more important. This suggests that T-cell-mediated FcγRI up-regulation promotes pronounced cartilage destruction. A likely Th1-cell-derived cytokine mediating FcγRI expression is interferon-γ (IFN-γ). In the present study we investigated whether IFN-γ is able to up-regulate cartilage destruction during experimental immune complex-mediated arthritis (ICA) and, if so, whether this mechanism is indeed regulated by FcγRI. IFN-γ was locally overexpressed in the murine knee joint prior to ICA induction by the use of adenoviral vectors. This had no significant effect on joint inflammation as studied by histology. However, irreversible cartilage destruction as studied by the degree of chondrocyte death was markedly enhanced. IFN-γ overexpression resulted in a fivefold increase in chondrocyte death, in comparison with the control group, which had received a control adenoviral vector expressing GFP (AdGFP). To study whether this effect of IFN-γ was related to the presence of ICs, IFN-γ was also overexpressed in a naive joint and during zymosan-induced arthritis, which is an IC-independent arthritis model. No severe cartilage destruction was found, implying a crucial role for ICs and their receptors (FcγRs) in the IFN-γ effect. When IFN-γ was overexpressed in murine knee joints, FcγRI mRNA expression was up-regulated in synovial cells. To prove that the aggravation of chondrocyte death by IFN-γ is indeed FcγRI-mediated, ICA was raised in FcγRI-/-. IFN-γ overexpression did not result in significant elevation of joint inflammation either in FcγRI-/- or their wild-type controls. Interestingly, although IFN-γ was overexpressed, chondrocyte death remained absent in FcγRI-/-, whereas in wild-type controls chondrocyte death was highly increased after IFN-γ overexpression. These results indicate that IFN-γ can aggravate cartilage destruction in an IC-dependent fashion, mediated by FcγRI.

Local overexpression of adeno-viral IL-4 protects cartilage from metallo proteinase-induced destruction during immune complex-mediated arthritis by preventing activation of pro-MMPs

Objective To determine whether IL-4 protects against metalloproteinase-induced cartilage destruction during immune complex mediated arthritis and to elucidate its mechanism.Methods Experimental immune complex arthritis (ICA) was raised by injecting lysozyme into the knee joints of mice which previously were given anti-lysozyme antibodies. Three days before ICA induction, mice were injected into the right knee joint with either IL-4 expressing or empty control recombinant human type 5 adenovirus. Joint inflammation and cartilage destruction (PG depletion, erosion) was measured by histology of total knee joints. Aggrecan breakdown in cartilage caused by metalloproteinases (MMPs) was studied by immunolocalization using anti-VDIPEN antibodies.Results Four days after ICA induction, histological analysis showed comparable exudate and infiltrate in both groups. Depletion of proteoglycans as measured by loss of red staining was also comparable in both groups. IL-4 treatment inhibited MMP-mediated neoepitope expression by 90%. Moreover, cartilage matrix erosion was evident in all animals (10 out of 10 mice) in the control group and significantly diminished (only two out of ten mice) in the IL-4 treated group. Incubation of patellae with APMA, which activates latent MMPs resulted in VDIPEN expression which was not significantly different from control ICA indicating that comparable amounts of latent pro-MMPs are present in IL-4 treated arthritic knee joints.Conclusion This study indicates that during ICA, IL-4 largely prevents MMP-mediated aggrecan breakdown and severe cartilage erosion. IL-4 does not inhibit production of latent MMPs by the chondrocyte but predominantly interferes with its activation.

Uptake of apoptotic leukocytes by synovial lining macrophages inhibits immune complex–mediated arthritis

Previously we have shown that synovial lining macrophages (SLMs) determine the onset of experimental immune complex-mediated arthritis (ICA). During joint inflammation, many leukocytes undergo apoptosis, and removal of leukocytes by SLMs may regulate resolution of inflammation. In this study we investigated binding and uptake of apoptotic leukocytes by SLMs and its impact on the onset of murine experimental arthritis. We used an in vitro model to evaluate phagocytosis of apoptotic cells on chemotaxis. Phagocytosis of apoptotic thymocytes resulted in a significant decrease (58%) of chemotactic activity for polymorphonuclear neutrophils (PMNs). If apoptotic cells were injected directly into a normal murine knee joint, SLMs resulted in a prominent uptake of cells. After ICA induction, electron micrographs showed that apoptotic leukocytes were evidently present in SLMs on days 1 and 2. Injection of apoptotic leukocytes into the knee joint 1 h before induction of ICA significantly inhibited PMN infiltration into the knee joint at 24 h (61% decrease). This study indicates that uptake of apoptotic leukocytes by SLM reduces chemotactic activity and inhibits the onset of experimental arthritis. These findings indicate an important mechanism in the resolution of joint inflammation.

Fc gamma R expression on macrophages is related to severity and chronicity of synovial inflammation and cartilage destruction during experimental immune-complex-mediated arthritis (ICA).

STATEMENT OF FINDINGS: We investigated the role of Fc gamma receptors (Fc gamma Rs) on synovial macrophages in immune-complex-mediated arthritis (ICA). ICA elicited in knee joints of C57BL/6 mice caused a short-lasting, florid inflammation and reversible loss of proteoglycans (PGs), moderate chondrocyte death, and minor erosion of the cartilage. In contrast, when ICA was induced in knee joints of Fc receptor (FcR) gamma-chain(-/-) C57BL/6 mice, which lack functional Fc gamma RI and RIII, inflammation and cartilage destruction were prevented. When ICA was elicited in DBA/1 mice, a very severe, chronic inflammation was observed, and significantly more chondrocyte death and cartilage erosion than in arthritic C57BL/6 mice. The synovial lining and peritoneal macrophages of naïve DBA/1 mice expressed a significantly higher level of Fc gamma Rs than was seen in C57BL/6 mice. Moreover, elevated and prolonged expression of IL-1 was found after stimulation of these cells with immune complexes. Zymosan or streptococcal cell walls caused comparable inflammation and only mild cartilage destruction in all strains. We conclude that Fc gamma R expression on synovial macrophages may be related to the severity of synovial inflammation and cartilage destruction during ICA.

Active Matrix Metalloproteinases Are Present in Cartilage During Immune Complex-Mediated Arthritis: A Pivotal Role for Stromelysin-1 in Cartilage Destruction

The involvement of immune complexes during experimental arthritis in induction of metalloproteinases (MMP)-induced neoepitopes in aggrecan in cartilage, as well as the role of stromelysin-1 (SLN-1) in the induction of this neoepitope, was investigated. Passive immune complex arthritis was induced, and generation of the MMP-specific cleavage product (VDIPEN) was studied by immunolocalization. The role of SLN-1 was studied with use of SLN-1-deficient (SLN-1KO) mice. VDIPEN expression was studied in vitro by exposing the cartilage to IL-1 and subsequent activation of latent MMPs. Immune complex arthritis was characterized by an acute inflammation, with influx of mainly polymorphonuclear cells into the joint cavity. Expression of VDIPEN neoepitopes was consistently found in areas extensively depleted from proteoglycans. SLN-1KO mice did not show expression of the VDIPEN neoepitope, although inflammation and proteoglycan depletion was comparable to wild-type mice. In addition, erosions of cartilage were absent in SLN-1KO mice, but were present in wild-type mice, suggesting an important role for SLN-1 in cartilage destruction. In vitro studies showed that SLN-1 is also pivotally involved in IL-1-induced MMP activity. Stimulated polymorphonuclear neutrophils were able to activate latent MMPs present in the cartilage. Neutrophil elastase was also capable of activating IL-1-induced latent MMPs, which identifies elastase as a possible activator for latent VDIPEN-inducing MMPs. This study suggests that IC are important in the activation of latent MMPs in cartilage, possibly through polymorphonuclear neutrophil activation on the cartilage edge. SLN-1 is a pivotal enzyme in overall MMP-activity in cartilage during immune complex-mediated arthritis.

Monocytes/macrophages rather than PMN are involved in early cartilage degradation in cationic immune complex arthritis in mice.

We investigated the involvement of polymorphonuclear granulocytes (PMN) and monocytes in cartilage degradation in immune complex-mediated arthritis (ICA). ICA induced with lysozyme-antilysozyme in the murine knee joint is characterized by a major influx of PMNs followed by monocytes and marked cartilage proteoglycan (PG) depletion develops within 2 days. Around 60% of 35S-prelabeled PG is lost at day 2. Influx of cells was manipulated using interleukin-1 (IL-1) receptor antagonist (IL-1ra) or antibodies to adhesion molecules. Cellular infiltrate was analyzed on hematoxylin-stained joint sections. Early systemic treatment with IL-1ra highly reduced PMN influx, whereas monocyte influx was hardly diminished. PG loss was not significantly reduced, declining from 62% in controls to 47% in IL-1ra-treated mice. Total blockade of cell influx was found after intravenous treatment with monoclonal antibodies 5C6 (anti-CD11b/CD18:anti-CR3) or NIMP.R14 (25-30 kDa protein mainly present on PMN) and PG loss was reduced to 5-10%. A similar reduction was observed after prior depletion of circulating PMNs with total body irradiation. Because amounts of IL-1 produced in leukopenic and control arthritic joints are comparable, this suggests that IL-1 is only marginally involved in PG loss in the first phase of ICA. This study indicates that monocytes rather than PMN might be involved in PG loss in this form of arthritis, either directly or by local activation of synovial layer cells of the joint.

Pneumococcal Meningitis Complicated by Immune Complex–Mediated Arthritis

Sir—.In a recent issue of the ARCHIVES, Likitnukul et al1 found arthritis to be a complication ofHaemophilus influenzae and Neisseria meningiditisismeningitis in 3% to 4% of cases. Arthritis was not identified, however, in 179 cases of pneumococcal meningitis. We describe herein a patient with pneumococcal meningitis complicated by possible immune complex–mediated Patient Report— A full-term male infant was born by cesarean section because of maternal preeclampsia and cephalopelvic disproportion. Membranes were ruptured for five hours prior to delivery, and there were no signs of maternal or fetal infection. Apgar scores were 8 at both one and five minutes. The infant remained well until the fourth day of life when irritability and a temperaure of 39.5°C Blood and cerebrospinal fluid specimens yieldedStreptococcus pneumoniaesusceptible to penicillin by oxacillin disk testing. Therapy with ampicillin and gentamicin was begun; the latter drug was discontinued the followingy. Repeated blood cultures obtained after two and five days of therapy were sterile, as were cerebrospinal fluid specimens examined after three days of treatment. His condition stabilized and his course