Molecular mechanisms of cell recruitment to inflammatory sites: general and tissue-specific pathways.
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Cell Adhesion Molecules↗
Biomedical subjects
C Pitzalis
Publications and source records attributed to C Pitzalis.
Association of CXCL13 and CCL21 expression with the progressive organization of lymphoid-like structures in Sjögren's syndrome.
OBJECTIVE: Ectopic lymphoneogenesis can occur in the salivary glands of Sjögren's syndrome (SS) patients and is associated with local antigen-driven B cell responses, autoantibody formation, and potential lymphomatous transformation. CXCL13 and CCL21 have been identified in salivary glands, but their role in ectopic lymphoneogenesis in SS remains unclear. This study aimed to evaluate the microanatomic association between CXCL13 and CCL21 expression and the acquisition of lymphoid features in periductal foci. METHODS: Salivary glands from 37 SS patients and 9 chronic sialadenitis patients were analyzed by immunohistochemistry for T cell/B cell segregation, CD21+ follicular dendritic cell networks, and peripheral lymph node addressin (PNAd)-positive high endothelial venules (HEVs) in relationship to the size of the aggregates and the expression of CXCL13 and CCL21 within infiltrating cells, epithelium, and endothelium. RESULTS: Grade 1 aggregates (10-50 lymphocytes) demonstrated predominance of nonorganized CD3+ cells, while grade 2 (>50 lymphocytes) and grade 3 (>50 with germinal centers) showed a progressive increase in CD20+ B cells and T cell/B cell segregation. This higher degree of lymphoid organization was significantly related to an increased expression of CXCL13 within infiltrating cells and PNAd+ HEV-associated CCL21-producing cells. Conversely, no association between lymphoid organization and lymphoid chemokine expression by epithelial cells was observed. CONCLUSION: The acquisition of lymphoid features by inflammatory foci in SS is critically associated with the enlargement of the inflammatory foci and with the expression of CXCL13 and CCL21 within the infiltrate, but is not associated with their expression by epithelial cells. These data strongly support an active participation of CXCL13 and CCL21 in regulating the progressive organization and maintenance of periductal foci.
Adult↗
Current concepts and new developments in the treatment of psoriatic arthritis.
OBJECTIVES: Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy characterized by the association of arthritis with psoriasis. Many agents have been proposed for the treatment of PsA, but their use is based more on clinical experience than on sound scientific evidence. METHODS: We reviewed MedLine up to November 2002, searching for 'psoriatic arthritis', 'drug therapy, 'controlled trials' and 'outcomes' and all possible acronyms for these terms. All relevant papers were then examined in detail. RESULTS: PsA is a condition that runs a variable clinical course. Mild forms can usually be controlled by non-steroidal anti-inflammatory drugs (NSAIDs). Intra-articular glucocorticoid injections are indicated in patients with persistent mono- or oligoarthritis. Patients with severe and progressive articular disease not responsive to NSAIDs should be treated with disease-modifying anti-rheumatic drugs (DMARDs) to prevent joint damage and disability. Currently, methotrexate and sulphasalazine are considered the DMARDs of choice, but the evidence for the use of methotrexate in PsA is still largely empirical, while the clinical benefit induced by sulphasalazine appears to be modest. Other DMARDs proposed for the treatment of PsA include cyclosporin, gold salts and, more recently, leflunomide. However, none of the DMARDs available to date are effective in the treatment of psoriatic pelvispondylitis; in addition, a number of patients with severe peripheral arthritis fail to respond to standard DMARDs. Recently, tumour necrosis factor alpha inhibitors have proved effective in many PsA patients with pelvispondylitis or recalcitrant peripheral synovitis. CONCLUSIONS: None of the current treatments for PsA is curative, but significant clinical amelioration can be achieved in the vast majority of patients. Identification and prompt treatment of patients with severe articular disease is crucial for the achievement of a satisfactory clinical response and the improvement of the long-term outcome.
Anti-Inflammatory Agents, Non-Steroidal↗
Stromal cell-derived factor 1 (CXCL12) induces monocyte migration into human synovium transplanted onto SCID Mice.
OBJECTIVE: The mechanisms by which monocyte/macrophage cells migrate to the joint involve a series of integrated adhesion and signaling events in which chemokines and their receptors are strongly implicated. This study was undertaken to investigate the hypothesis that stromal cell-derived factor 1 (SDF-1), a CXC chemokine (CXCL12), plays a critical role in monocyte/macrophage localization to synovium. METHODS: SDF-1 and CXC receptor 4 (CXCR4) expression in rheumatoid arthritis (RA) and osteoarthritis synovium and graft SDF-1, tumor necrosis factor alpha (TNF alpha), and human and murine vascular markers were examined by immunohistochemistry and double-immunofluorescence. The functional capacity of SDF-1 to modulate monocyte migration into joints was investigated by examining the localization of pro-myelomonocytic U937 cells into synovial tissue transplanted into SCID mice. SDF-1, TNF alpha, or saline was injected into graft sites and response determined by the number of fluorescently labeled U937 cells (injected intravenously) detected in grafts by ultraviolet microscopy. RESULTS: SDF-1 and CXCR4 were highly expressed in CD68+ cells in the RA synovium. SDF-1 induced U937 cell migration in vitro and in vivo in a dose-dependent manner and, in vivo, SDF-1 was more effective than TNF alpha. In contrast to TNF alpha, SDF-1 did not induce intracellular adhesion molecule 1 in transplant microvasculature. Furthermore, intragraft injection of SDF-1 did not up-regulate TNF alpha, or vice versa. CONCLUSION: This study demonstrates, for the first time, that SDF-1 is functional in vivo when injected into synovial grafts. In addition, SDF-1 is more potent than TNF alpha, and its mechanisms of action appear to be autonomous. Therefore, SDF-1 may be an important TNF-independent molecule involved in the migration to and retention of inflammatory effector cells in the joint.
Aged↗
Unmasking the anti-inflammatory cytokine response in rheumatoid synovitis.
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Arthritis, Rheumatoid↗
The role of TNF-alpha in the pathogenesis of inflammation and joint destruction in rheumatoid arthritis (RA): a study using a human RA/SCID mouse chimera.
OBJECTIVE: In order to elucidate which cytokine preferentially stimulates the synovium in patients with rheumatoid arthritis (RA), we investigated the roles of tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) using SCID mice engrafted with human RA tissue (SCID-HuRAg). METHODS: The SCID-HuRAg mice were prepared according to our previously described method. First, SCID-HuRAg mice were treated with chimeric anti-TNF-alpha monoclonal antibody (mAb, 100 microg/mouse) and histological changes were examined 4 weeks after the initial treatment. Secondly, a total of 100 microg of recombinant TNF-alpha or IL-6 (0.6 microg/h) was administered daily to mice using an osmium pump. The histological changes and serum cytokine levels were examined 4 weeks after the initial administration. Human immunoglobulin G (IgG) was administered to mice as a control. RESULTS: Synovial inflammatory cells were significantly decreased after the anti-TNF-alpha mAb treatment; conversely, the degree of synovial inflammation was significantly exacerbated by TNF-alpha administration. The levels of both IL-6 and TNF-alpha in sera were significantly increased by recombinant TNF-alpha administration, while TNF-alpha levels were unchanged by IL-6 administration. This suggests that TNF-alpha controls IL-6 production. Despite the profound changes in inflammation, we found no effects on bone and no articular cartilage damage was produced by TNF-alpha. CONCLUSION: This study provides strong evidence that TNF-alpha is a key molecule in the control of the inflammatory changes that occur in the RA synovium. In addition, TNF-alpha regulates IL-6 production. However, other inflammatory pathways independent of TNF-alpha may contribute to the bone and cartilage damage seen in RA.
Animals↗
[Role of chemokines in the pathogenesis of chronic synovitis during rheumatoid arthritis].
Chemokines play a central role in the pathogenesis of rheumatoid arthritis (RA) synovitis which is characterised by new blood vessel formation, thickening of the lining layer and infiltration of immune cells. The inflammatory infiltrate is generated by a series of events which include the recruitment of leukocytes from the blood stream into the tissue, their local retention and activation to effector cells. All these processes are finely regulated by the interplay of different cell adhesion molecules (CAMs) and chemoattractant factors called chemokines (CK). CK are a superfamily of small proteins that play a crucial role in immune and inflammatory reactions. These chemoattractant cytokines share structural similarities including four conserved cysteine residues which form disulphide bonds in the tertiary structure of the proteins. CK mediate their effects by binding specific receptors (CK-R) characterised by a domain structure which spans the cell membrane seven times and signal through heterotrimeric GPT-binding proteins. Activation of the CK network results in an amplification of the inflammatory cascade and consequently in the progressive destruction of RA joints. The recognition of the central role of CK in inflammation has paved the way to the development of new agents capable of interfering with CK and CK-R. This review will focus in particular on the role of CK in regulating leukocyte trafficking in RA joints.
Arthritis, Rheumatoid↗
The glucocorticoid inhibition of LFA-1 and CD2 expression by human mononuclear cells is reversed by IL-2, IL-7 and IL-15.
Glucocorticoids are agents endowed with powerful immunosuppressive and anti-inflammatory properties partially related to the inhibition of adhesion-related processes. We have previously demonstrated that glucocorticoids inhibit LFA-1 and CD2 expression in human peripheral blood mononuclear cells (PBMC) by down-regulating mRNA steady-state levels. In this study, we investigated whether glucocorticoids could also act indirectly by modulating the effect/function of cytokines whose expression are known to inhibit. To test this hypothesis, we replenished the following cytokines IL-2, IL-7, IL-15, TNF-alpha, IL-1beta, IL-4 and IL-10, in an in vitro PBMC culture system. Our results indicate that only the IL-2Rgamma-chain-dependent cytokines IL-2, IL-7 and IL-15, among the cytokines of this panel, could reverse the inhibition of glucocorticoids on PBMC adhesion molecule expression and the related functions of intercellular aggregation and proliferation. Furthermore, we also demonstrated that IL-2, IL-7 and IL-15 could induce de novo the synthesis of LFA-1 and CD2. Taken together, these data suggest that glucocorticoids inhibit PBMC LFA-1 and CD2 expression not only directly by modulating transcriptional events, but also indirectly through the inhibition of IL-2Rgamma-dependent cytokines.
CD2 Antigens↗
Pathogenesis of rheumatoid arthritis. The role of T cells and other beasts.
The evidence coming from the different experimental approaches reviewed in this article strongly supports the hypothesis that RA is T-cell driven at all stages of the disease. Although the effector phases responsible for the events that lead to joint destruction involve several different cell types, cytokines, and other mediators, T cells still direct operations behind the scenes. Direct experimental proof of this proposition in patients is still lacking, but the development of nondepleting modulating CD4 monoclonal antibodies may provide new tools to test this hypothesis. In this respect, it is encouraging that using one such reagent, we have recently shown that not only did the activity of the disease improve but, more importantly, the inflammatory indices and production of non-T-cell cytokines were reduced. This is not to dissimilar from the results of experiments described in animals, where by blocking synovial T cells, the production of IL-1 beta and TNF alpha could be decreased by more than 90%. From this perspective, it may be predicted that by modulating T cells in the joint, it is possible to achieve our ultimate goal of permanently switching off the disease.
Arthritis, Rheumatoid↗
Role of CD30+ T cells in rheumatoid arthritis: a counter-regulatory paradigm for Th1-driven diseases.
CD30 has been proposed to identify Th0/2-type clones. However, the in vivo relevance of this finding is still a matter of debate, as high serum levels of soluble CD30 have been found in both Th1- and Th2- dominated disorders. Among these, rheumatoid arthritis represents a condition where the Th1 predominance is combined with the presence of CD30(+) T-cell activity, particularly in specific stages of the disease. This article discusses the hypothesis that CD30(+) T cells might play a counter-regulatory role at sites of inflammation in Th1-mediated conditions, such as rheumatoid arthritis.
Animals↗
[Articular involvement in the course of primary hypogammaglobulinemia].
The Authors describe the main features of the most common forms of primary hypogammaglobulinaemia (PH) focusing on the articular involvement. Patients with Bruton's agammaglobulinemia (BA) and common variable immune deficiency (CVID) are predisposed to develop septic arthritis (including arthritis due to atypical microorganisms such as mycoplasma), arthralgia and symmetrical (usually non-erosive) polyarthritis. In BA and CVID complicated by recurrent infections, amyloidosis, which may be itself a cause of arthropathy, can occur. In addition, patients with CVID and selective IgA deficiency show an increased prevalence of juvenile rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome and primary biliary cirrhosis, while patients with selective IgA deficiency are prone to developing seronegative spondylarthropathies, including ankylosing spondylitis. The mainstay of treatment for BA and CVID is replacement therapy with human immunoglobulins. Septic arthritis should be promptly treated with antibiotics, whereas other types of arthritis usually respond well to non-steroidal antiinflammatory medications. In contrast, the second line agents commonly used to treat rheumatoid arthritis do not appear to be beneficial in patients with PH-associated arthritis.
Agammaglobulinemia↗
[Rheumatoid arthritis. Recent findings and new pathogenic concepts].
The etiology of rheumatoid arthritis (RA) is still unknown, and many uncertainties regarding its pathogenetic mechanisms persist. During the past decade, various hypotheses have been advanced, yet none of these has been able to explain the complexity of the disease. In light of the most recent research, a sub-division of the pathogenesis of RA, in four phases, has been proposed. The first phase is that of tissue damage, induced by unknown infective or traumatic factors with the liberation of possible arthrogenic antigens that are presented to the immune system. In the second phase the immune and inflammatory mechanisms should begin to function and, if they are effective, they should determine the resolution of the process; the failure of these mechanisms would create a further amplification of the immuno-inflammation response (the third phase). The fourth phase would then be a chronic inflammatory with progressive articular destruction, as well as anatomical and functional damage. This evolution, in response to common pathogenic agents, is dependent upon a particular hereditary genetic asset (not only the HLA system) that is able to control the production of citokines and also upon the neuroendocrine system. The final outcome of the process is, therefore, determinated by multiple interference between the inflammatory/immune system and other systems that also interact with it (the integrated pathogenetic hypothesis). This hypothesis reflects the complexity of the immune/inflammatory system that must be considered to be an acting part of an integrated network of diverse systems. A better knowledge of these interactions needed for the discovery of potential new therapies for RA.
Arthritis, Rheumatoid↗
CD30+ T cells in rheumatoid synovitis: mechanisms of recruitment and functional role.
High serum levels of soluble CD30 (sCD30) have been reported to better predict the response to second line therapy in rheumatoid arthritis (RA). It is believed that sCD30 is released by CD30+ T cells present in the RA synovium. However, both the mechanism of recruitment to the joint and the functional role of this T cell subset in the pathogenesis of the disease remain unknown. This study confirmed higher levels of sCD30 in the serum and synovial fluid (SF) of RA patients compared with normal controls. However, analysis of mRNA and cell surface CD30 expression showed that CD30+ T cells are detectable in the SF, but not in the synovial membrane. In contrast, T cells expressing the CD30 transcript, but not the surface molecule, were found in the peripheral blood of both RA and normal controls. CD30 surface expression was up-regulated by adhesion and migration through endothelium in vitro and in a delayed-type hypersensitivity model in vivo. Although the great majority of fresh or cloned CD30+ T cells from SF produced both IFN-gamma and IL-4, CD30 expression strictly correlated with IL-4 synthesis in synovial T cell clones. In addition, CD30+ T cell clones also produced high amounts of the anti-inflammatory cytokine IL-10. On this basis, we would like to propose that synovial CD30+ cells may play a role in the control of the inflammatory response. Serum sCD30 may reflect such cell activity and, therefore, explain the previously demonstrated correlation between high sCD30 serum levels and positive response to therapy.
Adult↗
The vascular endothelial system in the pathogenesis of inflammation and systemic rheumatic diseases: relation to the neuroendocrine system.
There is no doubt that the VES plays a central role in the pathogenesis of immune-mediated and inflammatory conditions. Equally, there is no doubt about the strong influence played by the neuroendocrine-immune system on the pathophysiology and homeostasis of the VES. Nevertheless, much remains to be done to unravel the precise mechanisms by which these systems interact in determining the microvascular dysfunction associated with chronic immune-mediated inflammation.
Androgens↗
Tumour necrosis factor-alpha (TNF-alpha) enhances lymphocyte migration into rheumatoid synovial tissue transplanted into severe combined immunodeficient (SCID) mice.
Adhesion mechanisms play a major role in the recruitment of peripheral blood lymphocytes (PBL) which characteristically infiltrate rheumatoid arthritis (RA) synovium and other chronically inflamed tissues. Through a sequential series of complex integrated adhesion and signalling events, 'multistep model of migration', specific subsets of PBL are recruited into inflamed tissues. In this process both leucocyte receptors and microvascular endothelial (MVE) counter-receptors play a critical role. The MVE in particular, during an inflammatory state, is the target of various inflammatory mediators that cause the up-regulation of several cell adhesion molecules (CAM). One of the most important factors known to be a powerful inducer of MVE CAM is TNF-alpha. Conversely, blocking TNF-alpha causes a down-modulation of CAM expression. To test directly the capacity of TNF-alpha to induce cell migration into RA synovium we adapted a model in which synovial grafts were implanted into SCID mice subcutaneously. Using this model we demonstrate that: (i) transplants remain viable and become vascularized and fed by mouse subdermal vessels; (ii) the mouse vasculature connects to the transplant vasculature which maintains the ability to express human CAM; (iii) intragraft injections of TNF-alpha up-regulate the expression of human CAM, following the down-regulation which occurred 4 weeks post-transplantation; and (iv) the up-regulation of graft CAM is associated with increased human PBL migration into the transplants. This study provides direct evidence in vivo of the capacity of TNF-alpha to induce cell migration. In addition, it provides the experimental background for the optimal use of this model.
Animals↗
Are differences in interleukin 10 production associated with joint damage?
OBJECTIVE: Constitutive differences between individuals in cytokine production may determine the variation in the course of inflammatory arthritis. METHODS: The association between interleukin 10 (IL-10) production and joint destruction was studied by comparing IL-10 mRNA content in synovial biopsies from seven patients with destructive joint disease and six patients with non-destructive joint disease. The IL-10 mRNA content was 0.4 +/- 0.6 arbitrary units in erosive joints compared with 2.3 +/- 1.2 arbitrary units in non-erosive joints (P: < 0.03, Mann-Whitney U:-test). As this difference suggested that IL-10 production was associated with joint destruction, we tested whether the IL-10 locus determined the extent of joint damage. RESULTS: Innate differences in IL-10 production are locus-dependent. In line with these data, we showed that innate differences in IL-10 protein production were also present as differences in IL-10 mRNA levels. We tested if polymorphisms in the promoter of IL-10 were associated with the extent of joint damage. DISCUSSION: In a cohort study of female rheumatoid arthritis patients followed for 12 yr, the extent of joint destruction differed significantly between patients with different IL-10 genotypes. In patients with the -1082AA genotype who were studied prospectively, the mean increase in radiographic damage score (modified Sharp score of X-rays of hands and feet) during the first 6 yr was 9 +/- 9 per yr vs 19 +/- 16 per yr for patients with the genotype -1082GG (P: < 0.02). In line with these data, cultures of endotoxin-stimulated whole blood from 158 donors showed that the presence of the allele associated with less joint destruction correlated with slightly higher IL-10 production. CONCLUSIONS: Both the immunogenetic and the synovial biopsies suggest that a variation in IL-10 production is associated with joint destruction.
Adult↗
Do B cells influence disease progression in chronic synovitis? Lessons from primary hypogammaglobulinaemia.
We describe a 62-yr-old male patient with primary hypogammaglobulinaemia (PH) who fulfilled the 1987 American Rheumatism Association/American College of Rheumatology revised diagnostic criteria for rheumatoid arthritis (RA) but, despite persistent symmetrical synovitis, did not develop erosions. Virology studies and blood and synovial fluid (SF) cultures were consistently negative; a search for crystals in the SF was unrevealing. Peripheral blood (PB) B cells were absent, whilst the PB CD3(+) cell count was normal. The ratio of naive (CD45RA(+)) to memory (CD45R0(+)) cells was also normal (1:1) but the CD4:CD8 ratio was reversed. To our knowledge, this is the first report which combines the immunophenotypic analysis of the PB with that of the SF and synovial membrane (SM). This confirmed the absence of B cells and the reversed CD4:CD8 ratio. However, as in other chronic arthropathies, the SF and SM cellular infiltrate consisted almost exclusively of memory T cells, consistent with the preferential localization of this subset to inflamed tissues. This case indicates that synovitis can proceed persistently in the absence of B cells and that the migratory mechanisms of T cells are not altered. However, the case suggests that the absence of B cells and negativity for rheumatoid factor, combined with an increased presence of CD8(+) (suppresser/cytotoxic) T cells in the joint, might contribute to the non-erosive nature of the synovitis.
Agammaglobulinemia↗
CD1 expression in psoriatic and rheumatoid arthritis.
OBJECTIVE: CD1 is a novel class of molecules which present non-protein antigens to T cells. The objective of this study was to evaluate the expression of CD1 in the skin and synovium of patients with psoriatic arthritis (PsA) in comparison with rheumatoid arthritis (RA) and osteoarthritis (OA). METHODS: Paired lesional skin (SK) and synovial membrane (SM) from four PsA patients, paired SK and SM from four RA patients, SM from eight RA and eight OA patients, and normal SK from four volunteers were studied using standard immunohistochemistry. RESULTS: In all PsA and RA skin samples CD1-positive cells were abundantly detected both in the dermis and in the epidermis. However, in the 24 SM examined CD1-positive cells were rarely found. In one patient only with RA, a few CD1a-positive cells were found in the SM. CD1b was scarcely expressed in the lining layer (LL) of five SM and in very few cells in the sublining layer (SL) of 11 SM. CD1c was rarely expressed in the LL of six SM and in very few cells in the SL of 13 SM. CONCLUSION: The paucity of CD1 in the PsA and RA synovium suggests that different subsets of antigen-presenting cells are involved in the pathogenesis of dermatitis and synovitis, respectively.
Adult↗