Lymphocyte extracellular matrix interactions. Induction of interferon by connective tissue components

High expression of p21 Waf1 in sarcoid granulomas: a putative role for long-lasting inflammation

In sarcoid granulomas, apoptotic events are reduced, which explains their characteristic long-lasting inflammation. We have described that interferon-gamma (IFN-gamma) inhibits apoptosis in macrophages through the expression of p21(Waf1). Here, we explore the molecular mechanisms involved in the inhibition of apoptosis in sarcoid granulomas. We analyzed skin biopsies from 19 sarcoidosis patients and 16 controls. Total RNA was subjected to semiquantitative reverse transcriptase-polymerase chain reaction analysis. There was no difference found in the expression of proapoptotic (Bax and Bcl-X(s)) or antiapoptotic (Bcl-2 and Bcl-X(L)) genes nor in the expression of the tumor suppressor gene p53. Furthermore, the expression of IFN-gamma and the cdk inhibitors p21(Waf1) and p27(Kip1) were analyzed. IFN-gamma was detected in 37% of the sarcoidosis patients, and controls were negative (P<0.02). In addition, a higher proportion of patients expressing p21(Waf1) (58%) versus controls (12%) was found (P<0.005). There was a significant correlation between the expression of IFN-gamma and p21(Waf1) (r=0.69) and between p21(Waf1) and fibronectin (r=0.65). Finally, using immunohistochemistry, high p21(Waf1) reactivity was observed inside the granuloma. We conclude that the high levels of p21(Waf1) in sarcoidosis may explain the absence of apoptosis in the granuloma and the persistence of inflammation.

Expression of extracellular matrix ligands and receptors in the muscular tissue and draining lymph nodes of mdx dystrophic mice

The mdx mouse, an animal model of Duchenne muscular dystrophy, develops an X-linked recessive inflammatory myopathy. During onset of disease and height of myonecrosis, mdx mice also display important changes in the microenvironment of lymphoid tissues. Draining lymph nodes showed reduced cellularity and atrophy accompanied by intense immunolabeling for fibronectin, laminin, and type-IV collagen. Following clinical amelioration of dystrophy, mdx mice showed enhanced cellularity and a consistent increase in the absolute numbers of CD4(+) and CD8(+) cells expressing alpha4(high) and alpha5(high) extracellular matrix receptors. Furthermore, infiltrating cells in the proximity of myonecrosis expressed alpha4, alpha5, and alpha6 integrin chains during both height of myonecrosis and muscular tissue regeneration. Such results indicate that during distinct phases of muscular dystrophy, altered expression of extracellular matrix ligands and receptors may be influencing myonecrosis by promoting adhesion and migration of mononuclear cells into the altered skeletal muscle and toward local draining lymphoid tissue.

Costimulation of CD28- T cells through CD3 and beta1-integrins induces a limited Th1 cytokine response

The costimulatory molecule CD28 regulates antigen-specific T-cell proliferation and the synthesis of multiple cytokines. The absence of CD28 on a subset of CD8bright+ T cells suggests that these cells may utilize alternative costimulatory pathways or have a limited cytokine response to presented antigen. We used fibronectin, a ligand for the beta1-integrins alpha4beta1 and alpha5beta1, as an alternate costimulatory ligand to assess the functional phenotype of CD8bright+CD28- T cells. CD25 expression was significantly up-regulated in CD8bright+CD28- T cells by immobilized anti-CD3i with fibronectin. Costimulation with fibronectin also significantly augmented anti-CD3i-induced IFN-gamma production only among CD8bright+CD28- T cells. The CD8bright+CD28- T cells did not produce significant IL-2 and IL-10 even in response to maximal stimulation with phorbol myristate acetate and ionomycin. These data support a costimulatory role for ss1-integrins in CD8bright+CD28- T cells and indicate that CD8bright+ CD28- T cells have a restricted Th1 cytokine repertoire.

T cell responses to human type II collagen in patients with rheumatoid arthritis and healthy controls

OBJECTIVE

To study the prevalence of T cell responses to human type II collagen (CII) in patients with rheumatoid arthritis (RA) with or without antibodies to CII, and in healthy controls.

METHODS

Assays were performed to study T cell proliferative responses to CII in peripheral blood from 69 patients with RA (11 with anti-CII antibodies and 58 without) and 28 healthy controls. Further analysis was made of the time course of the response and the epitopic specificity, using peptides derived from the cyanogen bromide 11 (CB11) fragment of CII.

RESULTS

Significant proliferative responses to CII were found in 50% of patients with anti-CII, 5.3% of RA patients without these antibodies, and 35.7% of healthy controls. Responses in RA patients differed from those in healthy controls; the former had kinetics suggestive of a recall response and the latter that of a primary response. Some common epitopes within CB11 were recognized by T cells from patients and controls.

CONCLUSION

Proliferative T cell responses to CII occur in some healthy individuals, suggesting that thymic tolerance for this antigen may be incomplete. Most patients with RA have no evidence of a T cell response to CII, possibly indicating the development of peripheral tolerance to this antigen as a consequence of cartilage breakdown. However, in a minority of patients, T and B cell responses to CII persist, and may contribute to joint damage.

Expression of adhesion molecules and their ligands in contact allergy

Sequential biopsies from skin lesions induced by nickel sulphate and sodium lauryl sulphate, respectively, were investigated with respect to expression of extracellular matrix proteins and adhesion molecules on lymphocytes, endothelial cells, and keratinocytes. The majority of the infiltrating lymphocytes expressed VLA-4, LFA-1, CD44 and ICAM-1, a variable fraction expressed Leu-8 and VLA-5, and few or no cells were positive for VLA-1, VLA-2 and VLA-6. Noteworthy, was that the infiltrating cells showed a substantial amount of fibronectin but relatively small or negligible presence of laminin, collagen type IV, IgG, IgA, IgM, and albumin. The fibronectin was associated with cell bodies as well as the area surrounding infiltrating cells. The number of infiltrating cells was larger in biopsies from nickel-sulphate induced lesions and the infiltrates contained more fibronectin than biopsies from lesions induced by sodium lauryl sulphate. However, at the single-cell level, the expression of VLA antigens, LFA-1, CD44 and ICAM-1 was similar in both groups. The endothelial cells of skin biopsies from nickel-sulphate-induced lesions showed a stronger expression of VCAM-1, ELAM-1 and ICAM-1 compared to biopsies from sodium lauryl sulphate-induced lesions. In the biopsies from nickel sulphate-induced lesions, the keratinocytes showed a tendency to less VLA-6 expression. These results suggest that fibronectin plays a role in lymphocyte extravasation or extravascular lymphocyte migration.

Evidence of intercellular adhesion molecule-1 expression on nasal epithelial cells in acute rhinoconjunctivitis caused by pollen exposure

Rhinoconjunctivitis caused by pollen allergy is characterized by typical signs and symptoms and mucosal infiltration by inflammatory cells during pollen season. It has been recently demonstrated that the adhesion molecule system is deeply involved in cell-to-cell interaction during inflammatory response consequent to allergic reactions. The aim of this study was to evaluate the expression of intercellular adhesion molecule-1 (ICAM-1 or CD54) on nasal epithelial cells, before and during natural seasonal exposure, in 10 allergic patients (Parietaria judaica-sensitized) and in 10 healthy volunteers, correlating this parameter with clinical and cytologic involvement. Nasal epithelial cells of allergic subjects showed a significant expression of CD54 during pollen season (p < 0.001). On the contrary, no CD54 expression was observed out of pollen season. In healthy volunteers no CD54 expression was observed both before and during pollen season. Cytologic evaluation demonstrated an infiltration by eosinophils (mainly activated [EG2+]), (p < 0.001), neutrophils (p < 0.001), and metachromatic cells (p < 0.001) during pollen season only in allergic subjects. Therefore results indicate that seasonal allergic rhinitis is characterized by an infiltration of inflammatory cells correlated with CD54 expression on nasal epithelial cells. This phenomenon is specific, being restricted only to allergic patients during pollen season.

Beta 1 integrin-mediated interaction with extracellular matrix proteins regulates cytokine gene expression in synovial fluid cells of rheumatoid arthritis patients

Inflammatory cytokines have been implicated in the pathogenesis of rheumatoid arthritis (RA), whereas the mechanisms for constitutive production of inflammatory cytokines in affected joints are largely unknown. Recently, integrin-mediated interaction with extracellular matrix (ECM) proteins has been demonstrated to play a role in regulating cytokine production in T cells and monocytes. In this study, we investigated the contribution of the beta 1 integrin-mediated interaction with ECM proteins to the persistent cytokine gene expression in RA synovial fluid mononuclear cells (SFMNC). We examined mRNA expression of 14 cytokines in the SFMNC of three RA patients, which were either fresh or cultured overnight in serum-free medium on ECM-coated plates, by polymerase chain reaction with a panel of oligonucleotide primers specific for each cytokine. The persistent expression of various cytokine mRNA found in fresh SFMNC was maintained after overnight culture in serum-free medium on ECM proteins, especially on laminin (LM), but not on serum albumin. This effect of LM was inhibited by an anti-integrin beta 1 chain (CD29) mAb, as well as by an anti-CD3 mAb, indicating an important role of the beta 1 integrin-mediated interaction with ECM proteins in regulating persistent cytokine gene expression in RA SFMNC, and a key role of T cells in regulating inflammatory monokine production.

Anchorage and lymphocyte function: extracellular matrix substrata control morphogenesis and interleukin production but have minor effects on DNA synthesis

Contact with collagen and fibronectin substrata triggers disruption of aggregates of activated lymphocytes, pseudopodia formation and migration of these lymphocytes onto the substrata. Monoclonal antibodies to the alpha 4 and alpha 5 chains of beta 1-integrins inhibit cell substrate adhesion and aggregate disruption on fibronectin substrata. A rat monoclonal antibody to the beta 1-integrin chain inhibits lymphocyte adhesion to collagen. Two-dimensional (2D) and three-dimensional (3D) collagen substrata have virtually the same capacity to abrogate lymphocyte aggregation. Fibronectin substrata trigger the initial phase(s) of aggregate disruption as effectively as collagen but the later part of the disruption process is relatively incomplete. Serum-coated plastic does not cause aggregate disruption. These results indicate that disruption of lymphocyte aggregates is a specific event induced via cell surface receptors for extracellular matrix (ECM) components. A major difference between lymphocytes on 2D and 3D extracellular matrix substrata seems to be that the cells detach from the former whereas on the latter infiltration dominates over detachment. Collagen and fibronectin substrata are non-mitogenic for lymphocytes but they can modulate lymphocyte activation induced by allogeneic cells and Con A. Thus, 3D collagen substrata augment and prolong such induced DNA synthesis, although they slightly delay entry into the S-phase and decrease IL-2 production. Collagen substrata, particularly in 3D form, also augment the DNA synthesis of preactivated lymphocytes above the magnitude on serum-coated plastic. The nature of the substratum determines IL-1 production. Accordingly, the spontaneous IL-1 production by mononuclear cells is substantially lower on collagen substrata than on plastic surfaces coated with serum or BSA. However, factors which induce IL-1 production (e.g. Con A or LPS) are more effective on collagen than on serum-coated plastic. Abrogation of cell aggregation, induction of morphogenesis and motile behaviour as well as control of IL-1 synthesis thus constitute major effects of ECM substrata on cells of the immune system. An additional but relatively minor influence of ECM substrata on these cells, as suggested by the present results, is exerted via modulation of DNA synthesis.

The role of adhesion molecules in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by infiltration of mononuclear cells, mainly T lymphocytes, into the synovial membrane (SM). The interaction of peripheral blood T cells with the different components of the rheumatoid synovium is mediated by cell surface proteins such as selectins, integrins, members of the immunoglobulin superfamily and homing receptors. T lymphocytes infiltrating the rheumatoid SM show an activated phenotype and display an increased avidity of their adhesion receptors that results in an enhanced interaction of these cells with both extracellular matrix proteins (ECM) and cellular ligands (VCAM-1, ICAMs). The interaction of T cell integrins with their ligands, besides an additional antigenic stimulus, could trigger a mitogenic response on these cells, a phenomenon that can contribute to increased cellularity observed into the rheumatoid SM. Moreover, cell attachment to ECM through integrins induces the secretion of several proteases that can contribute to the tissue damage observed in RA. The increased knowledge about the role of adhesion receptors in the pathogenesis of RA and other inflammatory diseases will allow the introduction of a new therapeutic approach by: the use of specific blocking reagents designed to interfere with the function of adhesion molecules.

Induction of alpha v beta 3 integrin-mediated attachment to extracellular matrix in beta 1 integrin (CD29)-negative B cell lines

beta 1 integrin containing complexes have been implicated as the primary adhesion structures in many lymphocyte extracellular matrix (ECM) interactions. However, many B lymphocytes lack surface expression of the beta 1 subunit, implying that this subpopulation of lymphoid cells must employ alternate adhesion structures if they are to maintain an interactive capacity with ECM. An examination of the adherence properties of the beta 1 integrin-negative B cell line JY indicated that these cells exhibit little or no basal adherence to any of the ECM components examined. However, these cells could be induced to adhere to the ECM components fibronectin, laminin, and vitronectin following treatment with PMA. Blocking studies with monoclonal antibodies indicated the alpha v beta 3 integrin complex was involved in the attachment to each of these ligands. However, the adherence to fibronectin displayed a complex pattern of inhibition suggesting the involvement of other ECM receptors. The utilization of the alpha v beta 3 complex was not unique to the JY cell line. Other B cell lines were observed to employ alpha v beta 3, and these lines similarly lacked expression of beta 1 integrin. These results indicate that alpha v beta 3 can act as a lymphoid ECM-adhesion structure which may provide an alternative means for lymphocytes to interact with ECM. Furthermore, these studies provide evidence for the presence of lymphoid-associated alpha v beta 3 integrins with regulatable activity, which contrasts with the constitutive adhesive potential of these complexes when present on other cell types.

T lymphocytes in human atherosclerotic plaques are memory cells expressing CD45RO and the integrin VLA-1

The cellular composition of human atherosclerotic plaques has been analyzed in several immunohistochemical studies in recent years. These studies have shown that the main cell types of the plaque are macrophages, smooth muscle cells, and T lymphocytes. To further characterize the T-lymphocyte population in atherosclerotic plaques, human plaque tissue was digested enzymatically and the released cells were labeled with fluorescent antibodies and analyzed by flow cytometry. Fifteen patients undergoing carotid endarterectomy were studied. Sixty-four percent of plaque T cells expressed the low-molecular-weight form (CD45RO) of the leukocyte common antigen (CD45). Many of these cells expressed the integrin very late activation antigen-1 (VLA-1), which suggests that they are in a state of late activation. In contrast, only 1% of peripheral blood T cells from the same patients expressed VLA-1. Other markers of T cell activation, such as Ta1 (CD26) and HLA-DR, were also increased on plaque T cells. The interleukin-2 receptor (CD25), which is transiently expressed after activation, was present on only a small proportion of the cells. Taken together, this analysis of plaque lymphocytes shows that the majority of plaque T cells are memory cells, many of which are in a state of late or chronic activation. This T-cell phenotype may be the result of a preferential recruitment and/or retention of activated peripheral blood T cells or local antigenic stimulation of resting T cells.

Intrahepatic up-regulated expression of extracellular matrix protein receptors in chronic active hepatitis type B

The aim of the present study was to investigate the differences in expression of beta 1 integrins between normal liver and the inflamed livers of patients with chronic active hepatitis B. Immunohistochemical staining with monoclonal antibodies that specifically recognize the common beta 1 chain and five different alpha subunits has been performed in frozen liver biopsy sections from 10 patients with chronic active hepatitis B and from 4 patients with normal livers. The major findings of our study were de novo expression in liver with chronic active hepatitis B of alpha 2 and alpha 3 subunits on both periportal hepatocytes and on lobular hepatocytes in close proximity to lymphocyte infiltrates. These results indicate the existence of an up-regulatory process in the expression of beta 1 integrins, especially the alpha 2 and alpha 3 subunits, in the inflamed liver tissue from patients with chronic active hepatitis B, suggesting that these integrins could play an important role in the development of liver fibrosis and in regulating intrahepatic lymphocyte migration.

T cell adhesion to extracellular matrix molecules secreted by endothelial cells cultured on a substrate of type IV collagen

T cell emigrating from the bloodstream into lymphoid organs or sites of inflammation in the connective tissue must adhere to, and traverse, the subendothelial basement membrane (BM). The goal of the current investigation was to develop a method to study the adhesion of T cells to endothelial cell (EC)-derived extracellular matrix (ECM) as a model for the interaction of T cells with the subendothelial BM in vivo. To be certain that we were truly measuring T cell adhesion to ECM molecules secreted by the EC, it was necessary to culture the EC on a substrate to which T cells could not attach. Non-tissue culture-treated microtiter plate wells which had been coated with type IV collagen (tIVC), a major constituent of BM in vivo, were found to be suitable for this purpose since EC, but very few T cells, adhered to such wells. After incubating the EC on a substrate of tIVC in non-treated wells for a period of 48 h, the EC were gently removed from their underlying ECM and T cell adhesion to that ECM was examined. Using this system, it was observed that approximately 15-40% of human peripheral blood T cells specifically adhered to ECM molecules produced by the EC. This method should be useful as a model for the interactions of T cells and other leukocytes with the vascular BM in vivo.

Fibronectin augments anti-CD3-mediated IL-2 receptor (CD25) expression on human peripheral blood lymphocytes

The extracellular matrix (ECM) is composed of a number of macromolecules that promote cell adhesion, cell migration, and differentiation. Receptors for these molecules have been identified and belong to a superfamily of cell surface proteins, collectively known as the integrins. In this study, we show that the matrix protein fibronectin (FN) acts synergistically with immobilized anti-CD3 antibody to promote proliferation of total human peripheral blood lymphocytes (HPBL) in the absence of exogenous IL-2. Proliferation was inhibited by both the alpha 5 beta 1 and alpha 4 beta 1 recognition peptides. ARG-GLY-ASP (RGD), and GLU-ILE-LEU-ASP-VAL-PRO-SER-THR (EILDVPST), respectively. Expression of CD25 (IL-2 receptor) was significantly higher on cells cultured on anti-CD3 and FN, indicative of T-cell activation. Additionally, cells cultured on immobilized anti-CD3 and FN for 3 days showed increased adhesion to FN and increased forward light scatter/side scatter profile. Synthesis of both IL-1 and to a lesser extent IL-2 was elevated in supernatants from cultures containing both anti-CD3 and FN. These data are consistent with published reports which demonstrate that ECM proteins can act as costimulants of lymphocyte proliferation. Finally, our results show that cells cultured on anti-CD3 antibody and FN have an activated phenotype and that cytokines may be involved in this process.

Antigen-independent T cell activation mediated by a very late activation antigen-like extracellular matrix receptor

Cell-cell and cell-extracellular matrix (ECM) binding mediated by integrin molecules has been implicated in lymphocyte migration and adhesion. We describe here that ECM binding triggers antigen-independent activation of T cell functions. Fibronectin and vitronectin, when coated on plates, not only acted synergistically on anti-CD3-induced serine esterase release in a murine cytotoxic T lymphocyte clone and interleukin 2 production in a murine helper T cell hybridoma but also could trigger these responses alone. All these stimulatory effects of ECM were abrogated by a monoclonal antibody which reacts with a unique very late activation antigen-like integrin and this monoclonal antibody, when coated on plates, exhibited a similar synergistic effect to that of ECM proteins. Therefore, ECM receptors expressed on activated T cells appear to play an important role in triggering T cell effector functions in localized tissues abundant in ECM proteins.