The preferential accumulation of helper-inducer T lymphocytes in inflammatory lesions: evidence for regulation by selective endothelial and homotypic adhesion

Re-programming immunosurveillance in persistent non-infectious ocular inflammation

Ocular function depends on a high level of anatomical integrity. This is threatened by inflammation, which alters the local tissue over short and long time-scales. Uveitis due to autoimmune disease, especially when it involves the retina, leads to persistent changes in how the eye interacts with the immune system. The normal pattern of immune surveillance, which for immune privileged tissues is limited, is re-programmed. Many cell types, that are not usually present in the eye, become detectable. There are changes in the tissue homeostasis and integrity. In both human disease and mouse models, in the most extreme cases, immunopathological findings consistent with development of ectopic lymphoid-like structures and disrupted angiogenesis accompany severely impaired eye function. Understanding how the ocular environment is shaped by persistent inflammation is crucial to developing novel approaches to treatment.

Up-regulation of ß1 integrin on tonsillar T cells and its induction by in vitro stimulation with α-streptococci in patients with pustulosis Palmaris et Plantaris

Pustulosis palmaris et plantaris (PPP) is a tonsil-related disease that can be cured with tonsillectomy. Recent immunological studies have shown that hyperactivation of tonsillar T cells is caused by a hyperimmune response to α-streptococci; recruitment of the T cells to lesions may be involved in the pathogenesis of PPP. ß1 integrin, expressed on T cells, not only provides a costimulatory signal for T-cell activation but also facilitates the accumulation of T cells in inflammatory skin lesions. In this study, we found that expression of ß1 integrin on both tonsillar and peripheral blood CD4-positive T cells was higher in PPP patients than in non-PPP patients. In vitro stimulation with α-streptococcal antigen significantly enhanced ß1 integrin expression on tonsillar CD4-positive T cells in PPP patients, but not in non-PPP patients. The chemotactic response of tonsillar CD4-positive T cells to vascular cell adhesion molecule-1, the ß1 integrin ligand, was significantly better in PPP patients than in non-PPP patients. The percentage of ß1 integrin-positive peripheral blood CD4-positive T cells decreased after tonsillectomy in PPP patients. The numbers of ß1 integrin-positive T cells and the expression of vascular cell adhesion molecule-1 were more elevated in plantar PPP skin lesions than in normal skin. These results suggest that ß1 integrin may play a key role in the pathogenesis of PPP.

CCL20 production is induced in human dental pulp upon stimulation by Streptococcus mutans and proinflammatory cytokines

INTRODUCTION

Pulpitis is characterized by the marked infiltration of inflammatory cells in response to an invasion of caries-related bacteria. It is well known that chemokines regulate the trafficking of lymphocytes, and CC chemokine ligand 20 (CCL20) has been recently shown to play a crucial role in the recruitment of memory T cells and immature dendritic cells into inflammatory lesions. We previously reported that CCL20 was mainly expressed in microvascular endothelial cells and macrophages that accumulated in inflamed pulp tissues and that its specific receptor, CCR6, was expressed on infiltrated lymphocytes. However, the mechanism of CCL20 expression remains unclear.

METHODS AND RESULTS

In this study, we investigated the expression of CCL20 in monocytes/macrophages, endothelial cells, and pulpal fibroblasts after stimulation with Streptococcus mutans, a representative of caries-related bacteria, or proinflammatory cytokines. CCL20 messenger RNA was detected by reverse transcription-polymerase chain reaction in inflamed pulp, but not in clinically normal pulp. By enzyme-linked immunosorbent assay, S. mutans induced a human monocytic cell line, differentiated macrophage-like THP-1 cells, and human umbilical vein endothelial cells (HUVEC) to produce an increased amount of CCL20. Lipoteichoic acid from S. mutans also elicited CCL20 production by HUVEC. Moreover, CCL20 production from pulpal fibroblasts was increased by stimulation with inetrleukin-1beta and tumor necrosis factor-alpha.

CONCLUSION

Our results indicate that CCL20 expression is induced by stimulation with caries-related bacteria that have invaded deeply into the dentinal tubules as well as by proinflammatory cytokines in the inflamed pulpal lesions. It may be involved in the progression of pulpitis via accumulation of inflammatory cells.

Preclinical evaluation of a dual-acting microbicidal prodrug WHI-07 in combination with vanadocene dithiocarbamate in the female reproductive tract of rabbit, pig, and cat

The mucosal safety of the combination antiretroviral spermicide,WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] and vanadocene dithiocarbamate (VDDTC), was evaluated in 3 different animal models. Twenty-seven NZW rabbits in four subgroups were exposed intravaginally to a gel-microemulsion (GM) with and without three dose levels of WHI-07 plus VDDTC (0.5+0.06%, 1.0+0.12% and 2.0+0.25%) or 4% nonoxynol-9 (N-9; Conceptrol) for 14 consecutive days. Ten nonestrus gilts (Duroc) in three subgroups received either a single or daily intravaginal application of GM with and without 2.0% WHI-07 plus 0.25% VDDTC or 2.0% benzalkonium chloride (BZK)-containing gel for 6 and 4 consecutive days, respectively. Five cats received a single intravaginal application of GM incorporating 2.0% WHI-07 plus 0.25% VDDTC. Genital tract histopathology was performed in the pig and rabbit at the end of dosing period but after 18 weeks post-dosing in the cat. Porcine cervicovaginal lavage (CVL) fluid was obtained for up to 72 hours after a single exposure and changes in the levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma, and TNF-alpha) were quantitated by a multiplexed chemiluminescence-based immunoassay. Rabbit vaginal tissues were evaluated for localized cellular inflammation and in situ apoptosis by immunohistochemical staining for CD45, nuclear factor (NF)-kappa B, and terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) using confocal laser scanning microscopy (CLSM), respectively. Vanadium content in selected organs and body fluids from rabbits and pigs was determined by atomic absorption spectroscopy. When compared with 4% N-9 (total irritation score 13-14 out of a possible 16), none of the rabbits given WHI-07 plus VDDTC intravaginally, developed histological alterations such as epithelial erosion, edema, leukocyte influx or vascular congestion characteristic of inflammation (total irritation score 4-6). CD45 and NF-kappa B immunoreactivity was limited to cells within the vascular lumen of both control and WHI-07 plus VDDTC-treated vaginal tissues. TUNEL assay revealed lack of increased apoptotic cells in vaginal mucosa exposed to increasing concentrations of WHI-07 plus VDDTC. Basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in porcine CVL were unaffected by intravaginal exposure to WHI-07 plus VDDTC when compared with BZK used as a positive control. Endpoint histology of the reproductive tract from cats and pigs after a single or repeated intravaginal exposure to WHI-07 plus VDDTC, respectively, revealed lack of irritation/inflammation in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues, and underlying/surrounding muscles. Vanadium was not preferentially incorporated into rabbit or porcine tissues and body fluids at levels above 1 microg/g. Based on comparative histologic data and surrogate markers for inflammation, repeated intravaginal administration of WHI-07 plus VDDTC via a gel-microemulsion did not result in vaginal irritation, mucosal toxicity, or systemic absorption of vanadium. Therefore, the combined use of WHI-07 and VDDTC via gel-microemulsion appears safe for topical use as a prophylactic anti-HIV microbicide.

Expression of Macrophage Inflammatory Protein 3α in Human Inflamed Dental Pulp Tissue

Severe pulpitis resulting from dental caries is characterized by marked inflammatory infiltrate such as lymphocytes. Little is known about the recruitment of these cells into the dental pulp lesions of carious teeth. Macrophage inflammatory protein-3alpha (MIP-3alpha), a CC chemokine attracts CC chemokine receptor 6 (CCR6)-expressing T cells. We examined the distribution of MIP-3alpha-positive and/or CCR6-positive cells in human inflamed and normal dental pulp by immunohistochemistry. MIP-3alpha was observed in all inflamed pulp sections, and was mostly distributed in macrophages that had accumulated in the area adjacent to carious lesions. Furthermore, CCR6 expression was also observed in the infiltrating lymphocytes. In contrast, MIP-3alpha and CCR6 were rarely detected in normal pulp. These findings suggest that MIP-3alpha plays a role in the advancement of pulpal inflammation via the recruitment of CCR6-expressing lymphocytes.

The beta chemokines CCL4 and CCL5 enhance adhesion of specific CD4+ T cell subsets to human brain endothelial cells

Chemokines are key mediators of inflammation, acting as subset-specific chemoattractants and activators of leukocytes. In the present study we investigated the effects of chemokine concentration gradients on CD4+ T cell (TC4) adhesion to human brain microvessel endothelial cells (HBMECs) in vitro. CCL4 or CCL5 were placed in a double chamber chemotaxis system beneath confluent resting HBMEC monolayers or cultures co-incubated with TNF-alpha and IFN-gamma to mimic an inflammatory milieu. Chemokines readily diffused across activated HBMEC monolayers while binding to the sub-endothelial regions, establishing a chemotactic and haptotactic gradient. Naïve or resting TC4 adhered poorly to resting HBMECs compared to memory or recently activated TC4, but all subsets adhered more readily to cytokine-treated HBMECs. Chemokine gradients (10-100 ng/ml) of both CCL4 and CCL5 significantly enhanced the adhesion of memory and recently activated TC4 to cytokine-treated HBMECs, as much as doubling adhesion in a manner that correlated with chemokine receptor expression. Neither chemokine influenced adhesion to resting HBMEC monolayers nor the adhesion of resting or naïve TC4. These findings emphasize the role and importance of CNS-derived beta-chemokines in regulating the traffic of recently activated TC subsets (those previously localized to the CNS in vivo) across cytokine-activated cerebral endothelium in inflammatory diseases.

Blood lymphocyte subsets in canine idiopathic pericardial effusion

The immunophenotype of peripheral blood lymphocytes was investigated in 23 dogs diagnosed with idiopathic pericardial effusion in order to provide information about a possible role of the immune system in this pathology. Flow cytometric analysis showed a significant reduction in nearly all lymphocyte subsets examined and a strong, significant (P < 0.001) reduction of the CD4 subset, which gave rise to a significantly lower CD4/CD8 ratio. Our data suggest that an imbalance in the immune system is present during the course of the disease, preferentially affecting the T helper cell response.

An association between the acute phase response and patterns of antigen induced T cell proliferation in juvenile idiopathic arthritis

The aim of this research was to determine whether all memory T cells have the same propensity to migrate to the joint in patients with juvenile idiopathic arthritis. Paired synovial fluid and peripheral blood mononuclear cell proliferative responses to a panel of antigens were measured and the results correlated with a detailed set of laboratory and clinical data from 39 patients with juvenile idiopathic arthritis. Two distinct patterns of proliferative response were found in the majority of patients: a diverse pattern, in which synovial fluid responses were greater than peripheral blood responses for all antigens tested; and a restricted pattern, in which peripheral blood responses to some antigens were more vigorous than those in the synovial fluid compartment. The diverse pattern was generally found in patients with a high acute phase response, whereas patients without elevated acute phase proteins were more likely to demonstrate a restricted pattern. We propose that an association between the synovial fluid T cell repertoire and the acute phase response suggests that proinflammatory cytokines may influence recruitment of memory T cells to an inflammatory site, independent of their antigen specificity. Additionally, increased responses to enteric bacteria and the presence of alphaEbeta7 T cells in synovial fluid may reflect accumulation of gut associated T cells in the synovial compartment, even in the absence of an elevated acute phase response. This is the first report of an association between the acute phase response and the T cell population recruited to an inflammatory site.

High CXCR3 expression in synovial mast cells associated with CXCL9 and CXCL10 expression in inflammatory synovial tissues of patients with rheumatoid arthritis

To improve our knowledge on the pathophysiology of rheumatoid arthritis (RA), we investigated gene expression patterns in synovial tissue from RA and osteoarthritis (OA) patients. DNA oligonucleotide microarray analysis was employed to identify differentially expressed genes in synovial tissue from pathologically classified tissue samples from RA (n = 20) and OA patients (n = 10). From 7131 gene sets displayed on the microarray chip, 101 genes were found to be upregulated and 300 genes to be downregulated in RA as compared with OA. Semiquantitative reverse-transcription polymerase chain reaction, Western blotting and immunohistochemistry were used to validate microarray expression levels. These experiments revealed that Cys-X-Cys receptor (CXCR)1, CXCR2 and CXCR3 mRNAs, as well as Cys-X-Cys ligand (CXCL)9 (monokine induced by IFN-gamma) and CXCL10 (IFN-gamma inducible protein 10) mRNAs, were significantly upregulated in RA as compared with OA disease. Elevated protein levels in RA synovial tissue were detected for CXCR1 and CXCR3 by Western blotting. Using immunohistochemistry, CXCR3 protein was found to be preferentially expressed on mast cells within synovial tissue from RA patients. These findings suggest that substantial expression of CXCR3 protein on mast cells within synovial tissue from RA patients plays a significant role in the pathophysiology of RA, accompanied by elevated levels of the chemokines CXCL9 and CXCL10. Mature mast cells are likely to contribute to and sustain the inflamed state in arthritic lesions (e.g. by production of inflammatory mediators such as histamine, proteinases, arachidonic acid metabolites and cytokines). Thus, the mast cell could become a potential target in therapeutic intervention.

Changes of interleukin expression correlate with Helicobacter pylori infection and lymph node metastases in gastric carcinoma

Helicobacter pylori (HP) infection induces expression of IL-8 and IL-10 in benign gastric epithelium. This study compared the expression of cytokines in CD4+ and CD8+ lymphocyte subsets of peripheral blood lymphocytes (PBL), benign mucosal lymphocytes (ML), and tumor infiltrative lymphocytes (TIL) as well as in the benign and malignant epithelial cells of the same patient, with respect to the presence of HP infection, lymph node metastases, and tumor histologic type. The mRNA of the cytokines was measured by a semiquantitative RT-PCR method. The levels were ranked and compared using the Wilcoxon sign-ranked test. Compared with CD8+ ML, the CD8+ TIL expresses higher levels of IL-6 and IL-8 but lower level of IL-4 in patients with lymph node metastases. In patients with HP infection, expression of IL-8 and IL-10 was higher in the gastric carcinoma cells than in the benign epithelial cells while expression of IL-6 and IL-8 were higher in CD8+ TIL than CD8+ ML. Overexpression of IL-8 in HP associated gastric carcinomas suggested that they might have arisen from HP-infected epithelial cells.

Simultaneous analysis of T cell clonality and cytokine production in rheumatoid arthritis using three-colour flow cytometry

In this study we examined the cytokine production by T cells and TCRVbeta subsets in peripheral blood (PB) and synovial fluid (SF) from six RA patients and PB from 10 normal subjects, using three-colour flow cytometry. In two RA subjects we assessed T cell clonality by RT PCR using TCRBV family-specific primers and analysed the CDR3 (complementarity determining region 3) length by GeneScan analysis. A high percentage of IFN-gamma- and IL-2- producing cells was observed among the PB T cells in both the RA patients and normal controls and among the SF T cells in RA patients. In contrast, the percentage of T cells producing IL-4 and IL-5 was small among PB T cells in both RA patients and normal controls and among SF T cells in RA patients. There was no significant difference in the production of IFN-gamma, IL-2 and IL-5 between the two compartments (PB and SF); however, there were significantly more IL-4-producing cells in SF. Molecular analysis revealed clonal expansions of four TCRBV families in SF of two of the RA patients studied: TCRBV6.7, TCRBV13.1 and TCRBV22 in one and TCRBV6.7, TCRBV21.3 and TCRBV22 in the second. These expansions demonstrated cytokine expression profiles that differed from total CD3+ cells, implying that T cell subsets bearing various TCR-Vbeta families may have the potential to modulate the immune response in RA patients.

Macrophage inflammatory protein 3alpha-CC chemokine receptor 6 interactions play an important role in CD4+ T-cell accumulation in periodontal diseased tissue

The regulatory role of chemokines and chemokine receptors on specific lymphocyte recruitment into periodontal diseased tissue is poorly characterized. We observed that lymphocytes infiltrating inflamed gingival tissue expressed marked levels of CCR6. In periodontal diseased tissue, the expression of MIP-3alpha mRNA was detected by RT-PCR and further, MIP-3alpha was distributed in the basal layer of gingival epithelial cells, microvascular endothelial cells and the areas of inflammatory cells as shown by immunohistochemistry. Moreover, CCR6-expressing cells infiltrated into periodontal diseased tissue, and the proportion of CCR6-positive CD4+ T cells was significantly elevated in periodontal diseased tissue compared with peripheral blood in the same patients. Furthermore, gingival lymphocytes isolated from patients showed migration toward MIP-3alpha in an in vitro chemotaxis assay in which migration was abrogated by specific antibody to CCR6. Thus, these findings suggested that CCR6 and the corresponding chemokine, MIP-3alpha may have an important regulatory role in specific lymphocyte migration into inflamed periodontal tissue.

Treatment with methylprednisolone in relapses of multiple sclerosis patients: immunological evidence of immediate and short-term but not long-lasting effects

Relapses of multiple sclerosis (MS) are treated commonly with high-dose intravenous methylprednisolone (MP) given over a period of 3-5 days. The mechanisms responsible for the beneficial effects of MP in attacks are not clearly established. It is also controversial whether this treatment may have a long-term effect. Here, peripheral blood samples from relapsing--remitting MS patients in acute relapse were analysed by flow cytometry just before steroid treatment and at different time points after initiation of the therapy. We observed an immediate (day 3) decrease in the percentage of CD4+ lymphocytes, with a relative increase in the memory (CD4+CD45R0+) subpopulation. A longer standing effect of MP on IFN-gamma production, CD54, CCR5, CXCR3 and CD95 (Fas) expression was also observed on CD4+ cells after 1 month of treatment initiation. Six months after the therapy, during clinical remission, no changes due to ivMP therapy were detected. These results support that MP treatment of relapses induces immediate post-treatment and short-term effects on the immune system that could partly account for the clinical and radiological improvement observed in MS patients. However, no conclusion can be drawn as to a possible long-term or even intermediate influence of ivMP treatment on the course of the disease.

Differential expression of beta1 and beta2 integrins and L-selectin on CD4+ and CD8+ T lymphocytes in human blood: comparative analysis between isolated cells, whole blood samples and cryopreserved preparations

Flow cytometric analysis was used to compare the expression of adhesion molecules on human CD4+ and CD8+ T lymphocytes in isolated blood mononuclear cells (MNCs) in whole blood samples and in cryopreserved MNC preparations. Examination of MNCs revealed that the CD11b and CD11c components of the beta2 integrins were preferentially expressed on CD8+ T cells, whereas CD62L was present on more CD4+ T cells. All CD4+ and CD8+ T lymphocytes were positive for CD11a but the CD8+ population had a higher intensity of expression of CD11a and also CD11b. Virtually identical results were obtained with T cells in whole blood samples. In relation to the beta1 integrins, the only difference between isolated CD4+ and CD8+ T cells was that the latter subset had a greater proportion of cells bearing CD49d. The naive cell marker CD45RA was present on the majority of CD8+ T cells whereas CD45RA and the memory marker CD45RO were evenly distributed within the CD4+ T cell subset. Although cryopreservation of lymphocytes did not modify the expression of beta1 and beta2 integrins it produced a marked reduction in the percentage of CD4+ and CD8+ T cells bearing CD62L. With regard to endothelial interactions, it appears that cryopreserved lymphocytes are suitable for inclusion in studies of integrin-mediated adhesion but not for those relating to tethering or recognition of addressins on high endothelial venules. Differences in adhesion molecule expression between CD4+ and CD8+ T lymphocytes could underlie the selective extravasation of these subsets into sites of infection and inflammation.

Involvement of T-lymphocytes in periodontal disease and in direct and indirect induction of bone resorption

Periodontal disease is a peripheral infection involving species of gram-negative organisms. T-lymphocytes can be found in the dense inflammatory infiltrate in this disease. CD4+ and CD8+ T-cells are present in periodontal lesions, as are memory/activated T-lymphocytes. In addition, Th1- and Th2-type T-lymphocytes and their associated cytokines with a subtle polarization to Th1 may be present. Th1-type T-cells up-regulate the production of pro-inflammatory cytokines IL-1 and TNF-alpha, which can induce bone resorption indirectly by promoting differentiation of osteoclast precursors and subsequently by activating osteoclasts. Such osteoclast differentiation is dependent on stimulation of osteoprotegerin ligand (OPG-L) production by osteoblastic cells. By contrast, activated T-cells, by virtue of direct production and expression of OPG-L, can directly promote osteoclast differentiation. OPG-L appears to be predominantly expressed on Th1-type cells. The direct and indirect T-cell involvement in periodontal bone resorption appears to be dependent on the degree of Th1-type T-cell recruitment into inflamed gingival tissues. This T-cell recruitment is regulated by adhesion molecules and chemokines/chemokine receptors. The adhesion molecules involved include alpha4 and alpha6 integrins, LFA-1, and ICAM-1. The Th1-type T-cells preferentially express CCR5 and CXCR3, which are found prominently in diseased gingivae. By contrast, little CCR4, expressed by Th2-type T-cells, can be detected. Also, the chemokine ligands RANTES, MIP1-alpha (both CCR5), and IP-10 (CXCR3 ligand) were elevated in inflamed periodontal tissues. The T-cell features in diseased periodontal tissues can be compared with those in rheumatoid arthritis, wherein bone resorption often attributed to Th1-type T-cell involvement has also been demonstrated.

TACI-ligand interactions are required for T cell activation and collagen-induced arthritis in mice

Interactions of the tumor necrosis factor superfamily members B lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL) with their receptors-transmembrane activator and CAML interactor (TACI) and B cell maturation molecule (BCMA)-on B cells play an important role in the humoral immune response. Whereas BCMA is restricted to B cells, TACI is also expressed on activated T cells; we show here that TACI-Fc blocks the activation of T cells in vitro and inhibits antigen-specific T cell activation and priming in vivo. In a mouse model for rheumatoid arthritis (RA), an autoimmune disease that involves both B and T cell components, TACI-Fc treatment substantially inhibited inflammation, bone and cartilage destruction and disease development. Thus, BLyS and/or APRIL are important not only for B cell function but for T cell-mediated immune responses. Inhibition of these ligands might have therapeutic benefits for autoimmune diseases, such as RA, that involve both B and T cells.

LFA-1 expression on CD4(+)CD45RO(+) peripheral blood T-lymphocytes in RR MS: effects induced by rIFNbeta-1a

We investigate the in vivo and in vitro effects of short-term treatment with recombinant Interferon beta-1a (rIFNbeta-1a) on CD4(+)CD45RO(+) activated/memory peripheral blood T-lymphocytes (PBTLs) expressing Leukocyte Function Antigen-1 (LFA-1; CD11a/CD18) in relapsing-remitting (RR) Multiple Sclerosis (MS) patients. Blood samples were obtained from 10 RR MS patients before and after 2, 4 and 6 months of rIFNbeta-1a (Avonex) treatment. For each sample, the percentage of CD4(+)CD45RO(+)CD11a(+) (CD11a(dim) and CD11a(bright)) T-cells was evaluated in in vivo PBTLs and in untreated or rIFNbeta-1a (1000 U/ml) or recombinant soluble Intercellular Adhesion Molecule-1 (ICAM-1, the ligand for LFA-1) (400 ng/ml) treated cultured PBTLs by triple fluorescence flow-cytometry (FACS analysis). Soluble ICAM-1 (sICAM-1) serum levels were evaluated by ELISA. In vivo, the percentage of CD4(+)CD45RO(+), CD4(+)CD45RO(+)CD11a(+), CD4(+)CD45RO(+)CD11a(dim) PBTLs increased after 4 and 6 months of rIFNbeta-1a treatment compared to pretreatment and 2 months of treatment (p<0.05). The CD11a expression per se did not change during the time course. Soluble ICAM-1 (sICAM-1) serum levels also increased (p<0.05) after 4 and 6 months of treatment. When T-cells, obtained from the blood of the same patients before and during in vivo treatment, were cultured either untreated or treated with rIFNbeta-1a, they showed an increase in the percentage of CD4(+)CD45RO(+) T-cells expressing CD11a(bright) (p<0.05). The addition of recombinant sICAM-1 to untreated cultures decreased the percentage of CD4(+)CD45RO(+) T-cells expressing CD11a. This last finding seems to support an indirect effect in vivo of rIFNbeta-1a via sICAM-1 on this T-cell subset, since the ICAM-1 soluble form, induced in vivo in serum by rIFNbeta-1a but lacking in in vitro conditions, keeps the percentage of CD11a(+) unchanged within CD4(+)CD45RO(+) T-cells and induces their expression of CD11a(dim), probably preventing T-cells from transmigrating.

Rheumatoid synovial CD4+ T cells exhibit a reduced capacity to differentiate into IL-4-producing T-helper-2 effector cells

CD4+ memory T cells (Tm) from rheumatoid arthritis peripheral blood (RAPB) or peripheral blood from normal donors produced IL-2, whereas fewer cells secreted IFN-gamma or IL-4 after a brief stimulation. RAPB Tm contained significantly more IFN-gamma producers than normal cells. Many rheumatoid arthritis (RA) synovial Tm produced IFN-gamma alone (40%) and fewer cells produced IL-2 or IL-4. An in vitro model was employed to generate polarized T-helper (Th) effectors. Normal and RAPB Tm differentiated into both IFN-gamma- and IL-4-producing effectors. RA synovial fluid (RASF) Tm demonstrated defective responsiveness, exhibiting diminished differentiation of IL-4 effectors, whereas RA synovial tissue (RAST) Tm exhibited defective generation of IFN-gamma and IL-4 producers.

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.

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.

T(h)1 transmigration anergy: a new concept of endothelial cell-T cell regulatory interaction

Stimulation of endothelial cells (EC) with IFN-gamma generates selective enhancement of T(h)1 cell transmigration and induction of MHC class II expression on EC. In the present study, we tested whether antigen presentation by EC could influence transmigrating T cells in an in vitro system. Bacterial antigen presentation by EC from primary culture and after cloning induced antigen-specific anergy of transmigrating T(h)1 clone cells in a MHC class II-dependent manner as characterized by non-responsiveness to subsequent antigen presentation and inability to produce IL-2. This T cell transmigration anergy induced by EC was abrogated by anti-rat CD28 mAb, suggesting that lack of B7 co-stimulatory signals by EC might be related to the induction of anergy. While MHC class II expression on primary and cloned EC was observed after IFN-gamma stimulation, these cells never expressed B7. B7-1 gene-transfected endothelial clone cells (ECC/B7-1) were developed to elucidate the influence of B7 co-stimulation by EC. ECC/B7-1 induced proliferation of T(h)1 clone cells, whereas ECC did not induce proliferation in co-culture of T(h)1 clone cells and EC stimulated with IFN-gamma and antigen. In the transmigration assay, ECC/B7-1 did not induce transmigration anergy of T(h)1 clones or T(h)1 lines unless anti-rat B7-1 blocking mAb was added. Therefore, in rats, the T cell anergy induced during transmigration across a layer of EC seemed to be due to antigen presentation in the absence of B7 on the EC. We introduce the concept of transmigration anergy in this manuscript. Thus, EC can play a critical immune regulatory role in the context of antigen presentation by MHC class II to transmigrating T cells.

Requirement of B7 costimulation for Th1-mediated inflammatory bone resorption in experimental periodontal disease

The CD28 costimulation at TCR signaling plays a pivotal role in the regulation of the T cell response. To elucidate the role of T cells in periodontal disease, a system of cell transfer with TCR/CD28-dependent Th1 or Th2 clones was developed in rats. Gingival injection of specific Ag, Actinobacillus actinomycetemcomitans 29-kDa outer membrane protein, and LPS could induce local bone resorption 10 days after the transfer of Ag-specific Th1 clone cells, but not after transfer of Th2 clone cells. Interestingly, the presence of LPS was required not only for the induction of bone resorption but also for Ag-specific IgG2a production. LPS injection elicited the induction of expression of both B7-1 and B7-2 expression on gingival macrophages, which otherwise expressed only MHC class II when animals were injected with Ag alone. The expression of B7 molecules was observed for up to 3 days, which corresponded to the duration of retention of T clone cells in gingival tissues. Either local or systemic administration of CTLA4Ig, a functional antagonist of CD28 binding to B7, could abrogate the bone resorption induced by Th1 clone cells combined with gingival challenge with both Ag and LPS. These results suggest that local Ag-specific activation of Th1-type T cells by B7 costimulation appeared to trigger inflammatory bone resorption, whereas inhibition of B7 expression by CTLA4Ig might be a therapeutic approach for intervention with inflammatory bone resorption.

Groalpha-mediated recruitment of neutrophils is required for elicitation of contact hypersensitivity

The factors mediating recruitment of immune T cells to challenge sites during contact hypersensitivity (CHS) responses remain unclear. To investigate the role of chemokines during elicitation of CHS, the temporal expression of chemokine genes in hapten-challenged ears was tested. KC (the murine homologoue of Groalpha) was expressed 30 min following hapten challenge in naive and hapten-sensitized mice. A rabbit KC-specific antiserum inhibited elicitation of CHS when administered to sensitized mice prior to hapten challenge. Injecting either neutrophils or immune CD8(+) T cells into the ear tissue of immune animals before hapten challenge circumvented the KC antiserum-mediated inhibition of CHS. Neutrophil depletion also inhibited CHS and was circumvented by injecting either neutrophils or hapten-primed CD8(+) T cells into ears of sensitized mice followed by specific hapten challenge. These results indicate that KC-directed neutrophil infiltration of hapten challenge sites is required for elicitation of CHS and suggest that neutrophils mediate recruitment of the hapten-specific CD8(+) T cells that subsequently produce cytokines mediating the hypersensitivity response.

Selective Diapedesis of Th1 Cells Induced by Endothelial Cell RANTES

Differentiated CD4 T cells can be divided into Th1 and Th2 types based on the cytokines they produce. Differential expression of chemokine receptors on either the Th1-type or the Th2-type cell suggests that Th1-type and Th2-type cells differ not only in cytokine production but also in their migratory capacity. Stimulation of endothelial cells with IFN-γ selectively enhanced transmigration of Th1-type cells, but not Th2-type cells, in a transendothelial migration assay. Enhanced transmigration of Th1-type cells was dependent on the chemokine RANTES produced by endothelial cells, as indicated by the findings that Ab neutralizing RANTES, or Ab to its receptor CCR5, inhibited transmigration. Neutralizing Ab to chemokines macrophage-inflammatory protein-1α or monocyte chemotactic protein-1 did not inhibit Th1 selective migration. Whereas anti-CD18 and anti-CD54 blocked basal levels of Th1-type cell adherence to endothelial cells and also inhibited transmigration, anti-RANTES blocked only transmigration, indicating that RANTES appeared to induce transmigration of adherent T cells. RANTES seemed to promote diapedesis of adherent Th1-type cells by augmenting pseudopod formation in conjunction with actin rearrangement by a pathway that was sensitive to the phosphoinositol 3-kinase inhibitor wortmannin and to the Rho GTP-binding protein inhibitor, epidermal cell differentiation inhibitor. Thus, enhancement of Th1-type selective migration appeared to be responsible for the diapedesis induced by interaction between CCR5 on Th1-type cells and RANTES produced by endothelial cells. Further evidence that CCR5 and RANTES play a modulatory role in Th1-type selective migration derives from the abrogation of this migration by anti-RANTES and anti-CCR5 Abs.

Molecular fingerprinting reveals non-overlapping T cell oligoclonality between an inflamed site and peripheral blood

We have demonstrated a stable expansion of CD8+ T cells in the peripheral blood of a child with chronic arthritis. The expanded TCRBV family (TCRBV14) was enriched for CD57hiCD28- T cells. Sequencing of the TCRBV14 amplification products showed a TCR sequence which contributed 32% of the total TCR in the CD8+TCRBV14 population. Using the modified heteroduplex technique, the CD8+TCRBV14 cells showed a clonal pattern and these bands were restricted to the CD28- population. This method also detected multiple other clones within the CD8+ population but few in the CD4+ cells. The dominant TCRBV14+ clone was not detectable in synovial fluid T cells from two inflamed joints by CDR3 length analysis or heteroduplex probing, suggesting that this long-lived clone is excluded from inflammatory sites. Synovial fluid T cells showed an unexpected discordance of the CD28 and CD57 phenotype compared to peripheral blood mononuclear cells. T cells from both inflamed joints both showed marked oligoclonality in all TCR families and had almost identical heteroduplex patterns. Taken together these data suggest that some clones are actively excluded from inflamed sites in juvenile chronic arthritis, yet the pattern of restricted T cell expansion is shared between sites of inflammation.

The recirculation of naive and memory lymphocytes

It has been clearly shown that continuous recirculation of lymphocytes is crucial for the development of primary immune responses and that naive CD4 cells are distinguished from memory CD4 cells by differences in expression of several adhesion molecules. These findings suggest that changes in migratory behavior accompany the naive to memory cell transition. This area is first reviewed and then to evaluate this hypothesis, we compare the tissue distributions of highly purified naive and memory CD4 cells after transfer to syngeneic recipients. Naive cells which express high levels of L-selectin, and low levels of alpha 4 and beta 2 integrins, and CD44 localized in secondary lymphoid organs and were detectable in these tissues and in the blood for several weeks after transfer. Memory cells, which have a reciprocal phenotype, showed a markedly different distribution, particularly with respect to tissues where entry is controlled through high endothelial venules.

In vitro differentiation of peripheral blood T cells towards a type 2 phenotype is impaired in rheumatoid arthritis (RA)

We have examined the capacity of peripheral blood T cells from RA patients to be polarized in vitro towards a type 1 (T1) or a type 2 (T2) phenotype. Peripheral blood T cells from RA patients and from healthy donors were primed by 1 week of culture with soluble OKT3 in the presence of polarizing cytokines. The recovered T cells were restimulated and their cytokine secretion profile determined. Priming of T cells from RA patients in the presence of recombinant (r)IL-2 plus rIL-12 induced a shift towards a TI pattern, characterized by increased production of interferon-gamma, that was more pronounced than in the case of healthy donors. Conversely, priming of T cells from RA patients in the presence of IL-4 failed to induce a shift towards a T2 profile after 1 week, whereas it induced T cells from healthy donors to acquire such a profile characterized by heightened production of IL-4, IL-5 and IL-13. However, a T2 polarization profile emerged in T cells from RA patients that were primed in the presence of rIL-4 and subsequently maintained in culture in rIL-2 alone for 1 or 2 additional weeks. We conclude that in vitro differentiation of peripheral T cells towards a type 2 phenotype is impaired in RA. Nevertheless, conditions required to drive peripheral T cells towards a type 2 phenotype were established. Administration of autologous polyclonal T cells expressing a type 2 cytokine secretion profile is proposed as a therapeutic strategy in RA.

The Role of Apoptosis in the Resolution of T Cell-Mediated Cutaneous Inflammation

We have investigated cutaneous purified protein derivative-induced delayed-type hypersensitivity (DTH) responses in healthy volunteers to determine features associated with both the generation and resolution of the reaction. The clinical peak of the response occurred at day 3; however, T cell numbers were maximal on day 7. There was a preferential increase of CD4+CD45RO+ T cells on day 7, which was largely due to proliferation, since a mean of 19% was in cycle. The proliferation of this subset was associated with the presence of IL-15, which was expressed as early as 12 h, and IL-2, which showed peak expression at 7 days. By day 14, there was a significant decrease in both the mean T cell number/unit area and IL-2 and IL-15 expression in perivascular infiltrates. Maximal CD95 (Fas/Apo-1) ligand and TNF-α expression were observed at 7 days and were associated with the presence of 1.83% (range 0.81–2.48%) apoptotic T cells. At 14 days, CD95 ligand and TNF-α expression were reduced significantly, and the presence of 2.5% (range 1.5–3.75%) of apoptotic T cells at this time was probably due to cytokine deprivation, associated with decreased Bcl-2 relative to Bax expression. The induction and resolution of the Mantoux reaction may depend on the expression of cytokines, such as IL-2 and IL-15, which regulate both proliferation and apoptosis in T cells. Failure to control either of these phases of the Mantoux reaction may contribute to the chronicity of inflammatory responses in certain cutaneous diseases.

Locomotion and chemotaxis of lymphocytes

The behaviour of locomotor T and B lymphocytes and the chemoattractants to which they respond in vitro are reviewed. Following activation, T cells respond by locomotion and chemotaxis to cytokine attractants including IL-15 and IL-2 and several chemokines. In activated B cells chemotaxis may be signalled through the antigen receptor. Conversely resting lymphocytes respond poorly to the above signals though their locomotion is activated by contact with high endothelial venular cells. These differences in locomotion between resting and activated lymphocytes, together with differences in adhesion, may explain why activated lymphocytes migrate preferentially into inflammatory sites while resting cells recirculate.

The chemokine receptors CXCR3 and CCR5 mark subsets of T cells associated with certain inflammatory reactions

T cells infiltrating inflammatory sites are usually of the activated/memory type. The precise mechanism for the positioning of these cells within tissues is unclear. Adhesion molecules certainly play a role; however, the intricate control of cell migration appears to be mediated by numerous chemokines and their receptors. Particularly important chemokines for activated/memory T cells are the CXCR3 ligands IP-10 and Mig and the CCR5 ligands RANTES, macrophage inflammatory protein-1alpha, and macrophage inflammatory protein-1beta. We raised anti-CXCR3 mAbs and were able to detect high levels of CXCR3 expression on activated T cells. Surprisingly, a proportion of circulating blood T cells, B cells, and natural killer cells also expressed CXCR3. CCR5 showed a similar expression pattern as CXCR3, but was expressed on fewer circulating T cells. Blood T cells expressing CXCR3 (and CCR5) were mostly CD45RO+, and generally expressed high levels of beta1 integrins. This phenotype resembled that of T cells infiltrating inflammatory lesions. Immunostaining of T cells in rheumatoid arthritis synovial fluid confirmed that virtually all such T cells expressed CXCR3 and approximately 80% expressed CCR5, representing high enrichment over levels of CXCR3+ and CCR5+ T cells in blood, 35 and 15%, respectively. Analysis by immunohistochemistry of various inflamed tissues gave comparable findings in that virtually all T cells within the lesions expressed CXCR3, particularly in perivascular regions, whereas far fewer T cells within normal lymph nodes expressed CXCR3 or CCR5. These results demonstrate that the chemokine receptor CXCR3 and CCR5 are markers for T cells associated with certain inflammatory reactions, particularly TH-1 type reactions. Moreover, CXCR3 and CCR5 appear to identify subsets of T cells in blood with a predilection for homing to these sites.

Functional CD40 ligand is expressed by T cells in rheumatoid arthritis

CD40 ligand (CD40-L), a member of the tumor necrosis family of transmembrane glycoproteins, is rapidly and transiently expressed on the surface of recently activated CD4+ T cells. Interactions between CD40-L and CD40 induce B cell immunoglobulin production as well as monocyte activation and dendritic cell differentiation. Since these features characterize rheumatoid arthritis (RA), the expression and function of CD40-L in RA was examined. Freshly isolated RA peripheral blood (PB) and synovial fluid (SF) T cells expressed CD40-L mRNA as well as low level cell surface CD40-L. An additional subset of CD4+ RA SF T cells upregulated cell surface CD40-L expression within 15 min of in vitro activation even in the presence of cycloheximide, but soluble CD40-L was not found in SF. CD40-L expressed by RA T cells was functional, since RA PB and SF T cells but not normal PB T cells stimulated CD40-L-dependent B cell immunoglobulin production and dendritic cell IL-12 expression in the absence of prolonged in vitro T cell activation. In view of the diverse proinflammatory effects of CD40-L, this molecule is likely to play a central role in the perpetuation of rheumatoid synovitis. Of importance, blockade of CD40-L may prove highly effective as a disease modifying therapy for RA.

Oligoclonal CD4+CD57+ T-Cell Expansions Contribute to the Imbalanced T-Cell Receptor Repertoire of Rheumatoid Arthritis Patients

A peculiar feature of rheumatoid arthritis patients is that they carry clonally expanded CD4+ and CD8+ cells in the peripheral blood. While the distortion of the repertoire of CD8+ cells has been ascribed to the increase of CD8+CD57+ large granular lymphocytes, often detected in these patients, the mechanism responsible for the clonal expansion of CD4+ cells remains unexplained. Here, we report that CD4+CD57+ cells, that in healthy individuals represent a small subset of peripheral CD4+ lymphocytes, are significantly expanded in the peripheral blood of a considerable percentage of rheumatoid arthritis patients. Furthermore, the expansion of these lymphocytes appears to correlate with the presence of rheumatoid factor. The molecular analysis of the T-cell receptor variable beta segments expressed by the CD4+CD57+ cells enriched in rheumatoid arthritis patients showed that they use restricted repertoires, that partially overlap with those of their CD4−CD57+ counterpart. The structural feature of the receptor ligand expressed by these cells revealed that their expansion is most likely mediated by strong antigenic pressures. However, since we also found that CD4+CD57+ and CD4−CD57+ cells can share the same clonal specificity, it is likely that their selection is not mediated by conventional major histocompatibility complex restricted mechanisms. Thus, while our data demonstrate that CD4+CD57+ cells play an important role in establishing the imbalance of the CD4+ cell repertoire observed in rheumatoid arthritis patients, they also suggest that these cells have common features with mouse CD4+CD8−NK1.1+/T cells.

Comparison of the effects of oral versus intravenous methylprednisolone regimens on peripheral blood T lymphocyte adhesion molecule expression, T cell subsets distribution and TNF alpha concentrations in multiple sclerosis

We investigated in multiple sclerosis the difference between two commonly used oral and intravenous steroid regimens on the level of adhesion molecule expression on blood T lymphocytes, the distribution of circulating T cell subsets, and the concentration of serum tumour necrosis factor alpha. Venous blood samples were collected from a cohort of 22 patients with acute relapses who were participating in a randomised trial comparing intravenous methylprednisolone 1000 mg daily for 3 days with oral methylprednisolone 48 mg daily for one week, 24 mg daily for one week, and finally 12 mg daily for one week. There was a similar significant reduction of T cell LFA-1 surface expression and serum TNF alpha concentrations after 4 days of treatment with each regimen. There was no change in other lymphocyte adhesion molecules expression (ICAM-1, LFA-3 or CD2) at day 4, although LFA-3 and CD2 expression was moderately decreased at day 28 and day 90 respectively; nor was there any change in the distribution of lymphocyte subsets (CD4, CD8, and CD45RA, CD45RO), although a small decrease in CD45RO circulatory T cells was noted at day 28. This study suggests that some of the beneficial effects of glucocorticosteroids may be related to the inhibition of lymphocyte adhesion as well as the modulation of proinflammatory cytokines.

Selective migration of highly differentiated primed T cells, defined by low expression of CD45RB, across human umbilical vein endothelial cells: effects of viral infection on transmigration

Low expression of CD45RB on CD45RO+ T lymphocytes defines a subset of highly differentiated T lymphocytes that accumulate in vivo within the affected joints of patients with rheumatoid arthritis (RA). Although it is known that CD45RO+ T lymphocytes migrate to sites of inflammation in vivo, it is not clear whether within this subset the CD45RBlo cells are selectively recruited or develop in situ within the joint. Using a transwell system we show that a small proportion of resting T lymphocytes migrated across unactivated human umbilical vein endothelial cells (HUVEC). These migrating cells were CD45RO+ and enriched for low CD45RB expression. In addition, both the CD45RO+CD45RBlo subset and migrating cells expressed increased levels of beta 1 and beta 2 integrins and CD44. The percentage of CD45RO+CD45RBlo T lymphocytes was increased in the circulation of patients with acute Epstein-Barr virus (EBV) infection. These in vivo activated cells also expressed increased levels beta 1 and beta 2 integrins and CD44, and showed an enhanced rate of transmigration compared with resting T lymphocytes. Transmigration of T lymphocytes was increased using the chemokines RANTES and lymphotactin and the cytokine interleukin-15 (IL-15). In addition, infection of the HUVEC with cytomegalovirus (CMV) led to an enhanced movement of T lymphocytes. In all of these cases the selective migration of the CD45RBlo subset was maintained. Thus although the rate of T-lymphocyte transmigration could be influenced by a number factors, the CD45RO+CD45RBlo subset has a migratory advantage suggesting that more differentiated CD45RO+CD45RBlo T lymphocytes are selectively recruited to sites of inflammation.

Human lymphocyte adhesion to xenogeneic porcine endothelial cells: modulation by human TNF-alpha and involvement of VLA-4 and LFA-1

Considering that in the allogeneic situation the adhesion of recipient lymphocytes to donor endothelial cells initiates the cellular rejection, we questioned the possible occurrence of a similar process in the xenogeneic situation. The adhesion of human peripheral blood lymphocytes (PBL) to porcine aortic endothelial cells (PAEC) was thus studied in an in vitro porcine-to-human xenogeneic model. It was found that 25.9% of human PBL adhered to resting PAEC. Furthermore, this adhesion increased significantly when the PAEC were stimulated by the human cytokine TNF-alpha (tumor necrosis factor-alpha). The effect of human TNF-alpha was concentration- and time-dependent and was maximal (from 25.9% to 35.6%) with 100 U/ml during 6 h. Moreover, blocking experiments with monoclonal antibody (mAb) demonstrated the role of the PBL adhesion molecules LFA-1 and especially VLA-4. Indeed, an anti-CD11a mAb decreased PBL adhesion to resting PAEC by 17.1% and to TNF-alpha stimulated PAEC by 16.9%, whereas an anti-CD49d mAb decreased dramatically PBL adhesion to resting PAEC by 53.1% and to TNF-alpha stimulated PAEC by 41.0%. Finally, phenotypic analysis of the adherent PBL showed that 50.5% of adherent cells to resting PAEC were NK (natural killer) cells, whereas 50.7% of adherent cells to TNF-alpha stimulated PAEC were T lymphocytes, showing the preferential adhesion of NK cells to resting PAEC, and that the stimulation of the PAEC with human TNF-alpha affects predominantly T lymphocyte adhesion. These results indicate that human PBL could bind to xenogeneic PAEC and that this interaction could be a first step of a xenogeneic cellular rejection.

Synovial distribution of alpha d/CD18, a novel leukointegrin. Comparison with other integrins and their ligands

OBJECTIVE

To define the synovial distribution of the novel leukointegrin alpha d/CD18, and compare this with other members of the beta 2-integrin family of adhesion molecules, and their counter-receptors.

METHODS

Monoclonal antibodies to the CD3, CD14, CD29, CD68, beta 2-integrin, and immunoglobulin supergene families were used to immunohistologically define the distribution of these molecules in synovial tissue samples from normal subjects and osteoarthritis (OA) and rheumatoid arthritis (RA) patients.

RESULTS

The normal synovial lining cell layer (SLC) expresses CD68, vascular cell adhesion molecule 1, beta 1-integrin (CD29), the beta 2-integrins CD11b/CD18 (alpha m/beta 2, Mac-1), and alpha d/CD18, whereas CD11a/CD18 (alpha L/beta 2, lymphocyte function-associated antigen 1) and CD11c/CD18 (alpha x/beta 2, gp150/95) expression is generally absent. In RA synovitis, expression of beta 2-integrins in the SLC increases in proportion to the degree of hyperplasia. The ratio of cells in the SLC which express CD11c/CD18 increases substantially, approaching that of CD11b/CD18 and alpha d/CD18, while there is minimal increase in CD11a/CD18 expression. In the sublining areas of the tissues, aggregates and diffuse infiltrates of CD3/CD11a/ICAM-3+ lymphocytes are interspersed among CD68/CD14/CD11b/alpha d+ macrophages. A number of aggregates demonstrate intense alpha d staining of the lymphocytes. The synovial endothelium variably expresses intercellular adhesion molecule-1 (ICAM-1), ICAM-2, and vascular cell adhesion molecule 1 (VCAM-1), with minimal evidence of ICAM-3 expression.

CONCLUSION

The leukointegrin alpha d/CD18 is expressed constitutively by synovial macrophages and macrophage-like lining cells. In rheumatoid synovitis, the intense coexpression of this integrin and its known counter-receptor, ICAM-3, in the inflammatory infiltrates, suggests a potential role for this adhesion pathway in cellular interactions occurring the synovium.

Phenotype, and migration properties of three major subsets of tissue homing T cells in sheep

T cells show a bias in their migration pathways: some T cells preferentially migrate to peripheral lymph nodes (LN), some to mucosal tissues, and some to peripheral tissues such as skin. These recirculation pathways were examined in sheep by collecting lymph draining into and out of peripheral and intestinal LN, and using fluorescent dyes to trace the recirculation of the lymph cells. Monoclonal antibodies (mAb) to alpha 4, beta 1, and beta 7 integrins, and L-selectin, were used to define three major populations of recirculating T cells. Naive-type T cells (L-selectin+, alpha 4 beta 1lo beta 7lo) migrated preferentially through peripheral LN. Two memory populations could be defined: alpha 4 beta 1hi beta 7- and alpha 4 beta 7hi beta 1lo. alpha 4 beta 1hi beta 7- T cells were present in lymph draining from the skin. T cells migrating preferentially through intestinal LN were alpha 4 beta 7hi beta 1lo. Consistent with this migration pattern, the endothelial receptor for alpha 4 beta 7, mucosal addressin cell adhesion molecule-1 (MAdCAM-1) was detected on high endothelial venules within intestinal LN and Peyer's patches, but only weakly on high endothelial venules within peripheral LN. Thus, there are at least three easily definable subsets of T cells, based on integrin expression, which show distinct migration preferences.

Pulmonary immune memory: localized production of antibody in the lung after antigen challenge

In comparison to primary immune responses after lung immunization, the level of antigen-specific antibody and the number of cells producing specific antibody are significantly increased after challenging the lungs with antigen. The response of immune memory cells in the lung to an antigen challenge could be responsible for this elevated immune response. However, increased numbers of antibody-producing cells, possibly produced in the lung-associated lymph nodes, are also found in the blood after an antigen challenge. Therefore, it is possible that both the response of immune memory cells in the lung, and the recruitment of antibody-producing cells from the blood, contribute to the elevated levels of antibody in the lung after an antigen challenge. This study compared the level of antibody produced in the lung by the response of pulmonary immune memory cells with the level of antibody produced by antibody-forming cells that enter the lung from blood after an antigen challenge. This comparison was made possible by immunizing and challenging two lung lobes of dogs with two antigens. The immune responses to both antigens were then evaluated in both lung lobes after primary immunization and challenge. Data from these evaluations showed that most antibody in the lung after an antigen challenge is produced by a localized anamnestic response of pulmonary immune memory cells. A significantly lower level of antibody entered the lung from the vasculature and/or was produced by antibody-forming cells that entered the lung from blood after an antigen challenge.

High frequencies of identical T cell clonotypes in synovial tissues of rheumatoid arthritis patients suggest the occurrence of common antigen-driven immune responses

OBJECTIVE

To investigate T cell antigen receptor (TCR) clonotypes in rheumatoid arthritis (RA) lesions.

METHODS

Reverse transcriptase-polymerase chain reaction with TCR V beta family-specific primers and subsequent single-strand conformation polymorphism (SSCP) analysis were performed. Direct nucleotide sequencing was also conducted.

RESULTS

A distinct clonal expansion of T cells was observed in the synovium. Furthermore, identical bands in samples of different areas of the same lesion were obtained by SSCP analysis. Nucleotide sequencing revealed that T cell clonotypes of identical mobility on SSCP analysis had the same nucleotide sequence and thus were identical clones. In 6 RA patients, 60-100% of the expanded T cell clonotypes had identical migration patterns in 2 different samples, indicating that this percentage represents commonly existing T cell clonotypes in the affected joint. Furthermore, the J beta 2.1 gene segment was used predominantly by the TCR V beta clonotypes that commonly expanded in the different portions of the same joint.

CONCLUSION

These results suggest that the immune response in RA is not random, but rather is driven by common stimuli.

Adhesion molecules in autoimmune disease

Leukocyte activation, circulation, and localization to inflammatory sites are dependent on adherence to molecules on other cells or to extracellular matrix ligands. Adhesion molecule expression and interactions are probably involved in initiation and propagation of autoimmune diseases. Adhesion molecules pertinent to the development of autoimmunity are the subject of this review. Material in this review was generated by a manual and a computerized search of medical literature pertaining to adhesion molecules and specific autoimmune diseases. Topics covered include adhesion molecule classification, regulation of adhesion, and characterization of adhesion receptors in specific autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus, Sjögren's syndrome, autoimmune thyroid disease, multiple sclerosis, and diabetes mellitus. Adhesion molecules are classified into selectin, integrin, and immunoglobulin supergene family groups. Increased adhesion molecule expression and avidity changes occurring with cellular activation are the principal methods regulating leukocyte adhesion. Tumor necrosis factor-alpha (TNF alpha), interferon-gamma (IFN-gamma), and interleukin-1 (IL-1) stimulate adhesion receptor expression on lymphoid and nonlymphoid tissues. Although differences between specific autoimmune diseases exist, key interactions facilitating the development of autoimmune inflammation appear to include L-selectin/P-selectin/E-selectin, lymphocyte function-associated antigen-1 (LFA-1)/intercellular adhesion molecule-1 (ICAM-1), very late antigen-4 (VLA-4)/vascular cell adhesion molecule-1 (VCAM-1), and alpha 4B7/MadCAM or VCAM-1 adhesion. Administration of anti-adhesion molecule antibodies in experimental animal models of autoimmunity and in a preliminary trial with RA patients has been successful in preventing or reducing autoimmune disease severity. A vast array of adhesive interactions occurs between immunocompetent cells, endothelium, extracellular matrix, and target tissues during the evolution of an autoimmune disease. Further characterization of leukocyte migration patterns and adherence should clarify pathogenic processes in specific autoimmune diseases and identify potential therapeutic targets for their treatment.

Cutaneous lymphocyte antigen-positive T lymphocytes preferentially migrate to the skin but not to the joint in psoriatic arthritis

OBJECTIVE

To investigate whether T cell migration into different sites of inflammation (skin and synovium) within the same individual is principally regulated by tissue-specific homing or by more general mechanisms related to inflammation.

METHODS

Expression of cutaneous lymphocyte antigen (CLA) and its ligand, E-selectin, was analyzed by immunohistochemistry and immunofluorescence using paired skin and synovial membrane (SM) samples from patients with psoriatic arthritis (PsA). To investigate disease specificity, delayed-type hypersensitivity (DTH) skin lesions, induced by tuberculin purified protein derivative, and SM from patients with rheumatoid arthritis (RA), were studied as controls. To directly examine cell migration in in vivo, the proportion of CLA+ T lymphocytes migrating into suction-induced skin blisters was assessed by flow cytometry. Using the same technique, levels of paired peripheral blood and synovial fluid (SF) T cells were also analyzed.

RESULTS

CLA+ T cells preferentially accumulated in the skin, but not in the joint, of patients with PsA. Similarly, CLA+ T lymphocytes predominated in the DTH skin lesions of RA patients, but were very rare in the SM of RA patients, and were scarcely represented in the SF of patients with several chronic inflammatory arthropathies. In addition, CLA+ T lymphocytes preferentially migrated into epidermal skin blisters. This preferential pattern of CLA+ T cell accumulation was not related to the selective expression of E-selectin, since this was similar in the skin and SM of both PsA and RA patients.

CONCLUSION

The distinct pattern of T cell infiltration into sites of inflammation within the skin and synovium is regulated by both organ-specific homing and general inflammation-related mechanisms.

C-C chemokines, but not the C-X-C chemokines interleukin-8 and interferon-gamma inducible protein-10, stimulate transendothelial chemotaxis of T lymphocytes

Eight chemokines were tested for ability to elicit transendothelial chemotaxis of unstimulated peripheral blood T lymphocytes. The C-C chemokines monocyte chemotactic protein (MCP)-2, MCP-3, RANTES, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and, as previously described, MCP-1 induced significant, dose-dependent transendothelial chemotaxis of CD3+ T lymphocytes. In contrast, the C-X-C chemokines interleukin-8 (IL-8) and interferon-gamma inducible protein-10 (IP-10) failed to induce transendothelial chemotaxis of CD3+ T lymphocytes or T lymphocyte subsets. RANTES, MIP-1 alpha, and MIP-1 beta induced significant transendothelial chemotaxis of CD4+, CD8+, and CD45R0+ T lymphocyte subsets. Phenotyping of mononuclear cells that underwent transendothelial migration to MCP-2, MCP-3, RANTES, or MIP-1 alpha showed both monocytes and activated (CD26 high), memory-type (CD45R0+) T cells. Both CD4+ and CD8+ T lymphocytes were recruited, but not natural killer cells or significant numbers of B cells. MCP-2 was the only C-C chemokine tested that attracted a significant number of naive-type (CD45RA+) T lymphocytes. In the absence of endothelium, IL-8 but not IP-10 promoted modest but significant chemotoxis of CD3+ T lymphocytes. Our data support the hypothesis that C-C, not the C-X-C chemokines IL-8 or IP-10, promote transendothelial chemotaxis of T lymphocytes.

Functional analysis of synovial fluid and peripheral blood T cells from patients with rheumatoid arthritis

Rheumatoid arthritis is a T cell-mediated autoimmune disease. The lack of knowledge of the involved target antigens severely hampers research on relevant T cells in patients. Here we describe the functional analysis of freshly isolated T cells from the peripheral blood and the site of the lesion (synovial fluid or synovial membrane) of patients with rheumatoid arthritis. Healthy donors and osteoarthritis patients served as controls. Using various polyclonal stimuli, we analyzed CD4+ T cells with respect to proliferation and their ability to produce lymphokines. Our data show that lesion-derived CD4+ T cells of patients with rheumatoid arthritis are severely defective in proliferation and lymphokine (interleukin-2, interleukin-4, tumor necrosis factor-alpha, interferon-gamma) production. This activation defect was most pronounced at lower cell densities and was present in both synovial fluid derived and synovial membrane derived CD4+ T cells of all patients tested. No difference was found between responses of synovial fluid derived CD4+ T cells from osteoarthritis patients and those observed with peripheral blood derived T cells from all groups. The observed defect in lesion-derived CD4+ T cells from rheumatoid arthritis patients was not due to the effect of inflammatory factors in the synovial fluid because preincubation with synovial fluid could not induce a similar defect in control T cells. Together, our data show a rheumatoid arthritis specific, general defect in the activation of lesion-derived CD4+ T cells.

Upregulated expression of IL-4 receptors and increased levels of IL-4 in rheumatoid arthritis patients

The level of IL-4R expression on peripheral lymphocyte subsets from rheumatoid arthritis (RA) patients and controls was studied by flow cytometric analysis of the binding of phycoerythrin-labelled IL-4 (PE-IL-4). In normal lymphocytes, IL-4R is mainly expressed on CD19+ cells, although it was also seen, at lower levels, on CD3+, CD4+ and CD8+ cells. In RA patients, a significantly increased spontaneous expression of IL-4R was observed, compared with controls, in the CD3+, CD4+ and CD19+ cell subsets. No significant differences in IL-4R expression were found between patients receiving steroids and those who were not, suggesting that steroids are not involved in upregulating IL-4R levels in vivo. Because IL-4 is a potent upregulator of IL-4R, we considered the possibility that incremented levels of circulating IL-4 in RA accounted for the high surface expression of IL-4R. By ELISA, we found abnormally high levels of immunoreactive IL-4 in 35.13% of patient serum samples, while it was undetectable in control sera. In addition, we examined IL-4 mRNA expression by polymerase chain reaction (PCR) in the PBMC of patients and controls. IL-4 PCR products were observed in four out of 10 patients studied but in none of the controls. No correlation was observed between the seric concentrations of IL-4 and IL-4R, indicating that activator factors other than IL-4 contribute to the upregulation of IL-4R expression in RA. Since the patients' sedimentation rate and CRP values did not correlate with the concentration of circulating IL-4, we conclude that this lymphokine does not contribute to the deleterious effect of the disease. Rather, due to its antiinflammatory properties, the overproduction of IL-4 in RA may be a compensatory mechanism neutralizing the harmful effect of activated macrophages.

Pathogenesis of degenerative joint disease in the human temporomandibular joint

The wide range of disease prevalences reported in epidemiological studies of temporomandibular degenerative joint disease reflects the fact that diagnoses are frequently guided by the presence or absence of non-specific signs and symptoms. Treatment is aimed at alleviating the disease symptoms rather than being guided by an understanding of the underlying disease processes. Much of our current understanding of disease processes in the temporomandibular joint is based on the study of other articular joints. Although it is likely that the molecular basis of pathogenesis is similar to that of other joints, additional study of the temporomandibular joint is required due to its unique structure and function. This review summarizes the unique structural and molecular features of the temporomandibular joint and the epidemiology of degenerative temporomandibular joint disease. As is discussed in this review, recent research has provided a better understanding of the molecular basis of degenerative joint disease processes, including insights into: the regulation of cytokine expression and activation, arachidonic acid metabolism, neural contributions to inflammation, mechanisms of extracellular matrix degradation, modulation of cell adhesion in inflammatory states, and the roles of free radicals and heat shock proteins in degenerative joint disease. Finally, the multiple cellular and molecular mechanisms involved in disease initiation and progression, along with factors that may modify the adaptive capacity of the joint, are presented as the basis for the rational design of new and more effective therapy.

Regulation and function of central nervous system chemokines

In this paper, we discuss the potential involvement of a new family of cytokines, termed chemokines, in CNS inflammatory pathology. Chemokines are a family of proinflammatory cytokines which are able to stimulate target-cell-specific directional migration of leukocytes. Because of this feature, chemokines may be potent mediators of inflammatory processes. We have previously reported observations indicating that chemokines may be involved in the process of lesion formation during autoimmune inflammation within CNS, and, in particular, are likely participants in the process of influx of inflammatory cells into the CNS parenchyma. We observed also that mechanical injury of brain and subsequent post-traumatic inflammation may in part be mediated by chemokines. Chemokines undoubtedly co-operate with cell-associated adhesion molecules during recruitment of leukocytes from blood to CNS. The sequential expression of soluble and membrane-bound signals for leukocyte migration is an intricate process that can be interrupted by a variety of strategies. Our data suggest that chemokines may represent a promising target for future therapy of inflammatory conditions, including CNS inflammation resulting from varied insults.