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Biomedical subjects

R N Maini

Publications and source records attributed to R N Maini.

At least 19 recordsLinked to original sources
PubMed1997

Reference sera for antinuclear antibodies. II. Further definition of antibody specificities in international antinuclear antibody reference sera by immunofluorescence and western blotting.

OBJECTIVE: To define the fine specificity of the 10 reference sera used for determination of antinuclear antibodies (ANA) and ANA subsets which are available from the Arthritis Foundation (AF) and from the Centers for Disease Control and Prevention (CDC). METHODS: AF/CDC sera were assessed by experienced laboratory staff, using indirect immunofluorescence and Western blotting. RESULTS: The original assignment of fluorescence patterns to 4 reference sera was confirmed, and the fluorescence intensities were determined using reference fluorescent beads. On Western blots, sera AF/CDC2 (anti-SS-B/La) and AF/CDC7 (anti-SS-A/Ro) did not detect Ro antigens, sera AF/CDC9 and AF/CDC10 appeared to be monospecific anti-Scl-70 and anti-Jo-1 sera, respectively, serum AF/CDC4 (anti-U1 small nuclear RNP) recognized the 70-kd band, and serum AF/CDC5 recognized the Sm antigen with its multiple bands. Semiquantitative analyses revealed that AF/CDC5, AF/CDC2, and AF/CDC10 were strongly reactive sera, whereas AF/CDC4 and AF/CDC9 were much weaker and should be used at lower dilutions on Western blots. CONCLUSION: The AF/CDC ANA reference sera, originally described as reference reagents for indirect immunofluorescence and double immunodiffusion techniques, are also useful for Western blotting. The data presented herein further support the use of these sera for reference purposes.

Antibodies, Antinuclear↗
PubMed1997

Dynamics of proinflammatory cytokine expression in the joints of mice with collagen-induced arthritis (CIA).

This report contains a description of the cellular localization and kinetics of proinflammatory cytokine expression in murine CIA, a model for rheumatoid arthritis. Tissue cryostat sections of undecalcified paws from type II collagen-immunized DBA/1 mice, taken 1-10 days after the onset of clinical arthritis, were examined for the presence of tumour necrosis factor-alpha (TNF-alpha), IL-1beta and IL-6 using an indirect immunoperoxidase technique. In parallel, interferon-gamma (IFN-gamma) production by lymph node cells, stimulated in vitro with type II collagen, was assessed as a marker of T cell activity. The main areas of TNF-alpha, IL-1beta and IL-6 expression were in the synovial lining layer and in tissue contiguous with cartilage and bone (the marginal zone), in particular at sites of pannus formation and joint erosion. There was a progressive increase in the number of TNF-alpha-, IL-1beta- and IL-6-positive cells from day 1 to day 10 of arthritis, during which time IFN-gamma production by CD4+ T cells from draining lymph nodes declined sharply. A further finding of potential significance was that TNF-alpha was consistently detected at day 1 of arthritis, whereas IL- 1beta-positive cells were not found until day 3, suggesting that the expression of TNF-alpha precedes that of IL-1beta.

Animals↗
PubMed1997

Suppression of fever and the acute-phase response in a patient with juvenile chronic arthritis treated with monoclonal antibody to tumour necrosis factor-alpha (cA2).

Juvenile chronic arthritis (JCA) is the commonest chronic rheumatic disorder of childhood. Although conventional therapy of JCA continues to improve, many patients experience long-term ill health as a result of their disease or treatment. In adult rheumatoid arthritis (RA), similar concerns have led to the development of therapies designed to interfere in key disease processes. One such therapy is cA2, a chimeric neutralizing monoclonal antibody to the inflammatory cytokine, tumour necrosis factor-alpha (TNF-alpha). The administration of cA2 in adult RA has led to impressive short-term suppression of disease, with a good safety profile. Here, we report the first use of cA2 in childhood arthritis, choosing a patient with severe systemic-onset JCA, resistant to conventional therapies. The patient received two i.v. infusions of cA2, each at a dose of 10 mg/kg, separated by 1 week. The treatment was well tolerated and induced rapid control of fever, anorexia and serositis, together with downregulation of interleukin (IL)-6, soluble TNF receptors (sTNFR) and IL-1ra, and the acute-phase proteins C-reactive protein (CRP) and serum amyloid A (SAA). In contrast, we saw no significant improvement in joint pain or tenderness. Our findings suggest that TNF-alpha is a mediator of fever and other systemic aspects of disease in systemic JCA. TNF-alpha blockade as a treatment modality in JCA deserves further study.

Acute-Phase Reaction↗
PubMed1997

Reduction of serum matrix metalloproteinase 1 and matrix metalloproteinase 3 in rheumatoid arthritis patients following anti-tumour necrosis factor-alpha (cA2) therapy.

Matrix metalloproteinase (MMP)-1 and MMP-3 levels were measured in serum samples from rheumatoid arthritis (RA) patients undergoing a double-blinded placebo-controlled trial with the chimaeric anti-tumour necrosis factor (TNF)-alpha antibody cA2. Both MMP-1 (P < 0.015), but to a larger extent MMP-3 (P < 0.001) levels were elevated in all RA patients prior to the commencement of the trial compared with normal control sera. Following cA2 therapy, MMP-1 and MMP-3 levels were assessed in the placebo, and 1 and 10 mg/kg cA2-treated groups at 7, 14, 21 and 28 days. In both the 1 and the 10 mg/kg cA2-treated groups, a significant decrease in serum MMP-3 levels at all time points was observed, reducing maximally to 41% of pre-infusion values at day 7. MMP-1 levels were also reduced, but less dramatically than MMP-3, to 85% of pre-infusion values after 14 days in the 10 mg/kg cA2 treated group. In a separate non-placebo-controlled study, we also evaluated the tissue inhibitor of metalloproteinase (TIMP)-1 levels in plasma following cA2 infusion. Pre-infusion TIMP-1 levels were above the normal control range, but were significantly reduced (P < 0.035) 14 days after infusion to 72% of pre-infusion values. This study confirms previous reports that MMP-3 levels are elevated and correlate with measures of inflammation in RA, and furthermore demonstrate that serum MMP-3 and MMP-1 levels are downmodulated following anti-TNF-alpha antibody therapy. Whilst serum MMP-3 levels correlated with C-reactive protein (CRP) both prior to and following anti-TNF-alpha antibody therapy, it remains to be demonstrated that serum MMP-3 and/or MMP-1 levels reflect the cartilage and bone resorptive processes which are evident in this disease.

Antibodies, Monoclonal↗
PubMed1997

TNF blockade in rheumatoid arthritis: implications for therapy and pathogenesis.

The role of the immune response in rheumatoid arthritis (RA) is a subject of debate, although it is widely believed to be a T-cell-driven disease. Progress is being hindered by lack of convincing evidence of a defined specific antigen initiating or perpetuating the response. Clinical trials using monoclonal antibodies directed against T-cell surface molecules such as CD4. CD5, and CD7 have thus far not provided evidence of efficacy. The negative data may reflect inadequate dosing or could suggest that indiscriminate depletion of T cells is insufficient by itself as a therapeutic strategy. Blocking proinflammatory cytokines (e.g. TNF alpha, IL-1) or augmenting anti-inflammatory cytokines (e.g. IL-10) offers an alternative approach to therapy. Clinical trials using monoclonal anti-TNF alpha have been particularly successful in controlling inflammation and markedly reducing acute phase proteins and cellular ingress. However, because disease invariably relapses, repeated therapy is necessary. Preliminary experience suggests that this is possible. Anti-TNF therapy for RA has defined a molecular target and new approach for treating immuno-inflammatory disorders.

Animals↗
PubMed1996

Paradoxical effects of a synthetic metalloproteinase inhibitor that blocks both p55 and p75 TNF receptor shedding and TNF alpha processing in RA synovial membrane cell cultures.

We have previously hypothesized that the pro-inflammatory cytokine TNF alpha has a pivotal role in the pathogenesis of rheumatoid arthritis (RA). It mediates its effects by cross-linking surface p55 TNF receptors (TNF-R), which can be proteolytically cleaved to yield soluble fragments. Upon binding TNF alpha soluble TNF-R (sTNF-R) can inhibit its function. We investigated the enzymatic nature of the proteases involved in TNF-R cleavage, and found that this process is blocked by a synthetic inhibitor of matrix metallo-proteinase activity (MMP), BB-2275. Inhibition of TNF-R cleavage was observed in a number of different cell types, as detected by retention of surface bound TNF receptor and by less sTNF-R released into the cell supernatant. The augmentation of surface TNF-R expression was of biological relevance as TNF alpha-mediated necrosis of human KYM.1D4 rhabdosarcoma cells was enhanced approximately 15-fold in the presence of BB-2275. The addition of BB-2275 to rheumatoid synovial membrane cell cultures totally inhibited MMP activity and also significantly reduced the levels of soluble TNF alpha (P < 0.006), p55 sTNF-R (P < 0.006), and p75 sTNF-R (P < 0.004). Paradoxically, despite the reduction in soluble TNF alpha levels, the production of IL-1 beta, IL-6, and IL-8, cytokines whose production was previously demonstrated to be inhibited by the addition of neutralizing anti-TNF alpha antibody were not down-regulated by BB-2275. These results raise the interesting possibility that a close relationship exits between the enzyme(s) which process membrane-bound TNF alpha, and those involved in surface TNF-R cleavage. Furthermore our observations suggest that hydroxamate inhibitors of MMP activity which block TNF alpha secretion and TNF-R cleavage may not modulate down-stream effects of TNA alpha, and as such suggest that the precise specificity of these compounds will be highly relevant to their clinical efficacy in inflammatory diseases.

Arthritis, Rheumatoid↗
PubMed1996

Interleukin-10 inhibition of the progression of established collagen-induced arthritis.

OBJECTIVE: Interleukin-10 (IL-10) is a potent inhibitor of the proinflammatory cytokines, including tumor necrosis factor alpha and IL-1, which are considered important in the pathogenesis of rheumatoid arthritis (RA). The study was undertaken to establish whether IL-10 can ameliorate arthritis in the collagen-induced arthritis (CIA) model of RA. METHODS: DBA/1 mice were immunized with bovine type II collagen in adjuvant, and treated daily after disease onset with recombinant murine IL-10 or with saline as a control. Mice were monitored for paw swelling and clinical score. Histologic analysis was also performed. RESULTS: IL-10 treatment of established CIA inhibited paw swelling (P < 0.0001), as well as disease progression as defined by clinical score (P < 0.0002). Cartilage destruction, as assessed histologically, was reduced in IL-10-treated mice compared with controls (P < 0.01). CONCLUSION: IL-10 suppresses established CIA, probably by inhibiting proinflammatory cytokine production. Our results, taken together with previously reported findings, indicate a potential therapeutic role for IL-10 in RA.

Animals↗
PubMed1996

Decrease in cellularity and expression of adhesion molecules by anti-tumor necrosis factor alpha monoclonal antibody treatment in patients with rheumatoid arthritis.

OBJECTIVE: The effect of chimeric anti-tumor necrosis factor alpha (TNF alpha) monoclonal antibody (MAb) therapy on synovial inflammation was studied in order to address the hypothesis that anti-TNF alpha therapy leads to down-regulation of adhesion molecules and a decrease in inflammatory cell influx in synovial tissue (ST). METHODS: The immunohistologic features of synovial biopsy specimens, both before and 4 weeks after anti-TNF alpha MAb (cA2) therapy, were studied in 14 patients with rheumatoid arthritis (RA). The patients either received a placebo (n = 2), or were given intravenous doses of cA2 at 10 mg/kg (n = 5) or 20 mg/kg (n = 7). RESULTS: A significant (P < 0.03) reduction in the mean scores for T cells and for the adhesion molecules, vascular cell adhesion molecule 1 and E-selectin, was observed after therapy with 10 mg/kg or 20 mg/kg of cA2 in RA patients. CONCLUSION: The reduced expression of adhesion molecules, and the decrease in cellularity of rheumatoid ST after cA2 administration support the hypothesis that the antiinflammatory effect of anti-TNF alpha therapy might be partly explained by down-regulation of cytokine-inducible vascular adhesion molecules in ST, with a consequent reduction of cell traffic into joints.

Antibodies, Monoclonal↗
PubMed1996

Deactivation of vascular endothelium by monoclonal anti-tumor necrosis factor alpha antibody in rheumatoid arthritis.

OBJECTIVE: To assess whether monoclonal antibody to tumor necrosis factor alpha (TNF alpha) reduces endothelial activation in rheumatoid arthritis (RA). METHODS: Levels of serum E-selectin, intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM-1), and circulating leukocytes (differential counts) were measured in RA patients before and up to 4 weeks after infusion of either placebo or chimeric anti-TNF alpha antibody cA2 (1 or 10 mg/kg). RESULTS: Treatment with anti-TNF alpha decreased serum E-selectin and ICAM-1 levels, with the earliest detectable changes observed on days 1-3 after anti-TNF alpha infusion. No effect on VCAM-1 levels was detected. In parallel, there was a rapid and sustained increase in circulating lymphocytes. The extent of the decrease in serum E-selectin and ICAM-1 levels and the increase in lymphocyte counts was significantly higher (P < or = 0.05) in patients in whom a clinical benefit of anti-TNF alpha was observed ( > or = 20% response, by Paulus criteria, at week 4) compared with that in patients who failed to respond to anti-TNF alpha at this time point. CONCLUSION: We propose that decreased serum levels of adhesion molecules may reflect diminished activation of endothelial cells in the synovial microvasculature, leading to reduced migration of leukocytes into synovial joints, and thus prolonging the therapeutic effect of anti-TNF alpha in RA.

Antibodies, Monoclonal↗
PubMed1996

Placental and fetal cardiac laminin are targets for cross-reacting autoantibodies from mothers of children with congenital heart block.

The association of congenital heart block (CHB) with maternal autoantibodies to the Ro and La ribonucleoprotein antigens may be due to cross-reactions between maternal anti-La antibodies and fetal cardiac specific antigens. One of the major components of cardiac myocytes, laminin, is accessible for binding by maternal autoantibodies and we have previously reported cross-reactivity of mouse laminin with anti-La antibodies affinity purified from the sera of patients with primary Sjögren's syndrome. Affinity purified anti-La antibodies from ten women who had at some time given birth to a child with CHB were examined for cross-reactivity with human placental laminin, which shares structural similarities with cardiac laminin. All ten anti-La antibodies bound to the surface of cryosections of normal full term placental trophoblasts. Binding could be inhibited by pre-incubation of antibodies with either La or placental laminin. Eight anti-La antibodies also reacted with placental laminin by ELISA and La inhibited up to 82% of binding to laminin while laminin inhibited up to 85% of binding to La in a dose dependent manner. Eight anti-La antibodies also bound to the surface of fetal cardiac myocytes at 10.3 weeks of gestation and five showed lower levels of reactivity with the surface of fetal cardiac myocytes at 16.5 weeks of gestation. None showed any surface staining of normal adult heart. These data confirm the cross-reactivity of anti-La antibodies with laminin and may support a placental role in preventing the majority of potentially pathogenic antibodies from reaching the fetal circulation.

Autoantibodies↗
PubMed1996

T cell clones from a Sjögren's syndrome salivary gland biopsy produce high levels of IL-10.

Sjögren's syndrome (SS) is characterized by a focal periductal salivary gland infiltrate consisting mainly of T and B lymphocytes. Most of the T cells bear the memory CD4+ Th1-like phenotype and express high levels of class II, though CD8+ cells are also present. We have studied 17 labial salivary gland and 15 peripheral blood T cell clones from a patient with primary SS. The tissue clones were 71% CD8+ and 29% CD4+, and the peripheral blood-derived clones were 60% CD8+ and 40% CD4+. The CD4+ T cell clones from both the salivary gland and autologous peripheral blood were of the Th1 phenotype, in that they produced interferon-gamma (IFN-gamma) and IL-2 but very little IL-4 after 24 h stimulation with phorbol myristate acetate and anti-CD3 antibody. The salivary gland-derived CD4+ clones produced 15 times more IL-10 (7.92 ng/ml) than peripheral blood-derived CD4+ clones (0.52 ng/ml, P < or = 0.02). The tissue CD8+ clones produced 1.2 times (P < 0.04) more IFN-gamma and CD4+ clones produced 3.5 times less IL-2 (P < 0.02) than the respective PBM-derived clones. The accumulation of Th1-type cells producing high levels of IL-10 in the salivary gland suggests a specific immunoregulatory function at the site of inflammation in SS.

Biopsy↗
PubMed1996

Analysis of V kappa genes in rheumatoid arthritis (RA) synovial B lymphocytes provides evidence for both polyclonal activation and antigen-driven selection.

To define mechanisms of sustained activation of synovial B lymphocytes in RA, we studied hybridomas established from the local synovial B cell repertoire of two RA patients for V kappa gene expression and for antigen-binding specificity. The analyses revealed that members of the main V kappa families (I, II and III) were utilized at frequencies consistent with random V kappa gene family use. Furthermore, although the hybridomas expressed genes frequently seen in response to other self- and exogenous antigens, only one V kappa I- and two of three V kappa III-expressing hybridomas exhibited reactivity with self-antigens. Nucleotide sequence analysis revealed that all hybridomas, with the exception of rheumatoid factor (RF)-producing hybridomas, expressed V kappa genes highly related to known germ-line genes (99.3-100% homology) and that diversity was generated by deletions and random nucleotide insertions at the V kappa-J kappa junction. Examination of the few nucleotide changes seen with the V kappa genes revealed a predominance of silent to replacement changes. Moreover, most of these changes can be attributable either to allotypic variations or to limited random nucleotide replacements independent of antigen selection. In contrast, one IgG-RF (B4D8) exhibited predominantly replacement nucleotide changes in the complementarity-determining regions, suggestive of antigen-driven selection. The random expression of immunoglobulin variable region genes with no, or little, evidence of mutation in the synovial B lymphocyte repertoire, including natural polyreactive antibodies, alongside mutated IgG-RF, suggest that both polyclonal activation and antigen-driven responses occur in RA synovia.

Amino Acid Sequence↗