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Biomedical subjects

R N Maini

Publications and source records attributed to R N Maini.

At least 127 records · Page 7Linked to original sources
PubMed1994

Immunoregulatory role of interleukin 10 in rheumatoid arthritis.

The presence and the role of interleukin 10 (IL-10), a potent cytokine synthesis inhibitory factor and antiinflammatory cytokine, were investigated in rheumatoid arthritis (RA). The expression of both mRNA and protein for IL-10 could be demonstrated in RA and osteoarthritis (OA) joints. Human IL-10 mRNA could be demonstrated by polymerase chain reaction amplification of cDNA made by reverse transcription of total RNA extracted directly from synovial tissue in five out of five RA and four out of five OA patients. IL-10 protein was demonstrated by specific immunoassay and immunohistology. IL-10 protein was spontaneously produced in all 11 RA and 17 OA synovial membrane cultures investigated, and this production was sustained for up to 5 d in culture in the absence of any extrinsic stimulation. IL-10 protein could also be detected by immunohistology in all five RA and four OA synovial membrane biopsies investigated, but not three normal synovial membranes. Immunohistology revealed that the IL-10 was localized to the synovial membrane lining layer and mononuclear cell aggregates. Immunofluorescence double staining revealed that the sources of IL-10 were monocytes in the lining layer, and T cells in the mononuclear cell aggregates. We found evidence that the IL-10 expression was functionally relevant, as neutralization of endogenously produced IL-10 in the RA synovial membrane cultures resulted in a two- to threefold increase in the protein levels of proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and IL-1 beta, although IL-6 and IL-8 levels were not affected. The addition of exogenous recombinant IL-10 to the RA synovial membrane cultures resulted in a two- to threefold decrease in the levels of TNF-alpha and IL-1 beta. IL-8 levels were reduced by day 5; however, IL-6 levels were not affected by exogenous IL-10. Neutralization of the endogenous IL-10 in two out of seven RA synovial membrane cultures resulted in the expression of detectable levels of interferon gamma (561-1,050 pg/ml). Taken together, the above findings suggest that IL-10 is spontaneously produced in RA and OA and is an important immunoregulatory component in the cytokine network of RA, regulating monocyte and in some cases T cell cytokine production.

Arthritis, Rheumatoid↗
PubMed1994

Synergy between anti-CD4 and anti-tumor necrosis factor in the amelioration of established collagen-induced arthritis.

Anti-CD4 treatment is reported to prevent collagen-induced arthritis if administered before the onset of clinical disease but has relatively little effect on established arthritis. In contrast, we have recently shown that anti-tumor necrosis factor alpha/beta (TNF) treatment reduces the severity of established arthritis. We now study the effect of combined administration of anti-CD4 monoclonal antibody (YTS 191.1.2/YTA 3.1.2) and anti-TNF monoclonal antibody (TN3-19.12) in established arthritis. Anti-CD4 treatment caused some reduction in paw-swelling but did not significantly prevent joint erosion. A suboptimal dose of anti-TNF alone had no significant effect on arthritis. In contrast, anti-CD4 plus suboptimal anti-TNF significantly reduced paw-swelling, limb involvement, and joint erosion. As previously reported, an optimal dose of anti-TNF alone inhibited paw-swelling, limb involvement, and joint erosion. However, optimal anti-TNF combined with anti-CD4 caused significantly greater reductions in paw-swelling and joint erosion than those achieved by optimal anti-TNF alone. Coadministration of anti-CD4 was also effective in preventing an antibody response to the hamster anti-TNF antibody, which may have implications for long-term therapy in human disease. Thus anti-CD4 acts synergistically with anti-TNF in ameliorating established collagen-induced arthritis and this combined therapeutic approach may provide effective long-term control of rheumatoid arthritis.

Animals↗
PubMed1994

Anti-CD5 therapy decreases severity of established disease in collagen type II-induced arthritis in DBA/1 mice.

Collagen-induced arthritis has been widely used as an animal model of rheumatoid arthritis. We have used this model with a view to determining potential therapeutic targets for the treatment of human disease. To do this we have attempted to modulate the progression of established arthritis over a 10-day time period following the first appearance of disease, by i.p. injection of one of three different MoAbs. These consist of a rat IgG2a specific for the CD5 antigen expressed on all T cells and a subpopulation of B cells, a mouse IgG2b recognizing the CD72 antigen, and a rat IgM specific for the B220 molecule, CD72 and B220 both being expressed on all B cells. None of the three MoAbs had depleting activity in vivo. The progression of arthritis was monitored both clinically, and histologically. The effects of treatment with anti-CD5 and anti-CD72 antibodies were compared with control antibodies of the same species class and subclass. In the case of anti-B220 antibodies, the effects of treatment were compared with administration of PBS. Of these MoAbs, only treatment with anti-CD5 resulted in disease amelioration with significant decrease in disease severity in 60% of the animals. These changes became apparent 6 days after initiation of treatment. There were no significant differences in serum levels of IgG antibodies to native bovine collagen type II between the groups of treated and control mice. Possible mechanisms underlying the modification of disease expression following treatment with anti-CD5 MoAb are discussed.

Animals↗
PubMed1994

Affinity maturation and isotype switch in clonally related anti-erythrocyte autoantibodies.

The NZB mouse is genetically predisposed to develop, at approximately 6 months of age, a spontaneous and severe autoimmune anaemia caused by production of pathogenic anti-mouse erythrocyte autoantibodies. Molecular analysis of a panel of five anti-erythrocyte monoclonal antibodies (MoAb) derived from splenocytes of unimmunized NZB mice revealed that these autoantibodies all had functionally rearranged genes from the VH J558 family of immunoglobulin genes with closest homology to germline genes H10 and H30. Owing to clustering of nucleotide differences within the CDRs, compared with the germline, it was concluded that these antibodies were most likely generated by an antigen-driven mechanism. We report here further molecular analysis of two (4.16.1 and B4.13.2) of the panel of five anti-mouse erythrocyte producing hybridomas which are apparently clonally related. Nucleotide analysis of the light chain cDNA indicated that both antibodies had closest homology to germline gene V kappa 24 and use J kappa 2 gene. Determination of the functional affinities of the MoAb reveal that B4.13.2 (IgG2a) has a > 10-fold higher affinity for mouse erythrocytes when compared to 4.16.1 (IgG1). This finding supports the view that these two autoantibodies are generated by an antigen-driven mechanism. The proposed mechanism would involve the selection and expansion of a small population of B-lymphocytes by antigen leading to isotype switch, somatic mutation and increased affinity. Our data also point to the possibility that some framework residues may be involved in the binding to antigen.

Amino Acid Sequence↗
PubMed1994

New directions for biological therapy in rheumatoid arthritis.

Advances in our understanding of the pathogenesis of rheumatoid arthritis (RA), together with developments in hybridoma and molecular technology have opened the way for more directed therapy in this disease. In reviewing the experience so far with T-cell-directed biological agents, we show that the early promise displayed by anti-CD4 monoclonal antibodies in open clinical trials has not been sustained in controlled studies. This outcome provides a challenge to the concept that CD4+ T cells are of prime importance in RA, and prompts a search for alternative therapeutic targets. Agents directed towards other leucocyte antigens such as CD5, CDw52 or the receptor for interleukin 2 have induced clinical responses in early studies, but at the expense of significant toxicity. Newer therapies targeting the monokines tumour necrosis factor alpha (TNF-alpha), IL-1 and IL-6, and the leucocyte adhesion molecule intercellular adhesion molecule 1 (ICAM-1) have provided encouraging clinical improvements and, in the case of anti-TNF-alpha and anti-IL-6, impressive modulation of the acute-phase response. Strategies allowing long-term blockade of such molecules, including antibody reshaping and the use of soluble cytokine receptors are discussed. Finally, the potential for using biological agents in combination with other therapies is outlined.

Antibodies, Monoclonal↗
PubMed1994

Chronic exposure to tumor necrosis factor (TNF) in vitro impairs the activation of T cells through the T cell receptor/CD3 complex; reversal in vivo by anti-TNF antibodies in patients with rheumatoid arthritis.

Experiments were designed to test the hypothesis that chronic exposure to tumor necrosis factor alpha (TNF) alters the function of activated T lymphocytes. Pretreatment of tetanus toxoid-specific T cell clones with TNF for up to 16 d impaired rechallenge proliferative responses to antigen in a dose- and time-dependent fashion. IL-2 and PHA responses were preserved. Prolonged treatment with TNF impaired production of IL-2, IL-10, IFN gamma, TNF, and lymphotoxin (LT) following stimulation with immobilized OKT3, and resulted in suboptimal expression of the IL-2R alpha chain (Tac) but not CD3, CD4, or HLA-DR antigens, when compared to untreated control cells. By contrast, pretreatment of T cells for prolonged periods in vitro with neutralizing anti-TNF monoclonal antibodies (mAb) enhanced proliferative responses, increased lymphokine production, and upregulated Tac expression following stimulation with OKT3. To determine whether TNF exerts immunosuppressive effects on T cells in vivo, we studied cell-mediated immunity in patients with active rheumatoid arthritis (RA), before and after treatment with a chimeric anti-TNF mAb. Treatment with anti-TNF restored the diminished proliferative responses of PBMC to mitogens and recall antigens towards normal in all patients tested. These data demonstrate that persistent expression of TNF in vitro and in vivo impairs cell-mediated immune responses.

Antibodies, Monoclonal↗
PubMed1994

Identification of hybridomas derived from mouse CD5+ B lymphocytes by fluorescent staining for cytoplasmic CD5 expression.

The production of hybridomas derived from CD5+ B lymphocytes is important for studying the immunoglobulin gene repertoire and antibody specificity of this B-lymphocyte subpopulation. However, hybridomas derived from these lymphocytes invariably lose surface membrane expression of CD5 following hybridization. This impedes the unequivocal assignment of the generated hybridomas to the CD5+ B-lymphocyte subpopulation from unsorted, or partially sorted, cells. Recent studies have shown that mRNA transcripts of the CD5 gene and the protein product can be detected in the cytoplasm of some mouse hybridomas, indicating that although surface expression has been lost, they may have been generated from CD5+ B lymphocytes. These studies, however, have been unable to discount completely the possibility that aberrant cytoplasmic expression of the CD5 gene occurred as a direct consequence of the hybridization process. To confirm that cytoplasmic CD5 expression in the hybridomas is in fact directly related to the B-lymphocyte origin we have generated hybridomas from FACS-sorted CD5+ and CD5- murine splenic B lymphocytes, and determined their surface and cytoplasmic CD5 expression by fluorescence-activated cell sorting. Our findings reveal that all hybridomas derived from CD5+ B lymphocytes (nine hybridomas) were negative for surface but positive for cytoplasmic CD5 expression, whereas all hybridomas derived from CD5- B lymphocytes (nine hybridomas) were negative for both surface and cytoplasmic CD5 expression. This finding shows that staining for cytoplasmic CD5 expression provides an accurate method of determining the cellular origin of murine B-lymphocyte hybridomas.

Animals↗
PubMed1994

High levels of anti-type II collagen IgG in west African patients with rheumatoid arthritis.

OBJECTIVE: To compare levels of antitype II collagen IgG in West African and British patients with rheumatoid arthritis (RA). METHODS: IgG levels to native and denatured type II collagen were measured by ELISA: RESULTS: Serum levels of antinative type II collagen IgG were raised in 17 of 58 (29%) West African patients with RA. In contrast, 14 of 89 (16%) British RA patients had raised levels of antinative type II collagen IgG. Levels of antinative type II collagen IgG were also higher in West African patients with RA than in the British patients. CONCLUSION: Our results suggest that type II collagen autoimmunity plays a more prominent role in RA in West Africa than in Britain.

Africa, Western↗
PubMed1994

TNF alpha as a therapeutic target in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease with inflammatory manifestations in the peripheral synovial joints, which are infiltrated by activated T cells, macrophages, and plasma cells. We have investigated the role of cytokines in RA and have proposed that tumour necrosis factor has a pivotal role in the pathogenesis of this disease. This chapter describes those studies, which led to the first clinical trial in RA patients using a chimeric anti TNF alpha antibody. In addition to pro-inflammatory cytokine production, at sites of inflammation such as the RA synovial joint, there is also evidence for homeostatic immunoregulatory mechanisms which include the production of cytokine inhibitors, such as soluble TNF-R and the IL-1 receptor antagonist, and cytokines with immunoregulatory properties like IL-10. The evidence for these inhibitors in RA is presented, and the relevance of this homeostatic mechanism in relation to chronic inflammatory diseases is discussed.

Animals↗
PubMed1993

Correlation between serum levels of soluble tumor necrosis factor receptor and disease activity in systemic lupus erythematosus.

OBJECTIVE: To determine the value of measurement of serum soluble tumor necrosis factor receptor (sTNFR), compared with established parameters such as anti-double-stranded DNA, in monitoring systemic lupus erythematosus (SLE) disease activity, and to determine whether serum sTNFR are bioactive and can effectively inhibit TNF bioactivity. METHODS: Fifty-three consecutive ambulatory or hospitalized SLE patients and 140 consecutive healthy subjects were enrolled in a prospective cohort study. Serum levels of sTNFR were measured by a unique 2-sided capture enzyme-linked immunosorbent assay using mouse monoclonal antibodies and rabbit antisera against the sTNFR. RESULTS: The mean +/- SD concentrations of both the p55 (type I) and p75 (type II) soluble receptors were significantly higher in a group of 46 SLE patients than in controls: 1.89 +/- 0.89 ng/ml versus 0.77 +/- 0.19 ng/ml and 7.25 +/- 3.89 ng/ml versus 3.02 +/- 0.57 ng/ml, respectively (P < 0.0001 for both). The incidence and the extent of the increase among the healthy subjects and these patients (as well as in 7 additional patients on whom sequential studies were performed) correlated with disease activity more than did the occurrence of serum anti-DNA antibodies (correlation coefficients with disease activity 0.81 and 0.85 for p55 and p75 sTNFR, respectively, and 0.51 for anti-DNA antibodies). The increase in sTNFR levels seems to reflect, largely, enhanced formation, and only to a minor extent, reduced clearance due to impairment of renal function. Sera of the SLE patients had a marked inhibitory effect on the in vitro cytocidal activity of TNF, and this was shown to result entirely from their higher sTNFR receptor concentration. CONCLUSION: An increase in serum levels of sTNFR may become a useful marker for SLE activity since it shows a stronger correlation than do any other laboratory or clinical parameters employed presently in the daily clinical setting. At the concentrations attained in the serum of SLE patients, sTNFR effectively inhibit the bioactivity of TNF and may thus be a significant determinant of the intensity of the manifestations of SLE.

Adult↗
PubMed1993

Treatment of rheumatoid arthritis with chimeric monoclonal antibodies to tumor necrosis factor alpha.

OBJECTIVE: To evaluate the safety and efficacy of a chimeric monoclonal antibody to tumor necrosis factor alpha (TNF alpha) in the treatment of patients with rheumatoid arthritis (RA). METHODS: Twenty patients with active RA were treated with 20 mg/kg of anti-TNF alpha in an open phase I/II trial lasting 8 weeks. RESULTS: The treatment was well tolerated, with no serious adverse events. Significant improvements were seen in the Ritchie Articular Index, which fell from a median of 28 at study entry to a median of 6 by week 6 (P < 0.001), the swollen joint count, which fell from 18 to 5 (P < 0.001) over the same period, and in the other major clinical assessments. Serum C-reactive protein levels fell from a median of 39.5 mg/liter at study entry to 8 mg/liter at week 6 (P < 0.001), and significant decreases were also seen in serum amyloid A and interleukin-6 levels. CONCLUSION: Treatment with anti-TNF alpha was safe and well tolerated and resulted in significant clinical and laboratory improvements. These preliminary results support the hypothesis that TNF alpha is an important regulator in RA, and suggest that it may be a useful new therapeutic target in this disease.

Adult↗
PubMed1993

Antibodies to neutrophil cytoplasmic antigens in rheumatoid arthritis.

In this study we examined the sera from 42 randomly selected patients with RA. ANCA was demonstrated by indirect immunofluorescence on human granulocytes in 10 patients with active disease and in none of the patients with inactive disease. ELISA's for the detection of specific antigens showed the presence of anti-myeloperoxidase in 3 patients, and anti-lactoferrin in 1 patient. The specificity of the remaining antibodies was unidentified. All 3 patients with antibodies to myeloperoxidase had vasculitis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Serological profile of rheumatoid arthritis in west Africa.

Rheumatoid arthritis (RA) in West Africa is atypical in a number of respects. In order to investigate this we evaluated the serological profile of a series of West African patients diagnosed as having RA. We found the presence of a wide range of autoantibodies including antinuclear antibodies (ANA), anticardiolipin antibodies and antineutrophil cytoplasmic antibodies but the pattern of these autoantibodies was similar to that reported in other studies. Our serological studies support the hypothesis that these patients do have RA and the presence of these autoantibodies is of interest with regards to implications for diagnosis.

Adult↗
PubMed1993

Differential regulation of tumour necrosis factor receptors (TNF-R) by IL-4; upregulation of P55 and P75 TNF-R on synovial joint mononuclear cells.

Interleukin 4 (IL-4) has previously been shown to downregulate the production of proinflammatory cytokines such as TNF-alpha, and hence has been considered to be a potential anti-inflammatory agent. In this study we have investigated the effects of IL-4 on the expression of both p55 and p75 TNF receptors (TNF-R) by flow cytometry and radioligand binding analyses and demonstrate that IL-4 downregulates both p55 and p75 TNF-R on HeLa and Jijoye cell lines in a dose dependent manner. IL-4 reduced the number of p55 TNF-R on HeLa cells from 6400 (Kd 5.1 nM) to 3900 (Kd 3.7 nM), and p75 TNF-R on Jijoye cells from 4800 (Kd 1.6 nM) to 3250 (Kd 1.5 nM). However, different effects were observed on peripheral blood mononuclear cells (PBMC). IL-4 inhibited the increase in p55 and p75 TNF-R on PBMC following adherence, whereas IL-4 upregulated p75 TNF-R expressed on PHA induced T cell blasts. To assess further the possible anti-inflammatory properties of IL-4, we studied its effects on synovial joint mononuclear cell cultures from 15 patients with inflammatory synovitis. In contrast to the differential effects of IL-4 on monocytes and T cells, IL-4 upregulated both p55 (P < 0.05) and p75 TNF-R (P < 0.005) on synovial joint cells in culture. IL-4 treatment caused a small decrease in levels of bioactive TNF-alpha in RA synovial culture supernatants, together with an increase in soluble p75 TNF-R levels although differences were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis↗