Pharmacological characterization and antidiabetic activity of a long-acting glucagon-like peptide-1 analogue conjugated to an antithrombin III-binding pentasaccharide.

AIMS: To examine the biological characteristics of a novel glucagon-like peptide-1 (GLP-1) conjugate, in which an antithrombin III (ATIII)-binding pentasaccharide is conjugated to d-Ala(8) GLP-1 using a tetraethylene glycol linker. METHODS: We assessed GLP-1 receptor binding, cAMP generation and insulin secretory activity of the GLP-1 conjugate in vitro. Circulating half-life, glucose homeostatic and subchronic therapeutic effectiveness were then examined in vivo. RESULTS: The half-life of the GLP-1 conjugate in mice was ∼11 h. In vitro insulin secretion from clonal ß cells and islets was increased (p < 0.001) by the conjugate. The conjugate had half maximum effective concentration values of 1.3 × 10(-7) and 9.9 × 10(-8) M for displacement of (125) I-GLP-1 in competitive GLP-1 receptor binding and cAMP generation, respectively. Glucose tolerance in normal mice, immediately and 4 h after conjugate injection, resulted in significant (p < 0.001) improvements in blood glucose. These effects persisted for >48 h after administration. Daily treatment (21 days) of high-fat-fed and ob/ob mice with 25 nmol/kg conjugate resulted in significant improvement in glucose tolerance (p < 0.001) and reductions in glycated haemoglobin (HbA1c; p < 0.01) equivalent to or better than with exenatide or liraglutide. Treatment of C57BL/KsJ db/db mice for 15 days with 100 nmol/kg conjugate significantly (p < 0.001) reduced glucose and raised plasma insulin. Oral glucose tolerance was significantly (p < 0.001) improved and both 24-h glucose profile (p < 0.001) and HbA1c levels (p < 0.001) were reduced. Islet size (p < 0.001) and pancreatic insulin content were increased without change of islet cell proliferation or apoptosis. CONCLUSION: These data show that d-Ala(8) GLP-1(Lys(37) ) pentasaccharide exerts significant antidiabetic actions and has a projected pharmacokinetic/pharmacodynamic profile that merits further evaluation in humans for a possible once-weekly dosing regimen.

Refinement and precision in the classification of murine lymphomas by genotyping with immunoglobulin and T cell receptor probes.

Of 114 murine leukemia virus induced lymphomas and 12 lymphoid hyperplasias, T cell receptor beta-chain gene and immunoglobulin gene constellation (immunogenotype) was compared with histology and surface marker expression (immunomorphology). In 53 out of 114 lymphomas (45%), definite conclusions concerning cell lineage were possible only after genotyping. Fifteen follicular center cell lymphomas with a clear phenotype (13 tumors with B and 2 tumors with T cell markers) were genotypically classified in agreement with their phenotype. Of another 21 follicular center cell tumors (12 null cell tumors lacking T or B cell-specific antigens and 9 tumors phenotypically composed of mixtures of T and B cells), B cell lineage was determined upon genotyping in 17 cases. All 41 lymphoblastic tumors with a T cell phenotype and 6 out of 7 lymphoblastic tumors with a T cell phenotype and 6 out of 7 lymphoblastic tumors with a B cell phenotype, upon DNA analysis were indeed classified as T and B cell tumors, respectively. Of another 10 lymphoblastic tumors (phenotypically 4 null cell lymphomas, 6 mixtures of T and B cells) genotyping established lineage in 9 cases. Fifteen lymphoblastic neoplasms showing lineage infidelity because of simultaneous expression of a T (Thy-1) and a B cell (B220) marker were clearly of T cell genotype. Only 4 out of 114 lymphomas tested retained both Ig and T cell receptor genes in germline configuration, although 6 lymphomas in these series had both Ig and T cell receptor genes rearranged. Four of twelve lesions histologically classified as hyperplasias nevertheless contained a monoclonal B cell population at the DNA level. Immunogenotypic evaluation of lymphomas allows precise lymphoma lineage determination even in cases where marker analysis falls short, and is clearly superior in detecting mono- or oligoclonality in lymphomas versus polyclonality in benign lesions.

Detection of intracellular interferon-gamma by light microscopy using an immunoperoxidase technique: correlation with the corresponding mRNA and protein product.

Identifying individual cytokine-producing cells may help to acquire insight into immunological processes. This study was designed to adapt a technique for the detection of individual cytokine-producing cells from an immunofluorescence to an immunoperoxidase staining procedure. The production of interferon-gamma (IFN-gamma) by anti-CD3-activated cloned human T cells was used as a model system. After the conditions for the staining procedure were optimized, the immunoperoxidase technique was slightly more sensitive than the immunofluorescence technique. The intracellular staining for IFN-gamma was preceded or paralleled by IFN-gamma mRNA production and followed by accumulation of IFN-gamma in the supernatant. It is concluded that intracellular IFN-gamma can easily be detected using an immunoperoxidase procedure. This procedure is highly sensitive and allows quantification of the production of multiple cytokines by counting the percentage of positively staining cells.

Induction of antibody-dependent cellular cytotoxicity against endothelial cells by renal transplantation.

Antibodies that induce antibody-dependent cellular cytotoxicity (ADCC) of human umbilical-vein endothelial cells (EC) were detected using serum of a renal transplant patient who had experienced a severe vascular rejection episode after receiving an HLA-identical kidney graft from a living-related donor. This reactivity was absent in sera obtained before transplantation. The antibody nature of the reactivity present in the post-transplantation sera was proven by gelfiltration studies, protein A absorption, pepsin-digestion experiments, and incubation with subclass specific monoclonal antibodies; predominantly IgG1 antibodies were found to bind to EC and induce ADCC. The specificity of the antibodies could be shown in panel studies using EC lines of various donors. In order to investigate the clinical relevance and incidence of anti-EC ADCC, we examined whether anti-EC reactivity could be observed in 9 additional renal transplant patients. Sera of 2 of these patients were found positive in the ADCC assay, whereas 20 normal serum donors were negative. ADCC against EC in these patients was not caused by classic antiendothelial-monocyte (EM) antibodies. Using various experimental systems (adherent cell depletion, monoclonal antibody blocking, cold target cell inhibition) it was shown that the natural killer/killer (NK/K) cells present within the peripheral blood mononuclear cell population were responsible for EC lysis. These findings demonstrate that IgG1 antibodies directed against polymorphic non-HLA, non-EM antigens on EC can be induced by renal allotransplantation. Via Fc-receptor interaction with NK/K cells, these antibodies can be responsible for ADCC against EC.

Donor-specific lysis of human kidney proximal tubular epithelial cells by renal allograft-infiltrating lymphocytes.

In the present study methods are described to obtain both graft infiltrating cells (GIC) of host origin and proximal tubular epithelial cells (PTEC) of donor origin simultaneously from biopsy material of renal allografts undergoing rejection. The identity of PTEC cultures was established using monoclonal antibodies. GIC were shown to exhibit T cell functional activity. These GIC were shown to lyse trypsinized PTEC as well as PTEC monolayers grown from the corresponding biopsy, and not PTEC isolated from biopsies obtained from other patients. Therefore the lytic activity appeared to be donor-specific. Major histocompatibility complex class I antigens were involved since donor PHA-blasts, a target population well known to express class I molecules, were lysed by GIC, and the anti-class I MoAb W6/32 blocked cytolytic activity of GIC against donor PHA-blasts and against donor PTEC. We thus established that donor-specific lysis of a defined population of kidney epithelial cells, namely PTEC, may occur. This model system, in which GIC and PTEC can be propagated from one biopsy specimen may be useful for further study of cell-cell interactions involved in allograft rejection.

Renal allograft-infiltrated lymphocytes and proximal tubular cells: further analysis of donor-specific lysis.

We obtained both graft-infiltrating cells of host origin and proximal tubular epithelial cells (PTEC) of donor origin (using a selective serum-free medium) simultaneously from biopsies of rejecting renal allografts. The identity of PTEC cultures was established with monoclonal antibodies. Major histocompatibility complex class I expression could be upregulated and major histocompatibility complex class II expression induced on PTEC by 24- to 48-hr incubation with 200 U interferon-gamma. Graft-infiltrating cells were shown to lyse PTEC grown from the corresponding biopsy and not PTEC from biopsies from other patients. Therefore the lytic activity appeared to be donor-specific. Preincubation of PTEC with interferon-gamma did not consistently increase PTEC lysis. Lysis by graft-infiltrating cells obtained from four patients could be blocked by target-preincubation with anti-class I monoclonal antibodies, in one case both anti-class I and anti-class II monoclonal antibodies could block PTEC lysis. Blocking could also be obtained with anti-CD3 monoclonal antibody. PTEC lysis occurred only with graft-infiltrating cells cultured from biopsies with cellular interstitial rejection. So, PTEC seem to be a target in renal allograft rejection both in vivo and in vitro. This model system may be useful for further studies of cellular interactions between graft-infiltrating cells and their targets.

Antibiotics as disease modifiers in arthritis.

The tetracyclines, especially minocycline, are supposed to have antiarthritic properties. Their efficacy has been tested in open clinical studies on RA patients. Recently a double-blind placebo-controlled trial was performed which revealed the antirheumatic properties of minocycline. The mode of action of the tetracyclines in arthritis is unknown, but could be linked to the immunosuppressive activity seen in vitro. The antiproliferative effect of minocycline in cloned synovial T-cells is demonstrated; moreover IFN-gamma production in cloned synovial T-cells is inhibited by minocycline.

T cell receptor rearrangements in juvenile rheumatoid arthritis: a search for oligoclonality.

Southern blot analysis of DNA from paired samples of synovial compartment (membrane and/or fluid) and peripheral blood T cells from nine children with juvenile rheumatoid arthritis (JRA) was carried out. Using a T cell receptor C beta probe, dominant TCR rearrangements were discovered in specimens from three patients: synovial fluid T cells from one, synovial fluid and synovial membrane cells from a second, and synovial membrane and peripheral blood cells from a third. The patient showing dominant bands in peripheral blood as well as in synovium was the only child in the series with systemic disease. Since non-specific T cell recruitment is likely to dilute antigen specific clones to low levels, the finding of dominant rearrangements in three of nine patients may indicate that oligoclonality is indeed a feature of JRA.

Chloroquine combined with cyclosporine in rheumatoid arthritis: more than the addition of 2 drugs alone.

Combination therapy in rheumatoid arthritis (RA) with 2 or more disease modifying antirheumatic drugs (DMARD) is theoretically attractive if the drugs exert additional or even synergistic effects and have different toxicity patterns to avoid cumulative toxicity. The combination of cyclosporin A (CsA) with chloroquine has shown in in vitro studies a synergistic ability to inhibit the proliferation of peripheral blood mononuclear cells and clonal T cells and the production of interferon gamma by clonal T cells. This synergy is probably based on different mechanisms of action of the 2 drugs: CsA primarily inhibits the production of interleukin 2 (IL-2) (and other cytokines) at the level of transcription, whereas chloroquine primarily inhibits the responsiveness of T cells to IL-2 stimulation. To evaluate whether these in vitro data can be extrapolated in vivo, a large 2 phase trial has been initiated in the Netherlands in which the combination of CsA with chloroquine is evaluated in patients with RA.

Synovial inflammation does not change in the absence of effective treatment: implications for the use of synovial histopathology as biomarker in early phase clinical trials in rheumatoid arthritis.

OBJECTIVES: To determine the impact on synovial histopathology of changes in clinical disease activity in the absence of effective treatment. METHODS: Twelve patients with active RA not receiving effective treatment were studied over a 14 week period. Synovial biopsy specimens obtained at baseline and week 14 were analysed by histology and immunohistochemistry. RESULTS: Over the course of 14 weeks, there was a trend towards a decrease of the DAS28, with 7/12 patients being good or moderate DAS28 responders despite the absence of effective treatment. Patients' assessment of global disease activity and swollen joint count both decreased significantly. Histologically, there was a decrease of lining layer hyperplasia and lymphoid aggregates, a similar trend for vascularity, but there was no effect on global synovial infiltration. Accordingly, there was no decrease of the cellular infiltration with T lymphocytes (CD3, CD4, CD8), B lymphocytes (CD20), plasma cells (CD38), dendritic cells (CD1a, CD83), and even an increase of CD163+ sublining macrophages, with a similar trend for CD68+ sublining macrophages. The changes in DAS28 scores in these patients did not correlate with changes in histological variables, with the exception of an inverse correlation with plasma cells. Remarkably, even in the DAS28 responders, no significant changes in synovial inflammatory infiltration were noted. CONCLUSIONS: Despite variations in global disease activity, synovial inflammatory infiltration did not change significantly in the absence of effective treatment. The lack of a placebo effect on synovial markers of treatment response such as sublining macrophages can facilitate conclusive early phase trials with small numbers of patients with RA.

Immobilized anti-CD3 antibody activates T cell clones to induce the production of interstitial collagenase, but not tissue inhibitor of metalloproteinases, in monocytic THP-1 cells and dermal fibroblasts.

In this study we have investigated whether direct cell to cell contact between activated paraformaldehyde-fixed T cell clones obtained from synovial tissue of patients with osteoarthritis (OA) or rheumatoid arthritis and target monocytic cells or dermal fibroblasts influenced the balance between interstitial collagenase and its specific inhibitor tissue inhibitor of metalloproteinases (TIMP) produced by the latter cell types. PHA/PMA-activated fixed T cell clones or their membranes strongly induced the production of collagenase both in monocytic THP-1 cells and in dermal fibroblasts. In contrast, only low levels of TIMP were induced in THP-1 cells and no change of TIMP expression was observed in fibroblasts as a result of stimulation with PHA/PMA-activated T cells or T cell membranes. Anti-CD3-activated T cell clones stimulated the production of collagenase both in THP-1 cells and fibroblasts, whereas TIMP levels were not influenced. Collagenase production in THP-1 cells induced by anti-CD3-activated T cell clones was 1) dependent on the dose of anti-CD3 used to stimulate the T cells, 2) initiated only when CD3 was cross-linked, and 3) inhibited when cyclosporin A was included during T cell activation. Our data collectively indicate that activated T cells in contact with monocytic cells or fibroblasts may alter the balance between interstitial collagenase and its specific inhibitor TIMP. This selective induction of a mediator profile representative of matrix breakdown as a result of target cell interaction with activated T cells may be an important factor in the local process of tissue destruction that characterizes osteoarthritis and rheumatoid arthritis.

Levels of soluble receptors for tumor necrosis factor type I and type II in paired synovial fluids of arthritis patients.

The objective of this study was to determine whether levels of soluble receptors for tumor necrosis factor type I and type II (sTNF-RI and sTNF-RII) as measured in paired synovial fluids (SF) of arthritis patients are associated with clinical or laboratory parameters of local inflammation. sTNF-RI and -RII were measured by ELISA. We found that sTNF-RI and -RII did not correlate with activity of local inflammation. sTNF-RI levels correlated with sTNF-RII concentrations. We concluded that sTNF-RI and -II did not represent markers for local disease activity in arthritis patients.

Short-term lymphokine stimulation of human peripheral blood mononuclear cells generates cytolytic activity against endothelial cells: involvement of natural killer cells.

UNLABELLED: We previously reported that incubation of human peripheral blood mononuclear cells (PBMC) for 5 days with T-cell growth factor (TCGF) resulted in lymphokine-activated killer activity against endothelial cells (EC). In this paper we report on the effects of short-term incubation of PBMC with lymphokines. We show that incubation of PBMC with lymphokines during an 18-hr period is sufficient to generate a strong cytolytic response against EC. The cytolytic capacity of the effector cells was directly dependent on the dose of lymphokine added during the induction phase. When PBMC were separated into adherent and non-adherent cells, the non-adherent fraction could be induced to lytic activity against EC, whereas the adherent cells could not. When PBMC were separated, using 2-amino-ethylisothiouronium bromide hydrobromide-treated sheep red blood cells (AET-SRBC), into T- and non-T-cell fractions, the latter fraction could be induced to lyse EC. TCGF-induced cell-mediated EC lysis could not be inhibited using anti-T3 nor anti-LFA-1 antibodies. Lysis of EC by TCGF-stimulated effector cells was strongly inhibited by the addition of unlabelled K562 target cells, whereas cold OKT3 hybridoma cells did not exert such an effect. IN CONCLUSION: the kinetics of the induction of lytic activity against EC, as well as the cell separation experiments, suggest that short-term-activated NK cells may lyse EC. This hypothesis was confirmed using monoclonal antibody and cold target cell analysis.

Lymphokine-activated killer cells lyse human renal cancer cell lines and cultured normal kidney cells.

In this study, we investigated whether or not lymphokine-activated killer (LAK) cells can damage renal tissue and therefore whether they may contribute to graft destruction during kidney allograft rejection. Human peripheral blood mononuclear cells were activated with a lymphokine preparation and the resulting LAK cells were tested against kidney cells from various sources. Renal cancer cells as well as cultured normal kidney cells were efficiently lysed by LAK cells, as assessed with Cr-labelled target cells, showing that both cell types are sensitive to LAK cell-mediated cytolysis.

IgA anti-dsDNA antibodies in systemic lupus erythematosus: occurrence, incidence and association with clinical and laboratory variables of disease activity.

The relationship between IgA anti-dsDNA antibodies and systemic lupus erythematosus (SLE) disease activity was investigated. IgA anti-dsDNA antibodies were measured using ELISA techniques. Elevated serum levels of IgA anti-dsDNA antibodies were detected in 51% of the patients with SLE (n = 57) and 8% of the diseased controls (n = 214). The presence of IgA anti-dsDNA antibodies was associated with kidney and joint abnormalities, with hypocomplementemia and with circulating immune complexes. We conclude that increased levels of IgA anti-dsDNA antibodies are associated with disease activity in patients with SLE.

Inhibition of T cell cytolytic potential by concanavalin A: a result of activation?

We investigated the effects of concanavalin A (Con A) on T cell-mediated lympholysis. Human cytotoxic T cell lines were generated from peripheral blood and these lines were shown to lyse lectin-coated K562 target cells. Addition of soluble Con A to the assay resulted in a dose-dependent inhibition of the cytolysis. Preincubation experiments demonstrated that this inhibitory effect was exerted at the effector cell level. F(ab')2 fragments of WT32, a monoclonal antibody against T3, blocked the cytolysis of Con A-preincubated K562 target cells to a large extent. We further showed that Con A strongly inhibited the cytolysis exerted by alloantigen-specific, major histocompatibility complex (MHC)-restricted cytotoxic T cell lines against their specific targets. On the other hand, Con A had no clear inhibitory effect on the cytotoxicity of freshly isolated peripheral blood mononuclear cells against K562 target cells. We hypothesize that Con A-induced inhibition of cytotoxicity may be explained by a direct triggering of the lytic potential of activated T cells.

Endothelial cell lysis induced by lymphokine-activated human peripheral blood mononuclear cells.

In vitro exposure of human peripheral blood mononuclear cells (PBMC) to interleukin 2 results in the generation of lymphokine-activated killer (LAK) cells. Such LAK cells exhibit cytotoxicity against a spectrum of tumor target cell lines whereas they apparently do not affect normal tissues. In this report we show that PBMC that have been activated with T cell growth factor lyse trypsinized human umbilical cord venous endothelial cells as well as endothelial cell monolayers in a dose-dependent manner. Microscopic analysis showed that during the 4-h incubation period cell clumps containing detached endothelial cells and LAK cells were formed. When these clumps were evaluated with trypan blue the endothelial cells stained positive whereas LAK cells excluded the dye. No lysis occurred when fresh PBMC were added to target endothelial cells. The endothelial cell kill could not be blocked with an anti-LFA-1 antibody nor with intact OKT3 or F(ab')2 fragments of WT32. We conclude that lymphokine-activated PBMC exhibit cell-mediated endothelial cell detachment and lysis.

Cytomegalovirus induced PMN adherence in relation to an ELAM-1 antigen present on infected endothelial cell monolayers.

In human umbilical vein endothelial cells infected with cytomegalovirus (CMV), an activation antigen recognized by monoclonal antibody (mAb) ENA1 appeared. mAb ENA1 reacts with an inducible endothelial surface antigen which has characteristics similar to those of ELAM-1. Incubation with anti-IL-1 partly inhibited this appearance and, parallel to this, the virus-induced polymorphonuclear cell (PMN) adhesion was decreased. In addition, the adhesion of PMN to virus-infected endothelial cells could be reduced by F(ab)2 fragments of mAb ENA1 to almost control level. The results obtained after incubation of PMN with mAb IB4 (against CD18) suggest that the adhesion of PMN to uninfected endothelial cells is CD18 glycoprotein dependent, and virus infection up-regulates this glycoprotein-dependent mechanism. These results indicate that the virus-induced PMN adhesion is regulated by the following mechanism: virus infection of endothelial cells induces IL-1 production, and the autocrine IL-1 causes the expression of ELAM-1 on the surface of endothelial cells. In turn this activation antigen ELAM-1 binds with its putative ligand present on the PMN membrane. The virus-induced PMN adhesion occurs also through a CD18 glycoprotein-dependent mechanism.

Interleukin-6 activity in paired samples of synovial fluid. Correlation of synovial fluid interleukin-6 levels with clinical and laboratory parameters of inflammation.

Paired synovial fluid (SF) samples obtained from the knees of 12 arthritis patients were studied to establish a relation between parameters of local inflammatory activity and SF interleukin-6 (IL-6) levels. Local disease activity was scored using joint temperature, swelling and pain as clinical parameters of inflammation. SF samples were assayed for laboratory parameters of inflammation such as leucocyte content, the percentage polymorphonuclear cells, the pH, and for immunoglobulin levels (IgG, IgM). SF IL-6 concentrations were determined using the B9-bioassay. Within individual patients the local activity of inflammation as measured using clinical parameters was found to be related to the local SF IL-6 level. When considering the total group of patients, a correlation (P less than 0.001) was found between the clinical parameters of local inflammation and the SF IL-6 levels. Furthermore, IL-6 levels were found to correlate with leucocyte counts (P less than 0.02), the percentage of polymorphonuclear cells (P less than 0.10), the pH value (P less than 0.01), but not with SF IgM and IgG concentrations.