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Biomedical subjects

A E Postlethwaite

Publications and source records attributed to A E Postlethwaite.

At least 19 recordsLinked to original sources
PubMed2006

Pamidronate infusion in patients with systemic sclerosis results in changes in blood mononuclear cell cytokine profiles.

A single infusion of pamidronate was given to patients with systemic sclerosis (scleroderma, SSc) to assess effects on cytokine production by peripheral blood mononuclear cells (PBMC) and lymphocyte subsets. Eighteen patients with SSc received a single intravenous dose of 60 mg of pamidronate and were followed for 6 months. Assessment of cytokine production [interferon (IFN)-gamma, interleukin (IL)-10, transforming growth factor (TGF)-beta1, tumour necrosis factor (TNF)-alpha and IL-4] by PBMC and lymphocyte subsets by flow cytometry was carried out before and after the pamidronate infusion. Unstimulated PBMC produced increased amounts of IFN-gamma and TNF-alpha and reduced levels of TGF-beta1 for up to 24 weeks after the infusion. gammadelta T cells from patients with SSc were activated in vitro and produced increased IFN-gamma. The effects of pamidronate on modulation of cytokine profiles in patients with SSc may merit future study.

Aged↗
PubMed2001

Juvenile arthritis and autoimmunity to type II collagen.

OBJECTIVE: Joint inflammation in juvenile rheumatoid arthritis (JRA) is sometimes associated with an autoimmune response to type II collagen (CII), a cartilage-specific protein. To test the hypothesis that down-regulation of autoimmunity to CII can be accomplished in JRA by oral administration of CII, an open-label study of CII was performed in 9 patients with JRA. METHODS: Seven rheumatoid factor-negative JRA patients with polyarticular disease and 2 JRA patients with pauciarticular disease (1 with early onset and 1 with late onset) were treated for 3 months with oral bovine CII. Patients were examined for disease activity and underwent routine laboratory testing at monthly intervals. Two of the patients had flares of disease when treatment was discontinued, and these patients were re-treated for an additional 3 months. To test the hypothesis that oral tolerance induces an immune deviation of T cells, peripheral blood mononuclear cells from patients were collected before and after treatment and cultured with CII. Supernatants and RNA were collected and analyzed for the presence of various cytokines. RESULTS: Eight patient trials met the criteria for clinical improvement outlined by Giannini and coworkers in 1997. None of the patients had any side effects from the treatment. In 6 of the 8 patients who improved, interferon-gamma production decreased after oral CII therapy, correlating with clinical improvement, while 6 patients had increases in levels of transforming growth factor beta3. CONCLUSION: These results are encouraging. The possible beneficial effect of oral CII in JRA merits further investigation.

Administration, Oral↗
PubMed2001

Can we induce tolerance in rheumatoid arthritis?

Oral tolerance (OT) has worked well in numerous laboratory animal models of autoimmune diseases. Humans have been orally tolerized to keyhole limpet hemocyanin (KLH); patients with systemic sclerosis (SSc, scleroderma) have been orally tolerized to oral type I collagen (CI). However, clinical trials of oral type II collagen (CII) therapy in rheumatoid arthritis (RA) have had mixed results. Clinical studies show that compounds (such as nonsteroidal antiinflammatory drugs and prednisone) that inhibit generation of PGE(2) block OT induction. In murine OT models, the PGE(1) analog, misoprostol, reverses the NSAID OT block. These animal studies suggest that OT to CII or other antigens in patients with RA should be inducible if measures are taken to maintain normal prostaglandin function in the gut- associated lymphoid tissue (GALT). A clinical trial is underway in patients with RA to assess whether withholding NSAIDs and prednisone will allow OT to to be induced, and whether oral CII has meaningful clinical efficacy in this disease.

Abortifacient Agents, Nonsteroidal↗
PubMed2000

Induction of immune tolerance to human type I collagen in patients with systemic sclerosis by oral administration of bovine type I collagen.

OBJECTIVE: To determine whether oral tolerance to type I collagen (CI) could be induced in patients with systemic sclerosis (SSc). METHODS: Twenty adult patients with limited or diffuse SSc were enrolled in a study to receive 0.1 mg of solubilized native bovine CI daily for 1 month, followed by 0.5 mg daily for 11 months. Peripheral blood mononuclear cells (PBMC) were obtained from the patients and cultured with human alpha1(I) and alpha2(I) chains, before and after CI treatment. Culture supernatants were analyzed for levels of interferon-gamma (IFNgamma) and interleukin-10 (IL-10). Sera obtained before and after treatment were analyzed for levels of soluble IL-2 receptor (sIL-2R). Although this study was not intended to assess the clinical efficacy of oral CI administration in SSc, selected measures of disease severity and organ involvement were evaluated. RESULTS: Oral administration of CI to SSc patients induced significant reductions in levels of IFNgamma and IL-10 in alpha1(I)- and alpha2(I)-stimulated PBMC culture supernatants, indicating that T cell immunity to CI was decreased by this treatment. Serum levels of sIL-2R also decreased significantly after oral CI treatment, suggesting a reduction in T cell activation. Significant improvements occurred in the modified Rodnan skin thickness score and the modified Health Assessment Questionnaire after 12 months of oral CI in this open trial. The lung carbon monoxide diffusing capacity improved statistically and showed a trend toward clinically significant improvement. CONCLUSION: Oral administration of bovine CI to patients with diffuse or limited SSc induces a reduction in T cell reactivity to human CI, appears to be well tolerated, and does not worsen the disease. Further evaluation of oral tolerance to CI in patients with SSc is justified to determine whether it has therapeutic efficacy.

Administration, Oral↗
PubMed2000

The genetic ablation of cyclooxygenase 2 prevents the development of autoimmune arthritis.

OBJECTIVE: To determine the effects of cyclooxygenase 1 (COX-1) and COX-2 gene deletion on collagen-induced arthritis (CIA). METHODS: Mice that were susceptible to CIA but lacked either the COX-1 or the COX-2 gene were immunized with type II collagen (CII), and the incidence and severity of arthritis were compared with findings in wild-type animals, by clinical and histologic examination. The immune response was assessed by measuring total CII IgG, IgG1, and IgG2 antibody production in sera from immunized mice. The passive transfer of arthritis, accomplished using anti-CII monoclonal antibodies, was tested in wild-type and COX-deficient (-/-) mice. Splenocytes cultured from CII-immunized wild-type and COX-/- mice were challenged with bovine alpha1(II), and cytokine production was assessed. RESULTS: COX-2 gene deletion reduced the incidence and severity of CIA compared with findings in wild-type and COX-1-/- mice. Histologic examination of joints after the onset of clinical arthritis revealed cartilage erosions, proliferation of the synovial lining, and inflammatory cell infiltration in wild-type and COX-1-/- mice, but not in COX-2-/- mice. COX-2-/- mice exhibited reduced anti-CII IgG antibody levels, indicating a decreased immune response. However, cytokine production by spleen cells from immunized mice indicated no cytokine deficiencies in COX-2-/- mice compared with wild-type or COX-1-/- mice. More important, arthritis could not be passively transferred to naive COX-2-/- mice, indicating a requirement for COX-2 in the pathogenesis of arthritis, independent of the immune response. CONCLUSION: COX-2-/- mice exhibit at least 2 defects resulting in down-modulation of the development of CIA: a reduced immune response to CII demonstrated by a markedly reduced antibody titer, and an "inflammatory" defect reflected by the inability to passively transfer arthritis to COX-2-/- mice.

Animals↗
PubMed1999

Intracellular IL-1 receptor antagonist is elevated in human dermal fibroblasts that overexpress intracellular precursor IL-1 alpha.

Cultured dermal fibroblasts from systemic sclerosis patients express higher levels of intracellular IL-1 alpha than fibroblasts from healthy controls. In this study, we found that systemic sclerosis dermal fibroblasts also express higher levels of the intracellular isoform of IL-1 receptor antagonist (icIL-1Ra) than normal fibroblasts after stimulation with IL-1 beta or TNF-alpha. A possible relationship between elevated precursor IL-1 alpha (preIL-1 alpha) and elevated icIL-1Ra was investigated by transducing normal dermal fibroblasts to overexpress preIL-1 alpha, preIL-1 beta, or icIL-1Ra. Fibroblasts that overexpressed icIL-1Ra did not have elevated levels of IL-1 alpha. On the other hand, fibroblasts that overexpressed preIL-1 alpha had at least 4-fold higher basal levels of icIL-1Ra than control fibroblasts and 4-fold higher levels of icIL-1Ra after induction with IL-1 beta or TNF-alpha. Fibroblasts overexpressing preIL-1 beta did not exhibit elevated icIL-1Ra. The differences in icIL-1Ra protein levels were reflected in differences in mRNA. In contrast, IL-1-stimulated levels of MCP-1 and IL-6 were not different in control and preIL-1 alpha-transduced fibroblasts. Addition of neutralizing anti-IL-1 alpha Abs to fibroblast cultures did not diminish basal or stimulated levels of icIL-1Ra in the preIL-1 alpha-transduced cells, supporting an intracellular site of action of preIL-1 alpha. This is the first report of an association between intracellular levels of these IL-1 family members. We hypothesize that intracellular preIL-1 alpha participates in the regulation of icIL-1Ra.

Adult↗
PubMed1999

Autoantibodies to the extracellular matrix microfibrillar protein, fibrillin-1, in patients with scleroderma and other connective tissue diseases.

A duplication in the fibrillin-1 gene has been implicated as the cause of the tight skin 1 (tsk1) phenotype, an animal model of scleroderma or systemic sclerosis (SSc). In addition to the production of abnormal fibrillin-1 protein, the tsk1 mouse also produces autoantibodies to fibrillin-1. Among a population of Choctaw Native Americans with the highest prevalence of SSc yet described, a chromosome 15q haplotype containing the fibrillin-1 gene has been strongly associated with SSc. With a recombinant human fibrillin-1 protein, autoantibodies to fibrillin-1 were detected in the sera of Native American SSc patients that correlated significantly with disease. Abs to fibrillin-1 also were detected in sera from Japanese, Caucasian, and African-American SSc patients. Compared with other ethnic groups, Japanese and Native American SSc patients had significantly higher frequencies of anti-fibrillin-1 Abs. Sera from patients with diffuse SSc, calcinosis, Raynaud's, esophageal dysmotility, sclerodactyly, and telangiectasias syndrome and mixed connective tissue disease also had significantly higher frequencies of anti-fibrillin-1 Abs than sera from controls or patients with other non-SSc connective tissue diseases (lupus, rheumatoid arthritis, and Sjögren's syndrome). Ab specificity for fibrillin-1 was demonstrated by the lack of binding to a panel of other purified autoantigens. The results presented demonstrate for the first time the presence of high levels of anti-fibrillin-1 Abs in a significant portion of patients with SSc.

Adult↗
PubMed1999

Lack of efficacy of oral bovine type II collagen added to existing therapy in rheumatoid arthritis.

OBJECTIVE: To investigate the efficacy of oral type II collagen (CII) in the treatment of rheumatoid arthritis (RA), when added to existing therapy. METHODS: Patients with active RA (n = 190) were randomized into a 6-month, double-blind, placebo-controlled trial. Patients continued to take their current arthritis medications. Patients received either placebo or bovine CII, 0.1 mg/day for 1 month, then 0.5 mg/day for 5 months. RESULTS: There were no significant differences between the baseline characteristics of either group. The primary response parameter was the American College of Rheumatology (ACR) preliminary definition of improvement in RA (ACR 20). There was no statistically significant difference in the ACR 20 after 6 months (20.0% of placebo patients; 16.84% of bovine CII patients). There were significant differences in several clinical variables after treatment, all favoring the placebo group. CONCLUSION: Oral solubilized bovine CII, added to existing therapy, did not improve disease activity in patients with RA.

Administration, Oral↗
PubMed1997

Identification of specific sites in the TNF-alpha molecule promoting insulin resistance in H-411E cells.

Data from a number of laboratories support a potential role for tumor necrosis factor-alpha (TNF-alpha) in the loss of insulin sensitivity and the pathogenesis of insulin resistance (IR) in diabetic animal models and human patients. We designed experiments to establish a dose-response relationship for TNF-alpha and IR in H-411E cells in culture. IR was measured by inhibition of the ability of graded amounts of insulin to stimulate expression of calmodulin (CaM) mRNA in these cells. This was assessed by autoradiographs of Northern blot(s) of CaM mRNA probed with labeled oligonucleotide cDNA for rat CaM. We found that TNF-alpha at 0.1, 1.0, and 10.0 ng/ml opposed 10,000 microU/ml insulin (i.e., %IR = 20%, 67%, and 88%, respectively). At 1.0 ng/ml TNF-alpha, insulin at the concentration of 1000 microU/ml (0.006 micromol/L) stimulated CaM mRNA at a 41% level and at 10,000 microU/ml (0.06 micromol/L) at a 63% level. Furthermore, oligopeptide TNF-alpha homologs (at 1000 x the molar concentration of TNF-alpha) TNF-alpha 69-100 and TNF-alpha 133-157 conferred 66% and 101% IR, respectively, while all other peptide fragments of TNF-alpha were essentially without effect. Studies done with both monoclonal and polyclonal antibodies to the TNF-alpha receptor demonstrated blocking activity by polyclonal but not by monoclonal anti TNF-alpha receptor antibody. This supports the concept that the activity of the peptide fragments occurs through the TNF-alpha receptor and not through nonspecific translocation across the plasma membrane. These data suggest that the epitopes on TNF-alpha that mediate IR reside in two regions of the molecule spanning amino acid residues 69-100 and 133-157.

Amino Acid Sequence↗
PubMed1997

Pioglitazone and metformin reverse insulin resistance induced by tumor necrosis factor-alpha in liver cells.

Tumor necrosis factor-alpha (TNF-alpha) has recently been implicated as a cause of insulin resistance (IR) in obesity and non-insulin dependent diabetes mellitus (NIDDM). To examine mechanisms involved, we induced IR induced IR in H-411 E cells with graded doses of TNF-alpha and measured the ability of insulin (INS) to stimulate both calmodulin (CaM) mRNA and glucose utilization. With TNF-alpha concentration at 1 ng/ml and 10(4) muU/ml INS, metformin 10 microM and pioglitazone 1.5 microM, reversed the IR induced by TNF-alpha restoring biologic response to 100% of INS effect alone. Furthermore, comparable results were obtained with glucose utilization/oxidation experiments in the H-411 E cells using glucose U-14C, trapping 14CO2 release in a hyamine filter and extracting 14C labelled lipids with Dole's reagent. In condusion, these data add scientific support for the use of both metformin and pioglitazone in treatment of IR in NIDDM patients and support a rationale for use of use of these drugs alone, and in conjuction with oral agents and/or INS treatment.

Animals↗
PubMed1996

Transforming growth factor-beta inhibits interferon-gamma-induced HLA-DR expression by cultured human fibroblasts.

This study shows the induction of HLA-DR (DR) in fibroblasts by IFN-gamma and investigates the molecular mechanisms involved in the further DR down-regulation by TGF-beta 1. Kinetics of DR induction on human dermal fibroblasts by IFN-gamma showed that 1 hr of exposure was required to induce detectable levels of DR, and maximal DR expression was achieved only after 2 days of exposure to IFN-gamma. TGF-beta 1 inhibited DR induction by IFN-gamma, although complete inhibition never could be achieved, even with high concentrations of TGF-beta 1 and low concentrations of IFN-gamma. Inhibition was not accounted for by reduction in cell numbers, as TGF-beta 1 stimulated growth of the fibroblasts. Inhibition of DR induction was seen only if TGF-beta 1 was added during the first 24 hr of IFN-gamma treatment. TGF-beta 1 inhibited equally well if the cells were pretreated for as little as 1 hr and then washed before addition of IFN-gamma. TGF-beta 1 did not cause an overall suppression of protein synthesis. Northern blot analysis revealed that TGF-beta 1 greatly reduced the steady-state level of DR beta mRNA induced by IFN-gamma at 24 hr, and then DRP transcripts became undetectable at later stages. It is concluded that early intracellular signals must build up to stimulate maximum DR synthesis, which, later on, are inactivated or degraded by the action of TGF-beta 1. We suggest that these mechanisms regulating DR gene transcription involve the action of genes coding for specific IFN-gamma-inducible transcriptional factors that are turned on and off in an expeditious manner.

Cells, Cultured↗
PubMed1996

Synovial fluid from patients with rheumatoid arthritis contains a unique inhibitor of interleukin 1 alpha.

OBJECTIVE: To partially purify and characterize a specific inhibitor of interleukin 1 alpha (IL-1 alpha) activity from synovial fluids (SF) of patients with rheumatoid arthritis. METHODS: SF inhibitor of IL-1 alpha (SFI alpha) was partially purified by ammonium sulfate precipitation, gel filtration, anion exchange chromatography, and chromatofocusing. Specificity of inhibition of IL-1 alpha activity was tested in T lymphocyte proliferation assays. The mechanism of this inhibition was investigated by binding assays and mobility shift on gel filtration. RESULTS: The SFI alpha inhibited all in vitro activities of IL-1 alpha tested, but did not inhibit activities of IL-1 beta or IL-2. Inhibitor activity was not diminished by neutralizing antibodies against the IL-1 receptor antagonist, and was not removed by immunoadsorption with antibodies against IL-1 receptors. It was not depleted by monoclonal antibodies against human IgG subclasses, IgA, or IgM. The SFI alpha specifically inhibited binding of IL-1 alpha to cell surface receptors, and appeared to form a high molecular weight complex with IL-1 alpha. CONCLUSION: SFI alpha appeared to block biological activities of IL-1 alpha by specific binding to this cytokine, thereby preventing receptor occupancy. The SFI alpha did not appear to be related to previously described inhibitors of IL-1.

Animals↗
PubMed1995

Identification of a chemotactic epitope in human transforming growth factor-beta 1 spanning amino acid residues 368-374.

TGF-beta 1 plays a critical role in inflammatory and repair processes due in part to its ability to provide a potent chemotactic stimulus for inflammatory cells such as neutrophils and monocytes and for fibroblasts which initiate the fibrogenic response. In the present study, we have used synthetic oligopeptides representing the amino acid sequence of the 12.1 kDa monomer of human TGF-beta 1 in an effort to identify a chemotactic epitope on the molecule. A seven residue peptide containing residues 368-374, Val Tyr Tyr Val Gly Arg Lys, was demonstrated to be capable of inducing chemotactic migration of human peripheral blood neutrophils, monocytes, monocyte leukemia cell line THP-1, and infant foreskin fibroblasts. Furthermore, larger peptides from the carboxy-terminal portion of TGF-beta 1 that contained residues 368-374 also induced migration of these cell types. None of the peptides representing the complete amino acid of TGF-beta 1 monomer were able to compete with [125I]hrTGF-beta 1 for binding to TGF-beta cell surface receptors or fibroblasts or THP-1 cells. Implications of these observations are discussed.

Amino Acid Sequence↗
PubMed1995

Connective tissue metabolism including cytokines in scleroderma.

Review of the currently published literature on systemic sclerosis emphasizes the role of adhesion molecules, growth factors, immune reactions, and aberrant fibroblast biology and metabolism in effecting vascular and connective tissue alterations in this disease and its variants.

Cell Adhesion↗
PubMed1995

Role of T cells and cytokines in effecting fibrosis.

A number of humoral and cellular immune abnormalities are present in patients with early scleroderma (systemic sclerosis). Most of these abnormalities reflect ongoing autoimmune reactions of the cellular and humoral types, resulting in a variety of autoantibodies to cellular and tissue constituents. Evidence exists for a defect(s) in immunoregulation favoring excessive helper T cell activity. The presence of circulating cytokines and shed interleukin-2 receptors suggest ongoing cellular immune reactions are occurring, generating cytokines and lymphokines that are capable of effecting the vascular and fibrotic lesions that are hallmarks of the disease. Future directions for research are suggested that would focus on determining if, and at what point, fibroblasts might function autonomously to generate excessive matrix components and on determining the nature of the original antigenic stimulus that starts the scleroderma process.

Cytokines↗
PubMed1994

Interleukin 1 beta propeptide is detected intracellularly and extracellularly when human monocytes are stimulated with LPS in vitro.

Human interleukin 1 beta (IL-1 beta) is synthesized as an inactive precursor that is cleaved by IL-1 converting enzyme (ICE) between Asp116 and Ala117 to form COOH-terminal mature IL-1 beta and NH2-terminal IL-1 beta propeptide. Little is known about the fate of the NH2-terminal cleavage product. In this study, human recombinant (hr)IL-1 beta propeptide (amino acids 2-116) was produced and used to prepare specific antibodies which do not recognize mature human IL-1 beta. These anti-propeptide antibodies were used for immunoprecipitation of biosynthetically labeled proteins from lipopolysaccharide-stimulated human monocytes. Analysis of immunoprecipitates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography revealed that these antibodies recognize precursor IL-1 beta and two unique proteins: one migrating at 17.5 kD and one at 14 kD. The larger of these two proteins has a migration nearly identical to that of the recombinant IL-1 beta propeptide, and most likely represents naturally derived propeptide. The protein migrating at 14 kD may result from a second cleavage by ICE, between Asp27 and Gly28. These proteins accumulate intracellularly and extracellularly during pulse-chase experiments, and therefore represent stable products of precursor IL-1 beta cleavage.

Antibody Specificity↗
PubMed1994

Osteogenic protein-1, a bone morphogenic protein member of the TGF-beta superfamily, shares chemotactic but not fibrogenic properties with TGF-beta.

We have previously shown that recombinant human osteogenic protein-1 (rhOP-1), a bone morphogenetic protein member of the TGF-beta superfamily, can induce new bone formation when implanted with an appropriate carrier at subcutaneous sites in rats and can restore completely large diaphyseal segmental defects in laboratory animals. The role of OP-1 in the early events of bone induction viz, chemotaxis of phagocytic leukocytes, and fibroblastic mesenchymal cells is currently unknown. In the present study, we examined the effect of rhOP-1 on chemotaxis of phagocytic leukocytes (human neutrophils and monocytes) and fibroblastic mesenchymal cells (infant foreskin fibroblasts). Since OP-1 is structurally related to TGF-beta 1, we assessed the effects of OP-1 on several other fibroblast functions (in addition to chemotaxis) known to be modulated by TGF-beta 1. Our results demonstrated that rhOP-1, like TGF-beta 1, is a potent chemoattractant for human neutrophils, monocytes, and fibroblasts. However, in contrast to TGF-beta 1, OP-1 does not to stimulate fibroblast mitogenesis, matrix synthesis [collagen and hyaluronic acid (hyaluronan)], or production of tissue inhibitor of metalloproteinase (TIMP), i.e., fibroblast functions associated with fibrogenesis. These results clearly demonstrate a dichotomy between these two members of the TGF-beta superfamily with a regard to fibrogenic effects on fibroblasts but a similarity in their chemotactic properties.

Bone Morphogenetic Protein 7↗