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S Endres

Publications and source records attributed to S Endres.

At least 55 records · Page 3Linked to original sources
PubMed1998

Spontaneous and cationic lipid-mediated uptake of antisense oligonucleotides in human monocytes and lymphocytes.

Monocytes are important target cells for anti-inflammatory antisense strategies. However, monocytes are characterized by strong phagocytic and catalytic activity which may limit the effect of antisense oligonucleotides. Intracellular distribution of oligonucleotides in monocytes and the effect of cationic lipids on oligonucleotide uptake in monocytes and other leukocytes have not been evaluated. We investigated cationic lipid-mediated uptake of oligonucleotides in human monocytes and lymphocyte subpopulations. Incorporation of oligonucleotides was quantified by flow cytometry and by confocal microscopy. In the absence of cationic lipids, nearly 100% of monocytes and of B lymphocytes incorporated oligonucleotides compared with only 12% of natural killer cells and 1% of T lymphocytes. The amount of oligonucleotide uptake per cell, as determined by mean fluoresence intensity of positive cells, was four times higher in monocytes than in B lymphocytes. Cationic lipids, which form complexes with oligonucleotides, markedly enhanced the amount of oligonucleotide uptake in all cell types and were most effective at a ratio of 1.1 of positive-to-negative molar charges. In monocytes, oligonucleotides incorporated spontaneously (without a lipid carrier) were trapped in cytoplasmic vesicles. In contrast, cationic lipid-mediated uptake of fluorescence-labeled oligonucleotides resulted in cytoplasmic and nuclear staining. We conclude that 1) monocyte and lymphocyte subpopulations differ in the degree of spontaneous oligonucleotide uptake, and 2) lipofectin both quantitatively and qualitatively affects this uptake. Our results may explain the necessary role of cationic lipids in most antisense models with leukocytes as target cells.

Flow Cytometry↗
PubMed1997

Suppression of tumor necrosis factor-alpha production by interleukin-10 is enhanced by cAMP-elevating agents.

The pro-inflammatory peptide tumor necrosis factor-alpha (TNF) stimulates production of the anti-inflammatory cytokine-interleukin-10 by monocytes which in turn inhibits the synthesis of TNF. This inhibitory effect of interleukin-10 may contribute to the balance of pro- and anti-inflammatory cytokines in several diseases, e.g., chronic inflammatory bowel disease. In the present study we addressed the question whether interleukin-10 in combination with other TNF-suppressing agents leads to enhanced suppression of TNF synthesis. We investigated the inhibitory potency of interleukin-10 in combination with rolipram, a specific type IV phosphodiesterase inhibitor, or with cicaprost, a stable prostacyclin analogue in lipopolysaccharide-stimulated human peripheral blood mononuclear cells. Peripheral blood mononuclear cells were stimulated with 10 ng/ml lipopolysaccharide in the absence or presence of interleukin-10 or one of the cAMP-elevating agents. First, we confirmed the TNF-suppressing effect of interleukin-10, rolipram and cicaprost alone and determined the IC50 for these substances. Second, for the combination of interleukin-10 with one of the cAMP-elevating substances we were able to demonstrate enhanced TNF inhibition. Of these, the combination of interleukin-10 and rolipram revealed an additive effect. The maximal TNF synthesis of 5.5 +/- 1.1 ng/ml after lipopolysaccharide stimulation alone was inhibited by 0.1 ng/ml interleukin-10 to 2.7 +/- 0.6 ng/ml TNF and by 100 nM rolipram to 3.1 +/- 0.6 ng/ml TNF. Both substances combined suppressed TNF synthesis to 1.5 +/- 0.3 ng/ml. After stimulation with Staphylococcus epidermidis we could demonstrate a more pronounced inhibition of TNF synthesis by interleukin-10 compared to rolipram which was more effective after stimulation with lipopolysaccharide. Finally, the additive inhibitory effect of interleukin-10 and rolipram could be confirmed on the level of TNF mRNA. The results obtained in the present investigation could form a prerequisite to study the combination of interleukin-10 and cAMP-elevating agents in in vivo models of acute or chronic inflammatory diseases.

Antineoplastic Agents↗
PubMed1997

Taming TNF: strategies to restrain this proinflammatory cytokine.

Recent studies have demonstrated the essential role of tumor necrosis factor alpha (TNF-alpha) in rheumatoid arthritis and Crohn's disease. This article discusses agents known to suppress the formation or activity of TNF-alpha, and summarizes clinical studies using anti-TNF-alpha antibodies.

Animals↗
PubMed1997

Endogenous adenosine curtails lipopolysaccharide-stimulated tumour necrosis factor synthesis.

Recent studies have demonstrated the inhibitory effect of exogenous adenosine on TNF production. During inflammation endogenous adenosine levels are elevated and may be one of several anti-inflammatory mediators that reduce TNF synthesis. In the present study the authors investigated this role of adenosine in freshly isolated human PBMC. The effect of endogenous adenosine on TNF formation was studied by four different approaches. First, adenosine deaminase was added to LPS-stimulated mononuclear cells. This enzyme specifically deaminates extracellular adenosine to the inactive metabolite inosine. TNF production was augmented from baseline stimulation (LPS alone) of 3.5 +/- 0.4 ng ml-1 -5.2 +/- 0.9 ng ml-1 in the presence of 10 U ml-1 adenosine deaminase. Second, TNF production was determined after stimulation in the presence of dipyridamole, an inhibitor of cellular re-uptake of adenosine which increases extracellular concentrations. TNF synthesis was reduced dose-dependently from 3.1 +/- 0.9 ng ml-1 -1.1 +/- 0.2 ng ml-1 by 10 microM dipyridamole. Third, the adenosine A2 receptor antagonist 8-(3-chlorostyryl)caffeine (100 nM) enhanced TNF synthesis from a baseline of 3.7 +/- 0.5 ng ml-1 -5.5 +/- 0.9 ng ml-1. In contrast, no increase resulted from the addition of 100 nM of the specific A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. Finally, the authors were able to show that suppression of TNF formation by the specific type IV phosphodiesterase inhibitor rolipram can be completely reversed by adenosine deaminase or by the application of the A2 receptor antagonist. The authors conclude that endogenous adenosine controls TNF production. This effect of adenosine may not only have a physiological role but also appears to contribute to the pharmacological inhibition of TNF synthesis by exogenous agents such as the specific type IV phosphodiesterase inhibitor rolipram.

Adenosine↗
PubMed1997

Lack of association between an interleukin-1 receptor antagonist gene polymorphism and ulcerative colitis.

BACKGROUND: Recently, the association of a polymorphism in the gene coding for the anti-inflammatory cytokine interleukin-1 receptor antagonist with ulcerative colitis has been reported. This was interpreted as a possible genetic predisposition for severity of the inflammatory response. AIMS: To examine this polymorphism in a southern German population. SUBJECTS: The study included 234 healthy controls, 57 patients with ulcerative colitis, including 31 patients with pancolitis, 44 first degree healthy relatives of patients with ulcerative colitis, and 65 patients with Crohn's disease. METHODS: Genotypes were determined by a polymerase chain reaction amplification of the intron 2 fragment harbouring a variable number of tandem repeat nucleotide sequences. Amplification products were separated on a 2% agarose gel. RESULTS: The allele frequency for allele 2 was 27% in healthy controls, 28% in Crohn's disease, and 21% in patients with ulcerative colitis. The same allele frequency (21%) was found in a subgroup of patients with ulcerative colitis affecting the whole colon. Thus for allele 2 as well as for all other alleles, genotypes, or carriage rates no significant differences were found compared with controls. All allele frequencies in the control population were similar to those in earlier studies. CONCLUSIONS: No association of a polymorphism in the interleukin-1 receptor antagonist gene with ulcerative colitis could be identified in this southern German population. The findings of an earlier study reporting an increased frequency of allele 2, particularly in patients with pancolitis, could not be confirmed.

Adult↗
PubMed1997

Cytokines and therapeutic oligonucleotides.

Therapeutic oligonucleotides - short strands of synthetic nucleic acids - encompass antisense and aptamer oligonucleotides. Antisense oligonucleotides are designed to bind to target RNA by complementary base pairing and to inhibit translation of the target protein. Antisense oligonucleotides enable specific inhibition of cytokine synthesis. In contrast, aptamer oligonucleotides are able to bind directly to specific proteins. This binding depends on the sequence of the oligonucleotide. Aptamer oligonucleotides with CpG motifs can exert strong immunostimulatory effects. Both kinds of therapeutic oligonucleotides - antisense and aptamer oligonucleotides - provide promising tools to modulate immunological functions. Recently, therapeutic oligonucleotides have moved towards clinical application. An antisense oligonucleotide directed against the proinflammatory intercellular adhesion molecule 1 (ICAM-1) is currently being tested in clinical trials for therapy of inflammatory disease. Immunostimulatory aptamer oligonucleotides are in preclinical development for immunotherapy. In the present review we summarize the application of therapeutic oligonucleotides to modulate immunological functions. We include technological aspects as well as current therapeutic concepts and clinical studies.

Animals↗
PubMed1996

Cicaprost and the type IV phosphodiesterase inhibitor, rolipram, synergize in suppression of tumor necrosis factor-alpha synthesis.

Suppression of tumor necrosis factor-alpha (TNF) synthesis is one major target in pharmacological immunomodulation. We now showed the synergistic suppressive effect of the specific type IV phosphodiesterase inhibitor, rolipram, and of the stable prostacyclin analogue, cicaprost, on TNF synthesis. This effect was seen with lipopolysaccharide and Staphylococcus epidermidis as stimuli in human peripheral blood mononuclear cells and in whole blood. Lipopolysaccharide-induced TNF synthesis by mononuclear cells decreased from 3.4 ng/ml to 1.5 ng/ml in the presence of 100 nM rolipram and to 0.7 ng/ml in the presence of 10 nM cicaprost. The combination of both agents suppressed TNF synthesis more than 10-fold, to 0.3 ng/ml. Synergistic suppression was also demonstrated for TNF mRNA.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1996

n-3 polyunsaturated fatty acids and human cytokine synthesis.

The cytokines interleukin-1 and tumor necrosis factor-alpha are potent peptide mediators of the immune response. They exert potent cellular effects at nanomolar concentrations with target tissues ranging from the vascular endothelium, to the central nervous system and immunocompetent cells. The synthesis of these two cytokines can be suppressed pharmacologically by steroids and other immunosuppressive agents such as cyclosporin A. In previous studies we have found that such an inhibition of inflammatory cytokine synthesis can also be achieved by increasing the content of n-3 polyunsaturated fatty acids in leukocyte membranes.

Animals↗
PubMed1996

Elevated cell-associated levels of interleukin 1beta and interleukin 6 in inflamed mucosa of inflammatory bowel disease.

The aim of this study was to investigate the involvement of the monocyte-derived cytokines interleukin 1beta (IL-1beta), interleukin 6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) in idiopathic inflammatory bowel disease. Endoscopic biopsies of normal and inflamed intestinal mucosa were obtained from patients with ulcerative colitis (n = 11) and with Crohn's disease (n = 10). Intestinal mucosal cells were isolated by collagenase digestion. Cell viability, morphology and CD14 expression were determined. To measure cell-associated cytokine levels, cells were lysed and analysed for IL-1beta and TNF-alpha in specific radioimmunoassays and for IL-6 using a biological assay. Compared with mucosal cells from control patients without inflammatory bowel disease the inflamed intestine in ulcerative colitis and Crohn's disease displayed markedly enhanced levels of IL-1beta (median 245 pg 10(-6) cells, range 30-1275) and IL-6 (median 22 U 10(-6) cells, range 1-298). Non-inflamed mucosa in patients with ulcerative colitis and Crohn's disease did not show elevated levels of IL-1beta (median 50 pg 10(-6) cells, range 33-90) or IL-6 (mean below detection limit of assay, i.e. 1 U 10(-6) cells). In contrast, no clear cut difference between inflamed and non-inflamed mucosa could be detected for TNF-alpha. High tissue levels of IL-6 were associated with a high endoscopic grade of local inflammation. These results suggest that the monocyte-derived cytokines IL-1beta and IL-6 are mediators of inflammation in inflammatory bowel disease.

Adult↗
PubMed1996

Oral aspirin and ibuprofen increase cytokine-induced synthesis of IL-1 beta and of tumour necrosis factor-alpha ex vivo.

We investigated the effect of oral aspirin and ibuprofen on the ex vivo synthesis of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-6, tumour necrosis factor-alpha (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) by stimulated peripheral blood mononuclear cells (PBMC) from healthy volunteers. Seven volunteers took 325 mg of aspirin daily for 14 days. Three weeks after ending aspirin medication, ex vivo IL-1 beta and TNF synthesis induced by exogenous IL-1 alpha was elevated threefold compared to the pre-aspirin value (P = 0.01 and P = 0.005, respectively). Using lipopolysaccharide (LPS) as a stimulus, no influence of oral aspirin was observed. The increase in cytokine synthesis did not parallel decreased synthesis of prostaglandin E2 (PGE2). Seven weeks after discontinuation of aspirin, cytokine and PGE-2 production returned to pre-aspirin levels. Another seven volunteers took 200 mg of ibuprofen daily for 12 days. Again, there was no effect on LPS- or Staphylococcus epidermidis-induced cytokine synthesis. However, IL-1 alpha-induced synthesis of IL-1 beta was elevated to a mean individual increase of 538% (P < 0.001) and synthesis of TNF was elevated to 270% (P < 0.001) at the end of ibuprofen medication and 2 weeks after discontinuation of ibuprofen. There were parallel increases in PGE2 and both returned to their pre-ibuprofen levels 5 weeks after stopping. Although inhibitors of cyclo-oxygenase blunt PGE2-mediated symptoms such as fever and pain, we conclude that short term use of either aspirin or ibuprofen results in a 'rebound' increase in cytokine-induced cytokine synthesis that is not observed in LPS-induced cytokines.

Administration, Oral↗
PubMed1996

Specific suppression of human tumor necrosis factor-alpha synthesis by antisense oligodeoxynucleotides.

Recent clinical studies using neutralizing antibodies point to a key role for tumor necrosis factor-alpha (TNF-alpha) in chronic inflammatory diseases. Antisense technique is a recent approach aiming at inhibition of single proteins. Previously, we described nonspecific induction of TNF by phosphorothioate oligonucleotides. In this study, we established an in vitro model that allows specific inhibition of TNF synthesis, bypassing TNF induction. Freshly isolated human monocytes were incubated with oligonucleotides and the cationic lipid lipofectin in different ratios. TNF synthesis was stimulated with lipopolysaccharide and quantified by a specific radioimmunoassay (RIA). Among all sequences tested, one of the antisense oligonucleotides complementary to the translation initiation region of TNF mRNA (5'-CAT GCT TTC AGT CAT-3') revealed highest efficacy. At 2 microM, the antisense oligonucleotide inhibited TNF synthesis by up to 79%. A concentration as low as 250 nM of the antisense oligonucleotide was effective. Scrambled controls and controls with different, defined degrees of mismatches confirmed a sequence-specific action. Examination with confocal fluorescence microscopy showed a marked difference comparing lipofectin-mediated vs. spontaneous uptake. This study defines criteria that from the prerequisite necessary for design and application of antisense oligonucleotides against TNF in vivo.

Fluorescent Dyes↗
PubMed1996

n-3 polyunsaturated fatty acids and human cytokine synthesis.

The cytokines interleukin-1 and tumor necrosis factor contribute to the pathogenesis of inflammatory diseases and, potentially, to atherogenesis. The synthesis of these cytokines in humans can be suppressed by oral intake of n-3 polyunsaturated fatty acids. This mechanism may contribute to the beneficial effect of long-term n-3 fatty acid supplementation in inflammatory diseases such as renal transplant rejection, immunoglobulin A nephropathy and rheumatoid arthritis.

Animals↗