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Biomedical subjects

I Köhler

Publications and source records attributed to I Köhler.

At least 19 recordsLinked to original sources
PubMed1995

Cytokine-mediated effects of peripheral blood mononuclear cells from patients with atopic eczema on keratinocytes (HaCaT) in a new coculture system.

Interactions between keratinocytes and mononuclear cells via cytokines and adhesion molecules are thought to play a crucial part in inflammatory skin diseases. The cytokine-mediated effects of peripheral blood mononuclear cells (PBMC) from patients with atopic eczema (AE) and healthy individuals on keratinocytes (HaCaT) were investigated in vitro. A new coculture model (Transwell system) which consists of a lower and an upper compartment, which are separated by a polycarbonate-treated membrane, was established. 3[H]thymidine incorporation of keratinocytes and lymphocytes, as well as IL-6, IL-8 and IFN-gamma synthesis, were measured. Keratinocyte proliferation was significantly enhanced in the presence of PBMC from patients with AE. In contrast, PBMC from normal donors did not enhance HaCaT cell proliferation when they were cocultured. Lymphocytes from patients with AE showed a significantly enhanced proliferation after coculture with keratinocytes. However, PBMC from normal donors did not proliferate in the presence of HaCaT cells. Keratinocyte supernatants incubated with PBMC from either atopic or normal volunteers induced a suppression of lymphocyte 3[H]thymidine incorporation. In supernatants from cocultures of PBMC from patients with AE and keratinocytes, significantly enhanced amounts of IL-6 and IL-8, compared with normal donor's lymphocytes and HaCaT cells, were measured. No differences in IFN gamma production were observed. When PBMC were cultured without HaCaT cells, supernatants contained equal levels of IL-6, IL-8 and IFN-gamma in normal donors and in patients with AE. Interestingly, HaCaT cells spontaneously secrete measurable amounts of IL-6, IL-8 and IFN-gamma. Blocking experiments with neutralizing antibodies against these interleukins showed a complete inhibition of keratinocyte proliferation when PBMC from normal donors were used whereas the proliferative potency of PBMC supernatants from patients with AE on keratinocytes remained. Our data indicate that (i) PBMC from patients with AE stimulate keratinocyte proliferation via soluble factor(s) that are different from IL-6, IL-8 and IFN-gamma; (ii) probably, HaCaT cells spontaneously produce lymphocyte/monocyte inhibitory soluble factors and IL-6, IL-8 as well as IFN-gamma; and (iii) secretion and/or activity of keratinocyte-derived inhibitory mediators is regulated via cytokines of PBMC infiltrating inflammatory skin.

Antibodies, Monoclonal↗
PubMed1995

Elevated serum levels of soluble adhesion molecules ICAM-1 and ELAM-1 in patients with severe atopic eczema and influence of UVA1 treatment.

BACKGROUND: ICAM-1 is known to be strongly expressed on keratinocytes in lesional atopic eczema correlating with the degree of inflammation. ELAM-1 was found to be expressed on dermal vascular endothelium in lesional atopic eczematous skin. OBJECTIVE: The present study was performed to investigate whether elevated serum levels of soluble forms of these molecules are detectable in patients with severe atopic eczema and whether these parameters could be useful markers for disease activity. METHODS: Serum levels of soluble ICAM-1 (sICAM-1) and ELAM-1 (sELAM-1) were measured by ELISA in 18 patients with severe atopic eczema before and after UVA1 therapy. RESULTS: Before onset of treatment, serum sICAM-1 (565 +/- 99 ng/ml) and sELAM-1 (89.7 +/- 29.9 ng/ml) levels were significantly (p < 0.001) elevated compared to 22 healthy control persons (296 +/- 46 and 48.8 +/- 22.7 ng/ml). After achievement of significant clinical improvement after 3 weeks of UVA1 therapy, there was neither a decrease in serum sICAM-1 nor in sELAM-1 levels. The posttherapeutic serum sICAM-1 and sELAM-1 values remained elevated (p < 0.001) above the normal range. CONCLUSION: Based on these data we suggest that (1) serum sICAM-1 and sELAM-1 are elevated in patients with severe atopic eczema, (2) sICAM-1 does not decrease together with reduction of ICAM-1-positive keratinocytes in atopic eczema following clinical improvement and might therefore be mainly of a different origin, i.e. leukocytes/endothelial cells, and that (3) sICAM-1 and sELAM-1 seem not to be suitable markers of actual disease activity in severe atopic eczema.

Adult↗
PubMed1995

Low dose versus medium dose UV-A1 treatment in severe atopic eczema.

Twenty-two patients with severe atopic eczema were included in a therapy study with UV-A1 (wavelengths > 340 nm) treatment. The patients were divided into two dose groups, each consisting of 11 patients. One group received 10 J/cm2 and the other 50 J/cm2 five times a week for 3 consecutive weeks. No topical or systemical steroids or antihistamines were allowed. Using the SCORAD index as a measure of disease activity before onset of therapy and after 10 and 15 treatments, we observed a significant improvement in both dose groups after 15 treatments (10 J/cm2: p < 0.05, 50 J/cm2: p < 0.005). After 10 treatments only the improvement in the 50 J/cm2 group was significant (p < 0.005); the difference between the two dose groups was significant (p < 0.05). The clinical efficacy of treatment was reflected neither by a decrease of serum IgE nor by a decrease of elevated serum levels of soluble adhesion molecules sICAM-1 and sELAM-1 in the two dose groups. In contrast, a marked but not significant decrease of serum ECP could be observed in the 50 J/cm2 group only. We conclude from these and other published data that although 10 J/cm2 UV-A1 has a limited effect on patients with severe atopic eczema, higher doses are of higher efficiency in the treatment of this condition.

Adult↗
PubMed1995

Activation of gene transcription by IL-4, IL-13 and IFN-gamma through a shared DNA binding motif.

Both interleukin-4 (IL-4) and interleukin-13 (IL-13) induce the transcription factor NF-IL4 (nuclear factor IL-4) which preexists in an inactive form and binds to an IL-4 responsive element (IL-4RE) in the promoter regions of IL-4/IL-13-dependent genes. UV-crosslinking and SDS gel electrophoresis indicate that NF-IL4 consists of at least two DNA-binding components of 50 kDa and 100-130 kDa. The IL-4 responsive element is also recognized by an interferon-gamma (IFN-gamma)-induced DNA binding protein for which a Mr of 50 kDa has been determined. A common DNA binding motif for different transcription factors might provide the basis for the frequently observed functional antagonism between IL-4/IL-13 and IFN-gamma. The activation of transcription factors by IL-4/IL-13 and IFN-gamma could be blocked by inhibitors of tyrosine kinases and ser/thr phosphatases but not by a PKC inhibitor, suggesting related signal transduction pathways for these cytokines.

Animals↗
PubMed1994

Human interleukin-13 activates the interleukin-4-dependent transcription factor NF-IL4 sharing a DNA binding motif with an interferon-gamma-induced nuclear binding factor.

The effects of interleukin-13 (IL-13) and interleukin-4 (IL-4) on cellular functions were shown to be quite similar. We provide evidence that in monocytes as well as in T lymphocytes both IL-4 and IL-13 activate the same recently identified transcription factor NF-IL4 which binds to the specific responsive element IL-4RE. In addition, we show that a nuclear factor activated by interferon-gamma also interacts with the IL-4RE. It differs from NF-IL4 in the electrophoretic mobility of the complex with DNA, in its DNA-binding specificity and in the proteins interacting with the DNA sequence. Sensitivity against various enzyme inhibitors suggests that components of the signal transduction pathway are shared by all three cytokines.

Animals↗
PubMed1993

Allergy-associated I epsilon and Ec epsilon receptor II (CD23b) genes activated via binding of an interleukin-4-induced transcription factor to a novel responsive element.

Interleukin-4 (IL-4) has important regulatory functions in the immune system, particularly in the generation of immunoglobulin E, the principal mediator of allergic responses. The molecular basis of IL-4 action has remained elusive so far. Here we report on a novel human transcription factor, termed nuclear factor IL-4 (NF-IL4), which is posttranslationally activated by IL-4 in lymphoid and monocytic cells. Homologous binding sequences for NF-IL4 were identified in the promoter regions of the IL-4 controlled CD23b and I epsilon genes. We defined a palindromic 9-bp consensus sequence (5'-TYCYRRGAA-3') as IL-4-responsive element (IL-4RE). Point mutation analysis of the CD23b promoter showed that binding of NF-IL4 to the IL-4RE is essential for the initiation of gene transcription in response to IL-4. NF-IL4 was not activated by Ca2+ ionophore, phorbol ester and cAMP either alone or in combination suggesting a non classical pathway for IL-4 signal transduction.

Base Sequence↗
PubMed1983

Synthesis of biotin-labelled dexamethasone derivatives. Novel hormone-affinity probes.

A new, general methodology for 'sandwich' affinity chromatography of steroid hormone receptors is proposed, the part purification of the human spleen tumor glucocorticoid receptor is quoted as an illustration. 9-Fluoro-16 alpha-methyl-11 beta, 17-dihydroxy-1,4-androstadiene-3-one-17 beta-carboxylic acid was coupled to biotin using pentamethylenediamine (BioDex 1) as a spacer. The bifunctional derivative binds to glucocorticoid receptors and avidin-Sepharose and efficiently protects the glucocorticoid receptor against inactivation when previously added during homogenisation. We have standardized the capacity and optimum conditions for elution of receptor-BioDex-1 complexes which are bound to avidin-Sepharose. Receptor purification of several thousand fold can be obtained with good yield.

Affinity Labels↗
PubMed1983

Methyl 17 beta-carboxyester derivatives of natural and synthetic glucocorticoids: correlation between receptor binding and inhibition of in vitro phytohaemagglutinin-induced lymphocyte blastogenesis.

Several methyl 17 beta-carboxyester derivatives of natural and fluorinated glucocorticoids were synthesized in order to compare their potency to compete for [3H]dexamethasone binding sites in human spleen tumour cytosols (as a source of large quantities of white blood cells) with their potency to inhibit phytohaemagglutinin-induced blastogenesis of normal human peripheral lymphocytes. The 17 beta-carboxylic acids neither show binding activity nor inhibition of blastogenesis. Methylation partially restores the binding capacity and the intensity of this effect depends on the kind of ring substitutions. The sequence of binding potency is identical compared to that of parent steroids and was found to be in the following order: desoxymethasone greater than dexamethasone greater than corticosterone greater than cortisol greater than progesterone greater than 17-hydroxyprogesterone. The phytohaemagglutinin-induced stimulation of [3H]thymidine incorporation resembles the order of binding potency. The methyl 17 beta-carboxyester derivatives of progesterone, 17-hydroxyprogesterone and betamethasone are inactive. The N-benzyl 17 beta-carboxamide analogs of dexamethasone and betamethasone behave like their corresponding carboxyesters, suggesting an important influence of the side chain conformation of 17 beta-carboxyl derivatives on glucocorticoid receptor binding.

Binding, Competitive↗
PubMed1982

Synthesis of a new disulfide affinity adsorbent for purification of human uterine progesterone receptor.

For purification of the human uterine progesterone receptor, an affinity adsorbent was synthesized in which the specific ligand (16 alpha-ethyl-3-oxo-19nor-androst-4-ene 17 beta-carboxylic acid) was bound to derivatized celulose using a disulfide-group-containing spacer. The purified receptor protein, isolated by reductive cleavage of the disulfide bond, bound the synthetic gestagen R5020 with high affinity (Kd 12.2 nmol/l). The affinity gel was highly efficient. A 24000-fold purification of progesterone receptor with a recovery of 40% could be achieved in a single step within 6 h. By means of dodecyl sulphate/polyacrylamide gel electrophoresis two main polypeptides with molecular weights of about 43000 and 108000 could be demonstrated.

Adsorption↗