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W Falk

Publications and source records attributed to W Falk.

At least 55 records · Page 3Linked to original sources
PubMed1999

Evaluation of the Etest for susceptibility testing of Mycoplasma hominis and Ureaplasma urealyticum.

The Etest was used for antibiotic susceptibility testing of Mycoplasma hominis and Ureaplasma urealyticum isolates and the results were compared with those obtained with the broth microdilution method. For 50 clinical isolates of M. hominis the MICs of doxycycline, ofloxacin and ciprofloxacin agreed within +/- one dilution and +/- two dilutions in 82-98% and 98-100% of cases, respectively. The MICs of erythromycin, azithromycin, doxycycline, ofloxacin and ciprofloxacin were evaluated for 50 clinical isolates of U. urealyticum. The corresponding levels of agreement were 70-98% and 94-100%, respectively. Reference isolates M. hominis PG-21 and U. urealyticum T-960 were also used. The Etest seems to be an alternative method for determination of MICs of antibiotics with M. hominis and U. urealyticum.

Anti-Bacterial Agents↗
PubMed1999

T-cell co-stimulatory molecules are upregulated on intestinal macrophages from inflammatory bowel disease mucosa.

BACKGROUND AND AIMS: Macrophages play an important role during mucosal inflammation in inflammatory bowel disease (IBD). As the co-stimulatory molecules B7-1 (CD80) and B7-2 (CD86) play an integral role in the activation of T cells by antigen-presenting cells (APC) we investigated the surface expression of B7-1 and B7-2 on colonic macrophages from normal and IBD mucosa. METHODS: Intestinal macrophages were isolated from biopsies of 13 control persons and 14 patients with IBD (seven with Crohn's disease (CD); and seven with ulcerative colitis (UC)). Cells were characterized by triple fluorescence flow cytometrical analysis using CD33 as macrophage marker. RESULTS: The expression of B7-1 (CD80) (9.2% +/- 4.2%) and B7-2 (CD86) (15.1% +/- 7.3%) was low on colonic macrophages from normal mucosa, indicating only a low antigen presenting potential. However, on macrophages from IBD colon there was a significant increase in the expression of co-stimulatory molecules (CD80, 33.8% +/- 8.9%, P = 0.00005 vs. control; CD86, 39.9% +/- 8.8%, P = 0.00002). There was no significant difference between CD and UC in the expression of CD80 (CD, 31.3% +/- 6.7%; UC, 34.4% +/- 13.3%) and CD86 (CD, 41.9% +/- 3.8%; UC, 35.6% +/- 13.8%). While in normal mucosa only 10.6% +/- 4.9% of the macrophages expressed CD14, more than 90% of the CD86/CD80 positive cells of the inflamed mucosa were positive for CD14. CONCLUSION: Colonic macrophages from normal mucosa rarely express the co-stimulatory molecules CD80 and CD86. In IBD a new macrophage population is found with high expression of co-stimulatory molecules presumably responsible for the perpetuated immune response.

Antigens, CD↗
PubMed1999

Anti-inflammatory effects of systemic anti-tumour necrosis factor alpha treatment in human/murine SCID arthritis.

OBJECTIVES: To evaluate in vivo the contribution of tumour necrosis factor alpha (TNFalpha) to the chimeric transfer model of human rheumatoid arthritis synovial membrane into SCID mice (hu/mu SCID arthritis), systemic anti-TNFalpha treatment was performed and the clinical, serological, and histopathological effects of this treatment assessed. METHODS: Animals were treated with the rat-antimouse TNFalpha monoclonal antibody V1q, starting on day 1 after hu/mu engraftment, twice weekly for 12 weeks. Joint swelling, serum concentrations of human and murine interleukin 6 (IL6), and serum amyloid P (SAP) were measured. Histopathological and immunohistochemical analyses of the joints were also performed at the end of treatment. RESULTS: Neutralisation of murine TNFalpha induced the following effects: (a) reduction of extent and duration of the acute arthritis phase, with significant reduction of joint swelling at two weeks; (b) decrease of murine SAP concentrations after the first antibody administration; and (c) increase of murine IL6 in the serum. At the end of treatment, there was a significant reduction of the inflammatory infiltration in the engrafted joints. Because of the mild degree of joint erosion, no treatment effects could be demonstrated on the destructive process. CONCLUSION: In the lymphocyte independent hu/mu SCID arthritis, anti-TNFalpha treatment reduces local and systemic signs of inflammation.

Acute Disease↗
PubMed1999

Strictures in Crohn's disease are characterised by an accumulation of mast cells colocalised with laminin but not with fibronectin or vitronectin.

BACKGROUND/AIMS: Intestinal fibrosis and stricture formation is an unresolved problem in Crohn's disease. The aim of this study was to investigate whether mast cells accumulate in these tissues and whether their localisation is associated with extracellular matrix components. METHODS: Mast cells were visualised by immunohistochemical staining of the mast cell specific proteases chymase and tryptase. Their localisation in relation to extracellular matrix components was shown by immunohistochemical double labelling. RESULTS: In strictures in Crohn's disease, a striking accumulation of mast cells was seen particularly in the hypertrophied and fibrotic muscularis propria, with a mean (SEM) mast cell number of 81.3 (14.9) v 1.5 (0.9)/mm(2) in normal bowel (p<0.0005). All mast cells in the muscularis propria were colocalised with patches of laminin. In contrast, in the submucosa, laminin was exclusively found in the basal lamina of blood vessels where many adherent mast cells were seen. No colocalisation of mast cells was found with fibronectin or vitronectin. CONCLUSIONS: The large accumulation of mast cells in the muscle layer of strictured bowel suggests a functional role for these cells in the hypertrophic and fibrotic response of the smooth muscle cells. The colocalisation with laminin indicates a mechanism of interaction between smooth muscle cells and mast cells that may be important in the role of mast cells in the process of fibrosis.

Aged↗
PubMed1999

Interleukin-12 activates NK cells for IFN-gamma-dependent and NKT cells for IFN-gamma-independent antimetastatic activity.

Mechanisms involved in the antimetastatic effect of IL-12 were analyzed in a mouse model of experimental metastasis with either syngeneic fibrosarcoma cells colonizing the lungs or syngeneic B cell lymphoma cells colonizing the liver. IL-12 pretreatment effectively reduced the number of tumor colonies in both systems. This effect was already manifest 24 hours after tumor cell injection, indicating a T and B cell-independent mechanism. Therefore, the involvement of NK and alphabetaNKT cells was investigated using mice with defective NK and alphabetaNKT cell functions. Mice with impaired NK functions due to NK cell depletion, were less responsive to the antimetastatic IL-12 effect. IL-12 treatment failed to inhibit metastasis in beta2-microglobulin-deficient mice which lack alphabetaNKT cells in addition to having impaired NK cell activity, thus, demonstrating the functional importance of IL-12-activated NK and alphabetaNKT cells. While the IL-12-induced antimetastatic effect of NK cells was dependent on IFN-gamma action, IL-12 activation of alphabetaNKT cells did not involve IFN-gamma. The neutralization of IFN-gamma or the use of IFN-gamma receptor-deficient mice did not alter the IL-12-induced effect in the absence of NK cells. Activation of effector cells of the innate immune system, such as NK and alphabetaNKT cells, seems to be the main mechanism for the antimetastatic effect of IL-12.

Animals↗
PubMed1998

Connective tissue growth factor: a novel regulator of mucosal repair and fibrosis in inflammatory bowel disease?

Inflammatory bowel disease (IBD) is a multifactorial disorder which is characterized by massive damage of the epithelium and the underlying mesenchyme of the intestine. Due to the potent effect of connective tissue growth factor (CTGF) on fibroblast proliferation and connective tissue deposition we speculated about a possible role of this mitogen in IBD. Here we demonstrate a strikingly increased expression of CTGF mRNA in surgical specimens of patients suffering from two forms of IBD, Crohn's disease and ulcerative colitis. In most specimens, the levels of CTGF mRNA correlated with the degree of inflammation as assessed by histological analysis of adjacent tissue samples and by expression analysis of the pro-inflammatory cytokine interleukin-1 beta. However, areas of little inflammation which were characterized by severe fibrosis also revealed high levels of CTGF mRNA. Expression of transforming growth factor beta-1 (TGF-beta 1), the only known inducer of CTGF so far, as well as of the CTGF target genes collagen I alpha 1, fibronectin and integrin alpha 5 revealed a strong correlation with the expression of CTGF. These data suggest a prominent role of CTGF in the repair of mucosal injury in IBD and in the aberrant deposition of extracellular matrix leading to fibrosis and stenosis, one major complication in IBD, especially in Crohn's disease.

Animals↗
PubMed1998

Isolation and phenotypic characterization of colonic macrophages.

Macrophages play an important role in the intestinal mucosal immune system. However, they are a poorly defined cell population. We therefore determined their phenotype in normal colonic mucosa. Macrophages were isolated from colonic biopsies and surgical specimens by collagenase digestion. Colonic macrophages were positively sorted by anti-CD33 magnetic beads. Flow cytometric triple fluorescence analysis was applied to study CD14, CD16, CD33, CD44, CD11b, CD11c, CD64, HLA-DR, CD80, CD86 and CD3/CD19 expression. CD33 was evaluated as a positive marker for intestinal macrophages. CD33+ cells isolated from normal colonic mucosa showed co-expression of the established intracellular macrophage marker CD68 in FACS analysis. CD33+ cells were capable of phagocytosis. Isolation of this cell population by magnetic anti-CD33 beads and culture resulted in a 4.2-40-fold increase in IL-1beta and 4.5-44-fold increase in tumour necrosis factor-alpha (TNF-alpha) secretion compared with unsorted lamina propria mononuclear cells (LPMC). Of the CD33+ cells, 90.9 +/- 6.9% (mean +/- s.d.) were CD44+. However, macrophages from colonic mucosa showed only a low expression of CD14 (10.5 +/- 3.8%), CD16 (10.1 +/- 3.9%), HLA-DR (27.3 +/- 9.2%), CD11b (17.4 +/- 6.8%), CD11c (17.8 +/- 10.4%). Furthermore, expression of CD80 (9.2 +/- 4.2%) and CD86 (15.1 +/- 7.3%) was low, suggesting a low ability of normal intestinal macrophages to activate T cells and T cell-mediated immune responses. We conclude that CD33 is useful for the isolation and flow cytometric characterization of colonic macrophages. These cells exhibit a single phenotype in normal mucosa (CD33++, CD44++, CD14-, CD16-, CD11b-, CD11c-, HLA-DRlow, CD80-, CD86-) lacking lipopolysaccharide (LPS) receptor and costimulatory molecules.

Antigen-Presenting Cells↗
PubMed1998

Interleukins and their antagonists but not TNF and its receptors are released in post-ERP pancreatitis.

OBJECTIVE: Usually it is not possible to study the initial systemic response in patients with acute pancreatitis in the first hours after onset of the disease. We used postendoscopic retrograde pancreatography (ERP) pancreatitis as a model to study cytokine and anticytokine release in the early phase of human acute pancreatitis. METHODS: Post-ERP pancreatitis was defined as a threefold increase in serum amylase and at least two of the following clinical symptoms: abdominal pain, nausea, vomiting or peritonism 24 h after ERP. Serum levels of pro-inflammatory cytokines interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), tumour necrosis factor alpha (TNF), as well as endogenous antagonistic mediators of the systemic inflammatory response such as soluble tumour necrosis factor alpha receptors p55 (TNFR p55) and p75 (TNFR p75), and IL-1-receptor antagonist (IL-1-RA) and interleukin-2-receptor (IL-2R) as indicators of lymphocyte activation were measured before and 0, 1, 4, 12, 24 and 48 h after ERP. In nine patients with acute post-ERP pancreatitis, these parameters were monitored daily until C-reactive protein (CRP) was within normal ranges and were compared to patients without pancreatitis after ERP. RESULTS: IL-1beta was not detectable in five patients with and four patients without post-ERP pancreatitis. The values of the remaining patients in both groups were lower than 3.9 pg/ml. IL-8 and IL-1-RA serum concentrations peaked 12 h after ERP (132.9 and 3245.0 pg/ml respectively) compared to patients without post-ERP pancreatitis (25.8 and 389.9 pg/ml respectively). The IL-6 concentration increased to 81.6 pg/ml (8.0 pg/ml in control patients) 24 h after ERP, while the peak values for CRP were measured 72 h after ERP (164.0 versus 7.7 mg/l). IL-2R content was maximally elevated 144 h after ERP (688.8 versus 255.9 U/ml), while concentrations of TNF and its receptors showed no significant change over time. CONCLUSION: The initial response of the cytokine network to damage of the human pancreas leading to acute pancreatitis includes the release of IL-8 and the IL-1 antagonist IL-1-RA, while IL-1beta is not found in the systemic circulation. The TNF system does not seem to be involved as indicated by the lack of detectable changes in TNF and the soluble TNFR p55 and p75 serum concentrations. Lymphocyte activation as indicated by elevated IL-2R levels occurred days after the initial trauma. Even mild post-ERP pancreatitis leads to significant systemic release of cytokines and their biological counterparts.

Acute Disease↗
PubMed1998

Tonic neurogenic inhibition of interleukin-6 secretion from murine spleen caused by opioidergic transmission.

The peripheral nervous system and the immune system were shown to have neurohumoral interactions. This study extends observations that demonstrated neuronal modulation of spontaneous interleukin-6 (IL-6) secretion in the spleen by norepinephrine (NE) and beta-endorphin. Spontaneous IL-6 secretion in vivo was markedly reduced by removal of macrophages with the clodronate technique. Furthermore, spontaneous IL-6 secretion was significantly inhibited at physiological concentrations of cortisol (10(-7) M). In the presence of 10(-7) M cortisol, addition of norepinephrine (NE; 10(-5) M) and isoproterenol (10(-6) and 10(-5) M) significantly increased spontaneous IL-6 secretion (+20%; P = 0.0280, P = 0.0005, and P = 0.0050, respectively). In contrast, addition of beta-endorphin significantly inhibited spontaneous IL-6 secretion in the presence of 10(-7) M cortisol (-40%; 10(-11) M, P = 0.0410; 10(-10) M, P = 0.0005). To study the effect of endogenously released transmitters on spontaneous IL-6 secretion, spleen slices were electrically stimulated with 1, 5, 10, 50, and 100 Hz. Spontaneous IL-6 secretion was markedly reduced at a frequency of 10 Hz with 10(-7) M cortisol present (P < 0.0001). This indicates that the combination of nerve firing at 5-10 Hz and physiological cortisol conditions inhibits spontaneous IL-6 secretion. Inhibition of spontaneous IL-6 secretion from spleen macrophages is most probably due to a net inhibitory effect of opioidergic transmission under these conditions.

Animals↗
PubMed1998

Serum dehydroepiandrosterone (DHEA) and DHEA sulfate are negatively correlated with serum interleukin-6 (IL-6), and DHEA inhibits IL-6 secretion from mononuclear cells in man in vitro: possible link between endocrinosenescence and immunosenescence.

Interleukin-6 (IL-6) is one of the pathogenetic elements in inflammatory and age-related diseases such as rheumatoid arthritis, osteoporosis, atherosclerosis, and late-onset B cell neoplasia. In these diseases or during aging, the decrease in production of sex hormones such as dehydroepiandrosterone (DHEA) is thought to play an important role in IL-6-mediated pathogenetic effects in mice. In humans, we investigated the correlation of serum levels of DHEA, DHEA sulfate (DHEAS), or androstenedione (ASD) and IL-6, tumor necrosis factor-alpha, or IL-2 with age in 120 female and male healthy subjects (15-75 yr of age). Serum DHEA, DHEAS, and ASD levels significantly decreased with age (all P < 0.001), whereas serum IL-6 levels significantly increased with age (P < 0.001). DHEA/DHEAS and IL-6 (but not tumor necrosis factor-alpha or IL-2) were inversely correlated (all patients: r = -0.242/-0.312; P = 0.010/0.001). In female and male subjects, DHEA and ASD concentration dependently inhibited IL-6 production from peripheral blood mononuclear cells (P = 0.001). The concentration-response curve for DHEA was U shaped (maximal effective concentration, 1-5 x 10(-8) mol/L), which may be the optimal range for immunomodulation. In summary, the data indicate a functional link between DHEA or ASD and IL-6. It is concluded that the increase in IL-6 production during the process of aging might be due to diminished DHEA and ASD secretion. Immunosenescence may be directly related to endocrinosenescence, which, in turn, may be a significant cofactor for the manifestation of inflammatory and age-related diseases.

Adolescent↗
PubMed1997

Activation of acid sphingomyelinase by interleukin-1 (IL-1) requires the IL-1 receptor accessory protein.

The cytokine interleukin-1 (IL-1) plays an important role in inflammation and regulation of immune responses, but the mechanisms of its signal transduction and cell activation processes are incompletely understood. Ceramide generated by sphingomyelinases (SMases) is known to function as an important second messenger molecule in the signaling pathway of IL-1 and tumor necrosis factor. To investigate the activation of SMases by IL-1, we used an IL-1 receptor type I (IL-1RI)-positive EL4 thymoma cell line, which is defective in IL-1R accessory protein (IL-1RAcP) expression. In this cell line (EL4D6/76), tumor necrosis factor induced ligand/receptor internalization, NFkappaB nuclear translocation, IL-2 production, and the activation of neutral (N)-SMase and acid (A)-SMase. In contrast, stimulation with IL-1 resulted only in the activation of N-SMase whereas ligand/receptor internalization, NFkappaB translocation, IL-2 production, and activation of A-SMase were not detected. Transfection of this functionally defective EL4D6/76 with IL-1RAcP cDNA restored these functions. These data suggest that A-SMase activity is strongly linked with the internalization of IL-1RI mediated by IL-1RAcP and that A-SMase and N-SMase are activated by different pathways.

Ceramides↗
PubMed1997

The interleukin-1 receptor accessory protein (IL-1RAcP) is essential for IL-1-induced activation of interleukin-1 receptor-associated kinase (IRAK) and stress-activated protein kinases (SAP kinases).

Interleukin-1 (IL-1) is a central mediator of the immune system involved in acute and chronic inflammatory responses. Although the sequences of two types of IL-1 receptors are known, the exact molecular events resulting in signal transduction and coupling to downstream signaling elements remain unclear. The recently cloned IL-1 receptor accessory protein (IL-1RAcP) has been suggested as a co-receptor molecule for IL-1RI, supported by the observation that its expression correlates to IL-1 responsiveness. We transfected the EL-4 subline D6/76 with IL-1RAcP cDNA. This cell line is an IL-1 non-responder expressing IL-1RI but lacking constitutive IL-1RAcP expression. The expression of IL-1RAcP in EL-4 D6/76 was sufficient to restore IL-1-induced activation of interleukin-1 receptor-associated kinase and of stress-activated protein kinases, translocation of the transcription factors NFkappaB and IL-1 NF to the nucleus, and induction of IL-2 mRNA synthesis. These results proved that IL-1RAcP is an indispensible molecule in the IL-1 receptor signal transduction complex, necessary to link events on the plasma membrane level to downstream signaling pathways, allowing IL-1-dependent activation of transcription factors and gene expression.

Animals↗
PubMed1997

A critical role for interleukin-1 receptor accessory protein in interleukin-1 signaling.

Interleukin-1 (IL-1) is a central molecule in inflammation and immune responses whose pleiotropic activities are mediated by the type I IL-1 receptor (IL-1RI). The IL-1RI alone on the cell surface is silent after binding of the ligand. We show that the recently identified IL-1RI accessory protein (IL-1RAcP) converts the silent into a fully functional IL-1RI complex. Although transfection of IL-1RAcP into IL-1RAcP-deficient EL4D6/76 cells did not alter the binding kinetics or dissociation constants of the 125I-labeled IL-1alpha/IL-1RI complex, a very early event, internalization of the activated receptor complex, and a late event, IL-1-stimulated IL-2 production, were successfully restored. Therefore, recruitment of IL-1RAcP is a critical early step in the signaling cascade mediated by the IL-1RI activation complex.

Animals↗
PubMed1997

Neuronal regulation of interleukin 6 secretion in murine spleen: adrenergic and opioidergic control.

The PNS was anticipated to be involved in the modulation of immune responses. To study aspects of this neuronal-immune communication, a recently developed tissue slice method was used to study the effects of adrenergic and opioidergic transmitters on interleukin 6 (IL-6) secretion in the spleen. The alpha 2-adrenergic agonist p-aminoclonidine (10(-7) M) inhibited IL-6 secretion (control vs. p-aminoclonidine, 100.0 +/- 4.76 vs. 59.3 +/- 6.6% of control values; p < 0.001). The alpha 1-adrenergic agonist methoxamine (10(-8) M) also inhibited IL-6 secretion (100.0 +/- 4.8 vs. 71.5 +/- 3.8%; p < 0.001). The endogenous opioids beta-endorphin (10(-10) M), methionine-enkephalin (10(-9) M), and leucine-enkephalin (10(-9) M) inhibited IL-6 secretion as well (p = 0.0051, p = 0.0337, and p = 0.0226, respectively). Electrical stimulation of spleen slices inhibited IL-6 secretion (100.0 +/- 4.3 vs. 56.7 +/- 4.6% of control values; p < 0.001). The involvement of alpha-adrenergic and opioidergic molecules in this electrically induced inhibition was shown by the use of antagonists. Electrical inhibition of IL-6 secretion was attenuated by phentolamine (10(-7) M; p = 0.0345), by naloxone (10(-6) M; p = 0.0046), by cyprodime (10(-8) M; p = 0.0014), and by the combination of cyprodime (10(-7) M) plus phentolamine (10(-8) M; p < 0.0001). We conclude from the complementary studies that the inhibition of IL-6 secretion induced by electrical pulses was mostly mediated by alpha-adrenergic and mu-opioidergic endogenous transmitters.

Adrenergic alpha-Agonists↗
PubMed1997

Alterations of the phenotype of colonic macrophages in inflammatory bowel disease.

BACKGROUND: Intestinal macrophages play an important role in mucosal inflammation. In normal colonic mucosa we recently demonstrated a unique macrophage phenotype with attenuated immune functions. Here we present an analysis of the alterations of the phenotype of colonic macrophages in inflammatory bowel disease (IBD). METHODS: Intestinal macrophages were isolated from biopsies of patients with IBD (n =20). Flow cytometric triple fluorescence analysis was applied to study CD14, CD16, CD33, HLA-DR, CD44, CD11b, CD11c and CD3/CD19 expression. RESULTS: In IBD there was an increase in expression not only of CD14 compared to control mucosa (36.0% +/- 13.2% vs. 10.5% +/- 3.8%, P< 0.0001) but also of CD16 (28.6% +/- 10.3% vs. 10.1% +/- 3.9%, P< 0.0001), HLA-DR (53.1% +/- 15.9% vs. 27.3% +/- 9.2%, P< 0.0005), CD11b (42.8% +/- 14.2% vs. 17.4% +/- 6.8%, P< 0.0001) and CD11c (35.1% +/- 15.9% vs. 17.8% +/- 10.4%, P< 0.005.). Furthermore, a hitherto undescribed new population of macrophages could be detected by flow cytometry only in patients with ulcerative colitis (CD16++, CD11b++, CD14(low), CD33(low), CD11c-) accounting for 5.8% of all cells isolated. CONCLUSION: In contrast to colonic macrophages from normal mucosa, there is a significantly higher expression of CD14, CD16, HLA-DR, CD11b and CD11c in IBD, indicating additional macrophage populations in the inflamed mucosa. This may reflect either a recruitment of new cells from the circulation or a change in phenotype of resident cells.

Antigens, CD↗