A. Van Den Ende

Treatment of Crohn's disease with recombinant human interleukin 10 induces the proinflammatory cytokine interferon gamma

Background: Interleukin 10 (IL-10) exerts anti-inflammatory actions by counteracting many biological effects of interferon γ (IFN-γ). Aims: To investigate this in humans, we studied the effects of human recombinant IL-10 administration on IFN-γ production by patient leucocytes. Furthermore, we assessed the IFN-γ inducible molecule neopterin and nitrite/nitrate serum levels, which are indicative of endogenous nitric oxide formation. Methods: As part of two placebo controlled double blind studies, we analysed patients with chronic active Crohns disease (CACD) who received either subcutaneous recombinant human IL-10 (n=44) or placebo (n=10) daily for 28 days, and patients with mild to moderate Crohns disease (MCD) treated with either subcutaneous IL-10 (n=52) or placebo (n=16) daily for 28 days. Neopterin and nitrite/nitrate concentrations were measured in serum, and ex vivo IFN-γ formation by lipopolysaccharide or phytohaemagglutinin (PHA) stimulated whole blood cells were investigated before, during, and after IL-10 therapy. Results: In patients with CACD, the highest dose of 20 μg/kg IL-10 caused a significant increase in serum neopterin on days +15 and +29 of therapy compared with pretreatment levels. No changes were observed for nitrite/nitrate levels under either condition. In MCD, treatment with 20 μg/kg IL-10 resulted in a significant increase in PHA induced IFN-γ production. Conclusions: High doses of IL-10 upregulate the production of IFN-γ and neopterin. This phenomenon may be responsible for the lack of efficacy of high doses of IL-10 in the treatment of CACD and MCD.

Distribution and Kinetics of Lipoprotein-Bound Endotoxin

ABSTRACT Lipopolysaccharide (LPS), the major glycolipid component of gram-negative bacterial outer membranes, is a potent endotoxin responsible for pathophysiological symptoms characteristic of infection. The observation that the majority of LPS is found in association with plasma lipoproteins has prompted the suggestion that sequestering of LPS by lipid particles may form an integral part of a humoral detoxification mechanism. Previous studies on the biological properties of isolated lipoproteins used differential ultracentrifugation to separate the major subclasses. To preserve the integrity of the lipoproteins, we have analyzed the LPS distribution, specificity, binding capacity, and kinetics of binding to lipoproteins in human whole blood or plasma by using high-performance gel permeation chromatography and fluorescent LPS of three different chemotypes. The average distribution of O111:B4, J5, or Re595 LPS in whole blood from 10 human volunteers was 60% (±8%) high-density lipoprotein (HDL), 25% (±7%) low-density lipoprotein, and 12% (±5%) very low density lipoprotein. The saturation capacity of lipoproteins for all three LPS chemotypes was in excess of 200 μg/ml. Kinetic analysis however, revealed a strict chemotype dependence. The binding of Re595 or J5 LPS was essentially complete within 10 min, and subsequent redistribution among the lipoprotein subclasses occurred to attain similar distributions as O111:B4 LPS at 40 min. We conclude that under simulated physiological conditions, the binding of LPS to lipoproteins is highly specific, HDL has the highest binding capacity for LPS, the saturation capacity of lipoproteins for endotoxin far exceeds the LPS concentrations measured in clinical situations, and the kinetics of LPS association with lipoproteins display chemotype-dependent differences.

The 20210 G→ A mutation in the 3'-untranslated region of the prothrombin gene and the risk for arterial thrombotic disease

A sequence variation in the 3′‐untranslated region of the prothrombin (PT) gene (20210 G → A) was recently claimed to be associated with elevated plasma prothrombin levels and an increased risk for venous and arterial thrombosis. We examined the prevalence of the 20210 A allele in the prothrombin gene in 400 healthy controls and in 263 patients with proven premature atherosclerotic disease. In addition, we measured prothrombin, prothrombin fragment 1 + 2, thrombin–antithrombin (TAT) complex and D‐dimer levels in plasma from carrier and non‐carrier patients. The frequency of the variant allele was 1% in the control subjects and 2.7% in the patient group, yielding a relative risk (RR) for the 20210 A allele of 2.7 (95% CI 0.8–9.4). All heterozygotes in the patient group were found to have had a myocardial infarction (MI), yielding a RR for MI of 4.2 (95% CI 1.2–14.6). Plasma prothrombin levels in carriers (126 ± 10) were higher than in non‐carriers (103 ± 1, P = 0.02). The levels of TAT complexes (16 ± 9 v 6 ± 1 μg/ml, P = 0.02) as well as of prothrombin fragment 1 + 2 (1.5 ± 0.3 v 1.0 ± 0.1 nmol/l, P = 0.02) were also elevated in carriers of the mutation. Our findings suggest that the 20210 G → A mutation in the prothrombin gene is a genetic risk factor for MI. In addition, our data provide evidence for an association of the mutation with excessive thrombin generation, which may contribute to the understanding of its role in venous and arterial disease.

Lipopolysaccharide Is Transferred from High-Density to Low-Density Lipoproteins by Lipopolysaccharide-Binding Protein and Phospholipid Transfer Protein

ABSTRACT Lipopolysaccharide (LPS), the major outer membrane component of gram-negative bacteria, is a potent endotoxin that triggers cytokine-mediated systemic inflammatory responses in the host. Plasma lipoproteins are capable of LPS sequestration, thereby attenuating the host response to infection, but ensuing dyslipidemia severely compromises this host defense mechanism. We have recently reported that Escherichia coli J5 and Re595 LPS chemotypes that contain relatively short O-antigen polysaccharide side chains are efficiently redistributed from high-density lipoproteins (HDL) to other lipoprotein subclasses in normal human whole blood (ex vivo). In this study, we examined the role of the acute-phase proteins LPS-binding protein (LBP) and phospholipid transfer protein (PLTP) in this process. By the use of isolated HDL containing fluorescent J5 LPS, the redistribution of endotoxin among the major lipoprotein subclasses in a model system was determined by gel permeation chromatography. The kinetics of LPS and lipid particle interactions were determined by using Biacore analysis. LBP and PLTP were found to transfer LPS from HDL predominantly to low-density lipoproteins (LDL), in a time- and dose-dependent manner, to induce remodeling of HDL into two subpopulations as a consequence of the LPS transfer and to enhance the steady-state association of LDL with HDL in a dose-dependent fashion. The presence of LPS on HDL further enhanced LBP-dependent interactions of LDL with HDL and increased the stability of the HDL-LDL complexes. We postulate that HDL remodeling induced by LBP- and PLTP-mediated LPS transfer may contribute to the plasma lipoprotein dyslipidemia characteristic of the acute-phase response to infection.

The role of plasma D-dimer concentration in the exclusion of pulmonary embolism

Objective. To determine the role of four ELISA D‐dimer assays in the exclusion of pulmonary embolism.

Effect of loperamide on fecal output and composition in well-established ileostomy and ileorectal anastomosis

The quantitative effects of the antidiarrheal drug loperamide (Imodium®) on several parameters of fecal composition and output were assessed in 7 patients with an ileorectal anastomosis and 7 patients with an ileostomy. Loperamide (two 2 mg capsules tid) or placebo were administered double-blind in two randomly assigned successive 7-day periods. Loperamide significantly decreased the daily volume, wet weight, water content, and fecal excretion rate and significantly increased the bulk density and viscosity of the fecal collections. Electrolyte loss was significantly diminished with loperamide: Daily sodium and chloride outputs significantly decreased; daily calcium, phosphate and potassium outputs slightly decreased. Sodium concentration significantly decreased, while potassium and calcium concentrations significantly increased, phosphate concentrations slightly increased, and chloride concentrations slightly decreased. The sodium/potassium ratio was significantly reduced. No effect on fecal dry weight or on lipid or bile acid outputs was observed. Differences in fecal composition between patients with an ileorectal anastomosis and those with an ileostomy were identified. Potassium concentration and output were significantly higher, and the sodium/potassium ratio was significantly lower in patients with an ileorectal anastomosis. This group also showed a tendency to slightly lower fecal volume, wet weight, water content, fecal excretion rate, sodium concentration, and output. A patient per patient evaluation of clinical responsiveness to loperamide was made by comparing several fecal variables before and after loperamide treatment. The therapeutic efficacy of loperamide was comparable in both patient groups. Results were rated “excellent” in 3 patients, “good” in 7, “questionable” in 3 and “poor” in 1. No adverse effects attributable to loperamide were observed. All patients reported feeling better during loperamide treatment and preferred the active drug period to the placebo period.

Gemfibrozil treatment of the high triglyceride‐low high‐density lipoprotein cholesterol trait in men with established atherosclerosis

Abstract. Objective. To study the short‐term efficacy, tolerability and safety of the treatment with gemfibrozil 600 mg twice daily or placebo in male patients with established atherosclerosis, with a lipid profile matching the ‘high triglyceride‐low high‐density lipoprotein (HDL) cholesterol trait”.

Magnesium pyridoxal-5'-phosphate glutamate, "A vitamin B6 derivative", does not affect lipoprotein levels in patients with familial hypercholesterolaemia

Objective: In this double-blind, randomized, placebo-controlled, dose-finding study we assessed the short-term efficacy and safety of increasing dosages of magnesium pyridoxal-5′-phosphate glutamate (MPPG) compared to placebo in patients with familial hypercholesterolaemia (FH). Twenty-three patients of either sex, over the age of 18 years and suffering from heterozygous FH, were treated with MPPG for a period of 16 weeks.Results:Baseline characteristics and lipoprotein profiles of the patients were comparable in the two treatment groups. Overall compliance was 90%. Neither after the first 8 weeks treatment period with 450 mg MPPG daily nor after the second 8 weeks treatment period with 600 mg MPPG daily were statistically significant changes in plasma total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol or triglyceride levels observed between the treatment and placebo groups. Plasma levels of lipoprotein (Lp)(a), apolipoprotein (apo) A1, apo B100, very low density lipoprotein (VLDL) cholesterol and VLDL triglyceride also did not change.Conclusion:Although it has been demonstrated that MPPG improves lipoprotein levels in patients with different forms of dyslipidaemia, MPPG is not effective for the treatment of FH patients.