Frank Ulrich Beil

Regulation of the human interleukin-2 gene by the alpha and beta isoforms of the glucocorticoid receptor.

The immunosuppressive effects of glucocorticoids are largely due to transcriptional inhibition of immunologically relevant genes, such as the interleukin-2 (IL-2) gene. These effects are mediated by the intracellular glucocorticoid receptor (GR). In humans, alternative splicing of the GR precursor mRNA gives rise to two receptor isoforms, termed GRalpha and GRbeta. We previously demonstrated that GRbeta could antagonize GRalpha-mediated transactivation of a glucocorticoid-responsive element (GRE)-driven reporter gene in COS-7 cells. The present study was designed to analyze the roles of the two GR isoforms on glucocorticoid-mediated transrepression of the IL-2 gene. Using a recently developed transfection technique, we demonstrate that in primary human lymphocytes, stimulation of a 548 bp IL-2 promoter-luciferase reporter construct by phorbol ester and calcium ionophore is reversed by dexamethasone to a similar extent as in Jurkat T lymphoma cells transfected with a GRalpha expression vector. Transfection of a GRbeta expression vector alone did not result in IL-2 promoter repression in response to glucocorticoids. Furthermore, GRbeta did not antagonize the repressive effects of GRalpha on IL-2 promoter activity. Surprisingly, overexpression of GRbeta in Jurkat cells did not cause significant inhibition of GRalpha-induced transactivation of a GRE-dependent luciferase reporter gene either. We conclude that the transrepressive effect of glucocorticoids on IL-2 gene transcription is exclusively mediated by GRalpha. GRbeta can neither antagonize GRalpha-mediated transactivation nor transrepression in Jurkat cells, indicating a cell type-specific pattern of GRbeta-mediated antiglucocorticoid activity.

Absence of somatostatin receptor type 2 A mutations and gip oncogene in pituitary somatotroph adenomas

Somatostatin, acting via specific receptors in the anterior pituitary, tonically inhibits pituitary growth hormone secretion and somatotroph proliferation. Reduction of growth hormone secretion and tumour regression in GH‐secreting pituitary adenomas treated with long‐acting somatostatin analogues varies widely. In 30–40% of these tumours dominant somatic mutations of the Gsα gene (gsp) have been demonstrated leading to constitutive adenylyl cyclase induction. A relationship between somatostatin sensitivity and tumour pathogenesis in some tumours has been suggested. Changes in the function of the somatostatin receptor or intracellular signal elements may be of relevance. Somatostatin receptor type 2 A (sst2A) and Gi2 are proposed to mediate selectively the inhibition of GH release in the somatotroph. We therefore investigated the presence of sst2A mutations and gip oncogene in somatotrophic pituitary adenomas.

Expression of leukemia inhibitory factor (LIF) and LIF receptor (LIF-R) in the human adrenal cortex: implications for steroidogenesis

It is well established that steroidogenesis in the adrenal cortex is regulated by extraadrenal factors, such as ACTH and angiotensin II. However, over the last years, it has become increasingly clear that paracrine and autocrine mechanisms are also important for steroid synthesis in the adrenal gland. The current study was designed to analyze whether the pleiotropic cytokine leukemia inhibitory factor (LIF) and/or its receptor (LIF-R) are expressed in the normal human adrenal cortex, and whether they may play a role in regulating steroidogenesis. Using LIF- and LIF-R-specific primers, we show by RT-PCR that both mRNAs are expressed in this tissue, as well as in the NCI-H295 adrenal carcinoma cell line. The correct sequences of the PCR products were verified by restriction enzyme analysis and DNA sequencing. Immunohistochemistry, employing specific antibodies against LIF and LIF-R, reveals expression of both proteins in the normal human adrenal cortex. Finally, we show that LIF can significantly enhance basal and ACTH-induced production of cortisol and aldosterone in NCI-H295 cells. In summary, we show for the first time that LIF and its receptor are expressed in the normal human adrenal cortex. Our stimulation experiments indicate that the intraadrenal LIF/LIF-R system may participate in regulating adrenal steroidogenesis.

Treatment of primary hypercholesterolemia: Fluvastatin versus bezafibrate

The effects of fluvastatin and bezafibrate on lipids, lipoproteins, and apoproteins (apo) were investigated in a multicenter randomized, double-blind, parallel-group study. After 8 weeks of strictly controlled (computer-based assessment) dietary stabilization, patients with primary hypercholesterolemia (low-density lipoprotein cholesterol [LDL-C] > or = 160 mg/dL; triglycerides < or = 300 mg/dL) were enrolled into a 6-week placebo phase. Altogether, 131 patients were randomized to receive either fluvastatin at 40 mg once daily (n = 64; mean age 53 years) or bezafibrate at 400 mg once daily (n = 67; mean age 52 years) for 12 weeks. Compliance with the diet was monitored (3-day food records) after 6 and 12 weeks. Fluvastatin led to significant reductions in LDL-C (-23%), total cholesterol (-17%), LDL-C/high-density lipoprotein cholesterol (HDL-C) (-24%) and apo B (-19%). Fluvastatin significantly increased LpA-I (+8%) and apo E (+20%). Bezafibrate produced significant reductions in LDL-C (-17%), total cholesterol (-13%), LDL-C/HDL-C (-24%), triglycerides (-28%), apo B (-15%), and LpA-I (-10%) and significantly increased HDL-C (+12%), apo A-I (+9%), apo A-II (+30%), apo E (+14%), and Lp(a) (+3%). No clinically notable increases in levels of liver enzymes or creatine phosphokinase were observed with either treatment. Both treatments were well tolerated. There was a low incidence of adverse events that tended to be mild and included headache, muscular pain, angina, and dyspepsia. The frequency of adverse events was similar in both treatment groups, and no significant differences in dietary behavior were observed. In conclusion, fluvastatin is a well tolerated 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor for the treatment of primary hypercholesterolemia. Effects of fluvastatin on LpA-I occur irrespective of changes in HDL-C.

Lovastatin versus Bezafibrate: Efficacy, Tolerability, and Effect on Urinary Mevalonate

Lovastatin and benzafibrate have proved effective in lowering low-density-lipoprotein (LDL) cholesterol and elevating high-density-lipoprotein (HDL) cholesterol. We compared their tolerability, safety, and effects on lipoproteins and urinary mevalonate excretion in a short-term study. Forty patients with primary hypercholesterolemia were enrolled in a single-blind randomized study with a diet/placebo period of 8 weeks and a treatment period of 12 weeks. Twenty patients received lovastatin (final average dose 70.5 mg/day), and 20 patients received bezafibrate 400 mg/day. LDL cholesterol was lowered by 35% (from 323 to 208 mg/dl) with lovastatin and by 8% (from 289 to 264 mg/dl) with benzafibrate. HDL cholesterol increased by 21 and 20% with lovastatin and benzafibrate, respectively. Twenty-four-hour urinary mevalonic acid output decreased by 37% during treatment with lovastatin and by 2% during treatment with bezafibrate. Thus, the lowering of cholesterol by lovastatin, but not by bezafibrate, can be attributed to inhibition of HMG CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase. Both lovastatin and bezafibrate are well tolerated.

Regulation of the human leukemia inhibitory factor gene by ETS transcription factors.

Objectives: Leukemia inhibitory factor (LIF) is a pleiotropic cytokine mainly produced by activated T lymphocytes. We previously demonstrated that human Jurkat T lymphoma cells represent a valid model of LIF gene expression. This study was designed to identify regions critical for LIF promoter activation in Jurkat cells. Methods: Luciferase constructs under the control of different portions of the human LIF promoter were transfected into Jurkat cells, and promoter activity was determined by luminometry. Similar experiments were performed with constructs bearing mutations in the putative ets binding regions in the LIF promoter. RT-PCR, Western blot and gelshift experiments were performed to study expression and DNA binding of ets factors in lymphoid cells. Results: With the exception of the shortest construct not including the putative ets binding sites, all wildtype LIF promoter constructs were strongly inducible by phorbol ester/ionomycin. In contrast, the mutant constructs were significantly less inducible. Cotransfection of the wild-type constructs with ets expression vectors resulted in significant enhancement of promoter activity. ets-1 and ets-2 mRNA and protein were shown to be expressed in Jurkat cells. Gelshift experiments revealed that proteins present in nuclear extracts from Jurkat cells specifically bind to both artificial ets consensus sites and ets binding sites present in the LIF promoter. Conclusions: We conclude that binding of ets transcription factors to the ets binding sites in the human LIF promoter is critical for its inducibility in response to T cell activators. ets transcription factors thus play an important functional role within the endocrine-immune network.

Current Strategies and Recent Advances in the Therapy of Hypercholesterolemia

Lipid therapy is an option for preventing atherosclerotic vascular disease that has been intensively studied and proved to be effective independent of the underlying risk factors. Since the optimal LDL-cholesterol appears to lie well below 100 mg/dl most potent lipid lowering drugs and adjunctive HDL-raising therapeutics are mandatory. Inhibition of cholesterol synthesis and absorption is currently the preferred measure. However, new developments may substantially increase the efficacy of lipid therapy. One is add-on colesevelam, a synthetic bile-acid sequestrant with increased binding affinity which allows smaller dosages for better tolerability. Alternatively HDL-cholesterol may be increased by 25% using niacin with improved tolerability due to the combination with laropiprant, an inhibitor of the receptor for prostaglandin D2-receptor, which minimizes flushing close to placebo level. Mipomersen, a specific oligonucleotide capable to reduce apolipoprotein B-100 up to 70%, is certainly the most advanced approach to challenge even apheresis as the most effective measure to lower exceptionally elevated cholesterol levels.

Primärprävention von Herz-Kreislauf-Erkrankungen

Preventive medicine has not been adequately established in our health care system. Despite growing in-sight into the causes underlying arteriosclerotic cardiovascular disease, half of the population dies and even more suffer from it. Generally the correction of risk factors is regarded as causal therapy. Modification of the lipid and carbohydrate metabolism or the blood pressure are certainly effective, however, intervention trials have also demonstrated the limitations. Mostly an unhealthy lifestyle underlies these risk factors so that correction of the lifestyle is the causal therapy in the true sense. That is the principle basis for primary prevention, while pharmacotherapy can only be an adjunct. Inadequate nutrition, physical inactivity and smoking are considered the true major risk factors in our society. Changes in nutrition in favor of plant products, some physical activity and refraining from smoking can serve an effective contribution to health. In the future not only medical, but also economic requirements will increasingly force us to establish prevention on the basis of lifestyle changes as a mainstay of medicine.ZusammenfassungUnser Gesundheitssystem vermochte bisher Prävention nicht adäquat umzusetzen. Trotz zunehmender Kenntnis der Gründe für arteriosklerotische Herz-Kreislauf-Erkrankungen stirbt daran die Hälfte der Bevölkerung und noch mehr erkranken. Gemeinhin wird die Korrektur von Risikofaktoren als die kausale Therapie angesehen. Die Beeinflussung des Fettstoffwechsels, Blutzuckers oder Blutdrucks sind zwar wirksam, Interventionsstudien haben aber auch die Grenzen aufgezeigt. Diesen Risikofaktoren liegt meist ein ungünstiger Lebensstil zugrunde, sodass die eigentliche kausale Therapie die Korrektur des Lebensstils ist. Sie muss prinzipiell der Ansatz für eine Primärprävention sein, während die Pharmakotherapie allenfalls unterstützend eingesetzt werden kann. Fehlernährung, körperliche Inaktivität und Rauchen gelten als die wesentlichen Risikofaktoren in unserer Gesellschaft. Änderung der Ernährung zugunsten pflanzlicher Produkte, gewisse körperliche Aktivität und Nikotinabstinenz können einen wirksamen Beitrag zur Gesundheit leisten. In Zukunft werden nicht nur medizinische, sondern auch ökonomische Notwendigkeiten zunehmend dazu zwingen, Prävention auf der Basis von Lebensstiländerungen zu einem Pfeiler unserer Medizin werden zu lassen.AbstractPreventive medicine has not been adequately established in our health care system. Despite growing in-sight into the causes underlying arteriosclerotic cardiovascular disease, half of the population dies and even more suffer from it. Generally the correction of risk factors is regarded as causal therapy. Modification of the lipid and carbohydrate metabolism or the blood pressure are certainly effective, however, intervention trials have also demonstrated the limitations. Mostly an unhealthy lifestyle underlies these risk factors so that correction of the lifestyle is the causal therapy in the true sense. That is the principle basis for primary prevention, while pharmacotherapy can only be an adjunct. Inadequate nutrition, physical inactivity and smoking are considered the true major risk factors in our society. Changes in nutrition in favor of plant products, some physical activity and refraining from smoking can serve an effective contribution to health. In the future not only medical, but also economic requirements will increasingly force us to establish prevention on the basis of lifestyle changes as a mainstay of medicine.

Behandlung des Hörsturzes durch Fibrinogen-LDL-Apherese

Sudden sensorineural hearing loss (SSHL) is thought to be of various origins. Disturbances of microcirculation, autoimmune pathology and viral infection are among the most likely causes. Acute reduction of plasma fibrinogen and serum LDL positively influences hemorheology and endothelial function and might thus be an effective therapy for SSHL. To test the hypothesis that fibrinogen/LDL-apheresis is as effective or superior to conventional therapy with plasma expanders and prednisolone in the treatment of SSHL. controlled, prospective, randomized, multicenter trial. 201 patients were recruited from 01/2000 to 6/2001 at the University Clinics of Munich, Berlin, Hamburg and Bochum. Inclusion criteria was sudden sensorineural hearing loss of unknown origin within 6 days of onset. Single fibrinogen/ LDL-apheresis infusion of prednisolone (250 mg, tapered by 25 mg daily), hydroxyethyl starch (500 ml, 6%) and pentoxifylin (400 mg/day). Improvement of pure tone thresholds 48 h after onset of therapy. Over all improvement of pure tone thresholds in the fibrinogen/ LDL-apheresis treated patients is slightly but not significantly better than in the standard therapy group. After 48 h, 50% speech perception in the fibrinogen/ LDL-apheresis group (21.6±20.1 dB) is significantly (p<0.034) better than in the standard group (29.3±29.4 dB). Patients with plasma fibrinogen levels of more than 295 mg/dl have a substantial and significantly (p<0.005) better improvement of speech perception (15.3±17.3 dB) than standard treated patients (6.1±10.4 dB). Fibrinogen/LDLapheresis is at least equally effective compared to prednisolone treatment in sudden hearing loss. Selected patients with plasma fibrinogen of more than 295 mg/dl improve significantly better when treated with fibrinogen/LDLapheresis. Der Hörsturz ist eine plötzliche, einseitige Funktionsstörung des Innenohrs, die sich in vielen Fällen innerhalb von Stunden oder Tagen zurückbildet. In den meisten, wenn auch nicht in allen Fällen handelt es sich hierbei um eine regionale Durchblutungsstörung der Kochlea. Mittels Fibrinogen/LDL-Apherese (H.E.L.P.-System: B. Braun Medizintechnologie, Melsungen, FRG) können Fibrinogen, Cholesterin und Lp(a) akut und drastisch im Plasma von Patienten reduziert werden. Die Senkung des Fibrinogens verbessert die Blutfließeigenschaften. Absenken des LDL-Cholesterins führt zu einer gesteigerten Freisetzung von vasodilatierendem NO und verbessert so die endotheliale Funktion und Regulation des regionalen Blutflusses. Wir verglichen die Wirksamkeit der H.E.L.P.-Apherese mit einer 10-tägigen stationären Standardinfusionstherapie (Prednisolon, HES, Pentoxifyllin) an insgesamt 201 Patienten. Der Vergleich der mittleren Hörschwellen zeigte einen geringen, wenn auch nicht signifikanten Vorteil der H.E.L.P.-behandelten Patienten. Die Remissionsrate ist mit 84% gegenüber 78% ebenfalls etwas besser in der H.E.L.P.-Gruppe. Signifikant besser ist das Sprachverständnis von Zahlen in der H.E.L.P.-Gruppe. Bemerkenswert ist die Tatsache, dass in der Gruppe der Patienten mit einem Fibrinogen über 300 mg/dl eine hoch signifikante Verbesserung des Gehörs (Sprachverständnis von Zahlen) verglichen zur herkömmlichen Standardtherapie erziehlt werden konnte.

Supplementierung von Phytosterinen

Zunehmend werden Lebensmittel mit Phytosterinen angeboten, die durch cholesterinsenkende Wirkung zur Prävention von kardiovaskulären Ereignissen beitragen können. Befürchtungen dahingehend, dass die geringen Mengen aufgenommener Phytosterine atherogen wirken und den Effekt der Cholesterinsenkung nivellieren könnten, scheinen unbegründet. Auch können Phytosterinspiegel, wie es sie bei der seltenen Phytosterinämie gibt, nicht durch Supplementierung von Phytosterinen erreicht werden.