Mild hepatitis at recommended doses of acetaminophen in patients with evidence of constitutionally enhanced cytochrome P450 system activity

Acetaminophen (paracetamol) is used throughout the world for pain relief and antipyresis in both children and adults. In many countries, it can be purchased without a medical prescription and it is also a common component of a number of over-the-counter remedies for colds, influenza and the like. Fasting, malnutrition and use of alcohol and/or other drugs are thought to play causal roles in hepatotoxicity associated with recommended doses of acetaminophen although liver injury provoked by therapeutic doses has also been observed in the absence of these factors. We describe two patients who experienced subclinical hepatotoxic reactions after taking acetaminophen at therapeutic doses. The results of an antipyrine metabolism test suggest the presence of constitutional hyperactivity of the cytochrome P450-dependent mixed function oxidative system in both patients. We hypothesize that the latter contributed to the hepatotoxicity and that it may play a role in idiosyncratic reactions to this drug.

Gender affects 13C-ketoisocaproic acid breath test

BACKGROUND AND AIMS

13C-Ketoisocaproic Acid Breath Test (13C-Kica-BT) has been proposed to assess mitochondrial function. Aim of this study is to evaluate whether gender affects mithocondrial oxidation by means of 13C-Kica-BT in healthy subjects in basal conditions and after an acute oxidative stress induced by ethanol.

METHODOLOGY

50 healthy volunteers were given 1 mg/kg of 13C-Kica together with 20 mg/kg of L-leucine dissolved in 200 ml of orange juice. Breath samples were taken at baseline, every 5 minutes for 45 minutes and then every 15 minutes until 2 hours. Forty-eight hours later the test was repeated 30 min after ethanol ingestion (0.5 g/kg body weight). 13CO2 enrichment in breath was analyzed by isotope ratio/mass spectrometry. Statistical analysis was performed using the student's t test.

RESULTS

At baseline conditions, the percentage of Ketoisocaproic acid in 2 hours was significantly higher in females than in males. Ethanol significantly reduces the oxidation of Ketoisocaproic acid. Conversely, no differences were observed between groups after the ethanol oral load.

CONCLUSIONS

Decarboxylation of 13C-Kica was significantly higher in females than in males. Ethanol decreases Kica decarboxylation in particular in women. Further studies remain needed to establish whether sexual hormones could interfere with the metabolism of Kica.

Expression and distribution of notch protein members in human placenta throughout pregnancy

Notch signaling is an evolutionarily conserved mechanism used by invertebrates and vertebrates to control cell fates through close-range cell interactions. Four Notch receptors have been identified in vertebrates and different ligands, divided into Delta-like and Serrate-like (Jagged). Several studies have demonstrated that Notch signaling is involved in different branches of the cell fate decision tree: differentiation, proliferation and apoptosis. These three processes are finely regulated in human placenta in order to allow a successful pregnancy and a correct fetal growth. Moreover, Notch and its ligands participate in the vascular remodelling and stabilization, other two processes much important and ticklish in human placenta. So, we decided to investigate the pattern of expression of Notch-1, Notch-4 and Jagged-1, together with two members related to Notch pathway and involved in angiogenesis: VEGF and p21, in human placenta during gestation by immunoblotting and immunohistochemistry. We showed a modulation of Notch proteins throughout the pregnancy; in particular we showed a slight decrease of Notch-1 throughout pregnancy, with a decreased cytoplasmic staining from the first to the third trimester of gestation in cytotrophoblast and syncytiotrophoblast. In contrast Jagged-1 showed an increase throughout pregnancy especially in syncytiotrophoblast and stroma during the third trimester of gestation. In addition, we found by immunoblotting an increase of VEGF expression from the first to the third trimester and an intense VEGF expression inside endothelial cells throughout the gestation as also confirmed by immunohistochemistry. We also showed a decrease of p21 expression during the pregnancy both through immunoblotting and immunohistochemistry assays. Moreover, we observed Notch localization in extravillous trophoblast cells that are able to invade the decidualized endometrium. Our results suggest an involvement of Notch signaling in regulation of placental cell fate decision and in angiogenesis that are dramatically important to maintain a normal physiology of this organ during pregnancy.

Alcoholic and nonalcoholic forms of fatty liver disease

Fatty liver (or steatosis) is an increasingly common finding in histolgical evaluation of liver biopsies. It is frequently associated with obesity, diabetes, metabolic syndromes, and/or alcohol abuse. When the steatosis is accompanied by inflammation and fibrosis, the risk of progression to severe liver disease is high. The aim of this paper is to review the clinical features, pathophysiology, natural history, and options for the treatment of nonalcoholic and alcoholic forms of fatty liver disease.

Sjogren's syndrome in a celiac patient: searching for environmental triggers

In the last few years many studies have shown the potential role of different triggers in the pathogenesis of several autoimmune diseases. In particular, in Sjogren's syndrome the presence of a genetic background is considered determining, but environmental factors have recently been described as triggers or precipitators. In this report, we describe the case of a young woman affected by celiac disease in which an Ascaris lumbricoides infestation and estrogen therapy could have played a role in the development of Sjogren's syndrome.

NOTCH signaling as a novel cancer therapeutic target

NOTCH-ligand interaction is a highly conserved mechanism that regulates specific cell fate decision during development. In addition to its functions in developmental and cell maturation processes, studies indicate that NOTCH activation plays a role in the onset and progression of many human malignancies. The prevailing new strategy for rationally targeted cancer treatment is aimed at the development of target-selective "smart" drugs on the basis of characterized mechanisms of action. The connection between NOTCH signaling and tumorigenesis suggests that NOTCH may be such a target candidate. Gamma-secretase is a large membrane-integral multisubunit protease complex, which is essential for NOTCH receptor activation. Inhibitors of this enzyme are being developed for Alzheimer's disease, due to its role in cleaving beta-amyloid precursor in the brain. Recently, Gamma-secretase inhibitors (GSIs), as well as various biopharmaceutical or genetic NOTCH signaling inhibitors have been suggested as potential novel cancer therapeutic strategies. This review summarizes the evidence linking NOTCH signaling to several types of cancer, as well as the possible therapeutic indications of NOTCH inhibitors and the challenges facing their clinical development.

Anticholinergic syndrome due to 'Devil's herb': when risks come from the ancient time

We describe a case of Mandragora autumnalis poisoning which occurred in a 72-year-old female patient who had eaten the venenous M. Autumnalis, picked near her home, mistaking it for the edible Borago Officinalis. M. Autumnalis is a solanaceous plant, common in the Sicilian countryside, which contains a variable concentration of solanum alkaloids, causing gastrointestinal irritation, and tropane alkaloids, with anticholinergic properties. Unluckily, M. Autumnalis is often mistaken for the edible B. Officinalis, likewise widespread in Sicilian countryside. The diagnosis of Mandragora poisoning was made on the basis of clinical symptoms and signs of anticholinergic syndrome associated with a history of vegetable meal of uncontrolled origin, moreover analysing the vegetable obtained from gastric lavage. Decontamination and symptomatic treatment were useful in our patient to control acute poisoning.

Nonalcoholic fatty liver disease: defining a common problem

Non Alcoholic Fatty Liver Disease (NAFLD), with prevalence of 10-51% in general population involving all ages, is the major cause of elevation of ALT and a common finding by ultrasound screening and may range from simple steatosis, to Non Alcoholic Steatohepatitis (NASH) and its clinical consequences as cirrhosis and hepatocellular carcinoma. In this review will be analyse factors influencing the onset of the disease. NAFLD, primarly associated with insulin resistance, is in fact considered the hepatic manifestation of the metabolic syndrome: a cluster of disorder that includes obesity, diabetes mellitus, dyslipidaemia, arteriosclerosis and hypertension. The increased incidence and prevalence of obesity and diabetes may explain growing interest in NAFLD. Racial, ethnic, enviromental and behaviour models are also reviewed.

The natural history and risk factors for progression of non-alcoholic fatty liver disease and steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a condition of increasing incidence in western Countries seldom associated to other diseases of high prevalence in general population (i.e. diabetes and obesity). NAFLD ranges from simple fatty liver to steatohepatitis (NASH), which may lead to cryptogenic cirrhosis and in some cases hepatocellular carcinoma (HCC). Natural history of NAFLD in humans is poorly understood and progression of liver disease seems to be due to interaction between hosting (i.e. genetic, gut flora, insulin resistance) and environmental factors (social and eating behaviours) that should be responsible of increased oxidative stress within hepatocytes. Even if we need non-invasive markers able to describe the progression of liver disease, only meaning of liver biopsy is useful to characterize the stigmata of worsening such as inflammation and fibrosis.

Hepatic steatosis and vascular disease

Nonalcoholic fatty liver disease (NAFLD) refers to a wide picture of liver damage, ranging from steatosis to steatohepatitis, fibrosis and cirrhosis. The epidemiological studies demonstrated an association of NAFLD with obesity, type 2 diabetes and hyperlipidemia. Under this light the metabolic syndrome (MS), including NAFLD, obesity, central fat distribution, diabetes, dyslipidemia, hypertension and atherosclerotic cardiovascular disease (CVD) can be considered the link to explain the presence of vascular diseases in patients with NAFLD. In NHANES III, the authors demonstrated that the presence of MS was associated with increased risk of myocardial infarction, stroke or both. In a prospective study on 1209 Finnish middle-aged men without CVD or diabetes at baseline, Lakka showed that MS per se is associated with an increased risk of CVD and all-cause mortality. Finally the Atherosclerosis Risk in Communities (ARIC) confirmed that subjects with MS were 2 times more likely to have prevalent coronary heart disease. From a pathophysiological point of view, growing evidences implicate the oxidative stress as the unifying mechanism for many CVD risk factors. Under this light there is emerging evidence suggesting that there is a significant increase in vascular oxidative stress in patients with MS, with the presence of endothelial dysfunction in the early stage of the syndrome. Indeed, the inflammation process evidentiated in these patients is initiated at the endothelial level, stressing the key role of this active and dynamic tissue in the pathophysiological pathways. Under this light the endothelium can be considered as the last effector of a multi-syndrome and the main target of all the future studies focused on the underlying mechamisms of this complex network. Because of the potential serious public health impact, the comprehension of these patophysiological pathways will be crucial to design new preventive measures and therapeutic strategies.

Fatty liver and drugs

Drug-induced liver diseases (DILD) are clinico-pathologic patterns of liver injury caused by drugs or other foreign compounds. Steatohepatitis is a rare form of DILD, and drugs account for fewer than 2% of non-alcoholic steatohepatitis (NASH). Drugs known to be capable of inducing steatosis and steatohepatitis can be divided into three broad groups: those that cause steatosis and steatohepatitis independently (e.g., amiodarone, perhexiline maleate); drugs which can precipitate latent NASH (e.g., tamoxifen); drugs whic duce sporadic events of steatosis/steatohepatitis (e.g., carbamazepine). Clinical DILD syndromes include acute viral hepatitis-like injury, acute liver failure, cholestatic hepatitis,liver disease with signs of hypersensitivity, autoimmune hepatitis-like injury, acute venous-Outflow obstruction, chronic cholestasis, ciirrhosis, steatosis and steatohepatitis. The clinical picture is by no means dependent on the mechanism of injury (direct hepatotoxicity, idiosyncratic reactions, hypersensitivity reactions). Reliable diagnosis of drug-induced liver disease requires demonstration of close correlation between the patient history and clinical, laboratory, and histological data.

Nutritional aspects in patients with non-alcoholic steatohepatitis (NASH)

BACKGROUND AND OBJECTIVES

Metabolic alterations are a common feature in patients affected by non-alcoholic steato-hepatitis (NASH). A strong correlation exists between overweight, in particular visceral fat accumulation, and prevalence of NASH, especially in men. Thus, diet-induced weight loss represents a fundamental tool in disease management of these patients. The aim of the present study was to evaluate body composition and nutrient utilisation in patients with NASH, comparing them with patients affected by chronic hepatitis related to hepatitis C virus (HCV) infection and with healthy subjects.

MATERIALS AND METHODS

Twenty male outpatients with NASH (age: 41 +/- 11 yr; BMI: 26.2 +/- 2.1 kg/m2) and 14 HCV male patients (age 44.6 +/- 13 yr; BMI: 24.8 +/- 2.8 kg/m2) were enrolled in the study. A group of 20 healthy male subjects (age: 39 +/- 10 yr; BMI: 23.3 +/- 1.1 kg/m2) were studied as controls. Body composition was assessed by anthropometry and dual-energy X-ray absorptiometry; resting metabolic rate and nutrient oxidation by indirect calorimetry. A 7-day food diary was collected. The main biochemical parameters were measured using standardised laboratory techniques.

RESULTS

Body weight was higher in NASH patients with respect to HCV patients and control subjects (respectively 75.2 +/- 8.9 vs 68.5 +/- 9.4 and vs 67.0 +/- 8.0 kg; P < 0.01) and this was essentially due to fat mass increase. Fat-free mass reduction was found in HCV patients with respect to both NASH and control subjects. Patients with NASH had a significantly higher waist circumference (P < 0.01) and a lower resting metabolic rate (RMR) with respect to HCV and control subjects. Energy intake was significantly higher in NASH patients (P < 0.01) compared to the other two groups.

CONCLUSIONS

NASH patients showed an increase in body weight, fat mass and visceral fat accumulation with respect to HCV and control subjects. The reduction in RMR, coupled with increase energy intake may explain the body composition alterations found in these patients.

Prognostic factors for survival in patients with early-intermediate hepatocellular carcinoma undergoing non-surgical therapy: comparison of Okuda, CLIP, and BCLC staging systems in a single Italian centre

BACKGROUND

Several prognostic models have been developed to stage hepatocellular carcinoma (HCC) but there is no general consensus on which is the most reliable. We compared three prognostic indices (Okuda, CLIP, and BCLC scoring systems) in a large series of cirrhotic patients with HCC undergoing non-surgical treatment in terms of their ability to classify patients into different risk groups

METHODS

We retrospectively studied 268 Italian patients with HCC. A total of 146 patients were treated with ablation, 132 with percutaneous ethanol injection, and 14 with radiofrequency ablation; 103 underwent transcatheter arterial chemoembolisation and 19 had supportive care alone. Factors determining survival were analysed by univariate and multivariate analysis using the Kaplan-Meier method and Cox proportional hazard regression models. Okuda, CLIP, and BCLC scores evaluated before treatment were applied.

RESULTS

Median survival was 25.7 months. In a multivariate analysis, portal vein thrombosis, alpha fetoprotein, total bilirubin, and tumour size were significant predictors of survival. Okuda, CLIP, and BCLC scores were all able to predict survival (p<0.001). They identified two, four, and six risk groups, respectively, with a median survival ranging from 27 to 19 months for Okuda, 30 to 5 months for CLIP, and 43 to 7 months for BCLC.

CONCLUSIONS

Both CLIP and BCLC scores were more effective than the Okuda score in stratifying patients into different risk groups with early-intermediate HCC. However, the BCLC scoring system gave a better prediction of prognosis in patients with disease diagnosis at a very early stage.

Anisakis infestation: a case of acute abdomen mimicking Crohn's disease and eosinophilic gastroenteritis

Anisakiasis is a rare parasitic disease transmitted to humans by the ingestion of raw fish, which can initially present with acute abdomen. We report the case of a man, a habitual consumer of raw fish, who underwent surgery for acute abdomen, initially attributed to Crohn's disease and then later interpreted as eosinophilic enteritis. Only the subsequent careful histological examination of the surgical specimen, revealing full thickness eosinophilic infiltrate, generally typical of infestation, led to the detection of Anisakis simplex larva. In cases of acute abdomen, in the presence of a positive history of raw fish ingestion, it is therefore reasonable to consider the possibility of anisakiasis.

High efficacy of 1-week doxycycline- and amoxicillin-based quadruple regimen in a culture-guided, third-line treatment approach for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori infection may persist after both first- and second-line current treatments.

AIM

To assess the efficacy of a third-line, culture-guided treatment approach for the eradication of H. pylori.

METHODS

Patterns of resistance were analysed in H. pylori isolates from 94 consecutive patients in whom H. pylori infection had persisted after two eradication attempts. Using the epsilometer test, susceptibility analysis was performed for amoxicillin, clarithromycin, metronidazole, tetracycline and levofloxacin. Patients were then treated with a culture-guided, third-line regimen: 89 patients with a 1-week quadruple regimen including omeprazole, bismuth, doxycycline and amoxicillin, and five patients with a 1-week triple regimen containing omeprazole, amoxicillin and levofloxacin or clarithromycin.

RESULTS

Ninety-four subjects (100%) were resistant to metronidazole, 89 (95%) to clarithromycin, 29 (31%) to levofloxacin and five (5%) to tetracycline. No resistance to amoxicillin was found in any patient. Overall, H. pylori eradication was obtained in 90% of subjects. The quadruple regimen was effective in 81 patients (92% by per protocol and 91% by intention-to-treat analysis). Four patients (80%, both per protocol and intention-to-treat analysis) were H. pylori-negative after the triple regimen.

CONCLUSIONS

A culture-guided, third-line therapeutic approach is effective for the eradication of H. pylori. Furthermore, the 1-week doxycycline- and amoxicillin-based quadruple regimen is a good third-line 'rescue' treatment option.

New developments about the association of SV40 with human mesothelioma

Simian virus 40 (SV40) has been detected in human tumors in over 40 different laboratories. Many of these reports linked SV40 to human mesotheliomas. The Vaccine Safety Committee of the Institute of Medicine (IOM), National Academy of Sciences, USA, recently reviewed the evidence associating polio vaccines and/or SV40 with human tumors. The IOM conclusions about polio vaccines and human cancer were: (1) 'the evidence is inadequate to accept or reject a causal relation between SV40-containing polio vaccines and cancer' because the 'epidemiological studies are sufficiently flawed'; (2) 'the biological evidence is of moderate strength that SV40 exposure from the polio vaccines is related to SV40 infection in humans'. The epidemiological studies were considered flawed because it was not possible to distinguish reliably among exposed and nonexposed cohorts. Concerning SV40, the IOM concluded that (1) 'the evidence is strong that SV40 is a transforming virus; (2) the evidence is of moderate strength that SV40 exposure could lead to cancer in humans under natural conditions' (IOM, 2002). Similar conclusions were reached at an International consensus meeting on SV40 and human tumors held at the University of Chicago in 2001. G Klein and C Croce, who chaired the final panel that reviewed all the published evidence linking SV40 to human tumors, stated that 'the presence of SV40 in human tumors has been convincingly demonstrated' (Klein et al., 2002). In addition, a workshop organized by the Biological Carcinogenesis Branch of the National Cancer Institute, Bethesda, MD, chaired by J Pagano, has reached similar conclusions (Wong et al., 2002). Therefore, three independent scientific panels have all agreed that there is compelling evidence that SV40 is present in some human cancers and that SV40 could contribute to the pathogenesis of some of them. It should be noted that the presence of SV40 in mesothelioma and other human tumor types has been challenged by a research team that has consistently reported negative findings (Strickler et al., 2001). However, a member of this research team has recently acknowledged - in sworn testimony -sensitivity problems and possible irregularities that raise concerns about these negative reports (MacLachlan, 2002). These revelations, together with the conclusions of the three independent panels mentioned above, appear to bring to an end the apparent controversy about the presence of SV40 in human mesotheliomas and brain tumors.

Cryoglobulinemia: a true internistic disease?

Cryoglobulinemia is a clinical condition characterised by the presence of circulating globulins that precipitate at a temperature lower than 37 degrees Celsius and re-dissolve with warming. We can distinguish 3 different types of cryoglobulinemia, according to their immunochemical characteristics. Cryoglobulinemia can be associated with infectious, inflammatory or neoplastic disease. Cryoglobulinemia type II can be associated with chronic HCV-hepatitis. Clinically, cryoglobulinemias cause hyperviscosity-related symptoms or lesions by immunocomplex deposition (cryoglobulinemic vasculitis). Many organs and systems can be involved, from the skin to the joints, from the central nervous system to the kidney. Diagnosis requires a careful clinical and physical evaluation and the demonstration of circulating cryoglobulins by cryoprecipitation and immunoelectrophoresis. The therapeutic goals are the treatment of the underlying diseases and the complication and prevention of progression/relapse. It is obvious that this disorder can involve different specialists, but the internist plays a central role: he identifies the disease and the associated condition, he treats the underlying disorder and refers the patient to the specialists for the organ-specific manifestations.

Gastrointestinal stromal tumor (GIST) and ulcerative colitis

A 57 year old woman, affected by Ulcerative Colitis (UC) in remission, was admitted to our unit with a history of episodic melena and progressive anemia. Computed tomography (CT) of the abdomen revealed a solid mass in the upper left pelvic cavity. After surgical laparotomy, the mass showed histological characteristics of a gastro intestinal stromal tumor. This report describes a GIST in a patient with extensive UC, which was in remission at the time of diagnosis. To our knowledge, this is the first report of an association of this type.

Review article: breath testing for human liver function assessment

Carbon-labelled breath tests were proposed as tools for the evaluation of human liver function 30 years ago, but have never become part of clinical routine. One reason for this is the complex role of the liver in metabolic regulation, making it difficult to provide essential information for the management of patients with liver disease with a single test and to satisfy the hepatology community. As a result, a battery of breath tests have been developed. Depending on the test compound administered, different metabolic pathways (microsomal, cytosolic, mitochondrial) can be examined. Most available data come from microsomal function tests, whilst information about cytosolic and mitochondrial liver function is more limited. However, breath tests have shown promise in some studies, in particular to predict the outcome of patients with chronic liver disease or to monitor hepatic function after treatment. Whilst we await new substrates that can be used to measure liver function in a more valid manner, and large prospective studies to assess the usefulness of available test compounds, the aim of this review is to describe how far we have come in this controversial and unresolved issue.

Prescribing second-generation antipsychotics and the evolving standard of care in Italy

The present study was carried out to investigate the routine use of second-generation antipsychotic drugs in the Italian psychiatric care system. Seven outpatient psychiatric services enrolled a consecutive case series of patients who were being treated, or had started treatment, with clozapine, olanzapine, risperidone, or quetiapine. Information on sociodemographic and clinical variables, current psychotropic drug use, side-effects and past use of typical drugs was collected. In addition, patient symptoms and functional status were evaluated by the Health of the Nation Outcome Scale. Patients receiving off-label prescribing of second-generation antipsychotics were identified. A total of 209 patients were collected. In comparison with patients receiving other second-generation antipsychotics, living in residential facilities, unemployment, long psychiatric histories, and problems with activities of daily living and living conditions were more common in clozapine-treated patients. Nearly 80 % of patients receiving clozapine had schizophrenia compared to less than 50 % of those receiving other second-generation antipsychotics. Overall, 109 patients (52 %) received off-label prescriptions of second-generation antipsychotic drugs. This survey indicates that clozapine was mostly reserved for severe cases and poor responders; the high rate of off-label prescriptions highlights the gap existing between recommendations derived from randomised clinical trials and the current use of drugs.

Jagged-1 mediated activation of notch signaling induces complete maturation of human keratinocytes through NF-kappaB and PPARgamma

Establishing an effective epidermal barrier requires a series of coordinated molecular events involving keratinocytes (KCs) within a stratified epithelium. Epidermal maturation depends on convergence of pathways involving components of NF-kappaB and peroxisome proliferator activated receptor (PPAR) signaling systems that promote terminal differentiation and production of a stratum corneum. The Notch-1 receptor and its ligand Delta-1 have been proposed by others to participate in early events in KC differentiation. Here, we establish differential expression patterns for several Notch receptors and ligands in normal human skin. These immunolocalization findings, together with functional studies demonstrating increased levels of Notch ligand/receptors occurring during the onset of differentiation, prompted use of a soluble Notch ligand, a peptide derived from the most conspicuously expressed ligand in skin, Jagged-1. Exposing submerged KC monolayers to this peptide (JAG-1) in co-presence of elevated calcium ion concentration, produced stratification with loricrin expression. Using a living human epidermal equivalent (EE) model system, when submerged cultures were raised to an air/liquid interface to generate a fully mature epidermis, activation of Notch signaling was detected. Addition of JAG-1 peptide to submerged EEs was sufficient to induce epidermal maturation. Moreover, a soluble decoy Notch inhibitor prevented such differentiation and corneogenesis in human EEs exposed to either an air/liquid interface or to the JAG-1 peptide. In KC monolayers, addition of JAG-1 peptide induced IKKalpha mediated NF-kappaB activation, as well as increased PPARgamma expression. Immunoprecipitation/Western blot analysis revealed a physical association between the p65 subunit of NF-kappaB and PPARgamma. These results indicate that activation of Notch signaling is necessary for maturation of human epidermis, and activation by a soluble Notch ligand is sufficient to trigger complete KC differentiation including cornification.

Notch-1 regulates NF-kappaB activity in hemopoietic progenitor cells

We investigated the interaction between two elements critical for differentiation of hemopoietic cells, the Notch-1 receptor and the transcription factor NF-kappaB. These factors were studied in hemopoietic progenitor cells (HPC) using Notch-1 antisense transgenic (Notch-AS-Tg) mice. DNA binding of NF-kappaB as well as its ability to activate transcription was strongly decreased in HPC from Notch-AS-Tg mice. NF-kappaB-driven transcriptional activity was completely restored after transduction of the cells with retroviral constructs containing activated Notch-1 gene. HPC from Notch-AS-Tg mice have decreased levels of several members of the NF-kappaB family, p65, p50, RelB, and c-Rel and this is due to down-regulation of the gene expression. To investigate functional consequences of decreased NF-kappaB activity in transgenic mice, we studied LPS-induced proliferation of B cells and GM-CSF-dependent differentiation of dendritic cells from HPC. These two processes are known to be closely dependent on NF-kappaB. B cells from Notch-AS-Tg mice had almost 3-fold lower response to LPS than B cells isolated from control mice. Differentiation of dendritic cells was significantly affected in Notch-AS-Tg mice. However, it was restored by transduction of activated Notch-1 into HPC. Taken together, these data indicate that in HPC NF-kappaB activity is regulated by Notch-1 via transcriptional control of NF-kappaB.