Myocarditis, a common heart disease pathologically defined as an inflammatory reaction of the myocardium, is most frequently caused by infectious agents, including viruses and bacteria, and may ...develop in later stages into dilated cardiomyopathy (DCM). Several studies have identified inflammatory components engaged in the transition from acute myocarditis to chronic DCM, and there is growing evidence that myocarditis and DCM are closely related. Novel technological advances in genomic screening have gained insight into molecular and cellular mechanisms involved the pathogenesis of inflammatory heart disease and, in particular, in the development of systolic dysfunction resulting from DCM. Detection of differential gene expression profiles have become valid tools in the study of inflammatory heart disease. Molecular signatures are defined as individual sets of genes, mRNA transcripts, proteins, genetic variations or other variables, which can be used as markers for a particular phenotype. These signatures may be useful for clinical diagnosis or risk assessment and, in addition, may help to identify molecules not previously known to be involved in the pathogenesis of these disease conditions.
Microarray analyses have dramatically refined our knowledge about tissue-specific gene expression patterns, simply by being able to study thousands of genes simultaneously in a single experiment. In the field of cardiovascular research, microarrays are increasingly used in the study of end-stage cardiomyopathies, such as DCM, that ultimately lead to symptoms of heart failure. By means of microarray analysis, a set of differentially expressed genes can be detected, among them are transcripts coding for sarcomeric and extracellular matrix proteins, stress response and inflammatory proteins as well as transcription factors and translational regulators. Expression profiling may be particularly helpful to improve the differential diagnosis of heart failure and enable novel insight into selected molecular pathways.
An ex-vivo model for the experimental evaluation of endoluminal thermal procedures for occlusion of saphenous veins was developed. Radiofrequency obliteration (RFO) and endovenous laser therapy (ELT) ...were compared using this model.
Experimental ex-vivo treatment study.
The model consists of the subcutaneous foot veins from freshly slaughtered cows which were reperfused in situ with heparinised bovine blood. The veins were treated with either radiofrequency (RFO n=5) or with endoluminal 980nm laser light (ELT n=5) using a continuous pull-back for RFO and a stepwise illumination and pull-back protocol for ELT. Immediately after treatment perivenous tissue and veins were examined macroscopically. In a second study the same treatment parameters were used in four further vein segments with RFO (n=2) and ELT (n=2). These vein segments were examined microscopically in HE-stained histological sections.
Induration of the vessel wall and contraction of the vessel lumen were observed after RFO. Laser treatment produced carbonised lesions of the vein wall. After 12–24 laser exposures these lesions often became transmural, causing complete perforation of the vessel wall.
Histological evaluation after radiofrequency treatment demonstrated homogenous circular thermal tissue alteration with disintegration of intima and media structures. Histological evaluation after endovenous laser treatment showed large variations of thermal tissue effects. Tissue effects ranged from major tissue ablation and vessel wall disruption to minor effects located between laser exposures and on the opposite vessel wall.
Our model is suitable for systematic scientific evaluation of endovenous thermal occlusion procedures. Our first results and theoretical considerations indicate that endovenous laser treatment should be modified in order to ensure controlled homogenous circular thermal damage, avoiding vessel wall perforation and damage to perivascular structures.
Dilated cardiomyopathy (DCM), clinically characterized by contractile dysfunction and ventricular chamber enlargement, is a heterogeneous heart disease leading to progressive systolic heart failure ...and sudden cardiac death. The etiology of the disease is multifactorial and involves genetic factors, viral infections, autoimmune phenomena, and toxic agents. Within the last two decades, a growing body of evidence has suggested that single-gene mutations play a pivotal role in the development of familial forms of dilated cardiomyopathies. Numerous genes encoding cytoskeletal, sarcomeric, and nuclear proteins have been linked to the pathogenesis of DCM, and most of the respective mutants disrupt the structural integrity of sarcomeres in cardiac myocytes. Frequently, point mutations in cytoskeletal proteins critically diminish force generation and interfere with mechanical transduction within the contractile apparatus of the myocardium, thereby ultimately leading to impaired systolic function. However, hitherto reported sarcomeric gene defects explain the etiology of the disease only in some families, leaving other forms of DCM subentities unresolved. Since one of the major factors in DCM pathogenesis involves autoimmune-mediated damage to cardiac tissue, candidate genes that are involved in controlling immune reactions have currently come into focus in genetic research. We and others have shown that a single-nucleotide polymorphism (SNP) in the gene encoding cytotoxic T-lymphocyte antigen 4 (CTLA4) is associated with the diagnosis of DCM. Cytotoxic T-lymphocyte antigen 4 is an inhibitory receptor molecule expressed on activated T lymphocytes, where it functions as an important negative regulator of T-cell activation by competing with the costimulatory CD28 receptor to bind to B7 receptors localized on the surface of antigen-presenting cells. The observed association between CTLA4 genotypes and DCM suggests that genetic factors contribute to both unbalanced immune responses in the myocardium and the development of left ventricular dysfunction. In this review, we will briefly discuss how these findings may stimulate the search for novel DCM-associated SNPs in human genes expressed in noncardiomyocytes.
Robert-Rossle-Clinic, Charite Humboldt University of Berlin, Lindenberger Weg 80, 13125 Berlin, Germany. wuchter@rrk-berlin.de
BACKGROUND AND OBJECTIVES: A multidrug-resistance (MDR) phenotype ...mediated by P-glycoprotein (P-gp) contributes to chemotherapy failure in acute leukemia. However, the exact prognostic significance of this resistance mechanism is still unclear, mostly due to methodologic problems in P-gp detection. We therefore investigated, whether P-gp expression levels or functional P-gp activity better predict response to induction chemotherapy, relapse rate and overall survival in acute leukemia. DESIGN AND METHODS: We examined cell samples of 121 adults with de novo acute myeloid leukemia (AML) and 102 children with newly diagnosed acute lymphoblastic leukemia (ALL) for P-gp expression and functional P-gp activity by flow cytometry. P-gp function was determined by the rhodamine 123 (rh123)-efflux test (AML n=121, ALL n=102) and P-gp expression levels using the P-gp specific monoclonal antibodies (moabs) MRK-16 (AML n=51, ALL n=31), 4.E3 (AML n=35, ALL n=32), or UIC-2 (AML n=68, ALL n=50). We correlated our findings with the immunophenotype, FAB morphology, cytogenetics and clinical data of the examined patients. RESULTS: P-gp expression levels as detected by MRK-16 and 4.E3 were very low and did not differ between AML and ALL as estimated using relative fluorescence intensity (RFI) values and D-values by Kolmogorow-Smirnov (KS) statistics. For moab UIC-2, P-gp expression levels were higher in AML than in ALL. Within AML, moab UIC-2 mainly reacted with myelomonocytic-differentiated leukemic cells of the FAB M4/5 subtypes. No correlation between P-gp expression levels as detected by MRK-16, 4.E3 or UIC-2 and the response to induction chemotherapy or relapse rate, both in AML and ALL, was observed. However, a prognostic impact of P-gp expression levels on overall survival in AML was seen for moab MRK-16. Moreover, within AML, P-gp function was higher in immature blast cells as defined by immunophenotype and FAB morphology and correlated with response to induction chemotherapy, relapse rate, overall survival as well as cytogenetic risk groups. In ALL, the overall functional P-gp activity was lower than in AML and did not correlate with immunophenotypical subgroups, response to induction chemotherapy, relapse rate or overall survival. INTERPRETATION AND CONCLUSIONS: Our data demonstrate a prognostic impact of P-gp in AML but not ALL and indicate that the functional rh123-efflux assay should be preferred for flow-cytometric P-gp evaluation in acute leukemia compared with P-gp expression analysis by monoclonal antibodies.
The TNF-related apoptosis-inducing ligand (TRAIL) is currently under evaluation as a possible (co-)therapeutic in cancer treatment. We therefore examined 129 cell samples from patients with de novo ...acute leukemia as to their constitutive susceptibility to TRAIL-induced apoptosis In vitro. Only 21 (16%) cell samples revealed at least 10% TRAIL-susceptible cells/sample as detected by flow cytometric annexinV staining after 24 h culture compared with medium control. Precursor B cell ALL samples (11 (27%) of 41) were more TRAIL-susceptible compared with AML (5 (9%) of 54; P < 0.05) but not compared with precursor T cell ALL (5 (15%) of 34; P = 0.20). Furthermore, we examined constitutive mRNA expression levels of TRAIL receptors R1-R4 by semi-quantitative RT-PCR (n = 58). Expression levels were heterogeneous, however, there was no significant correlation between the expression of the signal-transducing receptors (R1, R2) as well as of the decoy receptors (R3, R4) and TRAIL sensitivity in this series. Constitutive NF-kappa B activity has been shown to influence TRAIL susceptibility of leukemic cells. In 39 leukemic cell samples examined, we found a generally high NF-kappa B activity as detected by electrophoretic mobility shift assay which did not differ between TRAIL-susceptible and TRAIL-resistant cases. Finally, 49 acute leukemic cell samples were coincubated with doxorubicin in vitro. Doxorubicin sensitized four of 35 initially TRAIL-resistant samples and augmented TRAIL-induced apoptosis in two of 14 TRAIL-susceptible samples. In summary, constitutive TRAIL susceptibility differs between leukemia subtypes and does not correlate with mRNA expression levels of the TRAIL receptors R1-R4 as well as constitutive NF-kappa B activation status. The observed sensitization of leukemic cells to TRAIL by doxorubicin in vitro indicates that TRAIL should be further evaluated as to its possible role as an in vivo cotherapeutic in acute leukemia.
Inflammatory processes induced by viral or bacterial infections are believed to be one of the major pathogenetic mechanisms in myocardial diseases. Although the reason for progression to myocardial ...failure is not fully understood, postulated mechanisms include persistent viral infection alone or in combination with autoimmune processes. A variety of cardiotropic viruses have been identified to elicit myocarditis, with enteroviruses and adenoviruses as the most frequent causative agents in children and adolescents. However, parvovirus B19 (PVB19) has recently emerged as another potential pathogen in adult patients associated with inflammatory heart disease. Many dimensions of inflammatory heart disease coexist while different phases of the disease progress simultaneously: phase 1 is dominated by viral infection, phase 2 by the onset of (probably) multiple autoimmune reactions, and phase 3 by the progression to cardiac dilatation without the role of an infectious agent and cardiac inflammation. Taking these mechanisms into account, screening for viral and bacterial genome by polymerase chain reaction (PCR) and detection of inflammatory infiltrates by immunohistochemistry are considered crucial for establishing an aetiological diagnosis, thereby allowing initiation of specific therapeutic strategies. In a large cohort of 3345 consecutive patients with left ventricular dysfunction evaluated over a period of 10 years, prevalence of PVB19, coxsackievirus (CVB), human cytomegalovirus (HCMV), influenza A virus and adenovirus (ADV) genome was assessed by PCR. Inflammatory infiltrates within the myocardium were detected by immunohistochemistry according to the WHF criteria and by histopathology according to the Dallas criteria of myocarditis. For control, endomyocardial samples of patients with arterial hypertension were studied. Parvovirus B19 was the most often detected virus in all patient subgroups, with positivity ranging from 17% to 33%. Except for PVB19, CVB RNA (3%), ADV (2%) and CMV (3.9%) were the most frequently detected viral genomes. Interestingly, detection of PVB19 genome was significantly correlated with inflammatory heart disease and reduced ejection fraction. Importantly, an aetiological diagnosis requires the immunohistochemical and molecular biological investigation of endomyocardial biopsies. Such an approach may change the management of these diseases in the future. One of the aims of the study was to reveal the underlying dominant pathophysiological mechanisms in a for deciding on the most approriate therapy.
Atherosclerosis is crucially fueled by inflammatory pathways including pattern recognition receptor (PRR)-related signaling of the innate immune system. Currently, the impact of the cytoplasmic PRRs ...nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2 is incompletely characterized. We, therefore, generated
Nod1
/
Nod2
double knockout mice on a low-density lipoprotein receptor (
Ldlr
)-deficient background (=
Ldlr
−/−
Nod1/2
−/−
) which were subsequently analyzed regarding experimental atherosclerosis, lipid metabolism, insulin resistance and gut microbiota composition. Compared to
Ldlr
−/−
mice,
Ldlr
−/−
Nod1/2
−/−
mice showed reduced plasma lipids and increased hepatic expression of the scavenger receptor LDL receptor-related protein 1 after feeding a high-fat diet for 12 weeks. Furthermore, intestinal cholesterol and its bacterial degradation product coprostanol were elevated in
Ldlr
−/−
Nod1/2
−/−
mice, correlating with the increased abundance of
Eubacterium coprostanoligenes
as assessed by 3rd generation sequencing of the gut microbiota. Atherosclerotic plaques of
Ldlr
−/−
Nod1/2
−/−
mice exhibited less lipid deposition and macrophage accumulation. Moreover, macrophages from
Ldlr
−/−
Nod1/2
−/−
mice showed higher expression of the cholesterol efflux transporters
Abca1
and
Abcg1
and accordingly reduced foam cell formation. Deficiency of
Nod1
and
Nod2
led to reduced plaque lipid deposition and inflammatory cell infiltration in atherosclerotic plaques. This might be explained by diminished plasma lipid levels and foam cell formation due to altered expression of key regulators of the hepatic cholesterol pathway as well as differential intestinal cholesterol metabolism and microbiota composition.
Resistance to chemotherapy-induced apoptosis and a multidrug-resistance (MDR) phenotype, mainly mediated by P-glycoprotein (P-gp), contribute to chemotherapy failure in hematologic malignancies. To ...study apoptosis-regulating factors in acute myeloid leukemia (AML), we investigated cell samples of adults with de novo AML by flow cytometry for constitutive expression levels of the apoptosis-related molecules CD95 (n = 135), Bcl-2 (n = 131), and Bax (n = 66), as well as spontaneous apoptosis in vitro (n = 104) and susceptibility to anti-CD95-induced apoptosis (CD95 sensitivity) (n = 93). We correlated these findings with P-gp function as detected by the rhodamine123-efflux test (n = 121), immunophenotype, FAB morphology, cytogenetics, and clinical data of the examined patients. Immature FAB M0/1 AML cells expressed significantly more Bcl-2 (P < 0.0002) and less CD95 (P < 0.0003) compared with AML cells of the more mature FAB M2-5 subtypes. No maturation-dependent difference in Bax expression was observed. FAB M2-5 AML cells were more susceptible to anti-CD95-induced apoptosis (P < 0.008) and showed a lower P-gp function (P < 0.002) than FAB M0/1 AML cells. Leukemic cells of AML patients who achieved a complete remission (CR) after induction chemotherapy expressed less Bcl-2 than non-responder (NR) (69 CR, 23 NR; P = 0.05). CR was associated with a higher extent of spontaneous apoptosis in vitro (58 CR, 17 NR; P=0.05) and a tendency towards a higher CD95 expression (73 CR, 23 NR; P = 0.08) compared to NR. CR also correlated with a low P-gp function (70 CR, 21 NR; P = 0.008) and a tendency towards CD34 negativity (73 CR, 23 NR; P = 0.08). No correlation between Bax expression and response to induction chemotherapy (49 CR, 12 NR) was observed. In stepwise logistic regression analyses, P-gp function and the extent of spontaneous apoptosis in vitro as well as CD95 sensitivity but not Bcl-2, CD95, Bax, and CD34 expression levels emerged as significant markers for response to induction chemotherapy. We conclude that the constitutive expression of CD95 and Bcl-2, as well as CD95 sensitivity and P-gp function but not constitutive Bax expression depend on the maturation stage of leukemic cells in adult de novo AML. P-gp function, the extent of spontaneous apoptosis in vitro and CD95 sensitivity are more predictive for response to induction chemotherapy in adult de novoAML than the constitutive expression levels of the apoptosis-related molecules CD95, Bcl-2 and Bax.
In the present study, we investigated the in vitro apoptotic response of leukemic cells to the cellular stress induced by homoharringtonine (HHT), a plant alkaloid with antileukemic activity which is ...currently being tested for treatment of acute and chronic leukemias. A comparison of leukemic cell lines with different p53 gene status revealed a considerably higher sensitivity to HHT-induced apoptosis in the cells with a wt p53, and apoptotic events in wt p53 leukemia cells (MOLT-3 cell line) were studied in more detail. To this end, we examined components of apoptotic cascades including Bax expression and its intracellular localization, changes of mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, cytochrome c release from mitochondria and activation of caspases. Bax protein levels did not increase despite an up-regulation of bax at mRNA level. However, Bax translocation from cytosol towards mitochondria was observed. In addition, we observed a release of cytochrome c from the mitochondria, and the localization changes of both Bax and cytochrome c were found already at the early, annexin V-negative stage of HHT-induced apoptosis. HHT-treated MOLT-3 cells revealed loss of MMP as well as activation of caspases demonstrated by DEVD-, IETD- and LEHD-tetrapeptide cleavage activity in the cell lysates. ROS levels only slightly increased in HHT-treated cells and antioxidants did not prevent apoptosis and MMP changes. Therefore, wt p53 leukemic cells respond to HHT-specific cellular stress by induction of ROS-independent apoptotic pathway characterized by translocation of Bax, mitochondrial cytochrome c release and activation of caspases.
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