Ilka Engelmann
Research skills
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TechnicalVirology, Molecular Biology
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StatisticalParametric and Non parametric tests, Logistic and Cox regression, Kaplan Meier survival
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OtherMedical virology and microbiology, Diagnostic Methods
Research interests
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Interestsinfections host pathogen interactions diagnostics virology immunology transplantation
Other
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LanguagesGerman, English, French
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Scientific MembershipsSocieté francaise de microbiologie
Publications
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2.06Impact points
Incidence and impact of herpes simplex and cytomegalovirus detection in the respiratory tract after lung transplantation.
Transplant infectious disease : an official journal of the Transplantation Society. 12/2010; 13(3):259-65.
Herpesvirus infections cause morbidity in lung transplant recipients. The study was conducted to investigate the incidence and impact of herpes simplex virus (HSV) and cytomegalovirus (CMV) detection in the respiratory tract (RT) of lung and heart-lung transplant recipients (LTR) during the postoper... [more] Herpesvirus infections cause morbidity in lung transplant recipients. The study was conducted to investigate the incidence and impact of herpes simplex virus (HSV) and cytomegalovirus (CMV) detection in the respiratory tract (RT) of lung and heart-lung transplant recipients (LTR) during the postoperative phase. In a prospective cohort study, 91 LTR having at least 1 nasopharyngeal swab (NPS) sent for virus diagnostics were monitored for CMV and HSV detection in NPS during their post-transplant hospital stay on cardiothoracic surgery wards (median 4 weeks) by direct immunofluorescence testing for HSV, virus culture, and CMV and HSV polymerase chain reaction (PCR). Bronchoalveolar lavages (BALs) were analyzed with the same protocol except that HSV PCR was only performed on request. Risk factor analysis for the outcome '90-day mortality' was performed. Fifteen LTR had virus detection in NPS (16.5%): 9 had CMV, 5 had HSV, and 1 had both CMV and HSV. Four of 84 LTR had CMV detection in BAL (4.8%). Absence of CMV detection in NPS had a negative predictive value of 98.8% for absence of CMV detection in BAL. HSV DNA detection in NPS, especially if detected within 8 days after transplantation, was associated with 90-day mortality. In conclusion, detection of herpesviruses in the RT was clinically relevant and frequent, despite antiviral prophylaxis.
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3.50Impact points
Community-acquired respiratory viral infections in lung transplant recipients: a single season cohort study.
Transplantation. 06/2009; 87(10):1530-7.
BACKGROUND: The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated. METHODS: A single-center prospective cohort study was performed in LTx-outp... [more] BACKGROUND: The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated. METHODS: A single-center prospective cohort study was performed in LTx-outpatients between October 31, 2005 and April 30, 2006. Symptoms of respiratory tract infections were recorded and nasopharyngeal and oropharyngeal swabs were obtained. Lower respiratory sampling was performed when indicated. Immunofluorescence testing, cultures, and polymerase chain reaction for 12 different CARV were applied. Patients were followed up until December 31, 2007. New onset and BOS-stage was recorded 1 year after presentation. RESULTS: Three hundred eighty-eight LTx-recipients were screened. Fifty-one percent reported of symptoms of respiratory tract infection. Seven hundred seventy upper and 180 lower respiratory samples were obtained. Thirty-four CARV were detected in 30 patients (7.7%): 12 parainfluenza, 7 respiratory syncytial virus, 6 metapneumovirus, 5 coronavirus, 3 rhinovirus, and 1 influenza virus. At 1 year, 43 new cases of BOS developed. One-year incidence of BOS was 25.0% in CARV-positive versus 9.0% in CARV-negative patients (log-rank P=0.01). Symptomatic CARV-infection proved to be a significant covariate for 1-year BOS-free survival in multivariate analysis (P=0.002, adjusted hazard ratio 4.13). CARV-infection did not influence BOS progression in 88 patients with prior BOS (P 0.45). After paramyxovirus infection, 8 of 24 patients developed new-onset BOS, whereas no case was recorded after rhinovirus and coronavirus infection. DISCUSSION: Surveillance detected CARV in LTx outpatients infrequently. Symptomatic CARV-infection increases the risk for new onset of BOS, but not progression. Risk to develop BOS was especially increased after paramyxovirus infection.
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3.12Impact points
Detection of Epstein-Barr virus DNA in peripheral blood is associated with the development of bronchiolitis obliterans syndrome after lung transplantation.
Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology. 04/2009;
BACKGROUND: The long-term success of lung transplantation is limited by the development of bronchiolitis obliterans syndrome (BOS). Virus infections may be involved in the development of BOS. OBJECTIVES: The study intended to investigate whether there is an association of Epstein-Barr virus (EBV), c... [more] BACKGROUND: The long-term success of lung transplantation is limited by the development of bronchiolitis obliterans syndrome (BOS). Virus infections may be involved in the development of BOS. OBJECTIVES: The study intended to investigate whether there is an association of Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human adenovirus (HAdV) with the development of BOS and to identify risk factors for EBV detection in blood. STUDY DESIGN: A prospective cohort study was conducted in lung and heart-lung transplant recipients (LTR) who are followed in our outpatient clinic. 385 LTR were monitored for CMV pp65 antigen, EBV and HAdV DNA in blood at follow-up visits for 6 months. The development of BOS was recorded for a median of 21 months. RESULTS: EBV DNA, HAdV DNA and CMV pp65 antigen were detected at least once in, respectively, 202/385 LTR (52.5%), 10/382 LTR (2.6%) and 19/385 LTR (4.9%). Repeated EBV DNA detection and acute rejection were associated with the development of BOS. Variables associated with EBV DNA detection in blood were the diagnosis of BOS before study entry, retransplantation and immunosuppressive therapy with sirolimus or everolimus. CONCLUSIONS: EBV reactivation is frequent in LTR. The variables found associated with EBV reactivation probably reflect increased immunosuppression. Repeated EBV DNA detection in blood, possibly reflecting chronic EBV replication, is associated with the development of BOS. The elucidation of whether and how EBV DNAemia triggers the development of BOS could improve long-term survival of LTR.
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2.27Impact points
Comparison of the performance of the rapid antigen detection actim Influenza A&B test and RT-PCR in different respiratory specimens.
Journal of medical microbiology. 03/2009; 58(Pt 3):365-70.
Nowadays, influenza antigen detection test kits are used most frequently to detect influenza A or B virus to establish the diagnosis of influenza rapidly and initiate appropriate therapy. This study was conducted to evaluate the performance of the actim Influenza A&B test (Medix Biochemica). Ove... [more] Nowadays, influenza antigen detection test kits are used most frequently to detect influenza A or B virus to establish the diagnosis of influenza rapidly and initiate appropriate therapy. This study was conducted to evaluate the performance of the actim Influenza A&B test (Medix Biochemica). Overall, 473 respiratory specimens were analysed in the actim Influenza A&B test and the results were compared with those from an RT-PCR assay; 461 of these samples originated from paediatric patients aged 7 weeks to 6.5 years either with influenza-related symptoms or from the intensive care unit, and 12 samples originated from adults with underlying lung or haematological diseases. Diagnosis of influenza A or B virus could be established using the actim Influenza A&B test (9/473 samples for influenza A virus and 6/473 for influenza B virus). RT-PCR revealed 23 patients with influenza virus (13/473 for influenza A virus and 10/473 for influenza B virus). The sensitivity and specificity of the actim Influenza A&B test were 65 and 100 % compared with the RT-PCR assay. However, 32 external quality assessment samples containing seven different strains of influenza A subtypes H1N1 and H3N2 and the avian H5N1 were detected correctly by the actim Influenza A&B test. No cross-reactivity to a range of bacterial, fungal and other viral pathogens was observed. In conclusion, the actim Influenza A&B test is reliable for positive results due to its high specificity. Nevertheless, negative results from this test need to be confirmed by a more sensitive assay because of the low sensitivity observed with diagnostic samples.
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2.47Impact points
Rapid quantitative PCR assays for the simultaneous detection of herpes simplex virus, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, and human herpesvirus 6 DNA in blood and other clinical specimens.
Journal of medical virology. 04/2008; 80(3):467-77.
Rapid diagnosis of human herpesvirus primary infections or reactivations is facilitated by quantitative PCRs. Quantitative PCR assays with a standard thermal cycling profile permitting simultaneous detection of herpes simplex virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-... [more] Rapid diagnosis of human herpesvirus primary infections or reactivations is facilitated by quantitative PCRs. Quantitative PCR assays with a standard thermal cycling profile permitting simultaneous detection of herpes simplex virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV6) DNA were developed and validated for diagnostic use. High specificity and sensitivity were achieved and the new PCR assays correlated well with commercial PCR assays. Twenty two thousand eight hundred sixty eight PCR tests were undertaken on specimens obtained from immunosuppressed patients. DNAemia was frequent with EBV (43.5%), HHV6 (32.4%), CMV (12.8%), and VZV (12.9%). As already described for EBV and CMV, high virus loads of HHV6 and VZV were associated with clinical symptoms and poor clinical outcome, for example, three of four patients with VZV virus loads >10(5) copies/ml died. A high proportion of lower respiratory specimens was positive for EBV- (38.8%), HHV6- (29.4%), and CMV-DNA (18.2%). For CMV, infection was confirmed in 66.7% of patients by virus isolation or positive pp65 antigenaemia. Differentiation of HHV6A, -B and HSV-1, -2 by melting curve analysis revealed that HHV6A and HSV-2 represented only 1.8% and 3.3% of all positive specimens, respectively. In conclusion, these results indicate significant improvements for the early diagnosis of primary infections or reactivations of five human herpesviruses especially in immunosuppressed patients. Detection of coinfections with multiple herpesviruses is facilitated. Quantitative results enable monitoring of virus load during antiviral therapy. A standard thermal cycling profile permits time and cost effective use in a routine diagnostic setting.
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2.05Impact points
Adverse effects of rabies pre- and postexposure prophylaxis in 290 health-care-workers exposed to a rabies infected organ donor or transplant recipients.
Infection. 07/2007; 35(4):219-24.
The recent unfortunate rabies transmissions through solid organ transplants of an infected donor in Germany required the initiation of a vaccination program to protect health care workers (HCWs) with close contact to rabies-infected patients. A systematic follow-up of adverse effects was initiated. ... [more] The recent unfortunate rabies transmissions through solid organ transplants of an infected donor in Germany required the initiation of a vaccination program to protect health care workers (HCWs) with close contact to rabies-infected patients. A systematic follow-up of adverse effects was initiated. Rabies postexposure prophylaxis (PEP) was started in 269 HCWs at four German hospitals. Pre-exposure prophylaxis (PreEP) was administered to 74 HCWs caring for an already diagnosed rabies patient. At each vaccination date, HCWs were interviewed for symptoms possibly representing adverse effects. Adverse effects of PEP and PrePEP were compared. Out of 269 HCWs, 216 were included for the investigation of adverse effects. Of these 216 HCWs, 114 (53%) individuals developed at least one systemic adverse effect. Incidences of tiredness (30.6%), malaise (26.4%), headache (26.9%), dizziness (14.8%), and chills (13.0%) declined in the course of PEP (p < 0.05), whereas incidences of fever (7.4%), paraesthesias (7.9%), arthralgias (1.9%), myalgias (4.2%), nausea (9.3%), diarrheas (2.8%) and vomiting (1.4%) did not. In 11 (5.1%) HCWs PEP was discontinued mostly due to adverse reactions (four suffered strong headaches, two HCWs meningeal irritations, two chills, one paraesthesia, one malaise, and one a rush). Systemic effects of PEP or PreEP did not differ significantly. Despite relatively high incidences of moderate severe adverse reactions rabies PEP is safe. Strong headache, tiredness, dizziness, and paraesthesias are the most important postvaccinal symptoms. Vaccinees suffering from adverse effects of PEP must be strongly encouraged to complete PEP, as it is to date the only protection against fatal rabies.
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2.94Impact points
Placental Plasmodium falciparum infection: causes and consequences of in utero sensitization to parasite antigens.
Molecular and biochemical parasitology. 02/2007; 151(1):1-8.
Available evidence suggests that, in African populations, systemic blood-dwelling parasitoses of mothers are associated with enhanced susceptibility to infection of their offspring. Thus, children born to mothers with filariasis or schistosomiasis are infected earlier, and offspring of mothers with ... [more] Available evidence suggests that, in African populations, systemic blood-dwelling parasitoses of mothers are associated with enhanced susceptibility to infection of their offspring. Thus, children born to mothers with filariasis or schistosomiasis are infected earlier, and offspring of mothers with placental Plasmodium falciparum at delivery, commonly referred to as pregnancy-associated malaria or PAM, are themselves at higher risk of developing parasitaemia during infancy. Since foetal/neonatal antigen-presenting cells (APC) are either immature or provide insufficient costimulatory signals to T cells, thus favouring tolerance induction, it is commonly assumed that soluble parasite components [protein antigens], transferred transplacentally and inducing foetal immune tolerance, are largely, if not exclusively, responsible for these outcomes. Plasmodial asexual blood stage antigen-specific T cells are detectable in as many as two-thirds of all cord blood samples in malaria-endemic countries of sub-Saharan Africa, indicating that in utero sensitization may be a common phenomenon during pregnancy in these populations. Parasite antigen-specific T cell responses of neonates born to helminth-infected mothers display a highly skewed Th2-type cytokine pattern, with a prominent role for the regulatory cytokine interleukin (IL)-10. Similarly, the cord blood immune response of those born to mothers identified with on-going PAM is characterised by inducible parasite antigen-specific IL-10-producing regulatory T cells that can inhibit both APC HLA expression and Th1-type T cell responses. In contrast, plasmodial antigen-specific Th1-type responses, characterised by IFN-gamma production, predominate in cord blood of those born to mothers successfully treated for Pf malaria during gestation, suggesting that the duration and/or the nature of antigen exposure in utero governs the outcome with respect to neonatal immune responses. Aspects of APC function in the context of these differentially modulated responses, whether and how the latter translate into altered susceptibility to Pf infection during infancy, as well as the possible implications for vaccination in early life, are aspects that are discussed in this review.
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3.28Impact points
Differing activation status and immune effector molecule expression profiles of neonatal and maternal lymphocytes in an African population.
Immunology. 01/2007; 119(4):515-21.
Higher susceptibility of newborns to infections has been attributed to the hypo-responsiveness of their cellular immune system. Here we compared the activation status and expression of cytokines and cytotoxic molecules of cord versus maternal peripheral blood mononuclear cells in an African populati... [more] Higher susceptibility of newborns to infections has been attributed to the hypo-responsiveness of their cellular immune system. Here we compared the activation status and expression of cytokines and cytotoxic molecules of cord versus maternal peripheral blood mononuclear cells in an African population. Human leucocyte antigen-DR was expressed on a lower percentage of cord compared to maternal gammadelta and CD3(+) T cells. Similarly, a lower proportion of cord versus maternal gammadelta and CD3(+) T cells displayed perforin, granzyme B and cytokine activity either ex vivo or following non-specific stimulation in vitro. In contrast, comparable proportions of cord and maternal CD94(+) CD3(-) natural killer (NK) cells showed perforin and granzyme B expression ex vivo. We conclude that cord blood gammadelta and CD3(+) T cells are functionally hypo-responsive as reflected by reduced numbers of such cells expressing either an activation marker, T helper 1 (Th1) and Th2 cytokines or cytotoxic effector molecules. The similarity in numbers of cord and maternal CD94(+) CD3(-) cells expressing cytotoxic effector molecules suggests that neonatal Africans' NK cells may be functionally mature.
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4.93Impact points
Clinical relevance of and risk factors for HSV-related tracheobronchitis or pneumonia: results of an outbreak investigation.
Critical care (London, England). 01/2007; 11(6):R119.
INTRODUCTION: Herpes simplex virus (HSV) type 1 was identified in respiratory specimens from a cluster of eight patients on a surgical intensive care unit within 8 weeks. Six of these patients suffered from HSV-related tracheobronchitis and one from HSV-related pneumonia only. Our outbreak investiga... [more] INTRODUCTION: Herpes simplex virus (HSV) type 1 was identified in respiratory specimens from a cluster of eight patients on a surgical intensive care unit within 8 weeks. Six of these patients suffered from HSV-related tracheobronchitis and one from HSV-related pneumonia only. Our outbreak investigation aimed to determine the clinical relevance of and risk factors associated with HSV-related tracheobronchitis or pneumonia in critically ill patients, and to investigate whether the cluster was caused by nosocomial transmission. METHODS: A retrospective cohort study was performed to identify risk factors for the outcomes of HSV-related tracheobronchitis or pneumonia and death using univariable analysis as well as logistic regression analysis. Viruses were typed by molecular analysis of a fragment of the HSV type 1 glycoprotein G. RESULTS: The cohort of patients covering the outbreak period comprised 53 patients, including six patients with HSV-related tracheobronchitis and one patient with pneumonia only. HSV-related tracheobronchitis or pneumonia was associated with increased mortality (100% in patients with versus 17.8% in patients without HSV-related tracheobronchitis or pneumonia; P < 0.0001). The interaction of longer duration of ventilation and tracheotomy was associated with HSV-related tracheobronchitis or pneumonia in multivariable analysis.Identical HSV type 1 glycoprotein G sequences were found in three patients and in two patients. The group of three identical viral sequences belonged to a widely circulating strain. The two identical viral sequences were recovered from bronchoalveolar lavages of one patient with HSV-related tracheobronchitis and of one patient without clinical symptoms. These viral sequences showed unique polymorphisms, indicating probable nosocomial transmission. CONCLUSION: HSV-related tracheobronchitis or pneumonia is associated with increased mortality in critically ill patients. Care should be taken to avoid nosocomial transmission and early diagnosis should be attempted.
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8.20Impact points
An outbreak of epidemic keratoconjunctivitis caused by a new intermediate adenovirus 22/H8 identified by molecular typing.
Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 11/2006; 43(7):e64-6.
In a 4-week period, 12 patients contracted adenoviral keratoconjunctivitis. Eight of these patients had visited the same ophthalmologist's practice before onset of symptoms. Adenovirus was detected in swab specimens obtained from 9 patients. Sequence-based typing of 2 isolates revealed type 22/H... [more] In a 4-week period, 12 patients contracted adenoviral keratoconjunctivitis. Eight of these patients had visited the same ophthalmologist's practice before onset of symptoms. Adenovirus was detected in swab specimens obtained from 9 patients. Sequence-based typing of 2 isolates revealed type 22/H8. This is, to our knowledge, the first report of a keratoconjunctivitis outbreak caused by an intermediate adenovirus type 22/H8.
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5.87Impact points
Activation status of cord blood gamma delta T cells reflects in utero exposure to Plasmodium falciparum antigen.
The Journal of infectious diseases. 06/2005; 191(10):1612-22.
BACKGROUND: Placental Plasmodium falciparum infection modulates neonatal cell-mediated immune responses and is associated with increased susceptibility of infants to malaria. METHODS: By flow-cytometric analysis of maternal peripheral and cord blood samples collected at delivery, we measured and com... [more] BACKGROUND: Placental Plasmodium falciparum infection modulates neonatal cell-mediated immune responses and is associated with increased susceptibility of infants to malaria. METHODS: By flow-cytometric analysis of maternal peripheral and cord blood samples collected at delivery, we measured and compared the activation status and proinflammatory cytokine activity of T cells from women segregated into groups according to malaria status. RESULTS: Stimulation with phorbol myristate acetate/ionomycin resulted in the highest percentages of tumor necrosis factor-alpha- and interferon-gamma-positive gamma delta T cells in peripheral blood samples and in corresponding cord blood samples from those treated for malaria during pregnancy. Cord blood samples from this group also contained significantly higher percentages of CD69(+) and CD25(+) gamma delta T cells and CD3(+) T cells, compared with samples from either the group with active placental P. falciparum infection at delivery or the group with no infection. Proinflammatory cytokine activity of cells from the group with placental P. falciparum infection at delivery was either similar to or lower than that of cells from the group with no infection. CONCLUSIONS: The findings imply that treatment of P. falciparum malaria during pregnancy leads to enhanced innate immune T cell activation and proinflammatory cytokine responses in both maternal and fetal compartments. Ongoing placental P. falciparum infection, conversely, is associated with an absence of such activity.
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2.45Impact points
Reversible and oxidative inactivation of endogenous survival factors after removal of exogenous survival factors.
International journal of oncology. 08/2000; 17(1):97-102.
Serum contains exogenous survival factors for fibroblasts. Removal of these exogenous factors causes inactivation of endogenous survival factors, subsequent release of a constitutively expressed apoptosis machinery from negative control and apoptosis. Inactivation of endogenous survival factors afte... [more] Serum contains exogenous survival factors for fibroblasts. Removal of these exogenous factors causes inactivation of endogenous survival factors, subsequent release of a constitutively expressed apoptosis machinery from negative control and apoptosis. Inactivation of endogenous survival factors after serum withdrawal is mediated by reactive oxygen species and can be rapidly reversed through re-addition of serum. Oxidative inactivation of endogenous survival factors after depletion of exogenous survival factors as well as the process of reversion to the active state do not require protein synthesis, indicating the existence of a constitutively expressed regulatory system that controls the interaction of exogenous and endogenous survival factors.
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1.51Impact points
Transformed target cell-derived superoxide anions drive apoptosis induction by myeloperoxidase.
Redox report : communications in free radical research. 02/2000; 5(4):207-14.
Myeloperoxidase induces apoptosis in src- or raxs-transformed fibroblasts, but not in parental nontransformed fibroblasts. This selectivity seems to be based on superoxide anion production by transformed cells, a recently described characteristic feature of transformed cells. Myeloperoxidase-mediate... [more] Myeloperoxidase induces apoptosis in src- or raxs-transformed fibroblasts, but not in parental nontransformed fibroblasts. This selectivity seems to be based on superoxide anion production by transformed cells, a recently described characteristic feature of transformed cells. Myeloperoxidase-mediated apoptosis induction is inhibited by SOD, catalase, 4-aminobenzoyl hydrazide, taurine and DMSO. This pattern of inhibition allows us to conclude that transformed cell derived superoxide anions dismutate to hydrogen peroxide, which fosters HOCl formation by myeloperoxidase. Hydrogen peroxide formation thereby is the rate-limiting step and depends on the cell density. In a second step, HOCl interacts with superoxide anions to yield the highly reactive apoptosis inducing hydroxyl radical. This conclusion was verified through selective apoptosis induction in transformed cells by direct addition of HOCl, which was also inhibited by SOD and DMSO. Our findings demonstrate a specific interplay between target cell derived superoxide anions and MPO during selective apoptosis induction.
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1.43Impact points
Intercellular induction of apoptosis through modulation of endogenous survival factor concentration: a review.
Anticancer research. 19(1A):87-103.
Fibroblasts constitutively express a functional apoptosis machinery which is under negative control by operationally defined endogenous survival factors. Oncogenic transformation causes a marked downmodulation of endogenous survival factor concentration which renders transformed cells more sensitive... [more] Fibroblasts constitutively express a functional apoptosis machinery which is under negative control by operationally defined endogenous survival factors. Oncogenic transformation causes a marked downmodulation of endogenous survival factor concentration which renders transformed cells more sensitive to various apoptosis stimuli compared to their nontransformed counterparts. Endogenous survival factors can be inactivated by reactive oxygen species (ROS). Endogenous survival factors are the ultimate targets for apoptosis-inducing factors derived from TGF-beta-triggered nontransformed cells during intercellular induction of apoptosis. During this control step of oncogenesis, endogenous survival factors in transformed cells are inactivated by ROS and the apoptosis machinery is released from negative control. This mechanism leads to the specific elimination of transformed cells. Our data show that the transformed state causes both the ability of the cells to perceive the apoptosis-inducing signal and a decrease in the concentration of endogenous survival factors. These two mechanisms are of central importance for the regulation of intercellular induction of apoptosis.
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1.43Impact points
How can tumor cells escape intercellular induction of apoptosis?
Anticancer research. 20(4):2297-306.
A novel concept for the control of oncogenesis has been established for fibroblasts. Transformed fibroblasts are subject to intercellular induction of apoptosis by TGF-beta or FGF-triggered nontransformed neighboring cells. If this control system acts in vivo as efficiently as it does in vitro, tumo... [more] A novel concept for the control of oncogenesis has been established for fibroblasts. Transformed fibroblasts are subject to intercellular induction of apoptosis by TGF-beta or FGF-triggered nontransformed neighboring cells. If this control system acts in vivo as efficiently as it does in vitro, tumor formation should require the establishment of resistance mechanisms directed against intercellular induction of apoptosis. In line with this hypothesis, ex vivo tumor cells have been recently shown to be resistant to intercellular induction of apoptosis, whereas cells transformed in vitro and not passaged in an organism were regularly sensitive. Based on the knowledge of signaling between transformed and nontransformed cells during intercellular induction of apoptosis, several possible mechanisms for resistance of tumor cells are summarized in this paper.
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1.43Impact points
Ex vivo tumor cell lines are resistant to intercellular induction of apoptosis and independent of exogenous survival factors.
Anticancer research. 20(4):2361-70.
Elimination of transformed fibroblasts through intercellular induction of apoptosis has been postulated as representing an efficient control step during oncogenesis. Whereas fibroblasts transformed by chemical carcinogens in vitro were sensitive to intercellular induction of apoptosis, ex vivo tumou... [more] Elimination of transformed fibroblasts through intercellular induction of apoptosis has been postulated as representing an efficient control step during oncogenesis. Whereas fibroblasts transformed by chemical carcinogens in vitro were sensitive to intercellular induction of apoptosis, ex vivo tumour cells derived from animals treated with chemical carcinogens were resistant to this control step. Resistance was achieved through two different mechanisms. Two cell lines overexpressed endogenous survival factors and thus the action of intercellular signalling (ICS) was not sufficient for complete depletion of endogenous survival factors. One of the resistant ex vivo tumour lines contained the same concentration of endogenous survival factors as its in vitro transformed and sensitive counterpart, but the endogenous survival factors were protected from the action of ICS in the resistant tumour cell line. In addition, the ex vivo tumour cell lines showed a marked independence of exogenous survival factors. Our data indicate that tumour formation requires independence of control by neighbouring cells and by exogenous survival factors.
Following (3)
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Albert Heim
Medizinische Hochschule Hannover -
Ijad Madisch
Massachusetts General Hospital
