Bernhard Boehm

Publications of Bernhard Boehm

• Application of a novel highly sensitive activity-based probe for detection of cathepsin G.

  Authors: Fang Zou, Michael Schmon, Marcin Sienczyk, Renata Grzywa, David Palesch, Bernhard O Boehm, Zi Lin Sun, Colin Watts, Reinhold Schirmbeck, Timo Burster

  Analytical biochemistry. 11/2011; 421(2):667-72.

  Cathepsins are crucial in antigen processing in the major histocompatibility complex class II (MHC II) pathway. Within the proteolytic machinery, three classes of proteases (i.e., cysteine, aspartic,Cathepsins are crucial in antigen processing in the major histocompatibility complex class II (MHC II) pathway. Within the proteolytic machinery, three classes of proteases (i.e., cysteine, aspartic, and serine proteases) are present in the endocytic compartments. The combined action of these proteases generates antigenic peptides from antigens, which are loaded to MHC II molecules for CD4(+) T cell presentation. Detection of active serine proteases in primary human antigen-presenting cells (APCs) is restricted because of the small numbers of cells isolated from the peripheral blood. For this purpose, we developed a novel highly sensitive α-aminoalkylphosphonate diphenyl ester (DAP) activity-based probe to detect the serine protease cathepsin G (CatG) in primary APCs and after Epstein-Barr virus (EBV) exposure. Although CatG activity was not altered after short-term exposure of EBV in primary myeloid dendritic cells 1 (mDC1s), the aspartic protease cathepsin D (CatD) was reduced, suggesting that EBV is responsible for mitigating the presentation of a model antigen tetanus toxoid C-fragment (TTCF) by reduction of CatD. In addition, CatG activity was reduced to background levels in B cells during cell culture; however, these findings were independent of EBV transformation. In conclusion, our activity-based probe can be used for both Western blot and 96-well-based high-throughput CatG detection when cell numbers are limited.

• HLA-DR genotypes influence age at disease onset in children and juveniles with type 1 diabetes mellitus.

  Authors: W L Awa, B O Boehm, T Kapellen, B Rami, P Rupprath, W Marg, M Becker, R W Holl

  European journal of endocrinology / European Federation of Endocrine Societies. 04/2010; 163(1):97-104.

  To investigate HLA-DR genotype in association with chronological age or calendar year of disease onset and the time trend of genotype frequencies from 1969 to 2009. Additionally, to examine genotypeTo investigate HLA-DR genotype in association with chronological age or calendar year of disease onset and the time trend of genotype frequencies from 1969 to 2009. Additionally, to examine genotype frequency in relation to B-cell-, islet cell antibodies (ICA)-, autoantibodies to insulin-, insulinoma antigen 2 (IA2)-, glutamic acid decarboxylase-antibody positivity, thyroid antibody positivity, thyroid diseases or coeliac antibody positivity. Genotype associations with gender and ethnicity are also analyzed. HLA-typed children and juveniles (n=1445) aged <or=20 years at disease onset from the German/Austrian DPV-database were examined. chi(2) statistics and mixed hierarchical logistic regression models were used to compare genotype frequencies and establish associations with age at disease manifestation, autoimmune antibodies/diseases, ethnicity and time trend. Subjects aged <6 years predominantly carried the genotype HLA-DR3/4 (25.2%), whereas in subjects aged >12 years the most prevalent HLA-DR genotype was X/X (18.1%). IA2 positivity was associated with HLA-DR4/X and HLA-DR3/4 positivity (P=0.011), and hypothyroidism was linked to HLA-DR4/4 (P=0.0103). More females carried the HLA-DR4/4 genotype (18.2 vs 12.7% P=0.0048) or were thyroid antibody positive (24.5 vs 14.7% P=0.0001). Larger numbers of <6 year olds were coeliac antibody positive than >12 year olds (14.8 vs 9.1% P=0.0037). No associations between migration background and B-cell-, thyroid- or coeliac-antibody positivity, and no time trend were found. HLA-DR genotype associated with age at disease onset, ICA positivity and hypothyroidism; female gender with thyroid antibody positivity and low age of diabetes onset with coeliac antibody positivity.

• Vitamin C supplement use may protect against gallstones: an observational study on a randomly selected population.

  Authors: Thomas Walcher, Mark Haenle, Martina Kron, Birgit Hay, Richard Mason, Daniel Walcher, Gerald Steinbach, Peter Kern, Isolde Piechotowski, Guido Adler, Bernhard Boehm, Wolfgang Koenig, Wolfgang Kratzer, Emil Study Group

  BMC gastroenterology. 10/2009; 9(1):74.

  ABSTRACT: BACKGROUND: Animal experiments have shown a protective effect of vitamin C on the formation of gallstones. Few data in humans suggest an association between reduced vitamin C intake andABSTRACT: BACKGROUND: Animal experiments have shown a protective effect of vitamin C on the formation of gallstones. Few data in humans suggest an association between reduced vitamin C intake and increased prevalence of gallstone disease. The aim of this study was to assess the possible association of regular vitamin C supplementation with gallstone prevalence. METHODS: An observational, population-based study of 2129 subjects aged 18-65 years randomly selected from the general population in southern Germany was conducted. Abdominal ultrasound examination, completion of a standardized questionnaire, compilation of anthropometric data and blood tests were used. Data were collected in November and December 2002. Data analysis was conducted between December 2005 and January 2006. RESULTS: Prevalence of gallstones in the study population was 7.8% (167/2129). Subjects reporting vitamin C supplementation showed a prevalence of 4.7% (11/232), whereas in subjects not reporting regular vitamin C supplementation, the prevalence was 8.2% (156/1897). Female gender, hereditary predisposition, increasing age and body-mass index (BMI) were associated with increased prevalence of gallstones. Logistic regression with backward elimination adjusted for these factors showed reduced gallstone prevalence for vitamin C supplementation (odds ratio, OR 0.34; 95% confidence interval, CI 0.14 to 0.81; P=0.01), increased physical activity (OR 0.62; 95% CI, 0.42 to 0.94; P=0.02), and higher total cholesterol (OR 0.65; 95% CI, 0.52 to 0.79; P<0.001). CONCLUSIONS: Regular vitamin C supplementation and, to a lesser extent, increased physical activity and total cholesterol levels are associated with a reduced prevalence of gallstones. Regular vitamin C supplementation might exert a protective effect on the development of gallstones.

• Thyroid examination in highly radiation-exposed workers after the Chernobyl accident.

  Authors: Bernhard Boehm, Marianna Steinert, Johannes Dietrich, Ralf Peter, David Belyi, Gerard Wagemaker, Silke Rosinger, Theodor Fliedner, Melanie Weiss

  European journal of endocrinology / European Federation of Endocrine Societies. 02/2009;

  Context: Radioactive contamination from the Chernobyl nuclear accident which happened in the morning of 26 April 1986 had a major impact on thyroid health in the Belarus region. Objective:Context: Radioactive contamination from the Chernobyl nuclear accident which happened in the morning of 26 April 1986 had a major impact on thyroid health in the Belarus region. Objective: Observational study of a cohort of 99 adults, most strongly exposed to ionizing radioactivity. Design, Setting, and Patients: Observational study performed between 1998 and 2000. The cohort was comprised of 99 workers (92 male) of the Chernobly nuclear power plant. Examination including physical examination, ultrasonography of the thyroid gland and measurement of serum free thyroxin (fT4), free triiodothyronine (fT3), and thyroid stimulating hormone (TSH). Anti-TPO, anti-Tg antibodies and TSI were also determined. Main Outcome Measures: The impact of exposure to high dose radiation, including radioactive iodine, on the thyroid gland was examined. Results: Levels of fT4 in all probands were within the normal World Health Organization-defined range. Elevated levels of fT3 were found in two workers (2%), high titres of anti-TPO and anti-Tg antibodies was present in four subjects (4%). Mild hypothyroidism was present in one patient. Enlargement of the thyroid gland was observed in 17 workers (17%). There was no evidence of clinically overt thyroid cancer. Conclusions: The Chernobyl accident showed surprisingly little impact on the thyroid in a cohort of workers strongly exposed to radiation. Our data suggest an age-dependent heterogeneity in the response to short-lived radioiodine isotopes and favors long-term follow-up analysis.

• Angiogenic-regulatory network revealed by molecular profiling heart tissue following Akt1 induction in endothelial cells.

  Authors: Stephan Schiekofer, Kurt Belisle, Gennaro Galasso, Jochen Schneider, Bernhard Boehm, Timo Burster, Gerd Schmitz, Kenneth Walsh

  Angiogenesis. 05/2008;

  Akt is a pivotal signaling molecule involved in the regulation of angiogenesis. In order to further elucidate the role of Akt1 in blood vessel development, a tetracycline-regulated transgenic systemAkt is a pivotal signaling molecule involved in the regulation of angiogenesis. In order to further elucidate the role of Akt1 in blood vessel development, a tetracycline-regulated transgenic system was utilized to conditionally activate Akt1 signaling in endothelial cells to examine transcript expression changes associated with angiogenesis in the heart. Induction of Akt1 over the course of 6 weeks led to a 33% increase in capillary density without affecting overall heart growth. Transcript expression profiles in the hearts were analyzed with an Affymetrix GeneChip Mouse Expression Set 430 2.0, which represents approximately 45,000 cDNAs and ESTs. A total of 248 transcripts were differentially expressed between transgenic and control mice (fold change >/<1.8; false discovery rate < 0.1; P < 0.01). A subset of these differentially expressed transcripts included angiogenic growth factors, cytokines, and extracellular matrix proteins. More specifically, these transcripts included VEGF-receptor2, neuropilin-1, and connective tissue growth factor, each of which is implicated in blood vessel growth and the maintenance of vessel wall integrity. Furthermore, these factors may be involved in an autocrine-regulatory feedback system, one believed to promote vessel growth. Knowledge of these and other targets could be used to treat ischemic heart disease, a disease whose broad spectrum of manifestations range from patients with only effort-induced angina without myocardial damage, through stages of myocardial ischemia that are associated with reversible and irreversible impairment in left ventricular function, to states of irreversible myocardial injury and necrosis resulting in congestive heart failure (CHF).

• The diabetogenic, insulin-specific CD8 T cell response primed in the experimental autoimmune diabetes model in RIP-B7.1 mice.

  Authors: Wolfram Karges, Tarvo Rajasalu, Andreas Spyrantis, Andreas Wieland, Bernhard Boehm, Reinhold Schirmbeck

  European journal of immunology. 09/2007; 37(8):2097-103.

  Type 1 diabetes mellitus can result from the specific destruction of pancreatic beta cells by autoreactive T cells. As shown here, experimental autoimmune diabetes (EAD) is efficiently induced inType 1 diabetes mellitus can result from the specific destruction of pancreatic beta cells by autoreactive T cells. As shown here, experimental autoimmune diabetes (EAD) is efficiently induced in RIP-B7.1 mice by preproinsulin (ppins)-encoding DNA vaccines. EAD develops in RIP-B7.1 mice within 3-4 wk after a single immunization with ppins-encoding plasmid DNA. RIP-B7.1 mice develop insulitis, insulin deficiency and hyperglycemia after vaccination with plasmids encoding murine ppins-I or murine ppins-II or human hu-ppins. EAD induction critically depends on CD8 T cells and is independent of CD4 T cells. To be diabetogenic, ppins-specific CD8 T cells had to express IFN-gamma. Neither expression of perforin nor signaling through the type I IFN receptor is an essential component of this pathogenic CD8 T cell phenotype. Using plasmids encoding truncated ppins variants, we show that EAD is only induced by DNA vaccines encoding the insulin A-chain. Diabetogenic CD8 T cells specifically recognize the Kb-restricted A12-21 epitope of the insulin A-chain. The RIP-B7.1 model hence represents an attractive model for the characterization of cellular and molecular events involved in the CD8 T cell-mediated immune pathogenesis of diabetes.

• Prevalence of non-alcoholic fatty liver and characteristics in overweight adolescents in the general population.

  Authors: Armin Imhof, Wolfgang Kratzer, Bernhard Boehm, Katrin Meitinger, Gerlinde Trischler, Gerald Steinbach, Isolde Piechotowski, Wolfgang Koenig

  European journal of epidemiology. 02/2007; 22(12):889-97.

  Overweight and obesity among children and adolescents are increasing. Fatty liver disease (FLD) is an emerging problem in this age group. We investigated prevalence of overweight and non-invasive FLDOverweight and obesity among children and adolescents are increasing. Fatty liver disease (FLD) is an emerging problem in this age group. We investigated prevalence of overweight and non-invasive FLD and associated clinical characteristics in a representative population-based sample of 378 children and adolescents aged 12-20 years who were randomly selected from the general population in Leutkirch, Southern Germany. Overweight was defined as having a body mass index above the 90th percentile for the respective age and sex. About 15% of female (29 out of 194) and 12% of male participants (22/182) were overweight. Among females, only one non-overweight individual showed signs of FLD but in more than one third of the overweight males (8/22) signs of FLD were present. Overweight subjects in general had an unfavourable lipid profile and abnormal concentrations of obesity-related hormones such as significantly lower concentrations of adiponectin and increased levels of inflammatory markers including C-reactive protein and fibrinogen. Overweight males with signs of FLD showed even more severe altered metabolic responses compared to those who were overweight without signs of liver injury. FLD was not explained by alcohol consumption or other chronic liver disease. In this sample of children and adolescents representative of the general population a high prevalence of non-alcoholic fatty liver disease (NAFLD) is found in overweight males. These individuals showed the most severe metabolic alterations compared to non-overweight and overweight individuals without NAFLD indicating even higher risk for future overweight and obesity-related diseases such as type 2 diabetes and cardiovascular disease.

• Immunological mechanisms associated with long-term remission of human type 1 diabetes.

  Authors: Beate Karges, Ivana Durinovic-Belló, Eberhard Heinze, Klaus-Michael Debatin, Bernhard Boehm, Wolfram Karges

  Diabetes/metabolism research and reviews. 22(3):184-9.

  BACKGROUND: Preservation of beta cell function is a central goal in type 1 diabetes (type 1 DM) immune intervention. The characterization of individuals with recovery from established type 1 DMBACKGROUND: Preservation of beta cell function is a central goal in type 1 diabetes (type 1 DM) immune intervention. The characterization of individuals with recovery from established type 1 DM should provide insight into regulatory mechanisms of beta cell autoimmunity. METHODS: We studied a patient with antibody-positive type 1 DM with complete recovery of beta cell function for an observation period of 60 months. Using a preproinsulin (PPI) peptide library approach and in vitro cytokine profiling, cellular autoimmunity was characterized in peripheral blood mononuclear cells (PBMC) and CD4(+) T-helper cell subsets. RESULTS: A predominant secretion of interleukin-10 (IL-10) was detected in the patient's PBMC, mostly attributable to naïve and recently primed CD45(+)RA(+) T cells, with limited PPI epitope recognition. In contrast to a cohort of patients with permanent type 1 DM, interferon-gamma secretion was low in PBMC and CD45(+)RA(+), but not in CD45(+)RA(-) insulin-reactive T lymphocytes. Autoantibodies against islet cells, tyrosine phosphatase IA-2, GAD65 and insulin were positive at diabetes onset, but gradually declined during follow-up. CONCLUSIONS: Our observations support the concept that IL-10-dependent regulatory CD4(+) T-cell pathways are involved in beta cell recovery after the onset of hyperglycemia in autoimmune type 1 DM.