@article{LueckerathLapaSpahmannetal.2013,
  author    = {L{\"u}ckerath, Katharina and Lapa, Constantin and Spahmann, Annika and J{\"o}rg, Gerhard and Samnick, Samuel and Rosenwald, Andreas and Einsele, Herrmann and Knop, Stefan and Buck, Andreas},
  title     = {Targeting Paraprotein Biosynthesis for Non-Invasive Characterization of Myeloma Biology},
  doi       = {10.1371/journal.pone.0084840},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111319},
  year      = {2013},
  abstract  = {Purpose Multiple myeloma is a hematologic malignancy originating from clonal plasma cells. Despite effective therapies, outcomes are highly variable suggesting marked disease heterogeneity. The role of functional imaging for therapeutic management of myeloma, such as positron emission tomography with 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG-PET), remains to be determined. Although some studies already suggested a prognostic value of 18F-FDG-PET, more specific tracers addressing hallmarks of myeloma biology, e.g. paraprotein biosynthesis, are needed. This study evaluated the amino acid tracers L-methyl-[11C]-methionine (11C-MET) and [18F]-fluoroethyl-L-tyrosine (18F-Fet) for their potential to image myeloma and to characterize tumor heterogeneity. Experimental Design To study the utility of 11C-MET, 18F-Fet and 18F-FDG for myeloma imaging, time activity curves were compared in various human myeloma cell lines (INA-6, MM1.S, OPM-2) and correlated to cell-biological characteristics, such as marker gene expression and immunoglobulin levels. Likewise, patient-derived CD138+ plasma cells were characterized regarding uptake and biomedical features. Results Using myeloma cell lines and patient-derived CD138+ plasma cells, we found that the relative uptake of 11C-MET exceeds that of 18F-FDG 1.5- to 5-fold and that of 18F-Fet 7- to 20-fold. Importantly, 11C-MET uptake significantly differed between cell types associated with worse prognosis (e.g. t(4;14) in OPM-2 cells) and indolent ones and correlated with intracellular immunoglobulin light chain and cell surface CD138 and CXCR4 levels. Direct comparison of radiotracer uptake in primary samples further validated the superiority of 11C-MET. Conclusion These data suggest that 11C-MET might be a versatile biomarker for myeloma superior to routine functional imaging with 18F-FDG regarding diagnosis, risk stratification, prognosis and discrimination of tumor subtypes.},
  language  = {en}
}
@phdthesis{Schlippverh:Woelfel2011,
  author    = {Schlipp [verh.: W{\"o}lfel], Angela},
  title     = {Characterization of anti-beta1-adrenoceptor antibodies with F{\"o}rster resonance energy transfer microscopy},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67162},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Dilated cardiomyopathy (DCM) represents an important subgroup of patients suffering from heart failure. The disease is supposed to be associated with autoimmune mechanisms in about one third of the cases. In the latter patients functionally active conformational autoantibodies directed against the second extracellular loop of the β1-adrenergic receptor (AR, β1ECII-aabs) have been detected. Such antibodies chronically stimulate the β1-AR thereby inducing the adrenergic signaling cascade in cardiomyocytes, which, in the long run, contributes to heart failure progression. We analyzed the production of cAMP after aab-mediated β1-AR activation in vitro using a fluorescence resonance energy transfer (FRET) assay. This assay is based on HEK293 cells stably expressing human β1-AR as well as the cAMP-sensor Epac1-camps. The assay showed a concentration-dependent increase in intracellular cAMP upon stimulation with the full agonist (-) isoproterenol. This response was comparable to results obtained in isolated adult murine cardiomyocytes and was partially blockable by a selective β1-AR antagonist. In the same assay poly- and monoclonal anti-β1ECII-abs (induced in different animals) could activate the adrenergic signaling cascade, whereas isotypic control abs had no effect on intracellular cAMP levels. Using the same method, we were able to detect functionally activating aabs in the serum of heart failure patients with ischemic and hypertensive heart disease as well as patients with DCM, but not in sera of healthy control subjects. In patients with DCM we observed an inverse correlation between the stimulatory potential of anti-β1-aabs and left ventricular pump function. To adopt this assay for the detection of functionally activating anti-β1ECII-aabs in clinical routine we attempted to establish an automated large-scale approach. Neither flow cytometry nor FRET detection with a fluorescence plate reader provided an acceptable signal-to-noise ratio. It was possible to detect (-) isoproterenol in a concentration-dependent manner using two different FRET multiwell microscopes. However, due to focus problems large-scale detection of activating anti-β1ECII-abs could not be implemented. Neutralization of anti-β1-aabs with the corresponding epitope-mimicking peptides is a possible therapeutic approach to treat aab-associated autoimmune DCM. Using our FRET assay we could demonstrate a reduction in the stimulatory potential of anti-β1ECII-abs after in vitro incubation with β1ECII-mimicking peptides. Cyclic (and to a lesser extent linear) peptides in 40-fold molar excess acted as efficient ab-scavengers in vitro. Intravenously injected cyclic peptides in a rat model of DCM also neutralized functionally active anti-β1ECII-abs efficiently in vivo. For a detailed analysis of the receptor-epitope targeted by anti-β1ECII-abs we used sequentially alanine-mutated β1ECII-mimicking cyclic peptides. Our data revealed that the disulfide bridge between the cysteine residues C209 and C215 of the human β1-AR appears essential for the formation of the ab-epitope. Substitution of further amino acids relevant for ab-binding in the cyclic scavenger peptide by alanine reduced its affinity to the ab and the receptor-activating potential was blocked less efficiently. In contrast, the non-mutant cyclic peptide almost completely blocked ab-induced receptor activation. Using this ala-scan approach we were able to identify a "NDPK"-epitope as essential for ab binding to the β1ECII. In summary, neutralization of conformational activating anti-β1ECII-(a)abs by cyclic peptides is a plausible therapeutic concept in heart failure that should be further exploited based on the here presented data.},
  subject      = {Adrenerger Rezeptor},
  language  = {en}
}