[Immunotherapy in head and neck squamous cell carcinoma : Abscopal effects in combination with radiotherapy, extraordinary responses in combination with chemotherapy, and pseudoprogression]. / Immuntherapie bei Kopf-Hals-Plattenepithelkarzinomen : Abskopale Effekte in Kombination mit Radiotherapie, außergewöhnliche Reaktionen in Kombination mit Chemotherapie und Pseudoprogression.

BACKGROUND: The clinical implementation of immunotherapy has broadened the therapeutic options for recurrent and/or metastatic head and neck squamous cell carcinoma (HNSCC). Until 2016, the only molecularly targeted therapy was epidermal growth factor receptor (EGFR) blockade. However, immune checkpoint inhibition has recently become part of first-line treatment in recurrent and/or metastatic HNSCC. OBJECTIVES: The occurrence of abscopal effects of radiotherapy and synergisms between immunotherapy and chemotherapy as well as the phenomenon of pseudoprogression in HNSCC were investigated. MATERIALS AND METHODS: Key publications of recent clinical trials and preclinical studies on the underlying biological mechanisms were analyzed. RESULTS: As already observed in other tumor entities, synergistic effects upon combination of immunotherapy with radio- and/or chemotherapy are observed in the clinical management of recurrent and/or metastatic HNSCC, and this is mediated by (re)activation of host antitumor immune mechanisms. In selected patients, this may be radiologically detected as pseudoprogression. Reliable biomarkers for these phenomena have not yet been clinically established. CONCLUSIONS: For recurrent and/or metastatic HNSCC, the occurrence of systemic effects upon radiochemoimmunotherapy in the clinic is on the rise. Hence, the identification of biomarkers for abscopal effects of radiotherapy and unexpected synergisms between chemotherapy and immunotherapy as well as for pseudoprogression is gaining in importance.

Floquet Engineering of Correlated Tunneling in the Bose-Hubbard Model with Ultracold Atoms.

We report on the experimental implementation of tunable occupation-dependent tunneling in a Bose-Hubbard system of ultracold atoms via time-periodic modulation of the on-site interaction energy. The tunneling rate is inferred from a time-resolved measurement of the lattice site occupation after a quantum quench. We demonstrate coherent control of the tunneling dynamics in the correlated many-body system, including full suppression of tunneling as predicted within the framework of Floquet theory. We find that the tunneling rate explicitly depends on the atom number difference in neighboring lattice sites. Our results may open up ways to realize artificial gauge fields that feature density dependence with ultracold atoms.

Low and moderate doses of ionizing radiation up to 2 Gy modulate transmigration and chemotaxis of activated macrophages, provoke an anti-inflammatory cytokine milieu, but do not impact upon viability and phagocytic function.

Benign painful and inflammatory diseases have been treated for decades with low/moderate doses of ionizing radiation (LD-X-irradiation). Tissue macrophages regulate initiation and resolution of inflammation by the secretion of cytokines and by acting as professional phagocytes. Having these pivotal functions, we were interested in how activated macrophages are modulated by LD-X-irradiation, also with regard to radiation protection issues and carcinogenesis. We set up an ex-vivo model in which lipopolysaccharide pre-activated peritoneal macrophages (pMΦ) of radiosensitive BALB/c mice, mimicking activated macrophages under inflammatory conditions, were exposed to X-irradiation from 0·01 Gy up to 2 Gy. Afterwards, the viability of the pMΦ, their transmigration and chemotaxis, the phagocytic behaviour, the secretion of inflammatory cytokines and underlying signalling pathways were determined. Exposure of pMΦ up to a single dose of 2 Gy did not influence their viability and phagocytic function, an important fact regarding radiation protection. However, significantly reduced migration, but increased chemotaxis of pMΦ after exposure to 0·1 or 0·5 Gy, was detected. Both might relate to the resolution of inflammation. Cytokine analyses revealed that, in particular, the moderate dose of 0·5 Gy applied in low-dose radiotherapy for inflammatory diseases results in an anti-inflammatory cytokine microenvironment of pMΦ, as the secretion of the proinflammatory cytokine interleukin (IL)-1ß was reduced and that of the anti-inflammatory cytokine transforming growth factor (TGF)-ß increased. Further, the reduced secretion of IL-1ß correlated with reduced nuclear translocation of nuclear factor (NF)-κB p65, starting at exposure of pMΦ to 0·5 Gy of X-irradiation. We conclude that inflammation is modulated by LD-X-irradiation via changing the inflammatory phenotype of macrophages.

Probing the Excitations of a Lieb-Liniger Gas from Weak to Strong Coupling.

We probe the excitation spectrum of an ultracold one-dimensional Bose gas of cesium atoms with a repulsive contact interaction that we tune from the weakly to the strongly interacting regime via a magnetic Feshbach resonance. The dynamical structure factor, experimentally obtained using Bragg spectroscopy, is compared to integrability-based calculations valid at arbitrary interactions and finite temperatures. Our results unequivocally underlie the fact that holelike excitations, which have no counterpart in higher dimensions, actively shape the dynamical response of the gas.

Interaction-induced quantum phase revivals and evidence for the transition to the quantum chaotic regime in 1D atomic Bloch oscillations.

We study atomic Bloch oscillations in an ensemble of one-dimensional tilted superfluids in the Bose-Hubbard regime. For large values of the tilt, we observe interaction-induced coherent decay and matter-wave quantum phase revivals of the Bloch oscillating ensemble. We analyze the revival period dependence on interactions by means of a Feshbach resonance. When reducing the value of the tilt, we observe the disappearance of the quasiperiodic phase revival signature towards an irreversible decay of Bloch oscillations, indicating the transition from regular to quantum chaotic dynamics.

Quantum quench in an atomic one-dimensional Ising chain.

We study nonequilibrium dynamics for an ensemble of tilted one-dimensional atomic Bose-Hubbard chains after a sudden quench to the vicinity of the transition point of the Ising paramagnetic to antiferromagnetic quantum phase transition. The quench results in coherent oscillations for the orientation of effective Ising spins, detected via oscillations in the number of doubly occupied lattice sites. We characterize the quench by varying the system parameters. We report significant modification of the tunneling rate induced by interactions and show clear evidence for collective effects in the oscillatory response.

Preparation and spectroscopy of a metastable Mott-insulator state with attractive interactions.

We prepare and study a metastable attractive Mott-insulator state formed with bosonic atoms in a three-dimensional optical lattice. Starting from a Mott insulator with Cs atoms at weak repulsive interactions, we use a magnetic Feshbach resonance to tune the interactions to large attractive values and produce a metastable state pinned by attractive interactions with a lifetime on the order of 10 s. We probe the (de)excitation spectrum via lattice modulation spectroscopy, measuring the interaction dependence of two- and three-body bound-state energies. As a result of increased on-site three-body loss we observe resonance broadening and suppression of tunneling processes that produce three-body occupation.

[Preclinical imaging in animal models of radiation therapy]. / Präklinische Bildgebung im Tiermodell bei Strahlentherapie.

CLINICAL/METHODICAL ISSUE: Modern radiotherapy benefits from precise and targeted diagnostic and pretherapeutic imaging. STANDARD RADIOLOGICAL METHODS: Standard imaging modalities, such as computed tomography (CT) offer high morphological detail but only limited functional information on tumors. METHODICAL INNOVATIONS: Novel functional and molecular imaging modalities provide biological information about tumors in addition to detailed morphological information. PERFORMANCE: Perfusion magnetic resonance imaging (MRI) CT or ultrasound-based perfusion imaging as well as hybrid modalities, such as positron emission tomography (PET) CT or MRI-PET have the potential to identify and precisely delineate viable and/or perfused tumor areas, enabling optimization of targeted radiotherapy. Functional information on tissue microcirculation and/or glucose metabolism allow a more precise definition and treatment of tumors while reducing the radiation dose and sparing the surrounding healthy tissue. ACHIEVEMENTS: In the development of new imaging methods for planning individualized radiotherapy, preclinical imaging and research plays a pivotal role, as the value of multimodality imaging can only be assessed, tested and adequately developed in a preclinical setting, i.e. in animal tumor models. PRACTICAL RECOMMENDATIONS: New functional imaging modalities will play an increasing role for the surveillance of early treatment response during radiation therapy and in the assessment of the potential value of new combination therapies (e.g. combining anti-angiogenic drugs with radiotherapy).

Precision measurements on a tunable Mott insulator of ultracold atoms.

We perform precision measurements on a Mott-insulator quantum state of ultracold atoms with tunable interactions. We probe the dependence of the superfluid-to-Mott-insulator transition on the interaction strength and explore the limits of the standard Bose-Hubbard model description. By tuning the on-site interaction energies to values comparable to the interband separation, we are able to quantitatively measure number-dependent shifts in the excitation spectrum caused by effective multibody interactions.

Three-body correlation functions and recombination rates for bosons in three dimensions and one dimension.

We investigate local three-body correlations for bosonic particles in three dimensions and one dimension as a function of the interaction strength. The three-body correlation function g(3) is determined by measuring the three-body recombination rate in an ultracold gas of Cs atoms. In three dimensions, we measure the dependence of g(3) on the gas parameter in a BEC, finding good agreement with the theoretical prediction accounting for beyond-mean-field effects. In one dimension, we observe a reduction of g(3) by several orders of magnitude upon increasing interactions from the weakly interacting BEC to the strongly interacting Tonks-Girardeau regime, in good agreement with predictions from the Lieb-Liniger model for all strengths of interaction.

[The role of incomplete clearance of apoptotic cells in the etiology and pathogenesis of SLE]. / Die Bedeutung einer unvollständigen Beseitigung apoptotischer Zellen für Atiologie und Pathogenese des SLE.

Systemic lupus erythematosus (SLE) is a complex prototypic autoimmune disease that is based on genetic factors (complement deficiencies) and is influenced by gender (female), environment (infections and UV irradiation), as well as random events (somatic mutations). The course of the disease is influenced by genes (e.g. FcgammaRIIA) and behaviour (sun-exposure). Inefficient clearance of dying cells and subsequent accumulation of apoptotic cell remnants is an intrinsic defect causing the permanent presence of cellular debris responsible for the initiation of autoimmunity. We favour the hypothesis that post-apoptotic debris accumulates in germinal centres, activates complement, and serves as a survival signal for B-cells that had stochastically become autoreactive in the process of somatic hypermutation (etiology). In the presence of autoantibodies against apoptotic cells or adaptor molecules the accumulation of post-apoptotic remnants (SNEC) causes immune complex formation and their pathological elimination, maintaining auto-inflammation. The SLE-type autoimmunity addresses nucleic acid-containing complex antigens (viromimetica). Autoantibody-protein-nucleic-acid complexes are likely to be mistaken for opsonised viruses. As a consequence, the immune system responds with the production of type-I interferons, a hallmark of SLE (pathogenesis). We conclude that the pathogenicity of autoantibodies is strongly increased if autoantigens are accessible and immune complexes are formed, which may be considered a binary pyrogen formed from less pro-inflammatory components. The accessibility of cognate autoantigens is likely to be related to impaired or delayed clearance of apoptotic cells.

Taxane-mediated radiosensitization derives from chromosomal missegregation on tripolar mitotic spindles orchestrated by AURKA and TPX2.

Taxane-based radiochemotherapy is a central treatment option for various cancer entities in locally advanced stages. The therapeutic synergism of this combined modality approach due to taxane-mediated radiosensitization of cancer cells is well-known. However, the underlying molecular mechanisms remain largely elusive, and mechanism-derived predictive markers of taxane-based radiochemotherapy are currently not available. Here, we show that clinically relevant doses of Paclitaxel, the prototype taxane, stimulate a tripolar mode of mitosis leading to chromosomal missegregation and aneuploidization rather than interfering with cell cycle progression. This distinct mitotic phenotype was interlinked with Paclitaxel-mediated radiosensitization via overexpression of mitotic Aurora kinase A (AURKA) and its cofactor TPX2 whose knockdown rescued the bipolar mode of cell division and largely attenuated the radiosensitizing effects of Paclitaxel. In the cancer genome atlas (TCGA) lung adenocarcinoma cohort, high expression levels of AURKA and TPX2 were associated with specifically improved overall survival upon taxane-based radiochemotherapy, but not in case of non-taxane-based radiochemotherapy, chemo- or radiotherapy only. Thus, our data provide insights into Paclitaxel-mediated radiosensitization on a mechanistic and molecular level and identify AURKA and TPX2 as the first potential mechanism-based, predictive markers of taxane-based radiochemotherapy.

Prostaglandin D2 induces programmed cell death in Trypanosoma brucei bloodstream form.

African trypanosomes produce some prostanoids, especially PGD2, PGE2 and PGF2alpha (Kubata et al. 2000, J. Exp. Med. 192: 1327-1338), probably to interfere with the host's physiological response. However, addition of prostaglandin D2 (but not PGE2 or PGF2alpha) to cultured bloodstream form trypanosomes led also to a significant inhibition of cell growth. Based on morphological alterations and specific staining methods using vital dyes, necrosis and autophagy were excluded. Here, we report that in bloodstream form trypanosomes PGD2 induces an apoptosis-like programmed cell death, which includes maintenance of plasma membrane integrity, phosphatidylserine exposure, loss of mitochondrial membrane potential, nuclear chromatin condensation and DNA degradation. The use of caspase inhibitors cannot prevent the cell death, indicating that the process is caspase-independent. Based on these results, we suggest that PGD2-induced programmed cell death is part of the population density regulation as observed in infected animals.

STAT3 is essential for Hodgkin lymphoma cell proliferation and is a target of tyrphostin AG17 which confers sensitization for apoptosis.

Classical Hodgkin lymphoma (cHL) is a distinct malignancy of the immune system. Despite the progress made in the understanding of the biology of cHL, the transforming events remain to be elucidated. Recently, we demonstrated that the Janus kinase inhibitor AG490 blocked cellular proliferation and STAT3 phosphorylation in cHL. To explore the potential of constitutively activated STAT3 as a drug target and its role in cHL pathogenesis, different cHL cell lines were analyzed. Treatment of cHL cells by the protein tyrosine kinase inhibitor AG17 was associated with inhibition of cellular proliferation and cell cycle arrest. AG17 treatment was accompanied by decreased levels of STAT3 phosphorylation, whereas NF-kappaB and p38/SAPK2 signaling were not inhibited. Incubation with AG17 or AG490 sensitized cHL cells to CD95/Fas/Apo-1 or staurosporine-mediated apoptosis. Coincubation of tyrphostins with staurosporine was accompanied by rapid complete inhibition of STAT3 phosphorylation. RNA interference directed against STAT3 in L428 and L1236 cHL cells demonstrated that STAT3 is essential for cell proliferation of these cHL cells. In conclusion, these findings support the concept that STAT3 signaling is important in the pathogenesis of cHL and tyrphostins are agents for developing new therapeutic strategies.

Staurosporine and conventional anticancer drugs induce overlapping, yet distinct pathways of apoptosis and caspase activation.

Apoptosis can be induced by various stimuli including DNA-damaging anticancer drugs and the protein kinase inhibitor staurosporine. It is generally believed that the molecular events during execution of apoptosis are shared, as both anticancer drugs and staurosporine derivatives induce mitochondrial damage, cytochrome c release and the activation of the caspase-9 proteolytic cascade. In the present study we show that overexpression of a dominant-negative caspase-9 mutant abolished the activation of endogenous caspase-9, caspase-3 and the cleavage of the caspase substrate Bid in response to anticancer drug treatment. Surprisingly, however, only marginal effects were observed during staurosporine-induced apoptosis. Furthermore, we describe a Jurkat T-cell clone that is completely resistant towards different anticancer drugs, but remains sensitive towards staurosporine-induced apoptosis. In these cells only staurosporine, but neither anti-CD95 nor anticancer drugs were able to trigger caspase activity and the cleavage of caspase substrates. Our results therefore suggest that the mechanism of staurosporine-induced apoptosis is more complex and at least partially differs from anticancer drug-induced caspase activation. These distinct features of staurosporine may allow to bypass chemoresistance of tumor cells and may encourage further clinical trials for the use of staurosporine derivatives in antitumor therapy.

Caspase-8/FLICE functions as an executioner caspase in anticancer drug-induced apoptosis.

Caspase-8 plays an essential role in apoptosis triggered by death receptors. Through the cleavage of Bid, a proapoptotic Bcl-2 member, it further activates the mitochondrial cytochrome c/Apaf-1 pathway. Because caspase-8 can be processed also by anticancer drugs independently of death receptors, we investigated its exact role and order in the caspase cascade. We show that in Jurkat cells either deficient for caspase-8 or overexpressing its inhibitor c-FLIP apoptosis mediated by CD95, but not by anticancer drugs was inhibited. In the absence of active caspase-8, anticancer drugs still induced the processing of caspase-9, -3 and Bid, indicating that Bid cleavage does not require caspase-8. Overexpression of Bcl-x(L) prevented the processing of caspase-8 as well as caspase-9, -6 and Bid in response to drugs, but was less effective in CD95-induced apoptosis. Similar responses were observed by overexpression of a dominant-negative caspase-9 mutant. To further determine the order of caspase-8 activation, we employed MCF7 cells lacking caspase-3. In contrast to caspase-9 that was cleaved in these cells, anticancer drugs induced caspase-8 activation only in caspase-3 transfected MCF7 cells. Thus, our data indicate that, unlike its proximal role in receptor signaling, in the mitochondrial pathway caspase-8 rather functions as an amplifying executioner caspase.

Human mature red blood cells express caspase-3 and caspase-8, but are devoid of mitochondrial regulators of apoptosis.

Although proteases of the caspase family are essential mediators of apoptosis in nucleated cells, in anucleate cells their presence and potential functions are almost completely unknown. Human erythrocytes are a major cell population that does not contain a cell nucleus or other organelles. However, during senescence they undergo certain morphological alterations resembling apoptosis. In the present study, we found that mature erythrocytes contain considerable amounts of caspase-3 and -8, whereas essential components of the mitochondrial apoptotic cascade such as caspase-9, Apaf-1 and cytochrome c were missing. Strikingly, although caspases of erythrocytes were functionally active in vitro, they failed to become activated in intact erythrocytes either during prolonged storage or in response to various proapoptotic stimuli. Following an increase of cytosolic calcium, instead the cysteine protease calpain but not caspases became activated and mediated fodrin cleavage and other morphological alterations such as cell shrinkage. Our results therefore suggest that erythrocytes do not have a functional death system. In addition, because of the presence of procaspases and the absence of a cell nucleus and mitochondria erythrocytes may be an attractive system to dissect the role of certain apoptosis-regulatory pathways.

Human seminal plasma contains a protein that shares physicochemical, immunochemical, and immunosuppressive properties with pregnancy-associated plasma protein-A.

Pregnancy-associated plasma protein-A (PAPP-A) was detected by RIA in human seminal plasma. This was not due to interference with proteases or binding to seminal plasma proteins, since immunoreactivity was not affected by treatment with protease inhibitors, and the elution of [125I]PAPP-A was not altered by preincubation with seminal plasma. The major component of the seminal plasma PAPP-A coeluted with pure PAPP-A or plasma PAPP-A from pregnant and nonpregnant women. In the RIA, serial dilutions of seminal plasma gave parallel displacement curves to pregnancy plasma. Removing PAPP-A-like material from seminal plasma by adsorbtion to heparin-Sepharose reduced the inhibitory effect of seminal plasma on phytohemagglutinin-induced lymphocyte transformation. The source of seminal plasma PAPP-A-like immunoreactive material remains to be elucidated, but it is unlikely to be the testis, since PAPP-A levels in semen of vasectomized men were similar to those in nonvasectomized men.

Low intrathyroidal iodine concentration in non-endemic human goitres: a consequence rather than a cause of autonomous goitre growth.

Iodine may have an inhibitory and, in some circumstances, a stimulatory effect on thyroid follicular cell growth. Exogenous iodine deficiency causes the growth of endemic goitres and it has been claimed that low intrathyroidal iodine stores stimulate growth. On the other hand, the role of iodine, if any, in regulating the growth of human nodular goitres exposed to an ample supply of iodine has not been studied systematically. Very few data on intrathyroidal iodine concentration in this type of goitre are available. In the present work we have investigated total iodine content in 24 samples from 11 clinically and histomorphologically well-defined fast and autonomously growing human nodular goitres from a non-endemic area. Iodine was fractionated into thyroglobulin-iodine and non-thyroglobulin-iodine. The regional distribution of intrathyroidal iodo-compounds was also assessed in three goitres. Total iodine concentration, as well as its sub-fractions, i.e. thyroglobulin-iodine and non-thyroglobulin-iodine, were significantly lower than in normal thyroids. Furthermore, there was large inter- and intraindividual heterogeneity of all iodo-compounds as well as of thyroglobulin. Total iodine concentration varied by a factor of almost 40 between different goitre samples and by a factor of 20 between samples taken from the same goitre. Total non-thyroglobulin-iodine, the only fraction comprising possible cell growth-regulating iodo-compounds, varied by a factor of > 60 between different goitres and by a factor of > 6 between different samples of the same goitre. The low iodine concentration in all our goitre samples did not differ from values reported in the literature for endemic iodine-deficient goitres. Since all goitres studied here were actively growing while exposed to an ample supply of iodine, iodine shortage cannot be a primary and causal factor for the growth of this type of sporadic goitre. Rather, the low concentration and the large inter- and intraindividual heterogeneity of all iodo-compounds appear to be secondary incidental events well explained by the recently developed concept of autonomous thyroid growth.

Photometric determination of nitrogen. Wet incineration followed by formation of indophenol blue with salicylate/hypochlorite.

Ammonia in wet incineration residues has been analyzed photometrically by a modified Berthelot reaction using a water-free digestion mixture. Phenol is substituted by salicylate in the dye-producing reaction. The method can be adapted for any biological material with a minimum content of 0.04 mug N/sample. Nonprotein nitrogen may be determined in the supernatant of TCA precipitates.