Stefan Gattenlöhner

Macrophage-expressed IFN-β Contributes to Apoptotic Alveolar Epithelial Cell Injury in Severe Influenza Virus Pneumonia

Influenza viruses (IV) cause pneumonia in humans with progression to lung failure and fatal outcome. Dysregulated release of cytokines including type I interferons (IFNs) has been attributed a crucial role in immune-mediated pulmonary injury during severe IV infection. Using ex vivo and in vivo IV infection models, we demonstrate that alveolar macrophage (AM)-expressed IFN-β significantly contributes to IV-induced alveolar epithelial cell (AEC) injury by autocrine induction of the pro-apoptotic factor TNF-related apoptosis-inducing ligand (TRAIL). Of note, TRAIL was highly upregulated in and released from AM of patients with pandemic H1N1 IV-induced acute lung injury. Elucidating the cell-specific underlying signalling pathways revealed that IV infection induced IFN-β release in AM in a protein kinase R- (PKR-) and NF-κB-dependent way. Bone marrow chimeric mice lacking these signalling mediators in resident and lung-recruited AM and mice subjected to alveolar neutralization of IFN-β and TRAIL displayed reduced alveolar epithelial cell apoptosis and attenuated lung injury during severe IV pneumonia. Together, we demonstrate that macrophage-released type I IFNs, apart from their well-known anti-viral properties, contribute to IV-induced AEC damage and lung injury by autocrine induction of the pro-apoptotic factor TRAIL. Our data suggest that therapeutic targeting of the macrophage IFN-β-TRAIL axis might represent a promising strategy to attenuate IV-induced acute lung injury.

Differentially expressed miRNAs in Ewing sarcoma compared to mesenchymal stem cells: low miR-31 expression with effects on proliferation and invasion.

Ewing sarcoma, the second most common bone tumor in children and young adults, is an aggressive malignancy with a strong potential to metastasize. Ewing sarcoma is characterised by translocations encoding fusion transcription factors with an EWSR1 transactivation domain fused to an ETS family DNA binding domain. microRNAs are post-transcriptional regulators of gene expression and aberrantly expressed microRNAs have been identified as tumor suppressors or oncogenes in most cancer types. To identify potential oncogenic and tumor suppressor microRNAs in Ewing sarcoma, we determined and compared the expression of 377 microRNAs in 40 Ewing sarcoma biopsies, 6 Ewing sarcoma cell lines and mesenchymal stem cells, the putative cellular origin of Ewing sarcoma, from 6 healthy donors. Of the 35 differentially expressed microRNAs identified (fold change >4 and q<0.05), 19 were higher and 16 lower expressed in Ewing sarcoma. In comparisons between Ewing sarcoma samples with EWS-FLI or EWS-ERG translocations, with differing dissemination characteristics and of primary samples and metastases no significantly differential expressed microRNAs were detected using various stringency criteria. For miR-31, the microRNA with lowest expression in comparison to mesenchymal stem cells, functional analyses were performed to determine its potential as a tumor suppressor in Ewing sarcoma. Two of four miR-31 transfected Ewing sarcoma cell lines showed a significantly reduced proliferation (19% and 33% reduction) due to increased apoptosis in one and increased length of G1-phase in the other cell line. All three tested miR-31 transfected Ewing sarcoma cell lines showed significantly reduced invasiveness (56% to 71% reduction). In summary, we identified 35 microRNAs differentially expressed in Ewing sarcoma and demonstrate that miR-31 affects proliferation and invasion of Ewing sarcoma cell lines in ex vivo assays.

A Recurrent Activating PLCG1 Mutation in Cardiac Angiosarcomas Increases Apoptosis Resistance and Invasiveness of Endothelial Cells

Primary cardiac angiosarcomas are rare tumors with unfavorable prognosis. Pathogenic driver mutations are largely unknown. We therefore analyzed a collection of cases for genomic aberrations using SNP arrays and targeted next-generation sequencing (tNGS) of oncogenes and tumor-suppressor genes. Recurrent gains of chromosome 1q and a small region of chromosome 4 encompassing KDR and KIT were identified by SNP array analysis. Repeatedly mutated genes identified by tNGS were KDR with different nonsynonymous mutations, MLL2 with different nonsense mutations, and PLCG1 with a recurrent nonsynonymous mutation (R707Q) in the highly conserved autoinhibitory SH2 domain in three of 10 cases. PLCγ1 is usually activated by Y783 phosphorylation and activates protein kinase C and Ca(2+)-dependent second messengers, with effects on cellular proliferation, migration, and invasiveness. Ectopic expression of the PLCγ1-R707Q mutant in endothelial cells revealed reduced PLCγ1-Y783 phosphorylation with concomitant increased c-RAF/MEK/ERK1/2 phosphorylation, increased IP3 amounts, and increased Ca(2+)-dependent calcineurin activation compared with ectopic expressed PLCγ1-wild-type. Furthermore, cofilin, whose activation is associated with actin skeleton reorganization, showed decreased phosphorylation, and thus activation after expression of PLCγ1-R707Q compared with PLCγ1-wild-type. At the cellular level, expression of PLCγ1-R707Q in endothelial cells had no influence on proliferation rate, but increased apoptosis resistance and migration and invasiveness in in vitro assays. Together, these findings indicate that the PLCγ1-R707Q mutation causes constitutive activation of PLCγ1 and may represent an alternative way of activation of KDR/PLCγ1 signaling besides KDR activation in angiosarcomas, with implications for VEGF/KDR targeted therapies.

CD56-positive lymphocyte infiltration in relation to human papillomavirus association and prognostic significance in oropharyngeal squamous cell carcinoma

Human papillomavirus (HPV)‐related squamous cell carcinoma of the oropharynx (OSCC) are clinical and biological distinct from their HPV‐unrelated counterparts. Patients with HPV‐related OSCC display improved prognosis and therefore we investigated possible immune cell infiltrations associated with this tumor phenotype. We retrospectively analyzed a randomly selected cohort of 140 OSCC for presence of immune cells and HPV by immunohistochemistry and PCR followed by bead‐based hybridization (Luminex technology). HPV prevalence was 24.3% as determined by positive staining of p16INK4a and detection of high risk HPV‐DNA. We found significantly higher numbers of CD56 positive (CD56+) cells in tumor and surrounding microenvironment in HPV‐associated compared to HPV‐negative OSCC (t‐test: pu2009=u20090.004 and pu2009=u20090.002). For the entire cohort presence of CD56+ cells was associated with increased overall survival independent from HPV (Kaplan–Meier: pu2009=u20090.002; Cox regression: pu2009=u20090.042). Presence of CD56+ cells also correlated with a better outcome in HPV‐negative and especially in HPV‐negative OSCC with alcohol consumption ≤2 standard drinks per day (Kaplan–Meier: pu2009=u20090.05 and pu2009=u20090.003). Immunofluorescence localization of granular Granzyme B (GZMB) within CD56+ cells and coexpression of CD16 and CD56 suggests that detected CD56+ cells mainly represent cytotoxic Natural Killer (NK) cells. The fraction of potentially cytotoxic NK cells was significantly higher in HPV‐associated compared to HPV‐negative OSCC (Mann‐Whitney‐U‐Test: pu2009=u20090.011). The elevated abundance and activity of cytotoxic NK cells in OSCC with HPV driven carcinogenesis might contribute to favorable outcome in HPV‐related OSCC.

Human papillomavirus association is the most important predictor for surgically treated patients with oropharyngeal cancer

Background:Upfront surgery is a valuable treatment option for oropharyngeal squamous cell carcinoma (OPSCC) and risk stratification is emerging for treatment de-escalation in human papillomavirus (HPV)-related OPSCC. Available prognostic models are either based on selected, mainly non-surgically treated cohorts. Therefore, we investigated unselected OPSCC treated with predominantly upfront surgery.Methods:All patients diagnosed with OPSCC and treated with curative intent between 2000 and 2009 (n=359) were included. HPV association was determined by HPV-DNA detection and p16INK4a immunohistochemistry. Predictors with significant impact on overall survival (OS) in univariate analysis were included in recursive partitioning analysis.Results:Risk models generated from non-surgically treated patients showed low discrimination in our cohort. A new model developed for unselected patients predominantly treated with upfront surgery separates low-, intermediate- and high-risk patients with significant differences in 5-year OS (86%, 53% and 19%, P<0.001, respectively). HPV status is the most important parameter followed by T-stage in HPV-related and performance status in HPV-negative OPSCC. HPV status and ECOG remained important parameters in risk models for patients treated with or without surgery.Conclusions:Regardless of treatment strategies, HPV status is the strongest predictor of survival in unselected OPSCC patients. The proposed risk models are suitable to discriminate risk groups in unselected OPSCC patients treated with upfront surgery, which has substantial impact for design and interpretation of de-escalation trials.

SNAP-tag based agents for preclinical in vitro imaging in malignant diseases.

Although current cancer treatment strategies are highly aggressive, they are often not effective enough to destroy the collectivity of malignant cells. The residual tumor cells that survived the first-line treatment may continue to proliferate or even metastasize. Therefore, the development of novel more effective strategies to specifically eliminate also single cancer cells is urgently needed. In this respect, the development of antibody-based therapeutics, in particular example immunotoxins, has attracted broad interest. Since the internalization of immunotoxins is essential for their cytotoxic effectivity, it is of crucial importance to study their internalization behavior to assess the potential for their therapeutic use. In this study, we determined the internalization behavior of four different single-chain fragments variable (scFv) when binding to the corresponding target antigen as expressed on solid or non-solid tumor cell lines. The scFvs were recombinantly fused to the SNAP-tag, an engineered variant of the human repair enzyme O(6)-alkylguanine-DNA alkyltransferase that covalently reacts with benzylguanine derivatives. Since a large number of highly sensitive organic fluorescent dyes are already available or can easily be derivatized to react with the self-labeling SNAP-tag, this system provides versatile applications for imaging of intraand extracellular compartments of living cells. The fusion proteins were coupled to SNAP-surface(®) Alexa Fluor(®) 488 or SNAP-surface(®) Alexa Fluor(®) 647 and binding as well as internalization was monitored by flow cytometry and confocal microscopy, respectively. Depending on the respective target antigen, we could distinguish between slow and rapid internalization behavior. Moreover, we detected increased internalization rate for bivalent scFv constructs. Our approach allows for rapid and early stage evaluation of the internalization characteristics of new antibodies designated for further therapeutic development.

A CSPG4-specific immunotoxin kills rhabdomyosarcoma cells and binds to primary tumor tissues

The treatment of rhabdomyosarcoma (RMS) remains challenging, with metastatic and alveolar RMS offering a particularly poor prognosis. Therefore, the identification and evaluation of novel antigens, which are suitable targets for immunotherapy, is one attractive possibility to improve the treatment of this disease. Here we show that chondroitin sulfate proteoglycan 4 (CSPG4) is expressed on RMS cell lines and RMS patient material. We evaluated the immunotoxin (IT) αMCSP-ETA, which specifically recognizes CSPG4 on the RMS cell lines RD, FL-OH1, TE-671 and Rh30. It is internalized rapidly, induces apoptosis and thus kills RMS cells selectively. We also demonstrate the specific binding of this IT to RMS primary tumor material from three different patients.

On the relationship between tumor structure and complexity of the spatial distribution of cancer cell nuclei: a fractal geometrical model of prostate carcinoma.

A risk of the prostate cancer patient is defined by both the objective and subjective criteria, that is, PSA concentration, Gleason score, and pTNM‐stage. The subjectivity of tumor grading influences the risk assessment owing to a large inter‐ and intra‐observer variability. Pathologists propose a central prostate pathology review as a remedy for this problem; yet, the review cannot eliminate the subjectivity from the diagnostic algorithm. The spatial distribution of cancer cell nuclei changes during tumor progression. It implies changes in complexity measured by the capacity dimension D0, the information dimension D1, and the correlation dimension D2.

In vitro effects and ex vivo binding of an EGFR-specific immunotoxin on rhabdomyosarcoma cells.

PurposeRhabdomyosarcoma (RMS) is a rare and aggressive soft tissue sarcoma with limited treatment options and a high failure rate during standard therapy. New therapeutic strategies based on targeted immunotherapy are therefore much in demand. The epidermal growth factor receptor (EGFR) has all the characteristics of an ideal target. It is overexpressed in up to 80xa0% of embryonal RMS and up to 50xa0% of alveolar RMS tumors. We therefore tested the activity of the EGFR-specific recombinant immunotoxin (IT) 425(scFv)-ETA′ against EGFR+ RMS cells in vitro and ex vivo.MethodsWe tested the specific binding and internalization behavior of 425(scFv)-ETA′ in RMS cell lines in vitro by flow cytometry, compared to the corresponding imaging probe 425(scFv)-SNAP monitored by live cell imaging. The cytotoxic activity of 425(scFv)-ETA′ was tested using cell viability and apoptosis assays. Specific binding of the IT was confirmed on formalin-fixed paraffin-embedded tissue samples from two RMS patients.ResultsWe confirmed the specific binding of 425(scFv)-ETA′ to RMS cells in vitro and ex vivo. Both the IT and the corresponding imaging probe were rapidly internalized. The IT killed EGFR+ RMS cells in a dose-dependent manner, while showing no effect against control cells. It showed specific apoptotic activity against one selected RMS cell line.ConclusionsThis is the first study showing the promising therapeutic potential of a recombinant, EGFR-targeting, ETA′-based IT on RMS cells. We confirmed the selective killing with IC50 values of up to 50xa0pM, and immunohistochemical staining confirmed the specific ex vivo binding to primary RMS material.

Sequential karyotyping in Burkitt lymphoma reveals a linear clonal evolution with increase in karyotype complexity and a high frequency of recurrent secondary aberrations.

Typical Burkitt lymphoma is characterized by an IG‐MYC translocation and overall low genomic complexity. Clinically, Burkitt lymphoma has a favourable prognosis with very few relapses. However, the few patients experiencing disease progression and/or relapse have a dismal outcome. Here we report cytogenetic findings of seven cases of Burkitt lymphoma in which sequential karyotyping was performed at time of diagnosis and/or disease progression/relapse(s). After case selection, karyotype re‐review and additional molecular analyses were performed in six paediatric cases, treated in Berlin‐Frankfurt‐Münster‐Non‐Hodgkin lymphoma study group trials, and one additional adult patient. Moreover, we analysed 18 cases of Burkitt lymphoma from the Mitelman database in which sequential karyotyping was performed. Our findings show secondary karyotypes to have a significant increase in load of cytogenetic aberrations with a mean number of 2, 5 and 8 aberrations for primary, secondary and third investigations. Importantly, this increase in karyotype complexity seemed to result from recurrent secondary chromosomal changes involving mainly trisomy 21, gains of 1q and 7q, losses of 6q, 11q, 13q, and 17p. In addition, our findings indicate a linear clonal evolution to be the predominant manner of cytogenetic evolution. Our data may provide a biological framework for the dismal outcome of progressive and relapsing Burkitt lymphoma.