Gut microbiota regulate hepatic von Willebrand factor synthesis and arterial thrombus formation via Toll-like receptor-2.

The symbiotic gut microbiota play pivotal roles in host physiology and the development of cardiovascular diseases, but the microbiota-triggered pattern recognition signaling mechanisms that impact thrombosis are poorly defined. In this article, we show that germ-free (GF) and Toll-like receptor-2 (Tlr2)-deficient mice have reduced thrombus growth after carotid artery injury relative to conventionally raised controls. GF Tlr2-/- and wild-type (WT) mice were indistinguishable, but colonization with microbiota restored a significant difference in thrombus growth between the genotypes. We identify reduced plasma levels of von Willebrand factor (VWF) and reduced VWF synthesis, specifically in hepatic endothelial cells, as a critical factor that is regulated by gut microbiota and determines thrombus growth in Tlr2-/- mice. Static platelet aggregate formation on extracellular matrix was similarly reduced in GF WT, Tlr2-/- , and heterozygous Vwf+/- mice that are all characterized by a modest reduction in plasma VWF levels. Defective platelet matrix interaction can be restored by exposure to WT plasma or to purified VWF depending on the VWF integrin binding site. Moreover, administration of VWF rescues defective thrombus growth in Tlr2-/- mice in vivo. These experiments delineate an unexpected pathway in which microbiota-triggered TLR2 signaling alters the synthesis of proadhesive VWF by the liver endothelium and favors platelet integrin-dependent thrombus growth.

Erythrocytes do not activate purified and platelet soluble guanylate cyclases even in conditions favourable for NO synthesis.

BACKGROUND: Direct interaction between Red blood cells (RBCs) and platelets is known for a long time. The bleeding time is prolonged in anemic patients independent of their platelet count and could be corrected by transfusion of RBCs, which indicates that RBCs play an important role in hemostasis and platelet activation. However, in the last few years, opposing mechanisms of platelet inhibition by RBCs derived nitric oxide (NO) were proposed. The aim of our study was to identify whether RBCs could produce NO and activate soluble guanylate cyclase (sGC) in platelets. METHODS: To test whether RBCs could activate sGC under different conditions (whole blood, under hypoxia, or even loaded with NO), we used our well-established and highly sensitive models of NO-dependent sGC activation in platelets and activation of purified sGC. The activation of sGC was monitored by detecting the phosphorylation of Vasodilator Stimulated Phosphoprotein (VASP(S239)) by flow cytometry and Western blot. ANOVA followed by Bonferroni's test and Student's t-test were used as appropriate. RESULTS: We show that in the whole blood, RBCs prevent NO-mediated inhibition of ADP and TRAP6-induced platelet activation. Likewise, coincubation of RBCs with platelets results in strong inhibition of NO-induced sGC activation. Under hypoxic conditions, incubation of RBCs with NO donor leads to Hb-NO formation which inhibits sGC activation in platelets. Similarly, RBCs inhibit activation of purified sGC, even under conditions optimal for RBC-mediated generation of NO from nitrite. CONCLUSIONS: All our experiments demonstrate that RBCs act as strong NO scavengers and prevent NO-mediated inhibition of activated platelets. In all tested conditions, RBCs were not able to activate platelet or purified sGC.

The Zyxin-related protein thyroid receptor interacting protein 6 (TRIP6) is overexpressed in Ewing's sarcoma and promotes migration, invasion and cell growth.

BACKGROUND INFORMATION: Ewing's sarcoma (ES) is the second most common bone-associated malignancy in children and is driven by the fusion oncogene EWS/FLI1 and characterised by rapid growth and early metastasis. Here, we explored the role of the Zyxin-related protein thyroid receptor interacting protein 6 (TRIP6) in ES. The Zyxin family comprises seven homologous proteins involved in migration and proliferation of many cell types of which Zyxin has been described as a tumour suppressor in ES. RESULTS: By interrogation of published microarray data (n = 1254), we observed that of all Zyxin proteins, only TRIP6 is highly overexpressed in primary ES compared with normal tissues. Re-analysis of published EWS/FLI1 gain- and loss-of-function microarray experiments as well as chromatin-immunoprecipitation assays revealed that TRIP6 overexpression is not mediated by EWS/FLI1. Microarray and subsequent gene-set enrichment analyses of ES cells with and without RNA interference-mediated TRIP6 knockdown demonstrated that TRIP6 expression confers a pro-proliferative and pro-invasive transcriptional signature to ES cells. While short-term proliferation was not considerably affected by TRIP6 knockdown, silencing of the protein significantly reduced migration, invasion, long-term proliferation and clonogenicity of ES cells in vitro as well as tumourigenicity in vivo. CONCLUSIONS: Taken together, our data indicate that TRIP6 acts, in contrast to Zyxin, as an oncogene that partially accounts for the autonomous migratory, invasive and proliferative properties of ES cells independent of EWS/FLI1.

Functional hyper-IL-6 from vaccinia virus-colonized tumors triggers platelet formation and helps to alleviate toxicity of mitomycin C enhanced virus therapy.

BACKGROUND: Combination of oncolytic vaccinia virus therapy with conventional chemotherapy has shown promise for tumor therapy. However, side effects of chemotherapy including thrombocytopenia, still remain problematic. METHODS: Here, we describe a novel approach to optimize combination therapy of oncolytic virus and chemotherapy utilizing virus-encoding hyper-IL-6, GLV-1h90, to reduce chemotherapy-associated side effects. RESULTS: We showed that the hyper-IL-6 cytokine was successfully produced by GLV-1h90 and was functional both in cell culture as well as in tumor-bearing animals, in which the cytokine-producing vaccinia virus strain was well tolerated. When combined with the chemotherapeutic mitomycin C, the anti-tumor effect of the oncolytic virotherapy was significantly enhanced. Moreover, hyper-IL-6 expression greatly reduced the time interval during which the mice suffered from chemotherapy-induced thrombocytopenia. CONCLUSION: Therefore, future clinical application would benefit from careful investigation of additional cytokine treatment to reduce chemotherapy-induced side effects.

Distinct effects of the recurrent Mlh1G67R mutation on MMR functions, cancer, and meiosis.

Mutations in the human DNA mismatch repair (MMR) gene MLH1 are associated with hereditary nonpolyposis colorectal cancer (Lynch syndrome, HNPCC) and a significant proportion of sporadic colorectal cancer. The inactivation of MLH1 results in the accumulation of somatic mutations in the genome of tumor cells and resistance to the genotoxic effects of a variety of DNA damaging agents. To study the effect of MLH1 missense mutations on cancer susceptibility, we generated a mouse line carrying the recurrent Mlh1(G67R) mutation that is located in one of the ATP-binding domains of Mlh1. Although the Mlh1(G67R) mutation resulted in DNA repair deficiency in homozygous mutant mice, it did not affect the MMR-mediated cellular response to DNA damage, including the apoptotic response of epithelial cells in the intestinal mucosa to cisplatin, which was defective in Mlh1(-/-) mice but remained normal in Mlh1(G67R/G67R) mice. Similar to Mlh1(-/-) mice, Mlh1(G67R/G67R) mutant mice displayed a strong cancer predisposition phenotype. However, in contrast to Mlh1(-/-) mice, Mlh1(G67R/G67R) mutant mice developed significantly fewer intestinal tumors, indicating that Mlh1 missense mutations can affect MMR tumor suppressor functions in a tissue-specific manner. In addition, Mlh1(G67R/G67R) mice were sterile because of the inability of the mutant Mlh1(G67R) protein to interact with meiotic chromosomes at pachynema, demonstrating that the ATPase activity of Mlh1 is essential for fertility in mammals.

Alterations of the platelet proteome in type I Glanzmann thrombasthenia caused by different homozygous delG frameshift mutations in ITGA2B.

Glanzmann thrombasthenia (GT) is one of the best characterised inherited platelet function disorders but global platelet proteome has not been determined in these patients. We investigated the proteome and function of platelets from two patients with type I GT, caused by different homozygous ITGA2b mutations, from family members and unrelated controls. The global proteome of highly purified washed platelets was quantified by liquid chromatography-mass spectrometry (LC-MS) and targeted MS-methods. Platelet function was analysed by flow cytometry, light transmission aggregometry and flow-based assays. Platelets from GT patients showed less than 5 % relative levels of the integrin subunit αIIb and 5-9 % fibrinogen compared to controls. These patients demonstrated loss of αIIbß3-dependent platelet function, but normal platelet granule secretion induced by physiological agonists. Platelets from heterozygous family members of a patient expressed 50-60 % of control αIIb levels which were sufficient for normal αIIbß3-dependent platelet function. Studying type I GT as model disease we established quantitative LC-MS to detect and clearly distinguish normal platelets, platelets from GT heterozygotes and platelets from GT patients. Diminished levels of factor XIIIB chain, plasminogen and carboxypeptidase 2B were identified in thrombasthenic platelets. Additionally, GT platelets showed up to 2.5-fold increased levels of FcγRIIA and laminin-α4 chain. Elevated levels of platelet FcγRIIA was associated with increased CD63-surface expression after FcγRIIA-crosslinking in one GT-patient which might present a compensatory mechanism of platelet activation in GT. We demonstrate that quantitative LC-MS based proteomics is suitable to validate known but also to identify previously unknown protein level changes of dysfunctional platelets.

An anti-ubiquitin antibody response in transitional cell carcinoma of the urinary bladder.

BACKGROUND: To use combinatorial epitope mapping ("fingerprinting") of the antibody response to identify targets of the humoral immune response in patients with transitional cell carcinoma (TCC) of the bladder. METHODS: A combinatorial random peptide library was screened on the circulating pool of immunoglobulins purified from an index patient with a high risk TCC (pTa high grade plus carcinoma in situ) to identify corresponding target antigens. A patient cohort was investigated for antibody titers against ubiquitin. RESULTS: We selected, isolated, and validated an immunogenic peptide motif from ubiquitin as a dominant epitope of the humoral response. Patients with TCC had significantly higher antibody titers against ubiquitin than healthy donors (p<0.007), prostate cancer patients (p<0.0007), and all patients without TCC taken together (p<0.0001). Titers from superficial tumors were not significantly different from muscle invasive tumors (p = 0.0929). For antibody response against ubiquitin, sensitivity for detection of TCC was 0.44, specificity 0.96, positive predictive value 0.96 and negative predictive value 0.41. No significant titer changes were observed during the standard BCG induction immunotherapy. CONCLUSIONS: This is the first report to demonstrate an anti-ubiquitin antibody response in patients with TCC. Although sensitivity of antibody production was low, a high specificity and positive predictive value make ubiquitin an interesting candidate for further diagnostic and possibly immune modulating studies.

Loss of tumor suppressor mir-203 mediates overexpression of LIM and SH3 Protein 1 (LASP1) in high-risk prostate cancer thereby increasing cell proliferation and migration.

Several studies have linked overexpression of the LIM and SH3 domain protein 1 (LASP1) to progression of breast, colon, liver, and bladder cancer. However, its expression pattern and role in human prostate cancer (PCa) remained largely undefined. Analysis of published microarray data revealed a significant overexpression of LASP1 in PCa metastases compared to parental primary tumors and normal prostate epithelial cells. Subsequent gene-set enrichment analysis comparing LASP1-high and -low PCa identified an association of LASP1 with genes involved in locomotory behavior and chemokine signaling. These bioinformatic predictions were confirmed in vitro as the inducible short hairpin RNA-mediated LASP1 knockdown impaired migration and proliferation in LNCaP prostate cancer cells. By immunohistochemical staining and semi-quantitative image analysis of whole tissue sections we found an enhanced expression of LASP1 in primary PCa and lymph node metastases over benign prostatic hyperplasia. Strong cytosolic and nuclear LASP1 immunoreactivity correlated with PSA progression. Conversely, qRT-PCR analyses for mir-203, which is a known translational suppressor of LASP1 in matched RNA samples revealed an inverse correlation of LASP1 protein and mir-203 expression. Collectively, our results suggest that loss of mir-203 expression and thus uncontrolled LASP1 overexpression might drive progression of PCa.

Conditional inactivation of MLH1 in thymic and naive T-cells in mice leads to a limited incidence of lymphoblastic T-cell lymphomas.

Defects in the mismatch repair system (MMR) underlie hereditary non-polyposis colorectal cancer (HNPCC)/Lynch syndrome and also a significant number of sporadic colorectal cancers. Mice carrying a null allele for the MMR gene Mlh1 are preferentially prone to the development of lymphomas of B- and T-cell origin and to a lesser extent gastrointestinal tumors. Consistent with these findings in mice, MMR defects have also been observed in sporadic and hereditary hematological malignancies. To study the role of MLH1 for lymphomagenesis in more detail, we generated a new mouse model carrying a conditional Mlh1 allele (Mlh1(flox/flox)). Mating of these mice with EIIa-Cre recombinase transgenic mice allowed the constitutive inactivation of MLH1, and the resulting Mlh1(Δex4/Δex4) mouse line displays complete MMR deficiency and a cancer predisposition phenotype similar to Mlh1−/− mice. For T-cell specific MMR inactivation we combined the Mlh1(flox/flox) allele with the Lck-Cre transgene. In the resulting Mlh1(TΔex4/TΔex4) mice, MLH1 inactivation is limited to DP/SP thymocytes and naive peripheral T-cells. The development of T-cell lymphomas in Mlh1(TΔex4/TΔex4) mice is significantly reduced compared to Mlh1−/− mice, implying that MMR functions either at very early stages during T-cell development or even earlier in lymphoid precursor cells to suppress lymphomagenesis.

Reactive antibodies against bacillus Calmette-Guerin heat-shock protein-65 potentially predict the outcome of immunotherapy for high-grade transitional cell carcinoma of the bladder.

BACKGROUND: Intravesical immunotherapy with Mycobacterium bovis (M. bovis) bacillus Calmette-Guerin (BCG) is the current standard of care against superficial, high-grade transitional cell carcinoma (TCC) of the urinary bladder (carcinoma in situ and pathologic T1, grade 3 disease). However, individual patient outcome is barely predictable because of the lack of serum markers. Consequently, progression to muscle-invasive bladder cancer and critical delay of treatments (such as neoadjuvant combination chemotherapy and/or radical cystectomy) often occur. The objectives of this study were to identify a marker for measuring the BCG-induced immune response and to predict the outcomes and potential improvements of BCG immunotherapy. METHODS: Because host immunoresponse mediates BCG activity, the authors screened a combinatorial random peptide library on the circulating pool of immunoglobulins (Igs) purified from an index patient after successful BCG immunotherapy to identify the corresponding target antigen(s). RESULTS: An immunogenic peptide motif was selected, isolated, and validated from M. bovis BCG heat-shock protein 65 (HSP-65) as a dominant epitope of the humoral response to treatment. Increasing IgA and IgG anti-HSP-65 titers specifically predicted a positive patient outcome in a cohort of patients with bladder cancer relative to several cohorts of control patients. CONCLUSIONS: The current results indicated that antibody production against M. bovis BCG HSP-65 can serve as a serologic marker for the predictive outcome of BCG immunotherapy. Subsequent studies will determine the value of this candidate marker to modify BCG-based treatment for individual patients with bladder cancer.