Discovery and preclinical development of a therapeutically active nanobody-based chimeric antigen receptor targeting human CD22

Chimeric antigen receptor (CAR) T cell therapies targeting B cell-restricted antigens CD19, CD20, or CD22 can produce potent clinical responses for some B cell malignancies, but relapse remains common. Camelid single-domain antibodies (sdAbs or nanobodies) are smaller, simpler, and easier to recombine than single-chain variable fragments (scFvs) used in most CARs, but fewer sdAb-CARs have been reported. Thus, we sought to identify a therapeutically active sdAb-CAR targeting human CD22. Immunization of an adult Llama glama with CD22 protein, sdAb-cDNA library construction, and phage panning yielded >20 sdAbs with diverse epitope and binding properties. Expressing CD22-sdAb-CAR in Jurkat cells drove varying CD22-specific reactivity not correlated with antibody affinity. Changing CD28- to CD8-transmembrane design increased CAR persistence and expression in vitro. CD22-sdAb-CAR candidates showed similar CD22-dependent CAR-T expansion in vitro, although only membrane-proximal epitope targeting CD22-sdAb-CARs activated direct cytolytic killing and extended survival in a lymphoma xenograft model. Based on enhanced survival in blinded xenograft studies, a lead CD22sdCAR-T was selected, achieving comparable complete responses to a benchmark short linker m971-scFv CAR-T in high-dose experiments. Finally, immunohistochemistry and flow cytometry confirm tissue and cellular-level specificity of the lead CD22-sdAb. This presents a complete report on preclinical development of a novel CD22sdCAR therapeutic.

CLIC-01: Manufacture and distribution of non-cryopreserved CAR-T cells for patients with CD19 positive hematologic malignancies

Access to commercial CD19 CAR-T cells remains limited even in wealthy countries like Canada due to clinical, logistical, and financial barriers related to centrally manufactured products. We created a non-commercial academic platform for end-to-end manufacturing of CAR-T cells within Canada's publicly funded healthcare system. We report initial results from a single-arm, open-label study to determine the safety and efficacy of in-house manufactured CD19 CAR-T cells (entitled CLIC-1901) in participants with relapsed/refractory CD19 positive hematologic malignancies. Using a GMP compliant semi-automated, closed process on the Miltenyi Prodigy, T cells were transduced with lentiviral vector bearing a 4-1BB anti-CD19 CAR transgene and expanded. Participants underwent lymphodepletion with fludarabine and cyclophosphamide, followed by infusion of non-cryopreserved CAR-T cells. Thirty participants with non-Hodgkin's lymphoma (n=25) or acute lymphoblastic leukemia (n=5) were infused with CLIC-1901: 21 males (70%), median age 66 (range 18-75). Time from enrollment to CLIC-1901 infusion was a median of 20 days (range 15-48). The median CLIC-1901 dose infused was 2.3 × 10⁶ CAR-T cells/kg (range 0.13-3.6 × 10⁶/kg). Toxicity included ≥ grade 3 cytokine release syndrome (n=2) and neurotoxicity (n=1). Median follow-up was 6.5 months. Overall response rate at day 28 was 76.7%. Median progression-free and overall survival was 6 months (95%CI 3-not estimable) and 11 months (95% 6.6-not estimable), respectively. This is the first trial of in-house manufactured CAR-T cells in Canada and demonstrates that administering fresh CLIC-1901 product is fast, safe, and efficacious. Our experience may provide helpful guidance for other jurisdictions seeking to create feasible and sustainable CAR-T cell programs in research-oriented yet resource-constrained settings.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT03765177, identifier NCT03765177.

Tumor associated antigen PRAME exhibits dualistic functions that are targetable in diffuse large B-cell lymphoma

PRAME is a prominent member of the cancer testis antigen family of proteins, which triggers autologous T cell–mediated immune responses. Integrative genomic analysis in diffuse large B cell lymphoma (DLBCL) uncovered recurrent and highly focal deletions of 22q11.22, including the PRAME gene, which were associated with poor outcome. PRAME-deleted tumors showed cytotoxic T cell immune escape and were associated with cold tumor microenvironments. In addition, PRAME downmodulation was strongly associated with somatic EZH2 Y641 mutations in DLBCL. In turn, PRC2-regulated genes were repressed in isogenic PRAME-KO lymphoma cell lines, and PRAME was found to directly interact with EZH2 as a negative regulator. EZH2 inhibition with EPZ-6438 abrogated these extrinsic and intrinsic effects, leading to PRAME expression and microenvironment restoration in vivo. Our data highlight multiple functions of PRAME during lymphomagenesis and provide a preclinical rationale for synergistic therapies combining epigenetic reprogramming with PRAME-targeted therapies.

Tumor-infiltrating B cells and T cells: Working together to promote patient survival

We recently reported a novel cooperative relationship between tumor-infiltrating B cells and CD8⁺ T cells in ovarian cancer, leading to increased patient survival. Here, we discuss the mechanisms whereby B cells might enhance cellular immunity, including serving as antigen-presenting cells, organizing tertiary lymphoid structures and secreting polarizing cytokines. The enhancement of both B and T-cell responses may result in more potent and sustained antitumor immunity.

Diagnosis and prevalence of diabetic polyneuropathy: a cross-sectional study of Danish patients with type 2 diabetes

BACKGROUND AND PURPOSE

Diabetic polyneuropathy (DPN) is a common complication of diabetes. Using the Toronto criteria for diabetic polyneuropathy and the grading system for neuropathic pain, the performance of neuropathy scales and questionnaires were assessed by comparing them to a clinical gold standard diagnosis of DPN and painful DPN in a cohort of patients with recently diagnosed type 2 diabetes.

METHODS

A questionnaire on neuropathy and pain was sent to a cohort of 5514 Danish type 2 diabetes patients. A sample of 389 patients underwent a detailed clinical examination and completed neuropathy questionnaires and scales.

RESULTS

Of the 389 patients with a median diabetes duration of 5.9 years, 126 had definite DPN (including 53 with painful DPN), 88 had probable DPN and 53 had possible DPN. There were 49 patients with other causes of polyneuropathy, neuropathy symptoms or pain, 10 with subclinical DPN and 63 without DPN. The sensitivity of the Michigan Neuropathy Screening Instrument questionnaire to detect DPN was 25.7% and the specificity 84.6%. The sensitivity of the Toronto Clinical Neuropathy Scoring System, including questionnaire and clinical examination, was 62.9% and the specificity was 74.6%.

CONCLUSIONS

Diabetic polyneuropathy affects approximately one in five Danish patients with recently diagnosed type 2 diabetes but neuropathic pain is not as common as previously reported. Neuropathy scales with clinical examination perform better compared with questionnaires alone, but better scales are needed for future epidemiological studies.

456Risk of arterial calcification by conventional vitamin K antagonist treatment

Background

Vitamin K antagonists (VKA) are the most frequently prescribed oral anticoagulants worldwide although new oral anticoagulants (NOAC) have become an important alternative. VKA inhibits Vitamin K1 necessary to produce coagulation factors but also Vitamin K2, which is essential in the activation of matrix-Gla protein, thought to be a strong local inhibitor of arterial calcifications.

Purpose

The aim was to investigate, whether VKA treatment is associated with coronary artery calcification (CAC) in a population with no prior cardiovascular disease (CVD).

Methods

We collected data on cardiovascular risk factors and CAC scores from cardiac CT scans performed as part of clinical examinations (n=9,672) or research studies (n=14,166) in the period 2007–2017. Data on use of VKA and NOAC was obtained from the Danish National Health Service Prescription Database. The association between VKA treatment duration and categorized CAC score was investigated by ordered logistic regression while adjusting for covariates. The independent variables included in the model were: age, gender, smoking, body mass index (BMI), diabetes mellitus, hypertension, hypercholesterolemia and/or statin treatment, family history of CVD, estimated glomerular filtration rate, VKA treatment duration and NOAC treatment duration. The categorisation of CAC was: 0, 1–99, 100–399 and ≥400 AU, corresponding to no, mild, moderate and severe atherosclerotic plaque burden, respectively.

Results

The final study population consisted of 17,254 participants (median 67 years old, 75% males) with no prior CVD, of which 1,748 (10%) and 1,144 (7%) had been treated with VKA or NOAC, respectively. A longer duration of VKA treatment was associated with higher CAC categories (Figure). For each cumulative year of VKA treatment, the odds of being in a higher CAC category, i.e. having more severe atherosclerosis, increased (odds ratio (OR)=1.032, 95% CI 1.009–1.057). All traditional cardiovascular risk factors were also associated with CAC. In contrast, NOAC treatment duration was not associated with CAC category (OR=1.004, 95% CI 0.937–1.075). In a sensitivity analysis of patients without statin treatment (n=12,143), the association between VKA treatment and CAC category remained unchanged. There was no significant interaction between VKA treatment duration and age on CAC category.

Conclusion

Adjusted for cardiovascular risk factors, VKA treatment – in contrast to NOAC - is associated with more severe CAC. Additional studies are required to clarify the clinical importance of this association in terms of hard cardiovascular endpoints.

Acknowledgement/Funding

Novo Nordisk Foundation and Independent Research Fund Denmark

Early-onset type 2 diabetes: Age gradient in clinical and behavioural risk factors in 5115 persons with newly diagnosed type 2 diabetes-Results from the DD2 study

AIM

To examine the association between early onset of type 2 diabetes mellitus (DM) and clinical and behavioural risk factors for later complications of diabetes.

METHODS

We conducted a cross-sectional study of 5115 persons with incident type 2 DM enrolled during 2010-2015 in the Danish Centre for Strategic Research in Type 2 Diabetes-cohort. We compared risk factors at time of diagnosis among those diagnosed at ≤45 years (early onset) with diagnosis age 46 to 55, 56 to 65 (average onset = reference), 66 to 75, and >75 years (late onset). Prevalence ratios (PRs) were computed by using Poisson regression.

RESULTS

Poor glucose control, ie, HbA1c ≥ 75 mmol/mol (≥9.0%) in the early-, average-, and late-onset groups was observed in 12%, 7%, and 1%, respectively (PR 1.70 [95% confidence intervals (CI) 1.27, 2.28] and PR 0.17 [95% CI 0.06, 0.45]). A similar age gradient was observed for severe obesity (body mass index > 40 kg/m² : 19% vs. 8% vs. 2%; PR 2.41 [95% CI 1.83, 3.18] and 0.21 (95% CI 0.08, 0.57]), dyslipidemia (90% vs. 79% vs. 68%; PR 1.14 [95% CI 1.10, 1.19] and 0.86 [95% CI 0.79, 0.93]), and low-grade inflammation (C-reactive protein > 3.0 mg/L: 53% vs. 38% vs. 26%; PR 1.41 [95% CI 1.12, 1.78] and 0.68 [95% CI 0.42, 1.11]). Daily smoking was more frequent and meeting physical activity recommendations less likely in persons with early-onset type 2 DM.

CONCLUSIONS

We found a clear age gradient, with increasing prevalence of clinical and behavioural risk factors the younger the onset age of type 2 DM. Younger persons with early-onset type 2 DM need clinical awareness and support.

A library-based screening method identifies neoantigen-reactive T cells in peripheral blood prior to relapse of ovarian cancer

Mutated cancer antigens, or neoantigens, represent compelling immunological targets and appear to underlie the success of several forms of immunotherapy. While there are anecdotal reports of neoantigen-specific T cells being present in the peripheral blood and/or tumors of cancer patients, effective adoptive cell therapy (ACT) against neoantigens will require reliable methods to isolate and expand rare, neoantigen-specific T cells from clinically available biospecimens, ideally prior to clinical relapse. Here, we addressed this need using “mini-lines”, large libraries of parallel T cell cultures, each originating from only 2,000 T cells. Using small quantities of peripheral blood from multiple time points in an ovarian cancer patient, we screened over 3.3 × 10⁶ CD8⁺ T cells by ELISPOT for recognition of peptides corresponding to the full complement of somatic mutations (n = 37) from the patient's tumor. We identified ten T cell lines which collectively recognized peptides encoding five distinct mutations. Six of the ten T cell lines recognized a previously described neoantigen from this patient (HSDL1^L25V), whereas the remaining four lines recognized peptides corresponding to four other mutations. Only the HSDL1^L25V-specific T cell lines recognized autologous tumor. HSDL1^L25V-specific T cells comprised at least three distinct clonotypes and could be identified and expanded from peripheral blood 3–9 months prior to the first tumor recurrence. These T cells became undetectable at later time points, underscoring the dynamic nature of the response. Thus, neoantigen-specific T cells can be expanded from small volumes of blood during tumor remission, making pre-emptive ACT a plausible clinical strategy.

Towards water sensitive cities in Asia: an interdisciplinary journey

Rapid urbanisation, population growth and the effects of climate change drive the need for sustainable urban water management (SUWM) in Asian cities. The complexity of this challenge calls for the integration of knowledge from different disciplines and collaborative approaches. This paper identifies key issues and sets the stage for interdisciplinary research on SUWM in Asia. It reports on the initial stages of a SUWM research programme being undertaken at Monash University, Australia, and proposes a framework to guide the process of interdisciplinary research in urban water management. Three key themes are identified: (1) Technology and Innovation, (2) Urban Planning and Design, and (3) Governance and Society. Within these themes 12 research projects are being undertaken across Indonesia, China, India and Bangladesh. This outward-looking, interdisciplinary approach guides our research in an effort to transgress single-discipline solutions and contribute on-ground impact to SUWM practices in Asia.

Mapping the human T cell repertoire to recurrent driver mutations in MYD88 and EZH2 in lymphoma

Oncogenic "driver" mutations are theoretically attractive targets for the immunotherapy of lymphoid cancers, yet the proportion that can be recognized by T cells remains poorly defined. To address this issue without any confounding effects of the patient's immune system, we assessed T cells from 19 healthy donors for recognition of three common driver mutations in lymphoma: MYD88^L265P, EZH2^Y641F , and EZH2^Y641N . Donors collectively expressed the 10 most prevalent HLA class I alleles, including HLA-A*02:01. Peripheral blood T cells were primed with peptide-loaded dendritic cells (DC), and reactive T cells were assessed for recognition of naturally processed mutant versus wild type full-length proteins. After screening three driver mutations across 17-26 HLA class I alleles and 3 × 10⁶-3 × 10⁷ T cells per donor, we identified CD4⁺ T cells against EFISENCGEII from EZH2^Y641N (presented by HLA-DRB1*13:02) and CD8⁺ T cells against RPIPIKYKA from MYD88^L265P (presented by HLA-B*07:02). We failed to detect RPIPIKYKA-specific T cells in seven other HLA-B*07:02-positive donors, including two lymphoma patients. Thus, healthy donors harbor T cells specific for common driver mutations in lymphoma. However, such responses appear to be rare due to the combined limitations of antigen processing, HLA restriction, and T cell repertoire size, highlighting the need for highly individualized approaches for selecting targets.

Multiplex Droplet Digital PCR Quantification of Recurrent Somatic Mutations in Diffuse Large B-Cell and Follicular Lymphoma

BACKGROUND

A plethora of options to detect mutations in tumor-derived DNA currently exist but each suffers limitations in analytical sensitivity, cost, or scalability. Droplet digital PCR (ddPCR) is an appealing technology for detecting the presence of specific mutations based on a priori knowledge and can be applied to tumor biopsies, including formalin-fixed paraffin embedded (FFPE) tissues. More recently, ddPCR has gained popularity in its utility in quantifying circulating tumor DNA.

METHODS

We have developed a suite of novel ddPCR assays for detecting recurrent mutations that are prevalent in common B-cell non-Hodgkin lymphomas (NHLs), including diffuse large B-cell lymphoma, follicular lymphoma, and lymphoplasmacytic lymphoma. These assays allowed the differentiation and counting of mutant and wild-type molecules using one single hydrolysis probe. We also implemented multiplexing that allowed the simultaneous detection of distinct mutations and an "inverted" ddPCR assay design, based on employing probes matching wild-type alleles, capable of detecting the presence of multiple single nucleotide polymorphisms.

RESULTS

The assays successfully detected and quantified somatic mutations commonly affecting enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) (Y641) and signal transducer and activator of transcription 6 (STAT6) (D419) hotspots in fresh tumor, FFPE, and liquid biopsies. The "inverted" ddPCR approach effectively reported any single nucleotide variant affecting either of these 2 hotspots as well. Finally, we could effectively multiplex hydrolysis probes targeting 2 additional lymphoma-related hotspots: myeloid differentiation primary response 88 (MYD88; L265P) and cyclin D3 (CCND3; I290R).

CONCLUSIONS

Our suite of ddPCR assays provides sufficient analytical sensitivity and specificity for either the invasive or noninvasive detection of multiple recurrent somatic mutations in B-cell NHLs.

Low Mutation Burden in Ovarian Cancer May Limit the Utility of Neoantigen-Targeted Vaccines

Due to advances in sequencing technology, somatically mutated cancer antigens, or neoantigens, are now readily identifiable and have become compelling targets for immunotherapy. In particular, neoantigen-targeted vaccines have shown promise in several pre-clinical and clinical studies. However, to date, neoantigen-targeted vaccine studies have involved tumors with exceptionally high mutation burdens. It remains unclear whether neoantigen-targeted vaccines will be broadly applicable to cancers with intermediate to low mutation burdens, such as ovarian cancer. To address this, we assessed whether a derivative of the murine ovarian tumor model ID8 could be targeted with neoantigen vaccines. We performed whole exome and transcriptome sequencing on ID8-G7 cells. We identified 92 somatic mutations, 39 of which were transcribed, missense mutations. For the 17 top predicted MHC class I binding mutations, we immunized mice subcutaneously with synthetic long peptide vaccines encoding the relevant mutation. Seven of 17 vaccines induced robust mutation-specific CD4 and/or CD8 T cell responses. However, none of the vaccines prolonged survival of tumor-bearing mice in either the prophylactic or therapeutic setting. Moreover, none of the neoantigen-specific T cell lines recognized ID8-G7 tumor cells in vitro, indicating that the corresponding mutations did not give rise to bonafide MHC-presented epitopes. Additionally, bioinformatic analysis of The Cancer Genome Atlas data revealed that only 12% (26/220) of HGSC cases had a ≥90% likelihood of harboring at least one authentic, naturally processed and presented neoantigen versus 51% (80/158) of lung cancers. Our findings highlight the limitations of applying neoantigen-targeted vaccines to tumor types with intermediate/low mutation burdens.

Toward Personalized Lymphoma Immunotherapy: Identification of Common Driver Mutations Recognized by Patient CD8+ T Cells

PURPOSE

A fundamental challenge in the era of next-generation sequencing (NGS) is to design effective treatments tailored to the mutational profiles of tumors. Many newly discovered cancer mutations are difficult to target pharmacologically; however, T-cell-based therapies may provide a valuable alternative owing to the exquisite sensitivity and specificity of antigen recognition. To explore this concept, we assessed the immunogenicity of a panel of genes that are common sites of driver mutations in follicular lymphoma, an immunologically sensitive yet currently incurable disease.

EXPERIMENTAL DESIGN

Exon capture and NGS were used to interrogate tumor samples from 53 patients with follicular lymphoma for mutations in 10 frequently mutated genes. For 13 patients, predicted mutant peptides and proteins were evaluated for recognition by autologous peripheral blood T cells after in vitro priming.

RESULTS

Mutations were identified in 1-5 genes in 81% (43/53) of tumor samples. Autologous, mutation-specific CD8(+) T cells were identified in 23% (3/13) of evaluated cases. T-cell responses were directed toward putative driver mutations in CREBBP and MEF2B. Responding T cells showed exquisite specificity for mutant versus wild-type proteins and recognized lymphoma cells expressing the appropriate mutations. Responding T cells appeared to be from the naïve repertoire, as they were found at low frequencies and only at single time points in each patient.

CONCLUSIONS

Patients with follicular lymphoma harbor rare yet functionally competent CD8(+) T cells specific for recurrent mutations. Our results support the concept of using NGS to design individualized immunotherapies targeting common driver mutations in follicular lymphoma and other malignancies. Clin Cancer Res; 22(9); 2226-36. ©2015 AACR.

Prescribing practices and clinical predictors of glucose-lowering therapy within the first year in people with newly diagnosed Type 2 diabetes

AIM

To examine prescribing practices and predictors of glucose-lowering therapy within the first year following diagnosis of Type 2 diabetes mellitus in a clinical care setting.

METHODS

We followed people enrolled in the Danish Centre for Strategic Research in Type 2 Diabetes (DD2) cohort from outpatient hospital clinics and general practices throughout Denmark in 2010-2013. We used Poisson regression to compute age- and gender-adjusted risk ratios (RRs).

RESULTS

Among 1158 new Type 2 diabetes mellitus patients, 302 (26%) did not receive glucose-lowering therapy within the first year, 723 (62%) received monotherapy [685 (95%) with metformin], and 133 (12%) received more than one drug. Predictors of receiving any vs. no therapy and combination vs. monotherapy were: age < 40 years [RR: 1.29 (95% CI: 1.16-1.44) and 3.60 (95% CI: 2.36-5.50)]; high Charlson Comorbidity Index [RRs: 1.20 (95% CI: 1.05-1.38) and 2.08 (95% CI: 1.16-3.72)]; central obesity [RRs: 1.23 (95% CI: 1.04-1.44) and 1.93 (95% CI: 0.76-4.94)]; fasting blood glucose of ≥ 7.5 mmol/l [RRs: 1.25 (95% CI: 1.10-1.42) and 1.94 (95% CI: 1.02-3.71)]; and HbA1c ≥ 59 mmol/mol (≥ 7.5%) [RR: 1.26 (95% CI: 1.20-1.32) and 2.86 (95% CI: 1.97-4.14)]. Weight gain ≥ 30 kg since age 20, lack of physical exercise and C-peptide of < 300 pmol/l also predicted therapy.

CONCLUSIONS

Comorbidity, young age, central obesity and poor baseline glycaemic control are important predictors of therapy one year after Type 2 diabetes mellitus debut.

Rough-Form Lipopolysaccharide Increases Apoptosis in Human CD4⁺ and CD8⁺ T Lymphocytes

Immunosuppression induced by lymphocyte apoptosis is considered an important factor in the pathogenesis of sepsis and has been demonstrated in both animal models of lipopolysaccharide (LPS)-induced endotoxemia and septic patients. As rough-form LPS (R-LPS) has recently been shown to elicit a stronger immunological response than regular smooth-form LPS (S-LPS), we aimed to assess the apoptosis-inducing capabilities of R-LPS in different subsets of lymphocytes (CD4(+) T cells, CD8(+) T cell, B cells and NK cells). Using multicolour flow cytometry on human peripheral blood mononuclear cells, we found that R-LPS increased apoptosis in CD4(+) and CD8(+) T cells assessed by annexin V and propidium iodide (AV(+) PI(-)), compared with both S-LPS-stimulated and unstimulated cells. 7-Amino-actinomycin D and staining for intracellular active caspase-3, which are considered later signs of apoptosis, did not reveal the same results. Both forms appeared to inhibit apoptosis in B cells, but no LPS-form-specific effect was seen on B or NK cells. Our results indicate that R-LPS induces a stronger AV(+) PI(-)-assessed apoptotic response in T cells than S-LPS. Our findings emphasize the importance of T cell apoptosis in endotoxemia and advocates for control of LPS form in both endotoxemia research and clinical trials with Gram-negative infections.

Expression of NK cell and monocyte receptors in critically ill patients--potential biomarkers of sepsis

Sepsis is characterized by activation of both the innate and adaptive immune systems as a response to infection. During sepsis, the expression of surface receptors expressed on immune competent cells, such as NKG2D and NKp30 on NK cells and TLR4 and CD14 on monocytes, is partly regulated by pro- and anti-inflammatory mediators. In this observational study, we aimed to explore whether the expression of these receptors could be used as diagnostic and/or prognostic biomarkers in sepsis. Patients with severe sepsis or septic shock (n = 21) were compared with critically ill non-septic patients (n = 15). Healthy volunteers (n = 15) served as controls. To elucidate variations over time, all patients were followed for 4 days. Cell surface expression of NKG2D, NKp30, TLR4 and CD14 and serum levels of IL-1β, IL-6, IFN-γ, TNF-α, IL-4 and IL-10 was estimated by flow cytometry. We found that NK cell expression of NKG2D and monocyte expression of CD14 were lower in the septic patients compared with the non-septic patients, both at ICU admission and during the observation period (P < 0.01 for all comparisons). Both at ICU admission, and during the observation period, levels of IL-6 and IL-10 were higher in the septic patients compared with the non-septic patients (P < 0.001 for all comparisons).

CONCLUSION

As both NKG2D and CD14 levels appear to distinguish between septic and non-septic patients, both NKG2D and CD14 may be considered potential diagnostic biomarkers of severe sepsis and septic shock.

Podocalyxin enhances breast tumor growth and metastasis and is a target for monoclonal antibody therapy

Introduction

Podocalyxin (gene name PODXL) is a CD34-related sialomucin implicated in the regulation of cell adhesion, migration and polarity. Upregulated expression of podocalyxin is linked to poor patient survival in epithelial cancers. However, it is not known if podocalyxin has a functional role in tumor progression.

Methods

We silenced podocalyxin expression in the aggressive basal-like human (MDA-MB-231) and mouse (4T1) breast cancer cell lines and also overexpressed podocalyxin in the more benign human breast cancer cell line, MCF7. We evaluated how podocalyxin affects tumorsphere formation in vitro and compared the ability of podocalyxin-deficient and podocalyxin-replete cell lines to form tumors and metastasize using xenogenic or syngeneic transplant models in mice. Finally, in an effort to develop therapeutic treatments for systemic cancers, we generated a series of antihuman podocalyxin antibodies and screened these for their ability to inhibit tumor progression in xenografted mice.

Results

Although deletion of podocalyxin does not alter gross cell morphology and growth under standard (adherent) culture conditions, expression of PODXL is required for efficient formation of tumorspheres in vitro. Correspondingly, silencing podocalyxin resulted in attenuated primary tumor growth and invasiveness in mice and severely impaired the formation of distant metastases. Likewise, in competitive tumor engraftment assays where we injected a 50:50 mixture of control and shPODXL (short-hairpin RNA targeting PODXL)-expressing cells, we found that podocalyxin-deficient cells exhibited a striking decrease in the ability to form clonal tumors in the lung, liver and bone marrow. Finally, to validate podocalyxin as a viable target for immunotherapy, we screened a series of novel antihuman podocalyxin antibodies for their ability to inhibit tumor progression in vivo. One of these antibodies, PODOC1, potently blocked tumor growth and metastasis.

Conclusions

We show that podocalyxin plays a key role in the formation of primary tumors and distant tumor metastasis. In addition, we validate podocalyxin as potential target for monoclonal antibody therapy to inhibit primary tumor growth and systemic dissemination.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0562-7) contains supplementary material, which is available to authorized users.

Surveillance of the tumor mutanome by T cells during progression from primary to recurrent ovarian cancer

PURPOSE

Cancers accumulate mutations over time, each of which brings the potential for recognition by the immune system. We evaluated T-cell recognition of the tumor mutanome in patients with ovarian cancer undergoing standard treatment.

EXPERIMENTAL DESIGN

Tumor-associated T cells from 3 patients with ovarian cancer were assessed by ELISPOT for recognition of nonsynonymous mutations identified by whole exome sequencing of autologous tumor. The relative levels of mutations and responding T cells were monitored in serial tumor samples collected at primary surgery and first and second recurrence.

RESULTS

The vast majority of mutations (78/79) were not recognized by tumor-associated T cells; however, a highly specific CD8(+) T-cell response to the mutation hydroxysteroid dehydrogenase-like protein 1 (HSDL1)(L25V) was detected in one patient. In the primary tumor, the HSDL1(L25V) mutation had low prevalence and expression, and a corresponding T-cell response was undetectable. At first recurrence, there was a striking increase in the abundance of the mutation and corresponding MHC class I epitope, and this was accompanied by the emergence of the HSDL1(L25V)-specific CD8(+) T-cell response. At second recurrence, the HSDL1(L25V) mutation and epitope continued to be expressed; however, the corresponding T-cell response was no longer detectable.

CONCLUSION

The immune system can respond to the evolving ovarian cancer genome. However, the T-cell response detected here was rare, was transient, and ultimately failed to prevent disease progression. These findings reveal the limitations of spontaneous tumor immunity in the setting of standard treatments and suggest a high degree of ignorance of tumor mutations that could potentially be reversed by immunotherapy.

CD20+ tumor-infiltrating lymphocytes have an atypical CD27- memory phenotype and together with CD8+ T cells promote favorable prognosis in ovarian cancer

PURPOSE

Tumor-infiltrating lymphocytes (TIL), in particular CD8(+) T cells and CD20(+) B cells, are strongly associated with survival in ovarian cancer and other carcinomas. Although CD8(+) TIL can mediate direct cytolytic activity against tumors, the role of CD20(+) TIL is poorly understood. Here, we investigate the possible contributions of CD20(+) TIL to humoral and cellular tumor immunity.

EXPERIMENTAL DESIGN

Tumor and serum specimens were obtained from patients with high-grade serous ovarian cancer. CD8(+) and CD20(+) TIL were analyzed by immunohistochemistry and flow cytometry. Immunoglobulin molecules were evaluated by DNA sequencing. Serum autoantibody responses to the tumor antigens p53 and NY-ESO-1 were measured by ELISA.

RESULTS

The vast majority of CD20(+) TIL were antigen experienced, as evidenced by class-switching, somatic hypermutation, and oligoclonality, yet they failed to express the canonical memory marker CD27. CD20(+) TIL showed no correlation with serum autoantibodies to p53 or NY-ESO-1. Instead, they colocalized with activated CD8(+) TIL and expressed markers of antigen presentation, including MHC class I, MHC class II, CD40, CD80, and CD86. The presence of both CD20(+) and CD8(+) TIL correlated with increased patient survival compared with CD8(+) TIL alone.

CONCLUSIONS

In high-grade serous ovarian tumors, CD20(+) TIL have an antigen-experienced but atypical CD27(-) memory B-cell phenotype. They are uncoupled from serum autoantibodies, express markers of antigen-presenting cells, and colocalize with CD8(+) T cells. We propose that the association between CD20(+) TIL and patient survival may reflect a supportive role in cytolytic immune responses.

Scope insensitivity in contingent valuation studies of health care services: should we ask twice?

The main purpose of the present study was to test for outcome scope insensitivity. Respondents were initially asked to value one of two severe health states by way of a time-trade-off (TTO) exercise. Subsequent to the TTO exercise all respondents were asked to value an intervention, which offered a reduction in risk of falling into the health state they had evaluated. All respondents were subsequent to this initial CV exercise asked to value the same risk reduction, but in this case the outcome was death. Although our study passes the internal scope test, there is not a high degree of sensitivity to outcome. As many as 68% of respondents stated an identical maximum WTP in first and second CV valuation exercise implying that they value the interventions equally despite the fact that the health state presented in the initial CV question was deemed far better than death according to the TTO responses given by the same respondents. In contrast, the external scope test (comparison of response to initial CV across study arms) fared much better.

ESRRA-C11orf20 is a recurrent gene fusion in serous ovarian carcinoma

Every year, ovarian cancer kills approximately 14,000 women in the United States and more than 140,000 women worldwide. Most of these deaths are caused by tumors of the serous histological type, which is rarely diagnosed before it has disseminated. By deep paired-end sequencing of mRNA from serous ovarian cancers, followed by deep sequencing of the corresponding genomic region, we identified a recurrent fusion transcript. The fusion transcript joins the 5' exons of ESRRA, encoding a ligand-independent member of the nuclear-hormone receptor superfamily, to the 3' exons of C11orf20, a conserved but uncharacterized gene located immediately upstream of ESRRA in the reference genome. To estimate the prevalence of the fusion, we tested 67 cases of serous ovarian cancer by RT-PCR and sequencing and confirmed its presence in 10 of these. Targeted resequencing of the corresponding genomic region from two fusion-positive tumor samples identified a nearly clonal chromosomal rearrangement positioning ESRRA upstream of C11orf20 in one tumor, and evidence of local copy number variation in the ESRRA locus in the second tumor. We hypothesize that the recurrent novel fusion transcript may play a role in pathogenesis of a substantial fraction of serous ovarian cancers and could provide a molecular marker for detection of the cancer. Gene fusions involving adjacent or nearby genes can readily escape detection but may play important roles in the development and progression of cancer.

Polyfunctional T-cell responses are disrupted by the ovarian cancer ascites environment and only partially restored by clinically relevant cytokines

Background

Host T-cell responses are associated with favorable outcomes in epithelial ovarian cancer (EOC), but it remains unclear how best to promote these responses in patients. Toward this goal, we evaluated a panel of clinically relevant cytokines for the ability to enhance multiple T-cell effector functions (polyfunctionality) in the native tumor environment.

Methodology/Principal Findings

Experiments were performed with resident CD8+ and CD4+ T cells in bulk ascites cell preparations from high-grade serous EOC patients. T cells were stimulated with α-CD3 in the presence of 100% autologous ascites fluid with or without exogenous IL-2, IL-12, IL-18 or IL-21, alone or in combination. T-cell proliferation (Ki-67) and function (IFN-γ, TNF-α, IL-2, CCL4, and CD107a expression) were assessed by multi-parameter flow cytometry. In parallel, 27 cytokines were measured in culture supernatants. While ascites fluid had variable effects on CD8+ and CD4+ T-cell proliferation, it inhibited T-cell function in most patient samples, with CD107a, IFN-γ, and CCL4 showing the greatest inhibition. This was accompanied by reduced levels of IL-1β, IL-1ra, IL-9, IL-17, G-CSF, GM-CSF, Mip-1α, PDGF-bb, and bFGF in culture supernatants. T-cell proliferation was enhanced by exogenous IL-2, but other T-cell functions were largely unaffected by single cytokines. The combination of IL-2 with cytokines engaging complementary signaling pathways, in particular IL-12 and IL-18, enhanced expression of IFN-γ, TNF-α, and CCL4 in all patient samples by promoting polyfunctional T-cell responses. Despite this, other functional parameters generally remained inhibited.

Conclusions/Significance

The EOC ascites environment disrupts multiple T-cell functions, and exogenous cytokines engaging diverse signaling pathways only partially reverse these effects. Our results may explain the limited efficacy of cytokine therapies for EOC to date. Full restoration of T-cell function will require activation of signaling pathways beyond those engaged by IL-2, IL-12, IL-18, and IL-21.

Mammary tumors with diverse immunological phenotypes show differing sensitivity to adoptively transferred CD8+ T cells lacking the Cbl-b gene

We tested the efficacy of CD8+ T cells lacking the Cbl-b gene against a panel of mammary tumor lines with different intrinsic sensitivities to T cells. Mice bearing established tumors expressing an ovalbumin-tagged version of HER-2/neu underwent adoptive transfer with Cbl-b-replete or -null CD8+ T cells from OT-I T cell receptor transgenic donor mice. In general, Cbl-b-null OT-I cells showed enhanced expansion, persistence, and capacity for tumor infiltration. This resulted in markedly enhanced efficacy against two tumor lines that normally demonstrate complete (NOP21) or partial (NOP23) regression. Moreover, a third tumor line (NOP6) that normally demonstrates progressive disease underwent complete regression in response to Cbl-b-null OT-I cells. However, a fourth tumor line (NOP18) was resistant to Cbl-b-null OT-I cells owing to a profound barrier to lymphocyte infiltration. Thus, Cbl-b-null CD8+ T cells are generally more efficacious but are nonetheless unable to mediate curative responses against all tumor phenotypes.

CD34 is a key regulator of hematopoietic stem cell trafficking to bone marrow and mast cell progenitor trafficking in the periphery

CD34 is a cell-surface sialomucin widely used for hematopoietic stem cell purification and as a marker of most vascular endothelial cells, including those of capillaries in the majority of tissues. Surprisingly, despite extensive research, the function of this sialomucin has remained elusive, with proposed roles ranging from enhancing proliferation or inhibiting differentiation to acting as a proadhesive L-selectin ligand. Here, we review our recent studies, which suggest that CD34 does, indeed, play a role in leukocyte and HSC trafficking, but that this is through its action as a regulated blocker of cell adhesion and enhancer of migration.

The role of podocalyxin in health and disease

Podocalyxin, a sialomucin most closely related to CD34 and endoglycan, is expressed by kidney podocytes, hematopoietic progenitors, vascular endothelia, and a subset of neurons; aberrant expression has recently been implicated in a range of cancers. Through interactions with several intracellular proteins and at least one extracellular ligand, podocalyxin regulates both adhesion and cell morphology. In the developing kidney, podocalyxin plays an essential role in the formation and maintenance of podocyte foot processes, and its absence results in perinatal lethality. Podocalyxin expression in the hematopoietic system correlates with cell migration and the seeding of new hematopoietic tissues. In addition, it is abnormally expressed in subsets of breast, prostate, liver, pancreatic, and kidney cancer as well as leukemia. Strikingly, it is often associated with the most aggressive cases, and it is likely involved in metastasis. Thus, a thorough investigation of the normal activities of podocalyxin may facilitate the development of new cancer treatment strategies.

Novel functions of the CD34 family

For almost 30 years, the cell-surface protein CD34 has been widely used as a marker to assist in the identification and Summary isolation of hematopoietic stem cells (HSCs) and progenitors in preparation for bone-marrow transplantation. In addition, it has increasingly been used as a marker to help identify other tissue-specific stem cells, including muscle satellite cells and epidermal precursors. Despite its utility as a stem-cell marker, however, the function of CD34 has remained remarkably elusive. This is probably because: (1) it is subject to a range of tissue-specific post-transcriptional and post-translational modifications that are expected to alter its function dramatically; (2) the simple interpretation of CD34 gain- and loss-of-function experiments has been confounded by the overlapping expression of the two recently discovered CD34-related proteins podocalyxin and endoglycan; and (3) there has been a glaring lack of robust in vitro and in vivo functional assays that permit the structural and functional analysis of CD34 and its relatives. Here, we provide a brief review of the domain structure, genomic organization, and tissue distribution of the CD34 family. We also describe recent insights from gain- and loss-of-function experiments and improved assays, which are elucidating a fascinating role for these molecules in cell morphogenesis and migration.

Sinus node dysfunction in acute myocardial infarction

In a retrospective study of patients admitted for acute myocardial infarction (AMI) during six years, sinus node dysfunction (SND) was detected in 20 (1.04%). Twelve had persistent sinus bradycardia, 11 sinotrial block or sinus arrest and six bradytachy syndrome. Symptoms occurred in 17 patients, 12 of whom required temporary pacing for periods up to three weeks. A permanent cardiac pacemaker was implanted in three patients with brady-tachy syndrome. Three patients died during the primary admission and six during the observation period. Follow-up after a mean observation period of 34 months showed continuous signs of SND in 11 out of 19 patients. The arrhythmia caused symptoms in five patients, two of whom had a cardiac pacemaker and two received medical treatment. It is concluded that SND appearing during an AMI persists in a high number of these patients.

Sinus node dysfunction in 128 patients. A retrospective study with follow-up

A retrospective study covering all admissions during a 6-year period revealed 128 patients with sinus node dysfunction (SND). The patients were grouped according to the ECG criteria chosen: group I 33 patients with sinus bradycardia, group II 37 with sinoatrial block/sinus arrest, group III 58 with brady-tachy syndrome. Additional heart disease, predominantly ischaemic, was found in 56%. The frequency and severity of symptoms increased from group I to group III. Pacemaker treatment was given to 40% of the cases, while medical treatment alone was successful in 17%. A follow-up including 104 patients was carried out after a mean observation period of approximately three years. Sixteen patients had died. The cause of death may have been SND per se in only one case. Five patients died of apoplectic insults or complications to such. In total, nine possible or proven systemic embolic events were found--all occurring in patients with brady-tachy syndrome. A progression of the ECG abnormality from a lower to a higher group took place in nine patients during the observation period. It is concluded that SND is a condition with a broad clinical spectrum and a stationary or slowly progressive course. In general, it carries a good prognosis. A substantial number of deaths of disabilities in patients with brady-tachy syndrome may be ascribed to systemic embolism. Long-term anticoagulant therapy is proposed in this subgroup of patients with SND.

Reduced sarcoplasmic reticulum content of releasable Ca2+ in rat soleus muscle fibres after eccentric contractions

AIM

The purpose was to evaluate the effects of fatiguing eccentric contractions (EC) on calcium (Ca2+) handling properties in mammalian type I muscles. We hypothesized that EC reduces both endogenous sarcoplasmic reticulum (SR) content of releasable Ca2+ (eSRCa2+) and myofibrillar Ca2+ sensitivity.

METHODS

Isolated rat soleus muscles performed 30 EC bouts. Single fibres were isolated from the muscle and after mechanical removal of sarcolemma used to measure eSRCa2+, rate of SR Ca2+ loading and myofibrillar Ca2+ sensitivity.

RESULTS

Following EC maximal force in whole muscle was reduced by 30% and 16/100 Hz force ratio by 33%. The eSRCa2+ in fibres from non-stimulated muscles was 45 +/- 5% of the maximal loading capacity. After EC, eSRCa2+ per fibre CSA decreased by 38% (P = 0.05), and the maximal capacity of SR Ca2+ loading was depressed by 32%. There were no effects of EC on either myofibrillar Ca2+ sensitivity, maximal Ca2+ activated force per cross-sectional area and rate of SR Ca2+ loading, or in SR vesicle Ca2+ uptake and release.

CONCLUSIONS

We conclude that EC reduces endogenous SR content of releasable Ca2+ but that myofibrillar Ca2+ sensitivity and SR vesicle Ca2+ kinetics remain unchanged. The present data suggest that the long-lasting fatigue induced by EC, which was more pronounced at low frequencies (low frequency fatigue), is caused by reduced Ca2+ release occurring secondary to reduced SR content of releasable Ca2+.

The CD34-related molecule podocalyxin is a potent inducer of microvillus formation

BACKGROUND

Podocalyxin is a CD34-related transmembrane protein involved in hematopoietic cell homing, kidney morphogenesis, breast cancer progression, and epithelial cell polarization. Although this sialomucin has been shown to block cell adhesion, the mechanisms involved remain enigmatic. It has, however, been postulated that the adaptor proteins NHERF-1 and 2 could regulate apical targeting of Podocalyxin by linking it to the actin cytoskeleton.

PRINCIPAL FINDINGS

Here, in contrast, we find that full-length Podocalyxin acts to recruit NHERF-1 to the apical domain. Moreover, we show that ectopic expression of Podocalyxin in epithelial cells leads to microvillus formation along an expanded apical domain that extends laterally to the junctional complexes. Removal of the C-terminal PDZ-binding domain of Podocalyxin abolishes NHERF-1 recruitment but, surprisingly, has no effect on the formation of microvilli. Instead, we find that the extracellular domain and transmembrane region of Podocalyxin are sufficient to direct recruitment of filamentous actin and ezrin to the plasma membrane and induce microvillus formation.

CONCLUSIONS/SIGNIFICANCE

Our data suggest that this single molecule can modulate NHERF localization and, independently, act as a key orchestrator of apical cell morphology, thereby lending mechanistic insights into its multiple roles as a polarity regulator, tumor progression marker, and anti-adhesin.

Effects of lengthening contraction on calcium kinetics and skeletal muscle contractility in humans

AIM

We have tested the hypothesis that the altered muscle contractility after lengthening contractions (LC) is caused by altered calcium (Ca2+) kinetics.

METHODS

Subjects (n = 8) performed 100 drop jumps and muscle contractility was measured pre- and post-exercise by maximal voluntary contraction (MVC) and transcutaneous electrical stimulation (1, 20 and 50 Hz). Muscle biopsies were analysed for muscle metabolites, rates of SR Ca(2+) uptake (CaU) and release (CaR) and myosin heavy chain (MHC) composition.

RESULTS

The rates of torque relaxation and CaU were positively related to muscle fibre type composition (% MHC II). Muscle creatine (Cr) decreased and the ratio between phosphocreatine (PCr) and Cr increased 3 and 24 h post-exercise (P < 0.05 vs. pre-exercise). LC resulted in reduced MVC (-19%), twitch torque (-41%) and 20/50 Hz torque ratio (-30%) and a faster relaxation rate (P < 0.05). The contractile parameters recovered partially but remained altered 24 h post-exercise (P < 0.05). The average CaR was unchanged after LC (P > 0.05). However, the response varied between subjects and the relative post-exercise CaR was significantly related to the degree of LFF (post/pre 20/50 Hz force ratio) and to the decline in twitch force (post/pre twitch ratio). CaU was lower in seven of eight subjects after LC (P > 0.05).

CONCLUSION

The decline in torque after LC could not be explained by metabolic factors since PCr/Cr ratio increased. The relation between CaR and fatigue suggests that the mechanism of fatigue in part may be attributed to intrinsic changes in the SR Ca2+ release channel. The faster torque relaxation after LC could not be explained by an increased rate of CaU.

Prognostic significance of p53, Her-2, and EGFR overexpression in borderline and epithelial ovarian cancer

The objective of the study was to evaluate the prognostic effect of p53, Her-2, and EGFR in borderline and epithelial ovarian cancer. Tumor tissue from 85 patients with borderline and 783 patients with epithelial ovarian cancer stage I-IV were analyzed immunohistochemically for p53 positivity and over-expression of Her-2 and EGFR. In the ovarian cancer (OC) group 415 patients (53%) had p53-positive tumors, 272 (35%) had tumors with Her-2 over-expression, and 483 (62%) had over-expression of EGFR. In the OC group the classical prognostic factors (older age, higher FIGO stage, and poorer differentiated stage) had significant prognostic value in both uni- and multivariate analyses. Multivariate analyses in the OC group proved p53 positivity to increase mortality significantly depending on the grade of the tumor. Her-2 likewise increased the risk of mortality significantly in this group depending on the grade of the tumor. EGFR on the other hand did not have any additional prognostic effect in the OC group after adjustment for the classical prognostic and molecular factors was made. In the borderline group Her-2 and EGFR over-expression in combination, adjusted for age and p53, significantly improved the prognosis.

Podocalyxin is a CD34-related marker of murine hematopoietic stem cells and embryonic erythroid cells

Podocalyxin/podocalyxin-like protein 1 [PCLP1]/thrombomucin/MEP21 is a CD34-related sialomucin. We have performed a detailed analysis of its expression during murine development and assessed its utility as a marker of hematopoietic stem cells (HSCs) and their more differentiated progeny. We find that podocalyxin is highly expressed by the first primitive hematopoietic progenitors and nucleated red blood cells to form in the embryonic yolk sac. Likewise, podocalyxin is expressed by definitive multilineage hematopoietic progenitors and erythroid precursors in fetal liver. The level of podocalyxin expression gradually declines with further embryo maturation and reaches near-background levels at birth. This is followed by a postnatal burst of expression that correlates with the seeding of new hematopoietic progenitors to the spleen and bone marrow. Shortly thereafter, podocalyxin expression gradually declines, and by 4 weeks postpartum it is restricted to a rare population of Sca-1(+), c-kit(+), lineage marker(-) (Lin(-)) cells in the bone marrow. These rare podocalyxin-expressing cells are capable of serially reconstituting myeloid and lymphoid lineages in lethally irradiated recipients, suggesting they have HSC activity. In summary, we find that podocalyxin is a marker of embryonic HSCs and erythroid cells and of adult HSCs and that it may be a valuable marker for the purification of these cells for transplantation.

Overexpression of the anti-adhesin podocalyxin is an independent predictor of breast cancer progression

Podocalyxin is a CD34-related cell surface molecule with anti-adhesive qualities. We probed a tissue microarray (n = 272) linked to long-term outcome data and found that podocalyxin was highly overexpressed in a distinct subset of invasive breast carcinomas (n = 15; 6%). Univariate disease-specific (P < 0.01) and multivariate regression (P < 0.0005) analyses indicated that this overexpression is an independent indicator of poor outcome. Forced podocalyxin expression perturbed cell junctions between MCF-7 breast carcinoma cells, and it caused cell shedding from confluent monolayers. Therefore, podocalyxin overexpression is a novel predictor of breast cancer progression that may contribute to the process by perturbing tumor cell adhesion.

Avian models to study the transcriptional control of hematopoietic lineage commitment and to identify lineage-specific genes

E26 is an avian acute leukemia virus with a profound ability to transform multipotent hematopoietic progenitor cells both in vivo and in vitro. Progenitor cells transformed by this virus can be expanded in vitro as undifferentiated clones for up to two months and can also be induced to differentiate into cells of the erythroid, eosinophilic, thrombocytic, and myelomonocytic lineages with reproducible kinetics. Aside from the proliferative stimulus provided by the E26 oncoprotein, these cells are remarkably similar to normal hematopoietic progenitors. They therefore provide an ideal assay system for determining the influence of ectopically expressed transcription factors on both maturation and commitment to several hematopoietic lineages. Results from experiments using this system suggest that subtle shifts in the balance of lineage-restricted transcription factors can result in profound changes in phenotype and challenge the notion that lineage commitment is a uni-directional process. Analysis of the regulatory elements governing the expression of these genes has provided novel mechanistic insights into the transcriptional control of hematopoiesis. In addition to their utility in deciphering the control of lineage commitment, the ability to grow large numbers of undifferentiated and more mature hematopoietic cells has facilitated the discovery of a number of novel, lineage-restricted genes. Analysis of the proteins encoded by these genes is helping to clarify the role of a number of membrane proteins in the interaction between hematopoietic cells and their microenvironments.

Muscle fibre type, efficiency, and mechanical optima affect freely chosen pedal rate during cycling

This study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre-set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output ( approximately 40 and 70% of the power output at which maximum oxygen uptake (VO(2max)) was attained at 80 r.p.m.) with freely chosen and pre-set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56-88 r.p.m. at low and 61-102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21-97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = -0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre-set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively).

CONCLUSIONS

Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I ( approximately %MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre-set pedal rates, but for freely chosen pedal rate, these variables were unrelated.

Phospho-imaging as a tool for visualization and noninvasive measurement of P transport dynamics in arbuscular mycorrhizas

• A new method is described for monitoring hyphal ³² P transport in compartmented, monoxenic mycorrhizal root cultures. Nondestructive time-course measurements of P transport in hyphae were obtained by capturing digital autoradiograms on P-imaging screens, and comparing with growth observed by optical scanning. ³² P distribution measured by densitometry on the day of harvest closely agreed with values obtained by liquid scintillation counting after destructive harvest. • Virtually all labeled PO₄ was absorbed by arbuscular mycorrhizal (AM) hyphae, but transfer to the roots appeared to be incomplete. P transport was not unidirectional towards the roots, as ³² P was also transported from the root compartment to the hyphal compartment. Net P flux rates were calculated for hyphae crossing between compartments, taking bidirectional flow into account. • Amounts of transported P were poorly correlated with extra-radical hyphal length and root d. wt, but highly correlated with the number of hyphae crossing the barrier separating the two compartments. Such correlations were highest when only hyphae with detectable protoplasmic streaming were considered. • The method was tested using radiolabeled P sources, H₂ PO₄ ^- and cytidine triphosphate (CTP), and the AM fungi, Glomus intraradices and G. proliferum. Fungal transport of ³² P from CTP was much slower than from PO₄ for both fungi.

Low-current, vertical blowup in a stored laser-cooled ion beam

Using a novel technique for real-time transverse beam profile diagnostics of a stored ion beam, we have observed the transverse size of a stored laser-cooled ion beam. Earlier we observed that the density of the beam is independent of the beam current. At very low currents, we observe an abrupt change in this behavior: The vertical beam size increases suddenly by about an order of magnitude. This observation implies a sudden change in the indirect vertical cooling mediated by intrabeam scattering. Our results have serious implications for the ultimate beam quality attainable by laser cooling.

Effects of high extracellular [K+] and adrenaline on force development, relaxation and membrane potential in cardiac muscle from freshwater turtle and rainbow trout

Increases in extracellular K(+) concentrations reduced the twitch force amplitude of heart muscle from the freshwater turtle (Trachemys scripta elegans) and rainbow trout (Oncorhynchus mykiss). Adrenaline augmented twitch force amplitude and reduced the relative influence of [K(+)]. In the absence of adrenaline, high [K(+)] had less effect in reducing twitch force in turtle than in trout, whereas the reverse was true in the presence of adrenaline. Under anoxic conditions, twitch force was lower in 10 mmol l(−1) than in 2.5 mmol l(−1) K(+) in both preparations, but adrenaline removed this difference. A further analysis of turtle myocardium showed that action potential duration was shorter and resting potential more positive in high [K(+)] than in low [K(+)]. Adrenaline restored the duration of the action potential, but did not affect the depolarisation, which may attenuate Na(+)/Ca(2+) exchange, participating in excitation/contraction coupling. The contractile responses in the presence of adrenaline were, however, similar in both high and low K(+) concentrations when increases in extracellular Ca(2+) were applied to increase the demand on excitation/contraction coupling. The possibilities that adrenaline counteracts the effects of high [K(+)] via the sarcoplasmic reticulum or sarcolemmal Na(+)/K(+)-ATPase were examined by inhibiting the sarcoplasmic reticulum with ryanodine (10 micromol l(−1)) or Na(+)/K(+)-ATPase with ouabain (0.25 or 3 mmol l(−)). No evidence to support either of these possibilities was found. Adrenaline did not protect all aspects of excitation/contraction coupling because the maximal frequency giving regular twitches was lower at 10 mmol l(−1) K(+) than at 2.5 mmol l(−1) K(+).

Cloning and expression of cytochrome P450 enzymes catalyzing the conversion of tyrosine to p-hydroxyphenylacetaldoxime in the biosynthesis of cyanogenic glucosides in Triglochin maritima

Two cDNA clones encoding cytochrome P450 enzymes belonging to the CYP79 family have been isolated from Triglochin maritima. The two proteins show 94% sequence identity and have been designated CYP79E1 and CYP79E2. Heterologous expression of the native and the truncated forms of the two clones in Escherichia coli demonstrated that both encode multifunctional N-hydroxylases catalyzing the conversion of tyrosine to p-hydroxyphenylacetaldoxime in the biosynthesis of the two cyanogenic glucosides taxiphyllin and triglochinin in T. maritima. This renders CYP79E functionally identical to CYP79A1 from Sorghum bicolor, and unambiguously demonstrates that cyanogenic glucoside biosynthesis in T. maritima and S. bicolor is catalyzed by analogous enzyme systems with p-hydroxyphenylacetaldoxime as a free intermediate. This is in contrast to earlier reports stipulating p-hydroxyphenylacetonitrile as the only free intermediate in T. maritima. L-3,4-Dihydroxyphenyl[3-(14)C]Ala (DOPA) was not metabolized by CYP79E1, indicating that hydroxylation of the phenol ring at the meta position, as required for triglochinin formation, takes place at a later stage. In S. bicolor, CYP71E1 catalyzes the subsequent conversion of p-hydroxyphenylacetaldoxime to p-hydroxymandelonitrile. When CYP79E1 from T. maritima was reconstituted with CYP71E1 and NADPH-cytochrome P450 oxidoreductase from S. bicolor, efficient conversion of tyrosine to p-hydroxymandelonitrile was observed.

Recurrence of uterine intravenous leiomyomatosis with intracardiac extension. Diagnostic considerations and surgical removal

A 28-year-old woman (gravida 2, para 2) was admitted 20 months after a hysterectomy because of fibromyoma. The hysterectomy specimen had shown intravenous leiomyomatosis. The patient presented with unspecific abdominal symptoms, serologic signs of hepatic and renal failure and clinical right-sided heart failure. Progression despite treatment with a gonadotropin-releasing hormone analogue promoted transferral to the present centre. Abdominal ultrasonography, phlebography and transoesophageal echocardiography showed a left pelvic mass and a seemingly free-floating tumour extending from the left main iliac vein via the inferior caval vein to the right ventricle. During a combined cardiac and distal caval approach using extracorporeal circulation, a 45 cm massive leiomyoma was removed successfully. Seven weeks later the left pelvic tumour was removed radically together with left oophorectomy. At control 12 months later the patient was well and without any remaining symptoms.

The T-superfamily of conotoxins

We report the discovery and initial characterization of the T-superfamily of conotoxins. Eight different T-superfamily peptides from five Conus species were identified; they share a consensus signal sequence, and a conserved arrangement of cysteine residues (- -CC- -CC-). T-superfamily peptides were found expressed in venom ducts of all major feeding types of Conus; the results suggest that the T-superfamily will be a large and diverse group of peptides, widely distributed in the 500 different Conus species. These peptides are likely to be functionally diverse; although the peptides are small (11-17 amino acids), their sequences are strikingly divergent, with different peptides of the superfamily exhibiting varying extents of post-translational modification. Of the three peptides tested for in vivo biological activity, only one was active on mice but all three had effects on fish. The peptides that have been extensively characterized are as follows: p5a, GCCPKQMRCCTL*; tx5a, gammaCCgammaDGW(+)CCT( section sign)AAO; and au5a, FCCPFIRYCCW (where gamma = gamma-carboxyglutamate, W(+) = bromotryptophan, O = hydroxyproline, T( section sign) = glycosylated threonine, and * = COOH-terminal amidation). We also demonstrate that the precursor of tx5a contains a functional gamma-carboxylation recognition signal in the -1 to -20 propeptide region, consistent with the presence of gamma-carboxyglutamate residues in this peptide.

Biosynthesis of cyanogenic glucosides in Triglochin maritima and the involvement of cytochrome P450 enzymes

The biosynthesis of the two cyanogenic glucosides, taxiphyllin and triglochinin, in Triglochin maritima (seaside arrow grass) has been studied using undialyzed microsomal preparations from flowers and fruits. Tyrosine was converted to p-hydroxymandelonitrile with V(max) and K(m) values of 36 nmol mg(-1) g(-1) fresh weight and 0.14 mM, respectively. p-Hydroxyphenylacetaldoxime and p-hydroxyphenylacetonitrile accumulated as intermediates in the reaction mixtures. Using radiolabeled tyrosine as substrate, the radiolabel was easily trapped in p-hydroxyphenylacetaldoxime and p-hydroxyphenylacetonitrile when these were added as unlabeled compounds. p-Hydroxyphenylacetaldoxime was the only product obtained using microsomes prepared from green leaves or dialyzed microsomes prepared from flowers and fruits. These data contrast earlier reports (Hösel and Nahrstedt, Arch. Biochem. Biophys. 203, 753-757, 1980; and Cutler et al., J. Biol. Chem. 256, 4253-4258, 1981) where p-hydroxyphenylacetaldoxime was found not to accumulate. All steps in the conversion of tyrosine to p-hydroxymandelonitrile were found to be catalyzed by cytochrome P450 enzymes as documented by photoreversible carbon monoxide inhibition, inhibition by antibodies toward NADPH-cytochrome P450 oxidoreductase, and by cytochrome P450 inhibitors. We hypothesize that cyanogenic glucoside synthesis in T. maritima is catalyzed by multifunctional cytochrome P450 enzymes similar to CYP79A1 and CYP71E1 in Sorghum bicolor except that the homolog to CYP71E1 in T. maritima exhibits a less tight binding of p-hydroxyphenylacetonitrile, thus permitting the release of this intermediate and its conversion into triglochinin.

[Acute porphyria and multiple organ failure during treatment with lamotrigine]

A 38-year-old female suffered from an acute porphyric attack, multi-organ failure and disseminated intravascular coagulation (DIC) within two weeks of starting lamotrigine, a new antiepileptic drug. The porphyric attack was characterized by excess urinary excretion of aminolevulinic acid (ALA), porphobilinogen (PBG) and coproporphyrin III, a pattern similar to that seen in hereditary coproporphyria, however the diagnostic criteria for this specific porphyria were not fulfilled. We suggest that the observed clinical picture represents a rare adverse reaction to lamotrigine.