Targeting host deoxycytidine kinase mitigates Staphylococcus aureus abscess formation

Host-directed therapy (HDT) is an emerging approach to overcome antimicrobial resistance in pathogenic microorganisms. Specifically, HDT targets host-encoded factors required for pathogen replication and survival without interfering with microbial growth or metabolism, thereby eliminating the risk of resistance development. By applying HDT and a drug repurposing approach, we demonstrate that (R)-DI-87, a clinical-stage anticancer drug and potent inhibitor of mammalian deoxycytidine kinase (dCK), mitigates Staphylococcus aureus abscess formation in organ tissues upon invasive bloodstream infection. Mechanistically, (R)-DI-87 shields phagocytes from staphylococcal death-effector deoxyribonucleosides that target dCK and the mammalian purine salvage pathway-apoptosis axis. In this manner, (R)-DI-87-mediated protection of immune cells amplifies macrophage infiltration into deep-seated abscesses, a phenomenon coupled with enhanced pathogen control, ameliorated immunopathology, and reduced disease severity. Thus, pharmaceutical blockade of dCK represents an advanced anti-infective intervention strategy against which staphylococci cannot develop resistance and may help to fight fatal infectious diseases in hospitalized patients.

Targeting host deoxycytidine kinase mitigates Staphylococcus aureus abscess formation

Host-directed therapy (HDT) is an emerging approach to overcome antimicrobial resistance in pathogenic microorganisms. Specifically, HDT targets host-encoded factors required for pathogen replication and survival without interfering with microbial growth or metabolism, thereby eliminating the risk of resistance development. By applying HDT and a drug repurposing approach, we demonstrate that (R)-DI-87, a clinical-stage anti-cancer drug and potent inhibitor of mammalian deoxycytidine kinase (dCK), mitigates Staphylococcus aureus abscess formation in organ tissues upon invasive bloodstream infection. Mechanistically, (R)-DI-87 shields phagocytes from staphylococcal death-effector deoxyribonucleosides that target dCK and the mammalian purine salvage pathway-apoptosis axis. In this manner, (R)-DI-87-mediated protection of immune cells amplifies macrophage infiltration into deep-seated abscesses, a phenomenon coupled with enhanced pathogen control, ameliorated immunopathology, and reduced disease severity. Thus, pharmaceutical blockade of dCK represents an advanced anti-infective intervention strategy against which staphylococci cannot develop resistance and may help to fight fatal infectious diseases in hospitalized patients.

A European-Japanese study on peach allergy: IgE to Pru p 7 associates with severity

BACKGROUND

Pru p 3 and Pru p 7 have been implicated as risk factors for severe peach allergy. This study aimed to establish sensitization patterns to five peach components across Europe and in Japan, to explore their relation to pollen and foods and to predict symptom severity.

METHODS

In twelve European (EuroPrevall project) and one Japanese outpatient clinic, a standardized clinical evaluation was conducted in 1231 patients who reported symptoms to peach and/or were sensitized to peach. Specific IgE against Pru p 1, 2, 3, 4 and 7 and against Cup s 7 was measured in 474 of them. Univariable and multivariable Lasso regression was applied to identify combinations of parameters predicting severity.

RESULTS

Sensitization to Pru p 3 dominated in Southern Europe but was also quite common in Northern and Central Europe. Sensitization to Pru p 7 was low and variable in the European centers but very dominant in Japan. Severity could be predicted by a model combining age of onset of peach allergy, probable mugwort, Parietaria pollen and latex allergy, and sensitization to Japanese cedar pollen, Pru p 4 and Pru p 7 which resulted in an AUC of 0.73 (95% CI 0.73-0.74). Pru p 3 tended to be a risk factor in South Europe only.

CONCLUSIONS

Pru p 7 was confirmed as a significant risk factor for severe peach allergy in Europe and Japan. Combining outcomes from clinical and demographic background with serology resulted in a model that could better predict severity than CRD alone.

Targeting deoxycytidine kinase improves symptoms in mouse models of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease driven by lymphocyte activation against myelin autoantigens in the central nervous system leading to demyelination and neurodegeneration. The deoxyribonucleoside salvage pathway with the rate-limiting enzyme deoxycytidine kinase (dCK) captures extracellular deoxyribonucleosides for use in intracellular deoxyribonucleotide metabolism. Previous studies have shown that deoxyribonucleoside salvage activity is enriched in lymphocytes and required for early lymphocyte development. However, specific roles for the deoxyribonucleoside salvage pathway and dCK in autoimmune diseases such as MS are unknown. Here we demonstrate that dCK activity is necessary for the development of clinical symptoms in the MOG35-55 and MOG1-125 experimental autoimmune encephalomyelitis (EAE) mouse models of MS. During EAE disease, deoxyribonucleoside salvage activity is elevated in the spleen and lymph nodes. Targeting dCK with the small molecule dCK inhibitor TRE-515 limits disease severity when treatments are started at disease induction or when symptoms first appear. EAE mice treated with TRE-515 have significantly fewer infiltrating leukocytes in the spinal cord, and TRE-515 blocks activation-induced B and T cell proliferation and MOG35-55 -specific T cell expansion without affecting innate immune cells or naïve T and B cell populations. Our results demonstrate that targeting dCK limits symptoms in EAE mice and suggest that dCK activity is required for MOG35-55 -specific lymphocyte activation-induced proliferation.

18F-FDG PET Visualizes Systemic STING Agonist-Induced Lymphocyte Activation in Preclinical Models

Stimulator of interferon genes (STING) is a mediator of immune recognition of cytosolic DNA, which plays important roles in cancer, cytotoxic therapies, and infections with certain pathogens. Although pharmacologic STING activation stimulates potent antitumor immune responses in animal models, clinically applicable pharmacodynamic biomarkers that inform of the magnitude, duration, and location of immune activation elicited by systemic STING agonists are yet to be described. We investigated whether systemic STING activation induces metabolic alterations in immune cells that can be visualized by PET imaging. Methods: C57BL/6 mice were treated with systemic STING agonists and imaged with 18F-FDG PET after 24 h. Splenocytes were harvested 6 h after STING agonist administration and analyzed by single-cell RNA sequencing and flow cytometry. 18F-FDG uptake in total splenocytes and immunomagnetically enriched splenic B and T lymphocytes from STING agonist-treated mice was measured by γ-counting. In mice bearing prostate or pancreas cancer tumors, the effects of STING agonist treatment on 18F-FDG uptake, T-lymphocyte activation marker levels, and tumor growth were evaluated. Results: Systemic delivery of structurally distinct STING agonists in mice significantly increased 18F-FDG uptake in the spleen. The average spleen SUVmax in control mice was 1.90 (range, 1.56-2.34), compared with 4.55 (range, 3.35-6.20) in STING agonist-treated mice (P < 0.0001). Single-cell transcriptional and flow cytometry analyses of immune cells from systemic STING agonist-treated mice revealed enrichment of a glycolytic transcriptional signature in both T and B lymphocytes that correlated with the induction of immune cell activation markers. In tumor-bearing mice, STING agonist administration significantly delayed tumor growth and increased 18F-FDG uptake in secondary lymphoid organs. Conclusion: These findings reveal hitherto unknown functional links between STING signaling and immunometabolism and suggest that 18F-FDG PET may provide a widely applicable approach toward measuring the pharmacodynamic effects of systemic STING agonists at a whole-body level and guiding their clinical development.

Purine nucleoside phosphorylase enables dual metabolic checkpoints that prevent T cell immunodeficiency and TLR7-associated autoimmunity

Purine nucleoside phosphorylase (PNP) enables the breakdown and recycling of guanine nucleosides. PNP insufficiency in humans is paradoxically associated with both immunodeficiency and autoimmunity, but the mechanistic basis for these outcomes is incompletely understood. Here, we identify two immune lineage-dependent consequences of PNP inactivation dictated by distinct gene interactions. During T cell development, PNP inactivation is synthetically lethal with downregulation of the dNTP triphosphohydrolase SAMHD1. This interaction requires deoxycytidine kinase activity and is antagonized by microenvironmental deoxycytidine. In B lymphocytes and macrophages, PNP regulates Toll-like receptor 7 signaling by controlling the levels of its (deoxy)guanosine nucleoside ligands. Overriding this regulatory mechanism promotes germinal center formation in the absence of exogenous antigen and accelerates disease in a mouse model of autoimmunity. This work reveals that one purine metabolism gene protects against immunodeficiency and autoimmunity via independent mechanisms operating in distinct immune lineages and identifies PNP as a potentially novel metabolic immune checkpoint.

Abstract 1386: MAPK inhibition remodels antigen presentation in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a 5-year survival rate of less than 10%, highlighting the need for new therapeutic options. Hallmarks of this aggressive disease include constitutive activation of the MAPK signaling pathway via mutant KRAS (mKRAS) and an immunosuppressive tumor microenvironment (TME). Constituently-active KRAS has now been rendered targetable via clinical-stage mKRAS-specific small molecule inhibitors. While the impact of KRAS inhibition on tumor growth is well-studied, its ability to engender anti-tumor adaptive immune responses is not fully understood. Prior data generated by our group demonstrated mKRAS inhibition (mKRASi) increased expression of genes associated with antigen presentation in two models of PDAC in vitro. Additionally, proteomic analysis revealed increased expression of two tumor associated antigens (TAAs), MSLN and PSCA.

To better understand the alteration of antigen presentation in response to MAPK signaling perturbation, we measured surface expression of MHC-I and PD-L1 after mKRAS and/or SHP2 inhibition via flow cytometry in a PDAC-KRASG12C model in vitro. Results demonstrate an additive increase in MHC-I surface expression following inhibition of SHP2 and in combination with mKRASi that is more pronounced in the setting of type I interferon (IFN). Inhibition of MEK in a PDAC KRASG12D model recapitulates these findings. Addition of a JAK inhibitor did not suppress the additional MHC-I expression suggesting a potential JAK/STAT-independent mechanism for this observation.

To better understand the extent of alteration of presented epitopes in response to these perturbations we established an immunopeptidomics profiling workflow, using LC-MS/MS to identify peptide ligands eluted from MHC-I complexes after inhibition of mKRAS and/or SHP2. We additionally profiled epitope alterations after the addition of type I or II IFN. MAPK perturbation resulted in more unique epitopes identified, especially with dual inhibition of mKRAS and SHP2 and further potentiated by type I IFN. Furthermore, we were able to directly identify epitopes derived from MSLN and PSCA in our cell line models. This data demonstrates the potential for MAPK inhibition to render PDAC more sensitive to the adaptive immune system and synergize with immunotherapeutic treatment strategies. Additionally, direct identification of epitopes presented by cancer cells via mass spectrometry can aid in the rational design of targeted immunotherapies.

Citation Format: Amanda L. Creech, Thuc M. Le, Evan R. Abt, Joseph R. Capri, Timothy R. Donahue, Caius G. Radu. MAPK inhibition remodels antigen presentation in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1386.

Cardiomyocytes disrupt pyrimidine biosynthesis in nonmyocytes to regulate heart repair

Various populations of cells are recruited to the heart after cardiac injury, but little is known about whether cardiomyocytes directly regulate heart repair. Using a murine model of ischemic cardiac injury, we demonstrate that cardiomyocytes play a pivotal role in heart repair by regulating nucleotide metabolism and fates of nonmyocytes. Cardiac injury induced the expression of the ectonucleotidase ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which hydrolyzes extracellular ATP to form AMP. In response to AMP, cardiomyocytes released adenine and specific ribonucleosides that disrupted pyrimidine biosynthesis at the orotidine monophosphate (OMP) synthesis step and induced genotoxic stress and p53-mediated cell death of cycling nonmyocytes. As nonmyocytes are critical for heart repair, we showed that rescue of pyrimidine biosynthesis by administration of uridine or by genetic targeting of the ENPP1/AMP pathway enhanced repair after cardiac injury. We identified ENPP1 inhibitors using small molecule screening and showed that systemic administration of an ENPP1 inhibitor after heart injury rescued pyrimidine biosynthesis in nonmyocyte cells and augmented cardiac repair and postinfarct heart function. These observations demonstrate that the cardiac muscle cell regulates pyrimidine metabolism in nonmuscle cells by releasing adenine and specific nucleosides after heart injury and provide insight into how intercellular regulation of pyrimidine biosynthesis can be targeted and monitored for augmenting tissue repair.

Reprogramming of nucleotide metabolism by interferon confers dependence on the replication stress response pathway in pancreatic cancer cells

We determine that type I interferon (IFN) response biomarkers are enriched in a subset of pancreatic ductal adenocarcinoma (PDAC) tumors; however, actionable vulnerabilities associated with IFN signaling have not been systematically defined. Integration of a phosphoproteomic analysis and a chemical genomics synergy screen reveals that IFN activates the replication stress response kinase ataxia telangiectasia and Rad3-related protein (ATR) in PDAC cells and sensitizes them to ATR inhibitors. IFN triggers cell-cycle arrest in S-phase, which is accompanied by nucleotide pool insufficiency and nucleoside efflux. In combination with IFN, ATR inhibitors induce lethal DNA damage and downregulate nucleotide biosynthesis. ATR inhibition limits the growth of PDAC tumors in which IFN signaling is driven by stimulator of interferon genes (STING). These results identify a cross talk between IFN, DNA replication stress response networks, and nucleotide metabolism while providing the rationale for targeted therapeutic interventions that leverage IFN signaling in tumors.

[Choices of emergency treatment and surgical method for ruptured abdominal aortic aneurysms]

Objective: To investigate the emergency management process of ruptured abdominal aortic aneurysm (RAAA), and analyze the perioperative mortality factors of different surgical methods. Methods: The emergency data and hospitalization data of 91 patients with ruptured abdominal aortic aneurysm in Xiangya Hospital of Central South University from June 2010 to June 2019 were retrospectively analyzed.Twelve of the patients died preoperatively due to excessive blood loss, and the remaining 79 patients were hospitalized for open surgery (OSR) or endovascular repair (EVAR).The differences in age, time to hospital arrival, emergency preparation time, first creatinine value, emergency infusion volume, preoperative drop in blood pressure, preoperative use of vasoactive drugs and iliac artery involvement were compared between preoperative death group (n=12) and preoperative survival group (n=79), OSR group (n=50) and EVAR group (n=29), postoperative death group (n=23) and postoperative survival group (n=56). Results: Seventy-nine patients received open surgery or endovascular repair, and 23 died after operation. Age, time to hospital arrival, first creatinine value and emergency infusion volume were (77±11) years, (18±5)h, (469±150) μmol/L, (4 140±1 743) ml in the preoperative death group and (70±10) years, (12±8) h, (228±174) μmol/L, (1 358±1 211) ml in the preoperative survival group, respectively, and the differences were statistically significant (all P<0.05). There were no significant differences in preoperative data, intraoperative treatment and postoperative perioperative mortality between the open surgery group and the endovascular repair group (all P>0.05). The intraoperative blood loss, operation time and aortic occlusion rate in the endovascular repair group were 100 (50, 175) ml, (3.2±0.9) h, 13.8%, respectively, which were better than that in the open surgery group 1700 (600, 3425) ml, (5.2±1.1) h, 100%. The differences were statistically significant (all P<0.05). Age, emergency preparation time, first creatinine value, emergency infusion volume, blood pressure decline rate and vasoactive drug utilization rate in the death group were (77±8) years, (4.1±1.7) h, (456±172) μmol/L, (2 024±1 687) ml, 100%, 100%, respectively, and (68±10) years, (2.7±2.2) h, (135±26) μmol/L, (1 085±825) ml, 21.4%, 12.5% in the survival group, respectively. The differences were statistically significant (all P<0.05). Conclusions: Age, emergency preparation time, first creatinine value, emergency infusion volume, decreased blood pressure and use of vasoactive drugs are all associated with perioperative death in patients with ruptured abdominal aortic aneurysm. EVAR surgery is a better choice if conditions exist.

Mechanisms of Resistance to Prostate-Specific Membrane Antigen-Targeted Radioligand Therapy in a Mouse Model of Prostate Cancer

Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) is effective against prostate cancer (PCa), but all patients relapse eventually. Poor understanding of the underlying resistance mechanisms represents a key barrier to development of more effective RLT. We investigate the proteome and phosphoproteome in a mouse model of PCa to identify signaling adaptations triggered by PSMA RLT. Methods: Therapeutic efficacy of PSMA RLT was assessed by tumor volume measurements, time to progression, and survival in C4-2 or C4-2 TP53^-/- tumor-bearing nonobese diabetic scid γ-mice. Two days after RLT, the proteome and phosphoproteome were analyzed by mass spectrometry. Results: PSMA RLT significantly improved disease control in a dose-dependent manner. Proteome and phosphoproteome datasets revealed activation of genotoxic stress response pathways, including deregulation of DNA damage/replication stress response, TP53, androgen receptor, phosphatidylinositol-3-kinase/AKT, and MYC signaling. C4-2 TP53^-/- tumors were less sensitive to PSMA RLT than were parental counterparts, supporting a role for TP53 in mediating RLT responsiveness. Conclusion: We identified signaling alterations that may mediate resistance to PSMA RLT in a PCa mouse model. Our data enable the development of rational synergistic RLT-combination therapies to improve outcomes for PCa patients.

Therapeutics potentiating microglial p21-Nrf2 axis can rescue neurodegeneration caused by neuroinflammation

Neurodegenerative disorders are caused by progressive neuronal loss, and there is no complete treatment available yet. Neuroinflammation is a common feature across neurodegenerative disorders and implicated in the progression of neurodegeneration. Dysregulated activation of microglia causes neuroinflammation and has been highlighted as a treatment target in therapeutic strategies. Here, we identified novel therapeutic candidate ALGERNON2 (altered generation of neurons 2) and demonstrate that ALGERNON2 suppressed the production of proinflammatory cytokines and rescued neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease model. ALGERNON2 stabilized cyclinD1/p21 complex, leading to up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2), which contributes to antioxidative and anti-inflammatory responses. Notably, ALGERNON2 enhanced neuronal survival in other neuroinflammatory conditions such as the transplantation of induced pluripotent stem cell-derived dopaminergic neurons into murine brains. In conclusion, we present that the microglial potentiation of the p21-Nrf2 pathway can contribute to neuronal survival and provide novel therapeutic potential for neuroinflammation-triggered neurodegeneration.

Abstract 554: Histone deacetylase inhibition is synthetically lethal with arginine deprivation in pancreatic cancers with low argininosuccinate synthetase 1 expression

Background: Arginine (Arg) deprivation is a promising therapeutic approach for tumors with low argininosuccinate synthetase 1 (ASS1) expression. However, its efficacy as a single agent therapy needs to be improved as resistance is frequently observed.

Methods: A tissue microarray was performed to assess ASS1 expression in surgical specimens of pancreatic ductal adenocarcinoma (PDAC) and its correlation with disease prognosis. An RNA-Seq analysis examined the role of ASS1 in regulating global gene transcriptome. A high throughput screen of FDA-approved oncology drugs identified synthetic lethality between histone deacetylase (HDAC) inhibitors and Arg deprivation in PDAC cells with low ASS1 expression. We examined HDAC inhibitor panobinostat (PAN) and Arg deprivation in a panel of human PDAC cell lines, in ASS1-high and -knockdown/knockout isogenic models, in both anchorage-dependent and -independent cultures, and in multicellular complex cultures that model the PDAC tumor microenvironment. We examined the effects of combined Arg deprivation and PAN on DNA damage and the protein levels of key DNA repair enzymes. We also evaluate the efficacy of PAN and ADI-PEG20 (an Arg-degrading agent currently in Phase II clinical trials) in xenograft models with ASS1-low and -high PDAC tumors.

Results: Low ASS1 protein level is a negative prognostic indicator in PDAC. Arg deprivation in ASS1-deficient PDAC cells upregulated asparagine synthetase (ASNS) which redirected aspartate (Asp) from being used for de novo nucleotide biosynthesis, thus causing nucleotide insufficiency and impairing cell cycle S-phase progression. Comprehensively validated, HDAC inhibitors and Arg deprivation showed synthetic lethality in ASS1-low PDAC cells. Mechanistically, combined Arg deprivation and HDAC inhibition triggered degradation of a key DNA repair enzyme C-terminal-binding protein interacting protein (CtIP), resulting in DNA damage and apoptosis. In addition, S-phase-retained ASS1-low PDAC cells (due to Arg deprivation) were also sensitized to DNA damage, thus yielding effective cell death. Compared to single agents, the combination of PAN and ADI-PEG20 showed better efficacy in suppressing ASS1-low PDAC tumor growth in mouse xenograft models.

Conclusion: The combination of PAN and ADI-PEG20 is a rational translational therapeutic strategy for treating ASS1-low PDAC tumors through synergistic induction of DNA damage.

Citation Format: Stephanie S Kim, JING CUI, Shili Xu, Soumya Poddar, Thuc M. Le, Luyi Li, Nanping Wu, Alexandra Moore, Lei Zhou, Alice Yu, Amanda M. Dann, Irmina A. Elliott, Evan R. Abt, Woosuk Kim, David W. Dawson, Caius G. Radu, Timothy R. Donahue. Histone deacetylase inhibition is synthetically lethal with arginine deprivation in pancreatic cancers with low argininosuccinate synthetase 1 expression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 554.

Abstract A41: Nucleotide metabolism heterogeneity in mutant KRAS pancreatic cancer

Mutant KRAS orchestrates major metabolic adaptations critical for pancreatic ductal adenocarcinoma (PDAC) growth and survival, including changes in glucose, amino acid, lipid and energy metabolism. However, how nucleotide metabolism in PDAC is impacted by mutant KRAS has received much less attention, even though nucleotides play critical roles in major biologic processes including nucleic acid synthesis, phospholipid biosynthesis and protein glycosylation. Pyrimidine nucleotide metabolism is a highly complex and regulated system with multiple pathways contributing to its plasticity and robustness. Pyrimidine nucleotides can be produced via the de novo pathway (DNP) that utilizes glucose and amino acids, and the nucleoside scavenging pathway (NSP) that utilizes extracellular uridine and cytidine. We hypothesize that nucleotide products of RNA turnover can fuel a third route for pyrimidine biosynthesis, which we term the nucleotide recycling pathway (NRP). Among these three major pyrimidine nucleotide biosynthetic pathways, the DNP has been studied most extensively. The biologic and therapeutic significance of the NSP and NRP in PDAC, as well as their regulation and coordination with DNP in the context of mutant KRAS signaling, are poorly understood. We further hypothesize that since PDAC tumor microenvironment is characterized by insufficient supply of nutrients and oxygen, these tumors have limited DNP capacity and increased reliance on alternate pyrimidine biosynthetic pathways. Here, we describe a novel mass spectrometric (MS) method to measure the contributions of pyrimidine nucleotide convergent pathways to RNA and DNA synthesis in PDAC models. Applying this method to a panel of PDAC models, including patient-derived primary lines, revealed previously unappreciated pyrimidine biosynthetic heterogeneity, suggesting the existence of distinct pyrimidine nucleotide metabolic subtypes. Identifying and characterizing these subtypes in the context of oncogenic KRAS signaling may enable stratification of PDAC tumors and guide the development of novel therapeutic approaches.

Citation Format: Thuc M. Le, Woosuk Kim, Joseph R. Capri, Anthony E. Cabebe, Wes Armstrong, Evan Abt, Soumya Poddar, Shili Xu, Dave Dawson, Timothy R. Donahue, Caius G. Radu. Nucleotide metabolism heterogeneity in mutant KRAS pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr A41.

Abstract A46: CD73 inhibition enhances the effect of anti-PD-1 therapy on KRAS-mutated pancreatic cancer model

Background: CD73 catalyzes the extracellular generation of adenosine (ADO) from adenosine monophosphate (AMP). High levels of ADO, found in the tumor microenvironment (TME), have been shown to suppress immune responses and curtail T-cell activation in the presence of anti-PD-1/PD-L1 blocking antibodies. Oncogenic drivers resulting from activating mutations, such as KRAS, BRAF, and EGFR mutations, are commonly treated with tyrosine kinase inhibitors that result in robust but nondurable responses. We show here that KRAS mutations, of which 60% were derived from pancreatic adenocarcinoma (PDAC) samples, significantly upregulated CD73 expression and resulted in worsening prognosis. In a murine model of pancreatic cancer bearing KRASG12C mutation, coadministration of CD73 inhibitor with anti-PD-1 in established tumors resulted in significant tumor growth retardation, comparable to KRAS inhibitor alone. These data support the rationale for the clinical development of CD73 inhibitors in pancreatic cancer.

Methods: Linear models were used to evaluate the ability of 299 pan-cancer consensus oncogenic drivers to predict CD73 expression independent of tumor type in the TCGA dataset. Immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded (FFPE) samples was performed using CD73 (Cell Signaling, D7F9A) primary antibody and detected using anti-rabbit HRP. CD73 expressing cells were detected by DAB chromogen and quantified using QuPath Software. CD73 activity in fresh frozen tissues were detected using the Wachstein-Meisel method. C57BL/6J mice bearing established KP4662-G12C tumors (&gt;150 mm3) were treated with A0001421 (CD73i), 30 mg/kg; once a day; s.c. and anti-PD1 (Clone RMP 1-14): 10 mg/kg; twice a week; i.p. Mice were treated for two weeks starting from day 10 post-tumor. Treatment efficacy was monitored using micro-computed tomography (Genisys PET/CT G8 (Sofie Biosciences). All small-molecule inhibitors were synthesized by Arcus Biosciences, Inc.

Results: Out of the 299 oncogenes, alterations in KRAS, BRAF, and EGFR were the top 3 oncogenes upregulating CD73 expression. Increase in CD73 expression in KRAS-mutated tumors was further confirmed by IHC. Data extrapolated from Koyama et al. suggest that PD-1 nonresponsive mice express higher levels of adenosine pathway genes, including CD73 and CD39. Coadministration of CD73 inhibitor with anti-PD-1 was superior to anti-PD-1 alone in limiting tumor growth of an aggressive model of pancreatic cancer. Global changes in immune contexture and TME were also observed, consistent with the immune modulatory effects of inhibiting CD73 activity.

Conclusion: CD73 is a highly efficient ecto-enzyme that catalyzes the hydrolysis of AMP to immune-suppressive ADO and is associated with worsening prognosis across multiple malignancies. AB680, a potent and selective CD73 inhibitor with excellent safely and pharmacokinetic profile, is currently undergoing clinical evaluation in 1L metastatic PDAC in combination with AB122 and chemotherapy.

Citation Format: Thuc M. Le, Akshata Udyavar, Woosuk Kim, Arthur E. Cho, Luyi Li, Daniel DiRenzo, Brandon Rosen, Matthew J. Walters, Joanne B.L. Tan, Caius G. Radu. CD73 inhibition enhances the effect of anti-PD-1 therapy on KRAS-mutated pancreatic cancer model [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A46.

Isoquinoline thiosemicarbazone displays potent anticancer activity with in vivo efficacy against aggressive leukemias

A potent class of isoquinoline-based α-N-heterocyclic carboxaldehyde thiosemicarbazone (HCT) compounds has been rediscovered; based upon this scaffold, three series of antiproliferative agents were synthesized through iterative rounds of methylation and fluorination modifications, with anticancer activities being potentiated by physiologically relevant levels of copper. The lead compound, HCT-13, was highly potent against a panel of pancreatic, small cell lung carcinoma, prostate cancer, and leukemia models, with IC₅₀ values in the low-to-mid nanomolar range. Density functional theory (DFT) calculations showed that fluorination at the 6-position of HCT-13 was beneficial for ligand-copper complex formation, stability, and ease of metal-center reduction. Through a chemical genomics screen, we identify DNA damage response/replication stress response (DDR/RSR) pathways, specifically those mediated by ataxia-telangiectasia and Rad3-related protein kinase (ATR), as potential compensatory mechanism(s) of action following HCT-13 treatment. We further show that the cytotoxicity of HCT-13 is copper-dependent, that it promotes mitochondrial electron transport chain (mtETC) dysfunction, induces production of reactive oxygen species (ROS), and selectively depletes guanosine nucleotide pools. Lastly, we identify metabolic hallmarks for therapeutic target stratification and demonstrate the in vivo efficacy of HCT-13 against aggressive models of acute leukemias in mice.

Prevalence and Predictors of Uncontrolled Asthma in Children Referred for Asthma and Other Atopic Diseases

Background

Uncontrolled asthma in children is still highly prevalent despite the availability of effective asthma treatment. We investigated 1) the prevalence of uncontrolled asthma among children referred for asthma and referred for atopic diseases other than asthma (ie food allergy, allergic rhinitis or atopic dermatitis) to secondary care; and 2) the predictors associated with uncontrolled asthma.

Methods

All children (4 to 18 years) referred for asthma or atopic diseases other than asthma to 8 secondary care centers in The Netherlands were invited to an electronic portal (EP). The EP is a web-based application with several validated questionnaires including the ISAAC questionnaires and the Asthma Control Test (ACT). Children were eligible for inclusion in this study when their parents reported in the EP that their child had asthma diagnosed by a physician. The ACT was used to assess asthma control. Multiple predictors of asthma control (patient, asthma and atopic characteristics) were evaluated by univariable and multivariable logistic regression analyses.

Results

We included 408 children: 259 children (63%) with asthma referred for asthma and 149 children (37%) with asthma referred for atopic diseases other than asthma. Thirty-nine percent of all children had uncontrolled asthma: 47% of the children referred for asthma and 26% of the children referred for atopic diseases other than asthma. Predictors associated with uncontrolled asthma were a family history of asthma (odds ratio [OR] 2.08; 95% confidence interval [95% CI] 1.34 to 3.24), and recurrent upper and lower respiratory tract infections in the past year (OR 2.40; 95% CI 1.52 to 3.81 and OR 2.00; 95% CI 1.25 to 3.23, respectively).

Conclusion

Uncontrolled asthma is highly prevalent in children with asthma referred to secondary care, even if children are primarily referred for atopic diseases other than asthma. Thus, attention should be paid to asthma control in this population.

Correlates of body mass index among primary school children in Ho Chi Minh City, Vietnam

OBJECTIVES

To document the prevalence of overweight and obesity and examine associated risk factors.

STUDY DESIGN

A cross-sectional survey was conducted in 16 primary public schools in eight districts of Ho Chi Minh City in 2016. A multistage clustering sampling method was used to collect a sample of 1806 pupils attending the first, second, and third grades (7-9 years).

METHODS

Age- and sex-adjusted body mass index (BMI) status was defined using International Obesity Taskforce cut-offs. Ordered probit regression models were used to assess the association between child BMI and its socio-economic and demographic risk factors. The model was estimated separately for boys and girls to assess the extent to which the socio-economic gradients in BMI vary by gender.

RESULTS

The prevalence of obesity among boys was twice the rate for girls (24.7 vs 12.3%). The prevalence of overweight and obesity were also higher among pupils attending schools located in urban districts than in semi-rural districts. Gender, household wealth, the frequency of having breakfast at home, parental body weight, and school location were strong predictors of child BMI status. The protective effect of having breakfast more frequently at home against the risk of overweight/obesity was more pronounced in girls than in boys. Father's body weight and child BMI were more strongly associated with boys from poorer households than boys from wealthier households, while the differences were not significant for girls.

CONCLUSIONS

The high prevalence of childhood overweight and obesity indicates an urgent need for more gender-specific, effective intervention, and prevention programs.

Histone deacetylase inhibition is synthetically lethal with arginine deprivation in pancreatic cancers with low argininosuccinate synthetase 1 expression

Arginine (Arg) deprivation is a promising therapeutic approach for tumors with low argininosuccinate synthetase 1 (ASS1) expression. However, its efficacy as a single agent therapy needs to be improved as resistance is frequently observed.

Methods: A tissue microarray was performed to assess ASS1 expression in surgical specimens of pancreatic ductal adenocarcinoma (PDAC) and its correlation with disease prognosis. An RNA-Seq analysis examined the role of ASS1 in regulating the global gene transcriptome. A high throughput screen of FDA-approved oncology drugs identified synthetic lethality between histone deacetylase (HDAC) inhibitors and Arg deprivation in PDAC cells with low ASS1 expression. We examined HDAC inhibitor panobinostat (PAN) and Arg deprivation in a panel of human PDAC cell lines, in ASS1-high and -knockdown/knockout isogenic models, in both anchorage-dependent and -independent cultures, and in multicellular complex cultures that model the PDAC tumor microenvironment. We examined the effects of combined Arg deprivation and PAN on DNA damage and the protein levels of key DNA repair enzymes. We also evaluated the efficacy of PAN and ADI-PEG20 (an Arg-degrading agent currently in Phase 2 clinical trials) in xenograft models with ASS1-low and -high PDAC tumors.

Results: Low ASS1 protein level is a negative prognostic indicator in PDAC. Arg deprivation in ASS1-deficient PDAC cells upregulated asparagine synthetase (ASNS) which redirected aspartate (Asp) from being used for de novo nucleotide biosynthesis, thus causing nucleotide insufficiency and impairing cell cycle S-phase progression. Comprehensively validated, HDAC inhibitors and Arg deprivation showed synthetic lethality in ASS1-low PDAC cells. Mechanistically, combined Arg deprivation and HDAC inhibition triggered degradation of a key DNA repair enzyme C-terminal-binding protein interacting protein (CtIP), resulting in DNA damage and apoptosis. In addition, S-phase-retained ASS1-low PDAC cells (due to Arg deprivation) were also sensitized to DNA damage, thus yielding effective cell death. Compared to single agents, the combination of PAN and ADI-PEG20 showed better efficacy in suppressing ASS1-low PDAC tumor growth in mouse xenograft models.

Conclusion: The combination of PAN and ADI-PEG20 is a rational translational therapeutic strategy for treating ASS1-low PDAC tumors through synergistic induction of DNA damage.

Metabolic Modifier Screen Reveals Secondary Targets of Protein Kinase Inhibitors within Nucleotide Metabolism

Biosynthesis of the pyrimidine nucleotide uridine monophosphate (UMP) is essential for cell proliferation and is achieved by the activity of convergent de novo and salvage metabolic pathways. Here we report the development and application of a cell-based metabolic modifier screening platform that leverages the redundancy in pyrimidine metabolism for the discovery of selective UMP biosynthesis modulators. In evaluating a library of protein kinase inhibitors, we identified multiple compounds that possess nucleotide metabolism modifying activity. The JNK inhibitor JNK-IN-8 was found to potently inhibit nucleoside transport and engage ENT1. The PDK1 inhibitor OSU-03012 (also known as AR-12) and the RAF inhibitor TAK-632 were shown to inhibit the therapeutically relevant de novo pathway enzyme DHODH and their affinities were unambiguously confirmed through in vitro assays and co-crystallization with human DHODH.

Abstract 4264: Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion

Objective: Functional lysosomes are required for autophagy and macropinocytosis, the intra- and extracellular scavenging pathways cancer cells engage for nutrient acquisition. Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit high basal lysosomal activity, and genetic or pharmacologic inhibition of lysosome function suppresses PDAC cell proliferation and tumor growth. However, the codependencies induced by lysosomal inhibition in PDAC have not been systematically explored. We hypothesized that identification and targeting the lysosomal inhibition-induced codependencies in PDAC cells would be an effective therapeutic strategy.

Methods: A comprehensive pharmacological inhibition screen of the protein kinome was performed to identified lysosomal inhibition-induced codependency. LC-MS/MS-MRM and LC-MS methods were used to examine nucleotide biosynthesis and amino acid levels, respectively, to understand the mechanism of the identified codependency. A broad panel of PDAC cell lines, primary PDAC culture models, two- and three-dimentional culture models, a PDAC cell/stroma spheroid coculture model, and xenograft and syngeneic PDAC animal models were used to evaluate the treatment efficacy.

Results: We found that replication stress response (RSR) inhibitors were synthetically lethal with chloroquine (CQ) and other lysosomal inhibitors in PDAC cells. CQ treatment reduced de novo nucleotide biosynthesis and induced replication stress. We found that CQ treatment caused mitochondrial dysfunction and depletion of aspartate, an essential precursor for de novo nucleotide synthesis, as an underlying mechanism. Supplementation with aspartate in PDAC cell culture and overexpression of the aspartate transporter SLC1A3 in xenograft PDAC tumors partially rescued the phenotypes induced by CQ. The synergy of CQ and the RSR inhibitor VE-822 was comprehensively validated in a broad panel of PDAC cell lines and primary PDAC cultures, in two- and three-dimentional PDAC cultures, in heterotypic spheroid culture with cancer-associated fibroblasts, and in in vivo xenograft and syngeneic PDAC mouse models.

Conclusion: We discovered a codependency on functional lysosomes and an intact RSR pathway in PDAC, and developed the combination of CQ and RSR inhibitors as a translational therapeutic approach for PDAC.

Citation Format: Shili Xu, Irmina A. Elliott, Amanda M. Dann, Stephanie S. Kim, Evan R. Abe, Woosuk Kim, Soumya Poddar, Alexandra Moore, Lei Zhou, Jennifer L. Williams, Joseph R. Capri, Razmik Ghukasyan, Cynthia Matsumura, D. Andrew Tucker, Wesley R. Armstrong, Anthony E. Cabebe, Nanping Wu, Luyi Li, Thuc M. Le, Caius G. Radu, Timothy R. Donahue. Lysosome inhibition sensitizes pancreatic cancer to replication stress by aspartate depletion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4264.

Abstract 4971: Identification of new modulators of nucleotide metabolism and replication stress in PDAC

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States, with an overall survival of less than one year. An improved knowledge of PDAC biology, to uncover vulnerabilities specific to cancer cells, is needed to develop more effective therapeutic options. We are investigating the intersection between three aspects of PDAC biology that can, ultimately, be developed for therapeutics: (i) cytokine signaling, with a particular focus on the metabolic effects of interferons (IFNs), which are present in the highly inflamed and dense PDAC stromal microenvironment; (ii) nucleotide metabolism, a network of tightly regulated biochemical pathways that produce deoxyribonucleotide triphosphates (dNTPs), which are required for DNA replication; and (iii) the replication stress response pathway, an intracellular signaling mechanism that is activated by perturbations in DNA replication, and has been recently shown to govern key aspects of nucleotide metabolism. We hypothesize that IFN signaling reduces the levels of already limited dNTP pools in PDAC cancer cells, which respond by initiating metabolic and signaling mechanisms that coordinately function to increase dNTP recycling and biosynthetic mechanisms while simultaneously reducing their consumption. Our results, which include integrated metabolic, transcriptomic, and proteomic analyses, indicate that IFN signaling in PDAC cells induces a switch in nucleotide metabolism from a biosynthetic to a predominantly dNTP catabolic phenotype. This switch appears to be mediated by dNTP phosphohydrolysis catalyzed by the Sterile Alpha Motif and Histidine/aspartic acid Domain-containing protein (SAMHD1). Furthermore, we have investigated the effects of IFN signaling on dNTP phosphohydrolysis to deoxyribonucleosides across a panel of PDAC cancer cells, resembling the spectrum of the human disease. We also examined the biochemical fates of the deoxyribonucleoside products of SAMHD1 using targeted LC-MS/MS metabolic tracing experiments. We have also demonstrated a role for the replication stress response kinase Ataxia Telangiectasia and Rad3-related protein (ATR) in regulating dNTP levels in PDAC cells exposed to IFN. Furthermore, we have demonstrated that ATR activity is an actionable co-dependency of IFN-exposed cells and that pharmacologic inhibition of ATR eradicates PDAC cells exposed to IFN. Collectively, these studies increase our understanding of the interplay between cell extrinsic (IFN signaling) and intrinsic (replication stress) signal transduction networks, and the regulation of nucleotide metabolism in PDAC, and uncovered critical vulnerabilities to be exploited by new therapeutic approaches against this extremely aggressive and difficult to treat malignancy.

Citation Format: Evan R. Abt, Amanda Dann, Thuc M. Le, Joe R. Capri, Chloe M. Cheng, Juna Yi, Soumya Poddar, Woosuk Kim, Timothy R. Donahue, Caius G. Radu. Identification of new modulators of nucleotide metabolism and replication stress in PDAC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4971.

Metabolic characterization of isocitrate dehydrogenase (IDH) mutant and IDH wildtype gliomaspheres uncovers cell type-specific vulnerabilities

Background

There is considerable interest in defining the metabolic abnormalities of IDH mutant tumors to exploit for therapy. While most studies have attempted to discern function by using cell lines transduced with exogenous IDH mutant enzyme, in this study, we perform unbiased metabolomics to discover metabolic differences between a cohort of patient-derived IDH1 mutant and IDH wildtype gliomaspheres.

Methods

Using both our own microarray and the TCGA datasets, we performed KEGG analysis to define pathways differentially enriched in IDH1 mutant and IDH wildtype cells and tumors. Liquid chromatography coupled to mass spectrometry analysis with labeled glucose and deoxycytidine tracers was used to determine differences in overall cellular metabolism and nucleotide synthesis. Radiation-induced DNA damage and repair capacity was assessed using a comet assay. Differences between endogenous IDH1 mutant metabolism and that of IDH wildtype cells transduced with the IDH1 (R132H) mutation were also investigated.

Results

Our KEGG analysis revealed that IDH wildtype cells were enriched for pathways involved in de novo nucleotide synthesis, while IDH1 mutant cells were enriched for pathways involved in DNA repair. LC-MS analysis with fully labeled ¹³C-glucose revealed distinct labeling patterns between IDH1 mutant and wildtype cells. Additional LC-MS tracing experiments confirmed increased de novo nucleotide synthesis in IDH wildtype cells relative to IDH1 mutant cells. Endogenous IDH1 mutant cultures incurred less DNA damage than IDH wildtype cultures and sustained better overall growth following X-ray radiation. Overexpression of mutant IDH1 in a wildtype line did not reproduce the range of metabolic differences observed in lines expressing endogenous mutations, but resulted in depletion of glutamine and TCA cycle intermediates, an increase in DNA damage following radiation, and a rise in intracellular ROS.

Conclusions

These results demonstrate that IDH1 mutant and IDH wildtype cells are easily distinguishable metabolically by analyzing expression profiles and glucose consumption. Our results also highlight important differences in nucleotide synthesis utilization and DNA repair capacity that could be exploited for therapy. Altogether, this study demonstrates that IDH1 mutant gliomas are a distinct subclass of glioma with a less malignant, but also therapy-resistant, metabolic profile that will likely require distinct modes of therapy.

Co-targeting of convergent nucleotide biosynthetic pathways for leukemia eradication

Co-targeting of both de novo and salvage pathways for dCTP biosynthesis shows efficacy in T-ALL and B-ALL.

Pharmacological targeting of metabolic processes in cancer must overcome redundancy in biosynthetic pathways. Deoxycytidine (dC) triphosphate (dCTP) can be produced both by the de novo pathway (DNP) and by the nucleoside salvage pathway (NSP). However, the role of the NSP in dCTP production and DNA synthesis in cancer cells is currently not well understood. We show that acute lymphoblastic leukemia (ALL) cells avoid lethal replication stress after thymidine (dT)-induced inhibition of DNP dCTP synthesis by switching to NSP-mediated dCTP production. The metabolic switch in dCTP production triggered by DNP inhibition is accompanied by NSP up-regulation and can be prevented using DI-39, a new high-affinity small-molecule inhibitor of the NSP rate-limiting enzyme dC kinase (dCK). Positron emission tomography (PET) imaging was useful for following both the duration and degree of dCK inhibition by DI-39 treatment in vivo, thus providing a companion pharmacodynamic biomarker. Pharmacological co-targeting of the DNP with dT and the NSP with DI-39 was efficacious against ALL models in mice, without detectable host toxicity. These findings advance our understanding of nucleotide metabolism in leukemic cells, and identify dCTP biosynthesis as a potential new therapeutic target for metabolic interventions in ALL and possibly other hematological malignancies.

Anaphylactic versus mild reactions to hazelnut and apple in a birch-endemic area: different sensitization profiles?

BACKGROUND

Hazelnut and apple are common causes of food allergy in Europe. In northern Europe, symptoms are usually mild and associated with cross-reactivity to the birch pollen allergen, Bet v 1. In the Mediterranean area, symptoms are more frequently severe and associated with sensitization to lipid transfer protein (LTP). This study compared patients with anaphylactic versus mild reactions to hazelnut and apple in The Netherlands, a birch-endemic area, with respect to sensitization to Bet v 1-homologues (i.e. PR10-proteins) and LTP.

METHODS

Twenty-one patients fulfilling the criteria for anaphylaxis and 21 with only mild symptoms (oral allergy) to hazelnut and/or apple were recruited. Specific immunoglobulin E to birch pollen, apple, hazelnut and PR10-proteins (rBet v 1, rPru p 1, rMal d 1 and rCor a 1) and recombinant LTP (rPru p 3 and rCor a 8) was measured by ImmunoCAP.

RESULTS

Both mild and anaphylactic apple-allergic patients were sensitized to PR10-proteins, whereas only 1/7 of the mild and none of the anaphylactic apple-allergic patients was sensitized to LTP. In contrast, anaphylactic hazelnut-allergic patients displayed no such clear sensitization pattern: some were sensitized to both PR10-proteins and hazelnut LTP (1/9), and others to only LTP (2/9) or to only PR10-proteins (4/9) or to neither PR10-proteins nor LTP (2/9).

CONCLUSION

This study shows that in a birch-endemic area, the sensitization profile to PR10-proteins and LTP in anaphylactic patients may differ between different plant foods. In this patient group, anaphylaxis to hazelnut can be LTP-associated, whereas anaphylaxis to apple is not.

Suboptimal management of acute food-allergic reactions by patients, emergency departments and general practitioners

Suboptimal food allergy management by patients and doctors.

Estimation and presentation of blood flow and velocity from angiographic scans in the human cerebral arterial system

This paper provides an overview of blood flow in the arterial system and aims to estimate the blood velocity from cerebral angiography scans without having acquired data on velocity by using Murray's Law. The estimation technique post-processes the scan and provides crucial 3D visual data for the development of a visualization program of the blood flow in the human brain.

Reported food allergy to peanut, tree nuts and fruit: comparison of clinical manifestations, prescription of medication and impact on daily life

BACKGROUND

Peanut (PN), tree nuts (TN) and fruits are frequent causes of food allergy (FA). Peanut and TN are believed to cause more severe reactions than fruits. However, there are no studies comparing the severity of PN, TN and fruit allergy within one patient group.

METHODS

Four-hundred and eleven adult patients referred to our tertiary allergy center with suspicion of FA completed a standardized questionnaire. Patients with a typical history of immunoglobulin E (IgE)-mediated allergy, e.g. oropharyngeal symptoms to PN, TN (hazelnut, walnut, cashew nut) or fruit (apple, kiwi, peach, pear and cherry) were recruited (218/411). The objective was to evaluate differences in clinical severity between PN, TN and fruit allergy and how this was reflected by prescription of emergency medication and impact on daily life.

RESULTS

Eighty-two percent of the included 218 patients were sensitized to the respective foods. The percentages of severe symptoms (i.e. respiratory or cardiovascular symptoms) in PN, TN and fruit allergic patients were respectively 47%, 39% and 31% (respiratory) and 11%, 5.0% and 3.4% (cardiovascular). Prescription and use of emergency medication (epinephrine, antihistamines and steroids) did not differ among the three groups. The majority of patients with a PN or TN allergy (72%) and fruit allergy (62%) reported that FA influences their daily life considerably.

CONCLUSIONS

Fruit allergy causes less severe symptoms than TN and especially PN allergy. However, this is not reflected in the prescription or use of emergency medication. This may indicate that physicians are not fully acquainted with the guidelines for prescription of emergency medication. A high impact on daily life was found both in PN, TN and in fruit allergy.

Diversity of the surface properties of Lactococci and consequences on adhesion to food components

Bacteria possess surface properties, related to their charge, hydrophobicity and Lewis acid/base characteristics, that are involved in the attachment processes of microorganisms to surfaces. Fermentation bulks and food matrixes are complex heterogeneous media containing various components with different physicochemical characteristics. The aim of the present study was to investigate whether (i) bacteria present in a food matrix, interacted physicochemically at their surface level with the other constituents and (ii) the diversity of bacterial surface properties could result in a diversity of microbial adhesion to components and thus in a diversity of tolerance to toxic compounds. The surface properties of 20 lactic acid bacteria were characterized by the MATS method showing their relatively hydrophilic and various basic characteristics. The results obtained from a set of representative strains showed that (i) the strains with higher affinity for apolar solvents adsorbed more to lipids and hydrophobic compounds, (ii) the more the strains adsorbed to a toxic solvent, the less they were tolerant to this solvent. A diversity of bacterial surface properties was observed for the strains in the same species showing the importance of choosing bacteria according to their surface properties in function of technological objectives.

The 72-kDa component of signal recognition particle is cleaved during apoptosis

Proteins cleaved by apoptotic caspases are commonly recognized by autoantibodies found in the serum of patients with rheumatic disease. We report that the 72-kDa signal recognition particle (SRP) protein, a rare target of autoantibodies found in the serum of patients with dermatomyositis and systemic lupus erythematosus, is rapidly cleaved in Jurkat T cells treated with apoptotic (i.e. Fas ligation, treatment with gamma or ultraviolet radiation, or co-culture with anisomycin or staurosporine) but not proliferative (CD3 cross-linking) stimuli. Cleavage of SRP 72 produces a 66-kDa amino-terminal fragment and a 6-kDa carboxyl-terminal fragment that is selectively phosphorylated on serine residues. Cleavage of SRP 72 is prevented by chemical and peptide caspase inhibitors, and by overexpression of bcl-2, an inhibitor of apoptotic cell death. Analysis of the carboxyl terminus of SRP 72 has identified a putative cleavage site (SELD/A) for group III caspases, and carboxyl-terminal serine residues that are highly conserved in phylogeny. Both serine phosphorylation and caspase cleavage of SRP 72 are observed in cells derived from human, dog, rat, and mouse. Canine SRP 72 is cleaved in vitro by recombinant caspase 3 but retains the ability to mediate transport of a signal peptide-containing protein into the endoplasmic reticulum lumen. The 72-kDa component of the SRP joins a growing list of autoantigens that undergo post-translational modifications during programmed cell death.

Effect of temperature on the wing length-body weight relationship in Anopheles quadrimaculatus

The effect of temperature on the relationship between wing length and body weight in a cohort of Anopheles quadrimaculatus was analyzed in a laboratory experiment. Mosquitoes reared at 23 degrees C were heavier and had longer wings than did those reared at 28 degrees C. In addition, even after differences in body weight were removed statistically, mosquitoes raised at 23 degrees C had longer wings than did those at 28 degrees C. The concordance of these results with those of a previous photoperiod study suggests that temperature and photoperiod experienced during development have some similar effects on the morphology of An. quadrimaculatus.

A mouthrinse which optimizes in vivo generation of hypothiocyanite

We report here the properties of a mouthrinse which enhances one of the natural defense factors in human saliva, the salivary peroxidase system. Concentrations of the antimicrobial agent, the hypothiocyanite (OSCN-) ion, can be increased in vivo to bacteriostatic levels by use of a mouthrinse which is 4 mM (0.014%) in hydrogen peroxide and 1 mM (0.0097%) in potassium thiocyanate at pH 5.5. The volume of the rinse, the H2O2 concentrations, and the pH were shown to be determinants of the concentration of OSCN- generated by the rinse.