Immunomodulatory Functions of Glycolipids from Pathogens

The cell envelopes of pathogens comprise a wealth of unique glycolipids, which are important modulators of the host immune responses during infection and in some cases have been used as adjuvants. Despite this abundant basic knowledge, the identities of the host immune receptors for mycobacterial lipids have long been elusive (Ishikawa et al., Trends Immunol 38:66-76, 2017). We describe the method of how to isolate glycolipids from microorganisms and how to analyze the glycolipids' potential to activate reporter cells and bone marrow-derived dendritic cells (BMDCs), such as surface marker expression and reactive oxygen species (ROS) production. Additionally, we outline an in vitro BMDC/T cell coculture model to investigate functional consequences of leukocyte activation, such as cytokine production. In this chapter, we provide a guide for extracting glycolipids from microorganisms and how to use them to activate leukocytes. We also present methods on how to generate and activate reporter cells, as well as BMDCs and how to set up BMDC/T cell cocultures. We further outline how to generate samples and how to analyze the immunomodulatory effect glycolipid exposure has on these cells, via flow cytometry, ROS production assays and ELISA.

Self-referential immune recognition through C-type lectin receptors

The term "lectin" is derived from the Latin word lego- (aggregate) (Boyd & Shapleigh, 1954). Indeed, lectins' folds can flexibly alter their pocket structures just like Lego blocks, which enables them to grab a wide-variety of substances. Thus, this useful fold is well-conserved among various organisms. Through evolution, prototypic soluble lectins acquired transmembrane regions and signaling motifs to become C-type lectin receptors (CLRs). While CLRs seem to possess certain intrinsic affinity to self, some CLRs adapted to efficiently recognize glycoconjugates present in pathogens as pathogen-associated molecular patterns (PAMPs) and altered self. CLRs further extended their diversity to recognize non-glycosylated targets including pathogens and self-derived molecules. Thus, CLRs seem to have developed to monitor the internal/external stresses to maintain homeostasis by sensing various "unfamiliar" targets. In this review, we will summarize recent advances in our understanding of CLRs, their ligands and functions and discuss future perspectives.

β2-Integrins – Regulatory and Executive Bridges in the Signaling Network Controlling Leukocyte Trafficking and Migration

Leukocyte trafficking is an essential process of immunity, occurring as leukocytes travel within the bloodstream and as leukocyte migration within tissues. While it is now established that leukocytes can utilize the mesenchymal migration mode or amoeboid migration mode, differences in the migratory behavior of leukocyte subclasses and how these are realized on a molecular level in each subclass is not fully understood. To outline these differences, first migration modes and their dependence on parameters of the extracellular environments will be explained, as well as the intracellular molecular machinery that powers migration in general. Extracellular parameters are detected by adhesion receptors such as integrins. β2-integrins are surface receptors exclusively expressed on leukocytes and are essential for leukocytes exiting the bloodstream, as well as in mesenchymal migration modes, however, integrins are dispensable for the amoeboid migration mode. Additionally, the balance of different RhoGTPases – which are downstream of surface receptor signaling, including integrins – mediate formation of membrane structures as well as actin dynamics. Individual leukocyte subpopulations have been shown to express distinct RhoGTPase profiles along with their differences in migration behavior, which will be outlined. Emerging aspects of leukocyte migration include signal transduction from integrins via actin to the nucleus that regulates DNA status, gene expression profiles and ultimately leukocyte migratory phenotypes, as well as altered leukocyte migration in tumors, which will be touched upon.

Human Dectin-1 is O-glycosylated and serves as a ligand for C-type lectin receptor CLEC-2

C-type lectin receptors (CLRs) elicit immune responses upon recognition of glycoconjugates present on pathogens and self-components. While Dectin-1 is the best-characterized CLR recognizing β-glucan on pathogens, the endogenous targets of Dectin-1 are not fully understood. Herein, we report that human Dectin-1 is a ligand for CLEC-2, another CLR expressed on platelets. Biochemical analyses revealed that Dectin-1 is a mucin-like protein as its stalk region is highly O-glycosylated. A sialylated core 1 glycan attached to the EDxxT motif of human Dectin-1, which is absent in mouse Dectin-1, provides a ligand moiety for CLEC-2. Strikingly, the expression of human Dectin-1 in mice rescued the lethality and lymphatic defect resulting from a deficiency of Podoplanin, a known CLEC-2 ligand. This finding is the first example of an innate immune receptor also functioning as a physiological ligand to regulate ontogeny upon glycosylation.

β2-Integrin Adhesion Regulates Dendritic Cell Epigenetic and Transcriptional Landscapes to Restrict Dendritic Cell Maturation and Tumor Rejection

Dendritic cells (DC), the classic antigen-presenting cells of the immune system, switch from an adhesive, phagocytic phenotype in tissues, to a mature, nonadhesive phenotype that enables migration to lymph nodes to activate T cells and initiate antitumor responses. Monocyte-derived DCs are used in cancer immunotherapy, but their clinical efficacy is limited. Here, we show that cultured bone marrow-derived DCs (BM-DC) expressing dysfunctional β2-integrin adhesion receptors displayed enhanced tumor rejection capabilities in B16.OVA and B16-F10 melanoma models. This was associated with an increased CD8⁺ T-cell response. BM-DCs expressing dysfunctional β2-integrins or manipulated to disrupt integrin adhesion or integrin/actin/nuclear linkages displayed spontaneous maturation in ex vivo cultures (increased costimulatory marker expression, IL12 production, and 3D migration capabilities). This spontaneous maturation was associated with an altered DC epigenetic/transcriptional profile, including a global increase in chromatin accessibility and H3K4me3/H3K27me3 histone methylation. Genome-wide analyses showed that H3K4me3 methylation was increased on DC maturation genes, such as CD86, Il12, Ccr7, and Fscn1, and revealed a role for a transcription factor network involving Ikaros and RelA in the integrin-regulated phenotype of DCs. Manipulation of the integrin-regulated epigenetic landscape in wild-type ex vivo-cultured BM-DCs enhanced their functionality in tumor rejection in vivo. Thus, β2-integrin-mediated adhesion to the extracellular environment plays an important role in restricting DC maturation and antitumor responses through regulation of the cellular epigenetic and transcriptional landscape. Targeting β2-integrins could therefore be a new strategy to improve the performance of current DC-based cancer immunotherapies.

POS0834 LONG-TERM OUTCOME OF SSC ASSOCIATED ILD: IMPROVED SURVIVAL IN PPI TREATED PATIENTS

Background:

Gastroesophageal reflux disease (GERD) occurs frequently in patients with systemic sclerosis (SSc) and SSc-associated interstitial lung disease (SSc-ILD). PPI use has to been shown to improve survival in patients with idiopathic pulmonary fibrosis, whereas to date there are no data on the use of PPI in SSc-ILD.

Objectives:

This study was aimed to assess whether use of PPI is associated with progression of SSc-ILD and survival.

Methods:

We retrospectively analysed 1931 patients with SSc and SSc-ILD from the German Network for Systemic Sclerosis (DNSS) database (2003 onwards). Kaplan–Meier analysis compared overall survival (OS) and progression-free survival (PFS) in patients with vs. without GERD (SSc and SSc-ILD), and PPI vs. no PPI use (SSc-ILD only). Progression was defined as a decrease in either % predicted forced vital capacity ≥10% or single-breath diffusing capacity for carbon monoxide ≥15%, or death.

Results:

GERD was not associated with decreased OS or PFS in patients with either SSc or SSc-ILD. In patients with SSc-ILD, PPI use was associated with improved OS vs. no PPI use after 1 year (98.4% [95% confidence interval: 97.6–99.3]; n=760 vs. 90.8% [87.9–93.8]; n=290) and after 5 years (91.4% [89.2–93.8]; n=357 vs. 70.9% [65.2–77.1]; n=106; p<0.0001). PPI use was also associated with improved PFS vs. no PPI use after 1 year (95.9% [94.6–97.3]; n=745 vs. 86.4% [82.9–90.1]; n=278) and after 5 years (66.8% [63.0–70.8]; n=286 vs. 45.9% [39.6–53.2]; n=69; p<0.0001).

Conclusion:

GERD had no effect on survival in SSc or SSc-ILD. PPIs improved survival in patients with SSc-ILD; however, controlled, prospective trials are needed to confirm this finding.

Disclosure of Interests:

Michael Kreuter Speakers bureau: Boehringer, Consultant of: Boehringer, Grant/research support from: Boehringer, Francesco Bonella Speakers bureau: Boehringer, Roche, GSK, Consultant of: Boehringer, Roche, GSK, Grant/research support from: Boehringer, Kuhr Kathrin: None declared, Jörg Henes Speakers bureau: Abbvie, Boehringer, Chugai, Roche, Janssen, Novartis, SOBI, Pfizer and UCB, Consultant of: Boehringer, Celgene, Chugai, Roche, Janssen, Novartis, SOBI, Grant/research support from: Chugai, Roche, Janssen, Novartis, SOBI, Pfizer, Elise Siegert: None declared, Gabriela Riemekasten Speakers bureau: Novartis, Janssen, Roche, GSK, Boehringer, Consultant of: Janssen, Actelion, Boehringer, Norbert Blank Consultant of: Sobi, Novartis, Roche, UCB, MSD, Pfizer, Actelion, Abbvie, Boehringer, Grant/research support from: Novartis, Sobi, Christiane Pfeiffer: None declared, Ulf Müller-Ladner: None declared, Alexander Kreuter Speakers bureau: MSD, Boehringer, InfectoPharm, Paid instructor for: MSD, PETER KORSTEN Consultant of: Glaxo, Abbvie, Pfizer, BMS, Chugai, Sanofi, Lilly, Boehringer, Novartis, Grant/research support from: Glaxo, Aaron Juche: None declared, Marc Schmalzing Speakers bureau: Chugai Roche, Boehringer, Celgene, Medac, UCB, Paid instructor for: Novartis, Abbvie, Astra Zeneca, Chugai Roche, Janssen, Consultant of: Chugai Roche, Hexal Sandoz, Gilead, Abbvie, Janssen, Boehringer, Margitta Worm Speakers bureau: Boehringer, Ilona Jandova Speakers bureau: Boehringer, Novartis, Abbvie, Laura Susok Speakers bureau: MSD, Novartis, BMS, Sunpharma, Consultant of: MSD, Tim Schmeiser Consultant of: Abbvie, Boehringer, Novartis, UCB, Claudia Guenther Paid instructor for: Advisory Board Boehringer January 2020, Employee of: Novartis 2002-2005, Gernot Keyszer Consultant of: Boehringer, Jan Ehrchen Speakers bureau: Boehringer, Janssen, Chugai, Sobi, Employee of: Pfizer, Actelion (now Janssen), Andreas Ramming Speakers bureau: Boehringer, Gilead, Janssen, Pfizer, Roche, Consultant of: Boehringer, Pfizer, Grant/research support from: Novartis, Pfizer, Ina Kötter Speakers bureau: several companies, Consultant of: several companies, Grant/research support from: several companies, Hanns-Martin Lorenz Speakers bureau: Abbvie, Astra Zeneca, Actelion, Alexion Amgen, Bayer Vital, Baxter, Biogen, Boehringer, BMS, Celgene, Fresenius, Genzyme, GSK, Gilead, Hexal, Janssen, Lilly, Medac, MSD, Mundipharm, Mylan, Novartis, Octapharm, Pfizer, Roche Chugai, Sandoz, Sanofi, Shire SOBI, Thermo Fischer, UCB, Grant/research support from: basic research studies: Pfizer, Novartis, Abbvie, Gilead, Lilly, MSD, Roche Chugai, Pia Moinzadeh Speakers bureau: Boehringer, Actelion, Grant/research support from: Actelion, Nicolas Hunzelmann Speakers bureau: Boehringer Janssen, Roche, Sanofi, Consultant of: Boehringer

Molecular Mechanisms of Leukocyte Migration and Its Potential Targeting-Lessons Learned From MKL1/SRF-Related Primary Immunodeficiency Diseases

Megakaryoblastic leukemia 1 (MKL1) deficiency is one of the most recently discovered primary immunodeficiencies (PIDs) caused by cytoskeletal abnormalities. These immunological “actinopathies” primarily affect hematopoietic cells, resulting in defects in both the innate immune system (phagocyte defects) and adaptive immune system (T-cell and B-cell defects). MKL1 is a transcriptional coactivator that operates together with serum response factor (SRF) to regulate gene transcription. The MKL/SRF pathway has been originally described to have important functions in actin regulation in cells. Recent results indicate that MKL1 also has very important roles in immune cells, and that MKL1 deficiency results in an immunodeficiency affecting the migration and function of primarily myeloid cells such as neutrophils. Interestingly, several actinopathies are caused by mutations in genes which are recognized MKL(1/2)-dependent SRF-target genes, namely ACTB, WIPF1, WDR1, and MSN. Here we summarize these and related (ARPC1B) actinopathies and their effects on immune cell function, especially focusing on their effects on leukocyte adhesion and migration. Furthermore, we summarize recent therapeutic efforts targeting the MKL/SRF pathway in disease.

AB0584 DOES ANTI-ACID TREATMENT INFLUENCE DISEASE PROGRESSION IN SYSTEMIC SCLEROSIS INTERSTITIAL LUNG DISEASE (SSC-ILD)? DATA FROM THE GERMAN SSC-NETWORK

Background:

Gastroesophageal reflux (GER) is common in SSc and thus treatment with anti-acid therapy (AAT) is frequent. An association between GER and the development / progression of SSc-ILD has been hypothesized. However, outcomes of AAT on disease progression in SSc-ILD has only sparsely been studied.

Objectives:

Methods:

The German Network for Systemic Scleroderma (DNSS), which includes SSc pts. prospectively, was analyzed for SSc-ILD. Those without progression at ILD 1stdiagnosis were categorized in AAT vs. no-AAT users and disease outcome was assessed.

Results:

SSc-ILD was reported in 1165 (28.2%) out of 4131 pts. 712 of SSc-ILD pts had no disease progression at ILD 1stdiagnosis. 567 used AAT while 145 did not. Baseline characteristics were similar between groups with regards to age (mean 54.7 years), BMI, time since SSc diagnosis and immunosuppressant use. Significant differences in no-AAT vs. AAT were found for gender (male 18% vs. 25%, p=0.05), SSc subtype (p=0.002, diffuse more common in AAT), lung function (DLCO 66% vs. 58%, p=0.001; FVC 86% vs. 77%, p=0.001), mRSS (8 vs. 11.5, p<0.01), esophageal involvement (32% vs. 56%, p<0.01) and steroid use (30% vs. 43%, p=0.005). While mortality did not differ between groups (3.9%, p= 0.59), disease progression was more common in the AAT group than in no-AAT users (24.5% vs. 13%, p=0.03). Furthermore, there was a significant difference in decline of FVC≥10% with 30% in the AAT compared to 14% in no-AAT (p=0.018); a decline in DLCO≥15% was more common in the AAT group by trend (23% vs. 14%, p=0.087).

Conclusion:

While results may have partially been biased by differences in baseline characteristics, this current analysis disfavors the approach of AAT use for SSc-ILD.

Disclosure of Interests:

Michael Kreuter Grant/research support from: Roche, Boehringer, Consultant of: Roche, Boehringer, Speakers bureau: Boehringer, Roche, Francesco Bonella Grant/research support from: Boehringer, Consultant of: Boehringer, Roche, Bristol MS, Galapagos, Speakers bureau: Boehringer, Roche, Gabriela Riemekasten Consultant of: Cell Trend GmbH, Janssen, Actelion, Boehringer Ingelheim, Speakers bureau: Actelion, Novartis, Janssen, Roche, GlaxoSmithKline, Boehringer Ingelheim, Pfizer, Ulf Müller-Ladner Speakers bureau: Biogen, Jörg Henes Grant/research support from: Novartis, Roche-Chugai, Consultant of: Novartis, Roche, Celgene, Pfizer, Abbvie, Sanofi, Boehringer-Ingelheim,, Elise Siegert Grant/research support from: Actelion, Consultant of: AEC, Speakers bureau: NA, Claudia Guenther: None declared, Ina Koetter Grant/research support from: Novartis, Roche, Speakers bureau: Abbvie, Actelion, Celgene, MSD, UCB, Sanofi, Lilly, Pfizer, Novartis, Chugai, Roche, Boehringer, Norbert Blank Speakers bureau: Actelion, Roche, Boehringer, Pfizer, Chugai, Christiane Pfeiffer: None declared, Marc Schmalzing: None declared, Gabriele Zeidler: None declared, PETER KORSTEN Grant/research support from: Novartis, Juarms GmbH, Consultant of: Abbvie, Pfizer, Lilly, BMS, Speakers bureau: Abbvie, Pfizer, chugai, BMS, Lilly, Sanofi aventis, Laura Susok: None declared, Aaron Juche: None declared, Margitta Worm Consultant of: Mylan Gemany, Bencard Allergie, BBV Technologies S.A., Novartis, Biotest, Sanofi, Aimmune Therapies, Regeneron, Speakers bureau: ALK-Abello, Novartis, Sanofi, Biotest, Mylan, Actelion, HAL Allergie, Aimmune Bencard Allergie, Ilona Jandova: None declared, Jan Ehrchen: None declared, Cord Sunderkoetter: None declared, Gernot Keyszer: None declared, Andreas Ramming Grant/research support from: Pfizer, Novartis, Consultant of: Boehringer Ingelheim, Novartis, Gilead, Pfizer, Speakers bureau: Boehringer Ingelheim, Roche, Janssen, Tim Schmeiser Speakers bureau: Actelion, UCB, Pfizer, Alexander Kreuter Speakers bureau: Sanofi, Abbvie, Merck Sharp&Dohme, Boehringer, Kathrin Kuhr: None declared, Hanns-Martin Lorenz Grant/research support from: Consultancy and/or speaker fees and/or travel reimbursements: Abbvie, MSD, BMS, Pfizer, Celgene, Medac, GSK, Roche, Chugai, Novartis, UCB, Janssen-Cilag, Astra-Zeneca, Lilly. Scientific support and/or educational seminars and/or clinical studies: Abbvie, MSD, BMS, Pfizer, Celgene, Medac, GSK, Roche, Chugai, Novartis, UCB, Janssen-Cilag, Astra-Zeneca, Lilly, Baxter, SOBI, Biogen, Actelion, Bayer Vital, Shire, Octapharm, Sanofi, Hexal, Mundipharm, Thermo Fisher., Consultant of: see above, Pia Moinzadeh: None declared, Nicolas Hunzelmann Speakers bureau: Actelion, Boehringer

A β2-Integrin/MRTF-A/SRF Pathway Regulates Dendritic Cell Gene Expression, Adhesion, and Traction Force Generation

β2-integrins are essential for immune system function because they mediate immune cell adhesion and signaling. Consequently, a loss of β₂-integrin expression or function causes the immunodeficiency disorders, Leukocyte Adhesion Deficiency (LAD) type I and III. LAD-III is caused by mutations in an important integrin regulator, kindlin-3, but exactly how kindlin-3 regulates leukocyte adhesion has remained incompletely understood. Here we demonstrate that mutation of the kindlin-3 binding site in the β2-integrin (TTT/AAA-β2-integrin knock-in mouse/KI) abolishes activation of the actin-regulated myocardin related transcription factor A/serum response factor (MRTF-A/SRF) signaling pathway in dendritic cells and MRTF-A/SRF-dependent gene expression. We show that Ras homolog gene family, member A (RhoA) activation and filamentous-actin (F-actin) polymerization is abolished in murine TTT/AAA-β2-integrin KI dendritic cells, which leads to a failure of MRTF-A to localize to the cell nucleus to coactivate genes together with SRF. In addition, we show that dendritic cell gene expression, adhesion and integrin-mediated traction forces on ligand coated surfaces is dependent on the MRTF-A/SRF signaling pathway. The participation of β2-integrin and kindlin-3-mediated cell adhesion in the regulation of the ubiquitous MRTF-A/SRF signaling pathway in immune cells may help explain the role of β2-integrin and kindlin-3 in integrin-mediated gene regulation and immune system function.

Cell Adhesion Molecules and Their Roles and Regulation in the Immune and Tumor Microenvironment

The immune system and cancer have a complex relationship with the immune system playing a dual role in tumor development. The effector cells of the immune system can recognize and kill malignant cells while immune system-mediated inflammation can also promote tumor growth and regulatory cells suppress the anti-tumor responses. In the center of all anti-tumor responses is the ability of the immune cells to migrate to the tumor site and to interact with each other and with the malignant cells. Cell adhesion molecules including receptors of the immunoglobulin superfamily and integrins are of crucial importance in mediating these processes. Particularly integrins play a vital role in regulating all aspects of immune cell function including immune cell trafficking into tissues, effector cell activation and proliferation and the formation of the immunological synapse between immune cells or between immune cell and the target cell both during homeostasis and during inflammation and cancer. In this review we discuss the molecular mechanisms regulating integrin function and the role of integrins and other cell adhesion molecules in immune responses and in the tumor microenvironment. We also describe how malignant cells can utilize cell adhesion molecules to promote tumor growth and metastases and how these molecules could be targeted in cancer immunotherapy.

Beta2-Integrins and Interacting Proteins in Leukocyte Trafficking, Immune Suppression, and Immunodeficiency Disease

Beta2-integrins are complex leukocyte-specific adhesion molecules that are essential for leukocyte (e.g., neutrophil, lymphocyte) trafficking, as well as for other immunological processes such as neutrophil phagocytosis and ROS production, and T cell activation. Intriguingly, however, they have also been found to negatively regulate cytokine responses, maturation, and migratory responses in myeloid cells such as macrophages and dendritic cells, revealing new, and unexpected roles of these molecules in immunity. Because of their essential role in leukocyte function, a lack of expression or function of beta2-integrins causes rare immunodeficiency syndromes, Leukocyte adhesion deficiency type I, and type III (LAD-I and LAD-III). LAD-I is caused by reduced or lost expression of beta2-integrins, whilst in LAD-III, beta2-integrins are expressed but dysfunctional because a major integrin cytoplasmic regulator, kindlin-3, is mutated. Interestingly, some LAD-related phenotypes such as periodontitis have recently been shown to be due to an uncontrolled inflammatory response rather than to an uncontrolled infection, as was previously thought. This review will focus on the recent advances concerning the regulation and functions of beta2-integrins in leukocyte trafficking, immune suppression, and immune deficiency disease.

Filamin A Is Required for Optimal T Cell Integrin-Mediated Force Transmission, Flow Adhesion, and T Cell Trafficking

T cells traffic from the bloodstream into tissues to perform their functions in the immune system and are therefore subjected to a range of different mechanical forces. Integrins are essential for T cell trafficking into the tissues, as they mediate firm adhesion between the T cell and the endothelium under shear flow conditions. In addition, integrins are important for the formation of the contact between the T cell and the APC required for T cell activation. The actin-binding protein filamin A (FlnA) provides an important link between the integrin and the actin cytoskeleton. FlnA has been reported to function as an integrin inhibitor by competing with talin. However, its role in regulating integrin-dependent immune functions in vivo is currently poorly understood. In this study, we have investigated the role of FlnA in T cells, using T cell-specific FlnA knockout mice. We report that FlnA is required for the formation of strong integrin-ligand bonds under shear flow and for the generation of integrin-mediated T cell traction forces on ligand-coated hydrogels. Consequently, absence of FlnA leads to a reduction in T cell adhesion to integrin ligands under conditions of shear flow, as well as reduced T cell trafficking into lymph nodes and sites of skin inflammation. In addition, FlnA is not needed for T cell activation in vivo, which occurs in shear-free conditions in lymphoid organs. Our results therefore reveal a role of FlnA in integrin force transmission and T cell trafficking in vivo.

Filamin A Regulates Neutrophil Adhesion, Production of Reactive Oxygen Species, and Neutrophil Extracellular Trap Release

Neutrophils are of fundamental importance in the early immune response and use various mechanisms to neutralize invading pathogens. They kill endocytosed pathogens by releasing reactive oxygen species in the phagosome and release neutrophil extracellular traps (NETs) into their surroundings to immobilize and kill invading micro-organisms. Filamin A (FlnA) is an important actin cross-linking protein that is required for cellular processes involving actin rearrangements, such cell migration. It has also been shown to negatively regulate integrin activation and adhesion. However, its role in the regulation of β₂ integrin-dependent adhesion, as well as in other cellular functions in neutrophils, is poorly understood. Using a transgenic mouse model in which FlnA is selectively depleted in myeloid cells, such as neutrophils, we show that FlnA negatively regulates β₂ integrin adhesion to complement component iC3b and ICAM-1 in shear-free, but not shear-flow, conditions. FlnA deletion does not affect phagocytosis of Escherichia coli or Staphylococcus aureus or their intracellular killing. However, FlnA negatively regulates production of reactive oxygen species upon cell activation. Conversely, neutrophil activation through TLR4, as well as through activation by the Gram-negative bacteria E. coli, results in reduced NET production in FlnA-depleted neutrophils. Thus, FlnA is a negative regulator of β₂ integrin-dependent cell adhesion and reactive oxygen species production but is required for NET production in primary murine neutrophils.

Epigenetic Reprogramming Sensitizes CML Stem Cells to Combined EZH2 and Tyrosine Kinase Inhibition

A major obstacle to curing chronic myeloid leukemia (CML) is residual disease maintained by tyrosine kinase inhibitor (TKI)-persistent leukemic stem cells (LSC). These are BCR-ABL1 kinase independent, refractory to apoptosis, and serve as a reservoir to drive relapse or TKI resistance. We demonstrate that Polycomb Repressive Complex 2 is misregulated in chronic phase CML LSCs. This is associated with extensive reprogramming of H3K27me3 targets in LSCs, thus sensitizing them to apoptosis upon treatment with an EZH2-specific inhibitor (EZH2i). EZH2i does not impair normal hematopoietic stem cell survival. Strikingly, treatment of primary CML cells with either EZH2i or TKI alone caused significant upregulation of H3K27me3 targets, and combined treatment further potentiated these effects and resulted in significant loss of LSCs compared to TKI alone, in vitro, and in long-term bone marrow murine xenografts. Our findings point to a promising epigenetic-based therapeutic strategy to more effectively target LSCs in patients with CML receiving TKIs.

SIGNIFICANCE

In CML, TKI-persistent LSCs remain an obstacle to cure, and approaches to eradicate them remain a significant unmet clinical need. We demonstrate that EZH2 and H3K27me3 reprogramming is important for LSC survival, but renders LSCs sensitive to the combined effects of EZH2i and TKI. This represents a novel approach to more effectively target LSCs in patients receiving TKI treatment. Cancer Discov; 6(11); 1248-57. ©2016 AACR.See related article by Xie et al., p. 1237This article is highlighted in the In This Issue feature, p. 1197.

Blood cell integrins and diseases

Integrins are adhesion molecules on the surface of cells. In blood cells they are responsible for rapid changes during adhesion of the cell to the endothelium. Deficiency or defective function of integrins will result in severe illnesses. Surprisingly, certain variants of integrins are associated with an increased risk of developing SLE. In autoimmune diseases and as a result of organ transplantations integrins participate in reactions in which leukocytes attack the body's own tissues. This has resulted in the development of drugs in antibody form for inhibition of the action of integrins. These drugs may, however, exhibit severe adverse effects.

The progressive ankylosis protein regulates cementum apposition and extracellular matrix composition

BACKGROUND/AIMS

Tooth root cementum is sensitive to modulation of inorganic pyrophosphate (PP(i)), an inhibitor of hydroxyapatite precipitation. Factors increasing PP(i) include progressive ankylosis protein (ANK) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) while tissue nonspecific alkaline phosphatase hydrolyzes PP(i). Studies here aimed to define the role of ANK in root and cementum by analyzing tooth development in Ank knock-out (KO) mice versus wild type.

MATERIALS AND METHODS

Periodontal development in KO versus control mice was analyzed by histology, histomorphometry, immunohistochemistry, in situ hybridization, electron microscopy, and nanoindentation. Cementoblast cultures were used in vitro to provide mechanistic underpinnings for PP(i) modulation of cell function.

RESULTS

Over the course of root development, Ank KO cervical cementum became 8- to 12-fold thicker than control cervical cementum. Periodontal ligament width was maintained and other dentoalveolar tissues, including apical cementum, were unaltered. Cervical cementum uncharacteristically included numerous cells, from rapid cementogenesis. Ank KO increased osteopontin and dentin matrix protein 1 gene and protein expression, and markedly increased NPP1 protein expression in cementoblasts but not in other cell types. Conditional ablation of Ank in joints and periodontia confirmed a local role for ANK in cementogenesis. In vitro studies employing cementoblasts indicated that Ank and Enpp1 mRNA levels increased in step with mineral nodule formation, supporting a role for these factors in regulation of cementum matrix mineralization.

CONCLUSION

ANK, by modulating local PP(i), controls cervical cementum apposition and extracellular matrix. Loss of ANK created a local environment conducive to rapid cementogenesis; therefore, approaches modulating PP(i) in periodontal tissues have potential to promote cementum regeneration.

Determining epidural catheter location using nerve stimulation with radiological confirmation

BACKGROUND AND OBJECTIVES

The use of epidural stimulation to confirm epidural catheter placement has been shown. This case report describes the benefits and problems of using the epidural stimulation test to confirm epidural catheter placement and provides supporting evidence for these observations using radiological imaging.

CASE REPORT

METHODS

A nerve stimulator was connected to the proximal end of an epidural catheter via an adapter. The cathode lead was connected to the adapter. The anode lead was connected to an electrode placed on the upper extremity as a grounding site. Using 1 to 10 mA current, a segmental motor response indicated that the catheter was in the epidural space. The absence of a motor response indicated that it was not.

CASES

In the first patient, the new test predicted subcutaneous epidural catheter placement, which was subsequently confirmed radiologically. In the second patient, the catheter tip was found to be lying near a nerve root, which was again confirmed radiologically. In the third case, a negative test was initially observed with only local muscle movement over the biceps area (T2). After relocation of the grounding electrode to the lower extremity, segmental intercostal muscle movement (T4-5 level) was observed. The catheter placement was radiologically shown to be in the T4-5 region.

CONCLUSION

This report illustrates some of the potential benefits and problems of using the nerve stimulation test to confirm epidural catheter placement, with radiological verification.

Haemodialysis-membrane biocompatibility and mortality of patients with dialysis-dependent acute renal failure: a prospective randomised multicentre trial. International Multicentre Study Group

BACKGROUND

There is controversy as to whether haemodialysis-membrane biocompatibility (ie, the potential to activate complement and neutrophils) influences mortality of patients with acute renal failure. We did a prospective randomised multicentre trial in patients with dialysis-dependent acute renal failure treated with two different types of low-flux membrane.

METHODS

180 patients with acute renal failure were randomly assigned bioincompatible Cuprophan (n=90) or polymethyl-methacrylate (n=90) membranes. The main outcome was survival 14 days after the end of therapy (treatment success). Odds ratios for survival were calculated and the two groups were compared by Fisher's exact test. Analyses were based on patients treated according to protocol (76 Cuprophan, 84 polymethyl methacrylate).

FINDINGS

At the start of dialysis, the groups did not differ significantly in age, sex, severity of illness (as calculated by APACHE II scores), prevalence of oliguria, or biochemical measures of acute renal failure. 44 patients (58% [95% CI 46-69]) assigned Cuprophan membranes and 50 patients (60% [48-70]) assigned polymethyl-methacrylate membranes survived. The odds ratio for treatment failure on Cuprophan compared with polymethyl-methacrylate membranes was 1.07 (0.54-2.11; p=0.87). No difference between Cuprophan and polymethyl-methacrylate membranes was detected when the analysis was adjusted for age and APACHE II score. 18 patients in the Cuprophan group and 20 in the polymethyl-methacrylate group had clinical complications of therapy (mainly hypotension).

INTERPRETATION

There were no differences in outcome for patients with dialysis-dependent acute renal failure between those treated with Cuprophan membranes and those treated with polymethyl-methacrylate membranes.

The Caenorhabditis elegans gene ham-2 links Hox patterning to migration of the HSN motor neuron

The Caenorhabditis elegans HSN motor neurons permit genetic analysis of neuronal development at single-cell resolution. The egl-5 Hox gene, which patterns the posterior of the embryo, is required for both early (embryonic) and late (larval) development of the HSN. Here we show that ham-2 encodes a zinc finger protein that acts downstream of egl-5 to direct HSN cell migration, an early differentiation event. We also demonstrate that the EGL-43 zinc finger protein, also required for HSN migration, is expressed in the HSN specifically during its migration. In an egl-5 mutant background, the HSN still expresses EGL-43, but expression is no longer down-regulated at the end of the cell's migration. Finally, we find a new role in early HSN differentiation for UNC-86, a POU homeodomain transcription factor shown previously to act downstream of egl-5 in the regulation of late HSN differentiation. In an unc-86; ham-2 double mutant the HSNs are defective in EGL-43 down-regulation, an egl-5-like phenotype that is absent in either single mutant. Thus, in the HSN, a Hox gene, egl-5, regulates cell fate by activating the transcription of genes encoding the transcription factors HAM-2 and UNC-86 that in turn individually control some differentiation events and combinatorially affect others.

Asymmetric distribution of the C. elegans HAM-1 protein in neuroblasts enables daughter cells to adopt distinct fates

One mechanism of generating cellular diversity is to distribute developmental potential asymmetrically to daughter cells at mitosis. Two observations described in this report suggest that the C. elegans HAM-1 protein functions in dividing neuroblasts to produce daughter cells that adopt distinct fates. First, HAM-1 is asymmetrically distributed to the periphery of certain mitotic cells, ensuring that it will be inherited by only one daughter cell. Second, ham-1 mutations disrupt the asymmetric divisions of five neuroblasts. In one of these divisions, loss of ham-1 function causes the daughter cell that does not inherit HAM-1 to adopt the fate of the daughter cell that normally inherits HAM-1. We propose that asymmetric distribution of HAM-1 enables daughter cells to adopt distinct fates.

Effects of various vaccination protocols on passive and active immunity to Pasteurella haemolytica and Haemophilus somnus in beef calves

Two field trials were conducted in a beef cow herd in Saskatchewan to determine the effectiveness of a combined Pasteurella haemolytica and Haemophilus somnus vaccine in increasing passively and actively acquired antibodies in beef calves. Vaccination of dams at 4 and/or 7 weeks prepartum was associated with increased antibody titers to P. haemolytica and H. somnus in their serum (P < 0.05), colostrum(P < 0.05), and serum of their calves at 3 days and 1 month of age (P < 0.05). There was no significant(P > 0.05) difference in antibody titers in the colostrum and serum of calves from single or double vaccinated dams. Calves vaccinated at 1 and 2 months of age in the face of maternal antibodies toP. haemolytica and H. somnus had significantly(P < 0.05) higher antibodies to P. haemolytica and H. somnus at 4 and 6 months of age than did unvaccinated calves. Calves vaccinated at 3 and 4 months of age in the face of low levels of preexisting antibodies had significantly (P < 0.05) higher antibodies toP. haemolytica at 5 months of age and to H. somnus at 5 and 6 months of age than did unvaccinated calves. Calves vaccinated once at 4 months of age had significantly(P < 0.05) higher antibody titers toP. haemolytica and H. somnus at 4.5 months of age than did unvaccinated calves, but this difference was not apparent at 6 months of age. These results suggest that vaccination of beef cows with a combined Pasteurella haemolytica and Haemophilus somnus vaccine once at 4 weeks prepartum will significantly (P < 0.05) increase passive antibody titers toP. haemolytica and H. somnus in their calves. Double vaccination of calves with preexisting maternal antibodies at 1 and 2 months of age will increase antibody titers to P. haemolytica and H. somnus until 6 months of age. Vaccination of beef calves with low levels of preexisting antibody at 3 and 4 months of age will increase antibody titers to H. somnus until 6 months of age and to P. haemolytica until 5 months of age.However, the level of antibodies achieved by vaccination may depend on the calves being studied, the level of preexisting antibodies, and the efficiency of passive transfer.

RFLP analysis of chromosomal segregation in progeny from an interspecific hexaploid somatic hybrid between Solanum brevidens and Solanum tuberosum

Segregation of restriction fragment length polymorphism (RFLP) loci was monitored to determine the degree of homeologous pairing and recombination in a hexaploid somatic hybrid, A206, the result of protoplast fusion between Solanum tuberosum (PI 203900, a tetraploid cultivated potato) and Solanum brevidens (PI 218228), a diploid, sexually incompatible, distant relative harboring several traits for disease resistance. Somatic hybrid A206 was crossed to Katahdin, a tetraploid potato cultivar, to generate a segregating population of pentaploid progeny. Although the clones of the tetraploid S. tuberosum lines PI 203900 and Katahdin were highly polymorphic, the diploid S. brevidens clone was homozygous at all but two of the tested RFLP loci. Thus, homeologous recombination could be detected only when S. tuberosum and S. brevidens chromosomes paired and the S. brevidens homologs then segregated into separate gametes. A bias toward homologous pairing was observed for all 12 chromosomes. At least four and perhaps six chromosomes participated in homologous pairing only; each of 24 progeny contained all S. brevidens-derived RFLP markers for chromosomes 4, 8, 9 and 10. The remaining six chromosomes paired with their homolog(s) about twice as often as expected if hexaploid pairings were completely random. Where detectable with RFLPs, homeologous recombination (both single and double) occurred at a frequency of 1.31 per chromosome. Cytological observations of meiosis I in the somatic hybrid indicated that homeologous pairing had occurred. Enhanced recombinational activity was observed for chromosome 2. A specific small deletion from chromosome 4 was detected in A206 and 11 other somatic hybrids out of 14 screened.(ABSTRACT TRUNCATED AT 250 WORDS)

Migrations of the Caenorhabditis elegans HSNs are regulated by egl-43, a gene encoding two zinc finger proteins

During embryonic development, the two Caenorhabditis elegans HSN motor neurons migrate from their birthplace in the tail to positions near the middle of the embryo. Here, we demonstrate that of all cells that undergo long-range migrations, only the HSNs are affected in animals that lack function of the egl-43 gene. We also show that egl-43 function is required for normal development of phasmid neurons, which are sensory neurons located in the tail. The egl-43 gene encodes two proteins containing zinc finger motifs that are similar to the zinc fingers of the murine Evi-1 proto-oncoprotein. Our genetic and molecular results suggest that egl-43 encodes two transcription factors and acts to control HSN migration and phasmid neuron development, presumably by regulating other genes that function directly in these processes.

Closing in on a breast cancer gene on chromosome 17q

Linkage of early-onset familial breast and ovarian cancer to 11 markers on chromosome 17q12-q21 defines an 8-cM region which is very likely to include the disease gene BRCA 1. The most closely linked marker is D17S579, a highly informative CA repeat polymorphism. D17S579 has no recombinants with inherited breast or ovarian cancer in 79 informative meioses in the seven families with early-onset disease (lod score 9.12 at zero recombination). There is no evidence for linkage heterogeneity in the families with early-onset disease. The proportion of older-onset breast cancer attributable to BRCA 1 is not yet determinable, because both inherited and sporadic cases occur in older-onset families.

Serum proteins of neonatal pigs orally inoculated with Isospora suis oocysts

Serum proteins were evaluated by agarose electrophoresis at periodic intervals between postinoculation days (PID) 2 and 35 in 4 litters of pigs inoculated orally at 36 to 38 hours of age with 70,000 sporulated Isospora suis oocysts and in 4 litters of age-matched noninoculated control pigs. In inoculated pigs, clinical disease characterized by vomiting and diarrhea began at PID 3 to 4 and was resolved by PID 11. Isospora suis oocysts were detected in feces of inoculated pigs from PID 5 to 25, with peak numbers present on PID 5 to 6. Of 43 pigs inoculated with I suis oocysts, 4(9.3%) died of coccidiosis, and samples were not obtained for serum protein evaluation. Of 39 noninoculated control pigs, all remained clinically normal, and I suis oocysts were not detected in their feces. Serum protein fraction values in inoculated and control groups compared at each sample collection time did not differ significantly, except at PID 15, when beta-globulin values were lower in inoculated pigs (P = 0.02). At PID 35, total serum proteins, albumin, and alpha 1-, beta-, and gamma-globulin values of inoculated pigs were lower than those of controls, but there were too few pigs examined for definitive statistical analysis. Differences in trends over time were observed between inoculated and control groups for several serum protein fractions. In inoculated pigs, total proteins (P less than 0.1) and beta-globulins (P less than 0.01) decreased with time, whereas those of control pigs increased. Similar differences in trends were noticed for albumin and alpha 1-globulins, but these were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)