Cold Atmospheric Plasma Promotes the Immunoreactivity of Granulocytes In Vitro.

Cold atmospheric plasma (CAP) reduces bacteria and interacts with tissues and cells, thus improving wound healing. The CAP-related induction of neutrophils was recently described in stained sections of wound tissue in mice. Consequently, this study aimed to examine the functionality of human polymorphonuclear cells (PMN)/granulocytes through either a plasma-treated solution (PTS) or the direct CAP treatment with different plasma modes and treatment durations. PTS analysis yielded mode-dependent differences in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) after CAP treatment. Live-cell imaging did not show any chemo-attractive or NETosis-inducing effect on PMNs treated with PTS. The time to maximum ROS production (TmaxROS) in PMNs was reduced by PTS and direct CAP treatment. PMNs directly treated with CAP showed an altered cell migration dependent on the treatment duration as well as decreased TmaxROS without inducing apoptosis. Additionally, flow cytometry showed enhanced integrin and selectin expression, as a marker of activation, on PMN surfaces. In conclusion, the modification of PMN immunoreactivity may be a main supporting mechanism for CAP-induced improvement in wound healing.

Proprotein convertases: Key players in inflammation-related malignancies and metastasis.

Many cancers occur from locations of inflammation due to chronic irritation and/or infection. Tumor microenvironment contains various different inflammatory cells and mediators that orchestrate diverse neoplastic processes, including proliferation, survival, adhesion and migration. In parallel, tumor cells have adapted some of the signaling molecules used by inflammatory cells, such as selectins and chemokines as well as their receptors for invasion, extravasation and subsequently metastasis. Expression and/or activation of the majority of these molecules is mediated by the proprotein convertases (PCs); proteases expressed by both tumor cells and inflammatory cells. This review analyzes the potential role of these enzymatic system in inflammation-associated cancer impacting on the malignant and metastatic potential of cancer cells, describing the possible use of PCs as a new anti-inflammatory therapeutic approach to tumor progression and metastasis.

Selectins and Immune Cells in Acute Myocardial Infarction and Post-infarction Ventricular Remodeling: Pathophysiology and Novel Treatments.

The glycosciences aim to understand the impact of extracellular and intracellular carbohydrate structures on biological function. These glycans primarily fall into three major groups: lipid-linked carbohydrates that are referred to as glycosphingolipids or simply glycolipids; relatively short carbohydrate chains that are often O- or N-linked to proteins yielding common glycoproteins; and extended linear polymeric carbohydrate structures that are referred to as glycosaminoglycans (GAGs). Whereas, the impact of such carbohydrate structures has been extensively examined in cancer biology, their role in acute and chronic heart disease is less studied. In this context, a growing body of evidence indicates that glycans play an important role in immune mediated cell recruitment to damaged heart tissue to initiate wound healing and repair after injury. This is particularly important following ischemia and reperfusion that occurs in the heart in the setting of acute myocardial infarction. Here, immune system-mediated repair of the damaged myocardium plays a critical role in determining post-infarction ventricular remodeling, cardiac function, and patient outcome. Further, alterations in immune cell activity can promote the development of heart failure. The present review summarizes our current understanding of the phases of immune-mediated repair following myocardial infarction. It discusses what is known regarding glycans in mediating the recruitment of circulating immune cells during the early inflammatory stage of post-infarction repair, with focus on the selectin family of adhesion molecules. It offers future directions for research aimed at utilizing our knowledge of mechanisms underlying immune cell recruitment to either modulate leukocyte recruitment to the injured tissue or enhance the targeted delivery of biologic therapeutics such as stem cells in an attempt to promote repair of the damaged heart.

Immune imbalance of global gene expression, and cytokine, chemokine and selectin levels in the brains of offspring with social deficits via maternal immune activation.

The murine maternal immune activation (MIA) offspring model enables longitudinal studies to explore aberrant social behaviors similar to those observed in humans. High levels of cytokines, chemokines and cell adhesion molecules (CAM) have been found in the plasma and/or brains of psychiatric patients. We hypothesized that upregulation of the systemic or brain immune response has an augmenting effect by potentially increasing the interplay between the neuronal and immune systems during the growth of the MIA offspring. In this study, a C57BL/6j MIA female offspring model exhibiting social deficits was established. The expression of fetal interferon (IFN)-stimulated (gbp3, irgm1, ifi44), adolescent immunodevelopmental transcription factor (eg, r2, tfap2b), hormone (pomc, hcrt), adult selectin (sell, selp) and neuroligin (nlgn2) genes was altered. Systemic upregulation of endogenous IL-10 occurred at the adult stage, while both IL-1ß and IL-6 were increased and persisted in the sera throughout the growth of the MIA offspring. The cerebral IL-6 levels were endogenously upregulated, but both MCP-1 (macrophage inflammatory protein-1) and L-selectin levels were downregulated at the adolescent and/or adult stages. However, the MIA offspring were susceptible to lipopolysaccharide (LPS) stimulation. After reinjecting the MIA offspring with LPS in adulthood, a variety of sera and cerebral cytokines, chemokines and CAMs were increased. Particularly, both MCP-1 and L-selectin showed relatively high expression in the brain compared with the expression levels in phosphate-buffered saline (PBS)-treated offspring injected with LPS. Potentially, MCP-1 was attracted to the L-selectin-mediated immune cells due to augmentation of the immune response following stimulation in MIA female offspring.

Unmasking Fucosylation: from Cell Adhesion to Immune System Regulation and Diseases.

Fucosylation is a biological process broadly observed in vertebrates, invertebrates, plants, bacteria, and fungi. Fucose moieties on cell-surface glycans are increasingly recognized as critical to many cell-cell interaction and signaling processes. One of the characteristic roles of fucose is its regulation of selectin-dependent leukocyte adhesion that has been well studied over the last two decades. Recent studies of fucose in immune cell development and function regulation have significantly expanded the contemporary understanding of fucosylation. From cellular adhesion to immune regulation, herein we discuss the use of gene knockout studies, competitive inhibitors of fucose-containing glycan, and metabolic inhibitors of fucose biosynthesis to probe fucosylated glycan biosynthesis and signaling and its functional consequences. Promising clinical and preclinical applications in sickle cell disease, rheumatoid arthritis, tumor inhibition, metastasis prevention, antibody-dependent cell-mediated cytotoxicity, chemoresistance reversal, and in improving chemotherapy-related side effects and recovery are reviewed.

Lack of functional selectin-ligand interactions enhances innate immune resistance to systemic Listeria monocytogenes infection.

Selectin-ligand interactions are important for leukocyte homing and functionality. The roles of selectin-ligand interactions in modulating immunity to intracellular infections are not completely understood. Mice lacking the expression of fucosyltransferase-IV and -VII (Fucosyltransferase-IV and -VII double knockout, FtDKO) exhibit deficient functionality of selectin-ligand interactions. We addressed the kinetics of infection and immunity to Listeria monocytogenes (LM), an intracellular pathogen, in FtDKO mice. These mice exhibited enhanced ability to clear infection and increased survival to a lethal dose of LM infection relative to wild-type (WT) C57BL/6J controls. This was associated with increased levels of neutrophils, monocytes, and dendritic cells (DCs) in the blood and/or infected organs. Adoptive transfer of bone marrow (BM) cells from FtDKO mice to WT mice resulted in enhanced neutrophil numbers and improved clearance of LM bacteria in recipients. In vivo depletion of myeloid innate immune cells, particularly neutrophils, monocytes, macrophages, and DCs, using anti-Ly-6G (RB6-8C5) monoclonal antibody, reduced the ability of FtDKO mice to curtail LM infection. Nevertheless, depletion using anti-Ly-6G (1A8) known to exclusively deplete neutrophils did not abrogate increased resistance of FtDKO mice to LM infection, suggesting a role for other myeloid innate immune cells in this model. Examination of BM hematopoietic progenitors through flow cytometry and cell culture colony-forming unit assay showed increased frequencies of granulocyte-macrophage progenitors in FtDKO relative to WT mice, Overall, our results indicate that functional selectin ligand deficiency enhances innate immune-mediated resistance to systemic LM infection despite defective leukocyte migration and lymphocyte homing.

Selectins in cancer immunity.

Selectins are vascular adhesion molecules that mediate physiological responses such as inflammation, immunity and hemostasis. During cancer progression, selectins promote various steps enabling the interactions between tumor cells and the blood constituents, including platelets, endothelial cells and leukocytes. Selectins are carbohydrate-binding molecules that bind to sialylated, fucosylated glycan structures. The increased selectin ligand expression on tumor cells correlates with enhanced metastasis and poor prognosis for cancer patients. While, many studies focused on the role of selectin as a mediator of tumor cell adhesion and extravasation during metastasis, there is evidence for selectins to activate signaling cascade that regulates immune responses within a tumor microenvironment. L-Selectin binding induces activation of leukocytes, which can be further modulated by selectin-mediated interactions with platelets and endothelial cells. Selectin ligand on leukocytes, PSGL-1, triggers intracellular signaling in leukocytes that are induced through platelet's P-selectin or endothelial E-selectin binding. In this review, I summarize the evidence for selectin-induced immune modulation in cancer progression that represents a possible target for controlling tumor immunity.

Endothelial cell activation in central nervous system inflammation.

Leukocyte migration across the endothelial barrier plays an essential role in CNS inflammation. The migration process requires complex endothelial adhesion molecules concentrated at the junctions of endothelial cells. Recent findings suggest that cerebral endothelial cells play an active role in the pathogenesis of CNS inflammatory diseases. This review describes our current understanding of the effects of various inflammatory mediators of leukocyte migration on cerebral endothelial cells, the mechanisms underlying the leukocyte-endothelial cell interactions, and the crosstalk between endothelial cells and glial cells or platelets. These emerging mechanisms may provide new therapeutic strategies for a variety of CNS inflammatory diseases.

Superior isolation of antigen-specific brain infiltrating T cells using manual homogenization technique.

Effective recovery of activated brain infiltrating lymphocytes is critical for investigations involving murine neurological disease models. To optimize lymphocyte recovery, we compared two isolation methods using brains harvested from seven-day Theiler's murine encephalomyelitis virus (TMEV) and TMEV-OVA infected mice. Brains were processed using either a manual dounce based approach or enzymatic digestion using type IV collagenase. The resulting cell suspensions from these two techniques were transferred to a percoll gradient, centrifuged, and lymphocytes were recovered. Flow cytometric analysis of CD45hi cells showed greater percentage of CD44hiCD62lo activated lymphocytes and CD19+ B cells using the dounce method. In addition, we achieved a 3-fold greater recovery of activated virus-specific CD8 T cells specific for the immunodominant Db:VP2121-130 and engineered Kb:OVA257-264 epitopes through manual dounce homogenization approach as compared to collagenase digest. A greater percentage of viable cells was also achieved through dounce homogenization. Therefore, we conclude that manual homogenization is a superior approach to isolate activated T cells from the mouse brain.

Selectin-mediated leukocyte trafficking during the development of autoimmune disease.

Tissue inflammation is a finely regulated process that controls wound healing and allows the clearance of damaged cells, pathogens and irritants. However, excessive or uncontrolled inflammation is detrimental, causing tissue damage and leading to autoimmunity. The recruitment of circulating leukocytes to the target tissue is a key stage in the inflammatory process, and is controlled by a multistep cascade in which adhesive receptors known as selectins mediate initial leukocyte tethering and rolling along vascular surfaces, which is required for their subsequent adhesion and arrest. This review considers the role of selectins and their ligands in the recruitment of circulating leukocytes to peripheral tissues during inflammatory responses that lead to the development of autoimmunity, focusing on data from animal models and clinical trials suggesting that selectins may offer valuable therapeutic targets for the treatment of autoimmune diseases.

Differential Features of AIRE-Induced and AIRE-Independent Promiscuous Gene Expression in Thymic Epithelial Cells.

Establishment of self-tolerance in the thymus depends on promiscuous expression of tissue-restricted Ags (TRA) by thymic epithelial cells (TEC). This promiscuous gene expression (pGE) is regulated in part by the autoimmune regulator (AIRE). To evaluate the commonalities and discrepancies between AIRE-dependent and -independent pGE, we analyzed the transcriptome of the three main TEC subsets in wild-type and Aire knockout mice. We found that the impact of AIRE-dependent pGE is not limited to generation of TRA. AIRE decreases, via non-cell autonomous mechanisms, the expression of genes coding for positive regulators of cell proliferation, and it thereby reduces the number of cortical TEC. In mature medullary TEC, AIRE-driven pGE upregulates non-TRA coding genes that enhance cell-cell interactions (e.g., claudins, integrins, and selectins) and are probably of prime relevance to tolerance induction. We also found that AIRE-dependent and -independent TRA present several distinctive features. In particular, relative to AIRE-induced TRA, AIRE-independent TRA are more numerous and show greater splicing complexity. Furthermore, we report that AIRE-dependent versus -independent TRA project nonredundant representations of peripheral tissues in the thymus.

Omega 3 (n-3) fatty acids down-regulate nuclear factor-kappa B (NF-κB) gene and blood cell adhesion molecule expression in patients with homozygous sickle cell disease.

Chronic inflammation and reduced blood levels of omega-3 fatty acids (n-3) are known characteristics of sickle cell disease (SCD).The anti-inflammatory properties of n-3 fatty acids are well recognized. Omega-3 treated (n = 24), hydroxyurea (HU) treated (n = 18), and n-3 untreated (n=21) homozygous SCD patients (HbSS) and healthy (HbAA) controls (n = 25) matched for age (5-16 years), gender and socioeconomic status were studied. According to age (5-10) or (11-16) years, two or three capsules containing 277.8 mg docosahexaenoic (DHA) and 39.0mg eicosapentaenoic (EPA) or high oleic acid placebo (41%) were assigned to n-3 treated and n-3 untreated groups, respectively. Hydroxyurea treated group was on dosage more than 20 mg/kg/day. The effect of supplementation on systemic and blood cell markers of inflammation was investigated. The n-3 treated group had higher levels of DHA and EPA (p < 0.001) and lower white blood cell count and monocyte integrin (p < 0.05) compared with the n-3 untreated. No difference was detected between the two groups regarding C-reactive protein, granulocytes integrin and selectin, plasma tumour necrosis factor-α and interleukin-10. The n-3 treated group had lowered nuclear factor-kappa B (NF-κB) gene expression compared to n-3 untreated and HU treated groups (p < 0.05). This study provides evidence that supplementation with n-3 fatty acids may ameliorate inflammation and blood cell adhesion in patients with SCD.

Role of siglecs and related glycan-binding proteins in immune responses and immunoregulation.

Virtually all cells and extracellular material are heavily decorated by various glycans, yet our understanding of the structure and function of these moieties lags behind the understanding of nucleic acids, lipids, and proteins. Recent years have seen a tremendous acceleration of knowledge in the field of glycobiology, revealing many intricacies and functional contributions that were previously poorly appreciated or even unrecognized. This review highlights several topics relevant to glycoimmunology in which mammalian and pathogen-derived glycans displayed on glycoproteins and other scaffolds are recognized by specific glycan-binding proteins (GBPs), leading to a variety of proinflammatory and anti-inflammatory cellular responses. The focus for this review is mainly on 2 families of GBPs, sialic acid-binding immunoglobulin-like lectins (siglecs) and selectins, that are involved in multiple steps of the immune response, including distinguishing pathogens from self, cell trafficking to sites of inflammation, fine-tuning of immune responses leading to activation or tolerance, and regulation of cell survival. Importantly for the clinician, accelerated rates of discovery in the field of glycoimmunology are being translated into innovative medical approaches that harness the interaction of glycans and GBPs to the benefit of the host and might soon lead to novel diagnostics and therapeutics.

Regulation of T cell trafficking by the T cell immunoglobulin and mucin domain 1 glycoprotein.

Leukocyte trafficking is generally considered the initial stage of any immune response, and it involves a multistep intravascular process including capture, rolling, activation, arrest, crawling, and transmigration. Both capture and rolling are predominantly mediated by selectins, which allow circulating leukocytes to sense activating signals on the endothelium and adhere to vessel walls. In this review, we discuss recent data showing that the T cell immunoglobulin and mucin domain 1 (TIM-1) protein is a major ligand for endothelial P-selectin, mediating T helper (Th) cell Th1 and Th17 trafficking in inflamed tissues. We highlight structural and functional features showing that TIM-1 can be included in the restricted group of major adhesion receptors involved in leukocyte trafficking with a pathophysiological role in inflammation and autoimmunity.

Heterotropic modulation of selectin affinity by allosteric antibodies affects leukocyte rolling.

Selectins are a family of adhesion receptors designed for efficient leukocyte tethering to the endothelium under shear. As a key property to resist premature bond disruption, selectin adhesiveness is enhanced by tensile forces that promote the conversion of a bent into an extended conformation of the N-terminal lectin and epidermal growth factor-like domains. Conformation-specific Abs have been invaluable in deciphering the activation mechanism of integrins, but similar reagents are not available for selectins. In this study, we show that the anti-human L-selectin mAbs DREG-55 and LAM1-5 but not DREG-56, DREG-200, or LAM1-1 heterotropically modulate adhesion presumably by stabilizing the extended receptor conformation. Force-free affinity assays, flow chamber, and microkinetic studies reveal a ligand-specific modulation of L-selectin affinity by DREG-55 mAb, resulting in a dramatic decrease of rolling velocity under flow. Furthermore, secondary tethering of polymorphonuclear cells was blocked by DREG-200 but significantly boosted by DREG-55 mAb. The results emphasize the need for a new classification for selectin Abs and introduce the new concept of heterotropic modulation of receptor function.

Selectins and their ligands as potential immunotherapeutic targets in neurological diseases.

Selectins are a family of adhesion receptors that bind to highly glycosylated molecules expressed on the surface of leukocytes and endothelial cells. The interactions between selectins and their ligands control tethering and rolling of leukocytes on the vascular wall during the process of leukocyte migration into the tissues under physiological and pathological conditions. In recent years, it has been shown that leukocyte recruitment in the CNS plays a pivotal role in diseases such as multiple sclerosis, ischemic stroke, epilepsy and traumatic brain injury. In this review, we discuss the role of selectins in leukocyte-endothelial interactions in the pathogenesis of neurological diseases, highlighting new findings suggesting that selectins and their ligands may represent novel potential therapeutic targets for the treatment of CNS diseases.

Neutrophil cell surface receptors and their intracellular signal transduction pathways.

Neutrophils play a critical role in the host defense against bacterial and fungal infections, but their inappropriate activation also contributes to tissue damage during autoimmune and inflammatory diseases. Neutrophils express a large number of cell surface receptors for the recognition of pathogen invasion and the inflammatory environment. Those include G-protein-coupled chemokine and chemoattractant receptors, Fc-receptors, adhesion receptors such as selectins/selectin ligands and integrins, various cytokine receptors, as well as innate immune receptors such as Toll-like receptors and C-type lectins. The various cell surface receptors trigger very diverse signal transduction pathways including activation of heterotrimeric and monomeric G-proteins, receptor-induced and store-operated Ca(2+) signals, protein and lipid kinases, adapter proteins and cytoskeletal rearrangement. Here we provide an overview of the receptors involved in neutrophil activation and the intracellular signal transduction processes they trigger. This knowledge is crucial for understanding how neutrophils participate in antimicrobial host defense and inflammatory tissue damage and may also point to possible future targets of the pharmacological therapy of neutrophil-mediated autoimmune or inflammatory diseases.

The regulatory power of glycans and their binding partners in immunity.

Glycans and glycan-binding proteins are central to a properly functioning immune system. Perhaps the best known example of this is the selectin family of surface proteins that are primarily found on leukocytes, and which bind to endothelial glycans near sites of infection or inflammation and enable extravasation into tissues. In the past decade, however, several other immune pathways that are dependent on or sensitive to changes in glycan-mediated mechanisms have been revealed. These include antibody function, apoptosis, T helper (Th)1 versus Th2 skewing, T cell receptor signaling, and MHC class II antigen presentation. Here, we highlight how regulated changes in protein glycosylation both at the cell surface and on secreted glycoproteins can positively and negatively modulate the immune response.

Multifarious roles of sialic acids in immunity.

Sialic acids are a diverse family of monosaccharides widely expressed on all cell surfaces of vertebrates and so-called "higher" invertebrates, and on certain bacteria that interact with vertebrates. This overview surveys examples of biological roles of sialic acids in immunity, with emphasis on an evolutionary perspective. Given the breadth of the subject, the treatment of individual topics is brief. Subjects discussed include biophysical effects regulation of factor H; modulation of leukocyte trafficking via selectins; Siglecs in immune cell activation; sialic acids as ligands for microbes; impact of microbial and endogenous sialidases on immune cell responses; pathogen molecular mimicry of host sialic acids; Siglec recognition of sialylated pathogens; bacteriophage recognition of microbial sialic acids; polysialic acid modulation of immune cells; sialic acids as pathogen decoys or biological masks; modulation of immunity by sialic acid O-acetylation; sialic acids as antigens and xeno-autoantigens; antisialoglycan antibodies in reproductive incompatibility; and sialic-acid-based blood groups.

Signaling in innate immunity and inflammation.

Inflammation is triggered when innate immune cells detect infection or tissue injury. Surveillance mechanisms involve pattern recognition receptors (PRRs) on the cell surface and in the cytoplasm. Most PRRs respond to pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs) by triggering activation of NF-κB, AP1, CREB, c/EBP, and IRF transcription factors. Induction of genes encoding enzymes, chemokines, cytokines, adhesion molecules, and regulators of the extracellular matrix promotes the recruitment and activation of leukocytes, which are critical for eliminating foreign particles and host debris. A subset of PRRs activates the protease caspase-1, which causes maturation of the cytokines IL1ß and IL18. Cell adhesion molecules and chemokines facilitate leukocyte extravasation from the circulation to the affected site, the chemokines stimulating G-protein-coupled receptors (GPCRs). Binding initiates signals that regulate leukocyte motility and effector functions. Other triggers of inflammation include allergens, which form antibody complexes that stimulate Fc receptors on mast cells. Although the role of inflammation is to resolve infection and injury, increasing evidence indicates that chronic inflammation is a risk factor for cancer.