Getting leukocytes to the site of inflammation

Narciclasine exerts anti-inflammatory actions by blocking leukocyte-endothelial cell interactions and down-regulation of the endothelial TNF receptor 1

The alkaloid narciclasine has been characterized extensively as an anticancer compound. Accumulating evidence suggests that narciclasine has anti-inflammatory potential; however, the underlying mechanism remains poorly understood. We hypothesized that narciclasine affects the activation of endothelial cells (ECs), a hallmark of inflammatory processes, which is a prerequisite for leukocyte-EC interaction. Thus, we aimed to investigate narciclasine's action on this process in vivo and to analyze the underlying mechanisms in vitro. In a murine peritonitis model, narciclasine reduced leukocyte infiltration, proinflammatory cytokine expression, and inflammation-associated abdominal pain. Moreover, narciclasine decreased rolling and blocked adhesion and transmigration of leukocytes in vivo. In cultured ECs, narciclasine inhibited the expression of cell adhesion molecules intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin and blocked crucial steps of the NF-κB activation cascade: NF-κB promotor activity, p65 nuclear translocation, inhibitor of κB α (IκBα) phosphorylation and degradation, and IκBα kinase β and TGF-β-activated kinase 1 phosphorylation. Interestingly, these effects were based on the narciclasine-triggered loss of TNF receptor 1 (TNFR1). Our study highlights narciclasine as an interesting anti-inflammatory compound that effectively inhibits the interaction of leukocytes with ECs by blocking endothelial activation processes. Most importantly, we showed that the observed inhibitory action of narciclasine on TNF-triggered signaling pathways is based on the loss of TNFR1.-Stark, A., Schwenk, R., Wack, G., Zuchtriegel, G., Hatemler, M. G., Bräutigam, J., Schmidtko, A., Reichel, C. A., Bischoff, I., Fürst, R. Narciclasine exerts anti-inflammatory actions by blocking leukocyte-endothelial cell interactions and down-regulation of the endothelial TNF receptor 1.

Curcumin-primed exosomes potently ameliorate cognitive function in AD mice by inhibiting hyperphosphorylation of the Tau protein through the AKT/GSK-3β pathway

Alzheimer's disease (AD) is the progressive development of fatal neurodegenerative diseases. Owing to the unclearness of the pathogenesis of AD and the failure of the drug to cross the blood-brain barrier (BBB), there is currently a lack of effective diagnostic and therapeutic approaches in the treatment of AD. The aim of this study was to design exosomes (Exo) as a specifically designed carrier able to carry curcumin (cur) to prevent neuronal death in vitro and in vivo to alleviate the AD symptoms. Our results demonstrated that Exo improved the solubility and bioavailability of cur and increased drug penetration across the BBB by specific active targeting between Exo, inheriting the lymphocyte function-associated antigen 1 (LFA-1) and endothelial intercellular adhesion molecule 1 (ICAM-1). Exosomes derived from curcumin-treated (primed) cells (Exo-cur) can better prevent the death of neurons in vitro and in vivo to relieve the symptoms of AD by inhibiting phosphorylation of the Tau protein through activating the AKT/GSK-3β pathway. Our results suggested that Exo-cur featured highly effective BBB-crossing via receptor-mediated transcytosis to access brain tissues and inhibited Tau phosphorylation, holding great potential in improving targeted drug delivery and the recovery of neuronal function in AD therapy.

Traumatic brain injury induces long-lasting changes in immune and regenerative signaling

There are no existing treatments for the long-term degenerative effects of traumatic brain injury (TBI). This is due, in part, to our limited understanding of chronic TBI and uncertainty about which proposed mechanisms for long-term neurodegeneration are amenable to treatment with existing or novel drugs. Here, we used microarray and pathway analyses to interrogate TBI-induced gene expression in the rat hippocampus and cortex at several acute, subchronic and chronic intervals (24 hours, 2 weeks, 1, 2, 3, 6 and 12 months) after parasagittal fluid percussion injury. We used Ingenuity pathway analysis (IPA) and Gene Ontology enrichment analysis to identify significantly expressed genes and prominent cell signaling pathways that are dysregulated weeks to months after TBI and potentially amenable to therapeutic modulation. We noted long-term, coordinated changes in expression of genes belonging to canonical pathways associated with the innate immune response (i.e., NF-κB signaling, NFAT signaling, Complement System, Acute Phase Response, Toll-like receptor signaling, and Neuroinflammatory signaling). Bioinformatic analysis suggested that dysregulation of these immune mediators—many are key hub genes—would compromise multiple cell signaling pathways essential for homeostatic brain function, particularly those involved in cell survival and neuroplasticity. Importantly, the temporal profile of beneficial and maladaptive immunoregulatory genes in the weeks to months after the initial TBI suggests wider therapeutic windows than previously indicated.

The Neutrophil’s Role During Health and Disease

Neutrophils have always been considered as uncomplicated front-line troopers of the innate immune system equipped with limited proinflammatory duties. Yet recently, the role of the neutrophil has been undergoing a rejuvenation of sorts. Neutrophils are now considered complex cells capable of a significant array of specialized functions, and as an effector of the innate immune response, they are able to regulate many processes such as acute injury and repair, cancer, autoimmunity, and chronic inflammatory processes. Furthermore, evidence exists to indicate that neutrophils also contribute to adaptive immunity by aiding the development of specific adaptive immune responses or guiding the subsequent adaptive immune response. With this revived interest in neutrophils and their many novel functions, it is prudent to review what is currently known about neutrophils and, even more importantly, understand what information is lacking. We discuss the essential features of the neutrophil, from its origins, lifespan, subsets, margination and sequestration of the neutrophil to the death of the neutrophil. We highlight neutrophil recruitment to both infected and injured tissues and outline differences in recruitment of neutrophils between different tissues. Finally, we examine how neutrophils use different mechanisms to either bolster protective immune responses or negatively cause pathological outcomes at different locations.

Cathepsin B inhibition ameliorates leukocyte-endothelial adhesion in the BTBR mouse model of autism

AIMS

Autism spectrum disorder (ASD) is a wide range of neurodevelopmental disorders involving deficits in social interaction and communication. Unfortunately, autism remains a scientific and clinical challenge owing to the lack of understanding the cellular and molecular mechanisms underlying it. This study aimed to investigate the pathophysiological mechanism underlying leukocyte-endothelial adhesion in autism-related neurovascular inflammation.

METHODS

Male BTBR T+tf/J mice were used as an autism model. The dynamic pattern of leukocyte-endothelial adhesion in mouse cerebral vessels was detected by two-photon laser scanning microscopy (TPLSM). Using FACS, RT-PCR, and Western blotting, we explored the expression of cell adhesion molecules, the mRNA expression of endothelial chemokine, the protein levels of cathepsin B, and inflammatory mediators.

RESULTS

We found a significant increase in leukocyte-endothelial adhesion in BTBR mice, accompanied by elevated expression of the adhesion molecule neutrophils CD11b and endothelial ICAM-1. Our data further indicate that elevated neutrophil cathepsin B levels contribute to elevated endothelial chemokine CXCL7 levels in BTBR mice. The pharmacological inhibition of cathepsin B reverses the enhanced leukocyte-endothelial adhesion in the cerebral vessels of autistic mice.

CONCLUSION

Our results revealed the prominent role of cathepsin B in modulating leukocyte-endothelial adhesion during autism-related neurovascular inflammation and identified a promising novel approach for autism treatment.

Human Brain/Cloud Interface

The Internet comprises a decentralized global system that serves humanity's collective effort to generate, process, and store data, most of which is handled by the rapidly expanding cloud. A stable, secure, real-time system may allow for interfacing the cloud with the human brain. One promising strategy for enabling such a system, denoted here as a "human brain/cloud interface" ("B/CI"), would be based on technologies referred to here as "neuralnanorobotics." Future neuralnanorobotics technologies are anticipated to facilitate accurate diagnoses and eventual cures for the ∼400 conditions that affect the human brain. Neuralnanorobotics may also enable a B/CI with controlled connectivity between neural activity and external data storage and processing, via the direct monitoring of the brain's ∼86 × 109 neurons and ∼2 × 1014 synapses. Subsequent to navigating the human vasculature, three species of neuralnanorobots (endoneurobots, gliabots, and synaptobots) could traverse the blood-brain barrier (BBB), enter the brain parenchyma, ingress into individual human brain cells, and autoposition themselves at the axon initial segments of neurons (endoneurobots), within glial cells (gliabots), and in intimate proximity to synapses (synaptobots). They would then wirelessly transmit up to ∼6 × 1016 bits per second of synaptically processed and encoded human-brain electrical information via auxiliary nanorobotic fiber optics (30 cm3) with the capacity to handle up to 1018 bits/sec and provide rapid data transfer to a cloud based supercomputer for real-time brain-state monitoring and data extraction. A neuralnanorobotically enabled human B/CI might serve as a personalized conduit, allowing persons to obtain direct, instantaneous access to virtually any facet of cumulative human knowledge. Other anticipated applications include myriad opportunities to improve education, intelligence, entertainment, traveling, and other interactive experiences. A specialized application might be the capacity to engage in fully immersive experiential/sensory experiences, including what is referred to here as "transparent shadowing" (TS). Through TS, individuals might experience episodic segments of the lives of other willing participants (locally or remote) to, hopefully, encourage and inspire improved understanding and tolerance among all members of the human family.

Neutrophil transendothelial migration: updates and new perspectives

Neutrophils represent the first line of cellular defense against invading microorganism by rapidly moving across the blood-endothelial cell (EC) barrier and exerting effector cell functions. The neutrophil recruitment cascade to inflamed tissues involves elements of neutrophil rolling, firm adhesion, and crawling onto the EC surface before extravasating by breaching the EC barrier. The interaction between neutrophils and ECs occurs via various adhesive modules and is a critical event determining the mode of neutrophil transmigration, either at the EC junction (paracellular) or directly through the EC body (transcellular). Once thought to be a homogenous entity, new evidence clearly points to the plasticity of neutrophil functions. This review will focus on recent advances in our understanding of the mechanism of the neutrophil transmigration process. It will discuss how neutrophil-EC interactions and the subsequent mode of diapedesis, junctional or nonjunctional, can be context dependent and how this plasticity may be exploited clinically.

Staphylococcal Superantigen-like protein 11 mediates neutrophil adhesion and motility arrest, a unique bacterial toxin action

Methicillin resistant Staphylococcus aureus (MRSA) is a major human pathogen, which causes superficial to lethal clinical infections. Neutrophils are the most abundant leukocytes in the blood and are the first defense mechanism against S. aureus infections. Here we show Staphylococcal Superantigen-Like protein 11 (SSL11) from MRSA USA300_FPR3757 mediated differentiated human neutrophil-like cells (dHL60) motility arrest by inducing cell adhesion and “locking” cells in adhesion stage, without inducing oxidative burst. Pre-incubation of SSL11 with the glycan Sialyl Lewis X blocked SSL11 function and de-glycosylation of dHL60 cells by PNGase F abolished SSL11 binding, suggesting that SSL11 functions via interacting with glycans. This is the first description of a bacterial toxin inhibiting neutrophil motility by inducing adhesion and “locking” cells in an adhesion stage. Therefore, this study might provide a new target against S. aureus infections.

Immunoregulatory Effects of Neuropeptides on Endothelial Cells: Relevance to Dermatological Disorders

Many skin diseases, including psoriasis and atopic dermatitis, have a neurogenic component. In this regard, bidirectional interactions between components of the nervous system and multiple target cells in the skin and elsewhere have been receiving increasing attention. Neuropeptides released by sensory nerves that innervate the skin can directly modulate functions of keratinocytes, Langerhans cells, dermal dendritic cells, mast cells, dermal microvascular endothelial cells and infiltrating immune cells. As a result, neuropeptides and neuropeptide receptors participate in a complex, interdependent network of mediators that modulate the skin immune system, skin inflammation, and wound healing. In this review, we will focus on recent studies demonstrating the roles of α-melanocyte-stimulating hormone, calcitonin gene-related peptide, substance P, somatostatin, vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, and nerve growth factor in modulating inflammation and immunity in the skin through their effects on dermal microvascular endothelial cells.

Adipose Tissue-Derived Mesenchymal Stem Cell Modulates the Immune Response of Allergic Rhinitis in a Rat Model

This study was designed to investigate the potential effects and underlying mechanism of adipose tissue-derived mesenchymal stem cells (MSCs) on allergic inflammation compared to Montelukast as an antileukotriene drug in a rat model of allergic rhinitis (AR). The effect of MSCs was evaluated in albino rats that were randomly divided into four (control, AR, AR + Montelukast, and AR + MSCs) groups. Rats of AR group were sensitized by ovalbumin (OVA) and then challenged with daily nasal drops of OVA diluted in sterile physiological saline (50 μL/nostril, 100 mg/mL, 10% OVA) from day 15 to day 21 of treatment with/without Montelukast (1 h before each challenge) or MSCs I/P injection (1 × 10⁶ MCSs; weekly for three constitutive weeks). Both Montelukast and MSCs treatment started from day 15 of the experiment. At the end of the 5th week, blood samples were collected from all rats for immunological assays, histological, and molecular biology examinations. Both oral Montelukast and intraperitoneal injection of MSCs significantly reduced allergic symptoms and OVA-specific immunoglobulin E (IgE), IgG1, IgG2a and histamine as well as increasing prostaglandin E2 (PGE2). Further analysis revealed that induction of nasal innate cytokines, such as interleukin (IL)-4 and TNF-α; and chemokines, such as CCL11 and vascular cell adhesion molecule-1 (VCAM-1), were suppressed; and transforming growth factor-β (TGF-β) was up-regulated in Montelukast and MSCs-treated groups with superior effect to MSCs, which explained their underlying mechanism. In addition, the adipose tissue-derived MSCs-treated group had more restoring effects on nasal mucosa structure demonstrated by electron microscopical examination.

Methods to label, image, and analyze the complex structural architectures of microvascular networks

Microvascular networks play key roles in oxygen transport and nutrient delivery to meet the varied and dynamic metabolic needs of different tissues throughout the body, and their spatial architectures of interconnected blood vessel segments are highly complex. Moreover, functional adaptations of the microcirculation enabled by structural adaptations in microvascular network architecture are required for development, wound healing, and often invoked in disease conditions, including the top eight causes of death in the Unites States. Effective characterization of microvascular network architectures is not only limited by the available techniques to visualize microvessels but also reliant on the available quantitative metrics that accurately delineate between spatial patterns in altered networks. In this review, we survey models used for studying the microvasculature, methods to label and image microvessels, and the metrics and software packages used to quantify microvascular networks. These programs have provided researchers with invaluable tools, yet we estimate that they have collectively attained low adoption rates, possibly due to limitations with basic validation, segmentation performance, and nonstandard sets of quantification metrics. To address these existing constraints, we discuss opportunities to improve effectiveness, rigor, and reproducibility of microvascular network quantification to better serve the current and future needs of microvascular research.

Organ-Specific Mechanisms of Transendothelial Neutrophil Migration in the Lung, Liver, Kidney, and Aorta

Immune responses are dependent on the recruitment of leukocytes to the site of inflammation. The classical leukocyte recruitment cascade, consisting of capture, rolling, arrest, adhesion, crawling, and transendothelial migration, is thoroughly studied but mostly in model systems, such as the cremasteric microcirculation. This cascade paradigm, which is widely accepted, might be applicable to many tissues, however recruitment mechanisms might substantially vary in different organs. Over the last decade, several studies shed light on organ-specific mechanisms of leukocyte recruitment. An improved awareness of this matter opens new therapeutic windows and allows targeting inflammation in a tissue-specific manner. The aim of this review is to summarize the current understanding of the leukocyte recruitment in general and how this varies in different organs. In particular we focus on neutrophils, as these are the first circulating leukocytes to reach the site of inflammation. Specifically, the recruitment mechanism in large arteries, as well as vessels in the lungs, liver, and kidney will be addressed.

Interleukin-1β induces CXCR3-mediated chemotaxis to promote umbilical cord mesenchymal stem cell transendothelial migration

BACKGROUND

Mesenchymal stem cells (MSCs) are known to home to injured and inflamed regions via the bloodstream to assist in tissue regeneration in response to signals of cellular damage. However, the factors and mechanisms that affect their transendothelial migration are still unclear. In this study, the mechanisms involved in interleukin-1β (IL-1β) enhancing the transendothelial migration of MSCs were investigated.

METHODS

Immunofluorescence staining and Western blotting were used to observe IL-1β-induced CXC chemokine receptor 3 (CXCR3) expression on MSCs. Quantitative real-time PCR and ELISA were used to demonstrate IL-1β upregulated both chemokine (C-X-C motif) ligand 9 (CXCL9) mRNA and CXCL9 ligand secretion in human umbilical vein endothelial cells (HUVECs). Monolayer co-cultivation, agarose drop chemotaxis, and transwell assay were conducted to investigate the chemotaxis invasion and transendothelial migration ability of IL-1β-induced MSCs in response to CXCL9.

RESULTS

In this study, our immunofluorescence staining showed that IL-1β induces CXCR3 expression on MSCs. This result was confirmed by Western blotting. Following pretreatment with protein synthesis inhibitor cycloheximide, we found that IL-1β induced CXCR3 on the surface of MSCs via protein synthesis pathway. Quantitative real-time PCR and ELISA validated that IL-1β upregulated both CXCL9 mRNA and CXCL9 ligand secretion in HUVECs. In response to CXCL9, chemotaxis invasion and transendothelial migration ability were increased in IL-1β-stimulated MSCs. In addition, we pretreated MSCs with CXCR3 antagonist AMG-487 and p38 MAPK inhibitor SB203580 to confirm CXCR3-CXCL9 interaction and the role of CXCR3 in IL-1β-induced chemotaxis invasion and transendothelial migration.

CONCLUSION

We found that IL-1β induces the expression of CXCR3 through p38 MAPK signaling and that IL-1β also enhances CXCL9 ligand secretion in HUVECs. These results indicated that IL-1β promotes the transendothelial migration of MSCs through CXCR3-CXCL9 axis. The implication of the finding could enhance the efficacy of MSCs homing to target sites.

Involvement of inflammatory responses in the early development of calcific aortic valve disease: lessons from statin therapy

Calcific aortic valve disease (CAVD) is the most common degenerative heart valve disease. Among the many risk factors for this disease are age, hypercholesterolemia, hypertension, smoking, type-2 diabetes, rheumatic fever, and chronic kidney disease. Since many of these overlap with risk factors for atherosclerosis, the molecular and cellular mechanisms of CAVD development have been presumed to be similar to those for atherogenesis. Thus, attempts have been made to evaluate the therapeutic efficacy of statins, representative anti-atherosclerosis drugs with lipid-lowering and anti-inflammatory effects, against CAVD. Unfortunately, statins have shown little or no effect on CAVD development. But some reports suggest that statins may prevent or reduce the development of early stage CAVD in which having calcification is absent or minimal. These results suggest that therapeutic approaches should differ according to the stage of disease, and that a precise understanding of the mechanism of aortic valve calcification is required to identify novel therapeutic targets for advanced CAVD. Given the involvement of inflammatory processes in the development and progression of CAVD, current therapeutic approaches for chronic inflammatory cardiovascular disease like atherosclerosis may help to prevent or minimize the early development of CAVD. In this review, we focus on several inflammatory cellular and molecular components involved in CAVD that might be considered drug targets for preventing CAVD.

The Many Faces of Rap1 GTPase

This review addresses the issue of the numerous roles played by Rap1 GTPase (guanosine triphosphatase) in different cell types, in terms of both physiology and pathology. It is one among a myriad of small G proteins with endogenous GTP-hydrolyzing activity that is considerably stimulated by posttranslational modifications (geranylgeranylation) or guanine nucleotide exchange factors (GEFs), and inhibited by GTPase-activating proteins (GAPs). Rap1 is a ubiquitous protein that plays an essential role in the control of metabolic processes, such as signal transduction from plasma membrane receptors, cytoskeleton rearrangements necessary for cell division, intracellular and substratum adhesion, as well as cell motility, which is needed for extravasation or fusion. We present several examples of how Rap1 affects cells and organs, pointing to possible molecular manipulations that could have application in the therapy of several diseases.

Selectin-Targeting Peptide-Glycosaminoglycan Conjugates Modulate Neutrophil-Endothelial Interactions

Introduction

The glycocalyx is a layer of glycoproteins, proteoglycans and glycosaminoglycans that coats the luminal surface of most blood vessels. It effectively regulates adhesive interactions between leukocytes in flowing blood and the endothelium, where during inflammation, binding to E- and P-selectins and intercellular adhesion molecule-1 (ICAM-1) promotes cell tethering and arrest under shear flow.

Methods

In this study, we examine the targeting of E-selectin by an engineered peptide moiety bound to a dermatan sulfate backbone. We further investigate this conjugate, denoted as EC-SEAL, by observing its binding to inflamed endothelium, and quantifying its ability to modulate neutrophil–endothelium interactions.

Results

Binding data reveal that EC-SEAL recognizes domains on E-selectin, and to a lesser degree on P- and L-selectin, and ICAM-1. Further, EC-SEAL increases neutrophil rolling velocity, and decreases neutrophil arrest and migration on inflamed human microvascular endothelial cells under physiologically relevant flow conditions.

Conclusions

We conclude that simple targeting strategies can mimic glycocalyx function under inflammatory conditions, effectively reducing neutrophil recruitment.

Electronic supplementary material

The online version of this article (10.1007/s12195-018-0555-6) contains supplementary material, which is available to authorized users.

Pulmonary influenza A virus infection leads to suppression of the innate immune response to dermal injury

The innate immune system is responsible for many important functions in the body including responding to infection, clearing cancerous cells, healing wounds, and removing foreign substances. Although many of these functions happen simultaneously in life, most laboratory studies of the innate immune response focus on one activity. How the innate immune system responds to concurrent insults in different parts of the body is not well understood. This study explores the impact of a lung infection on the cutaneous wound healing process. We used two complimentary models of injury: the excisional tail wound and subcutaneous implantation of polyvinyl alcohol (PVA) sponges. These models allow for assessment of the rate of closure and measurement of cellular and cytokine responses during acute wound healing, respectively. When mice with these healing wounds were infected with influenza A virus (IAV) in the lung there was a delay in wound healing. The viral lung infection suppressed the innate immune response in a healing wound, including cellular infiltrate, chemokines, growth factors, and cytokines. However, there was not a global immune suppression as there was an increase in inflammation systemically in mice with both infection and healing wounds compared to mice with only wounds or IAV infection. In addition, the lung immune response was largely unaffected indicating that responding to a lung infection is prioritized over a healing wound. This study introduces the concept of immune triage, in that when faced with multiple insults the immune system prioritizes responses. This paradigm likely applies to many situations that involve the innate immune system, and understanding how the innate immune system handles multiple insults is essential to understanding how it can efficiently clear pathogens while responding to other inflammatory events.

In a natural setting, the innate immune system is frequently faced with multiple insults, against which it must mount overlapping inflammatory responses. We are interested in how the innate immune system deals with multiple, simultaneously occurring inflammatory insults, and if the response to one will take priority. For example, the innate immune system is essential in mediating both the early control of pathogen replication in infected tissue and in the early stages of wound healing. Pulmonary infections occur frequently in injured patient populations; therefore, we set out to determine the impact of a respiratory infection on a healing wound. To examine this, mice with healing dermal wounds were infected with influenza A virus (IAV), a common cause of viral pneumonia. We found that the innate immune response to the lung infection took priority at the expense of the healing wound, in that the initial control of viral replication in the lung was not impacted, while the wound healing response was suppressed. Very little work has been done examining how the immune response can respond to overlapping inflammatory insults. Our work shows that not all immune responses are created equal, and that the cells of the innate immune system are preferentially routed towards fighting a lung infection rather than the healing dermal wound. This apparent prioritization of the innate immune response opens up a new direction of study. It is relevant to many fields where competing insults may alter the disease state.

Pathogenesis of Pediatric Rheumatologic Diseases

The pathogenesis of pediatric rheumatologic conditions varies with the specific disorder; however, certain commonalities are seen: altered migration of cells into tissues, production of inflammatory mediators, and enhanced activation of cells. Autoantibodies signal loss of tolerance and B and T cells may be seen on pathologic evaluation. Neutrophils are commonly observed in tissues for many diseases and are recruited through the activation of endothelial cells. These cellular infiltrates define the inflammatory response character and in some cases provide a therapeutic framework. Increased knowledge of the interactions of these cells and their products allow targeted treatments for rheumatic diseases.

Endothelial BMP4 Regulates Leukocyte Diapedesis and Promotes Inflammation

Leukocyte recruitment is a fundamental event in the response of the innate immune system to injury. This process is promoted in part by the opening of endothelial cell adherens junctions that allows leukocyte extravasation through gaps between adjacent endothelial cells. VE-cadherin is a key component of endothelial cell adherens junctions and a negative regulator of leukocyte emigration. Accumulating evidence implicates bone morphogenetic protein (BMP) 4 as a critical regulator in vascular biology, but its role in leukocyte extravasation in vitro and in vivo has not been investigated so far. To assess the impact of BMP4 on leukocyte emigration in vivo, we used the thioglycollate-induced peritonitis model. C57BL/6 mice were intraperitoneally (i.p.) injected with recombinant BMP4 in addition to thioglycollate. Compared to solvent-treated controls, we observed higher accumulation of leukocytes in the peritoneal lavage of BMP4-treated mice indicating that BMP4 promotes leukocyte diapedesis into the inflamed peritoneal cavity. Endothelial cell-specific deletion of BMP4 in mice markedly diminished leukocyte diapedesis following thioglycollate administration suggesting that endothelial BMP4 is required for leukocyte recruitment. Consistent with these in vivo results, transwell migration assays with human umbilical vein endothelial cells (HUVECs) in vitro revealed that recombinant BMP4 enhanced leukocyte transmigration through the endothelial monolayer. Conversely, silencing of endothelial BMP4 by siRNA dampened leukocyte diapedesis in vitro. Mechanistic studies showed that loss of BMP4 improved endothelial junction stability by upregulation of VE-cadherin expression in vitro and in vivo. Vice versa, treatment of HUVECs with recombinant BMP4 decreased expression of VE-cadherin and impaired endothelial junction stability shown by Western blotting and immunocytochemistry. Finally, severe endothelial damage in HUVECs in response to serum of patients collected 24 h after survived cardiac arrest was accompanied by increase in leukocyte migration in transwell assays and activation of the BMP pathway most probably by upregulation of endothelial BMP4 RNA and protein expression. Collectively, the present study provides novel evidence that endothelial BMP4 controls leukocyte recruitment through a VE-cadherin-dependent mechanism and that BMP4-induced inflammation might be involved in the pathogenesis of endothelial cell damage following successful resuscitation after cardiac arrest.

Heterocellular molecular contacts in the mammalian stem cell niche

Adult tissue homeostasis and repair relies on prompt and appropriate intervention by tissue-specific adult stem cells (SCs). SCs have the ability to self-renew; upon appropriate stimulation, they proliferate and give rise to specialized cells. An array of environmental signals is important for maintenance of the SC pool and SC survival, behavior, and fate. Within this special microenvironment, commonly known as the stem cell niche (SCN), SC behavior and fate are regulated by soluble molecules and direct molecular contacts via adhesion molecules providing connections to local supporting cells and the extracellular matrix. Besides the extensively discussed array of soluble molecules, the expression of adhesion molecules and molecular contacts is another fundamental mechanism regulating niche occupancy and SC mobilization upon activation. Some adhesion molecules are differentially expressed and have tissue-specific consequences, likely reflecting the structural differences in niche composition and design, especially the presence or absence of a stromal counterpart. However, the distribution and identity of intercellular molecular contacts for adhesion and adhesion-mediated signaling within stromal and non-stromal SCN have not been thoroughly studied. This review highlights common details or significant differences in cell-to-cell contacts within representative stromal and non-stromal niches that could unveil new standpoints for stem cell biology and therapy.

Role of an indole-thiazolidiene PPAR pan ligand on actions elicited by G-protein coupled receptor activated neutrophils

Neutrophils are the first line of defence during inflammatory processes; nevertheless, exacerbated influx and actions of neutrophils in terms of uncontrolled inflammation are harmful to the host. Hence, neutrophil activity is the target of drugs seeking to address undesired inflammation. Here, we investigated the mechanisms of action of a ligand of the three isoforms of peroxisome proliferator-activated receptors (PPAR; (5Z)-5-[(5-bromo-1H-indole-3-yl)methylene]-3-(4-chlorobenzyl)-thiazolidine-2,4-dione), dubbed LYSO-7, on neutrophils activated by N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLP), an agonist of G-protein coupled receptors (GPCRs) that binds to membrane-formylated peptide and activates intracellular inflammation pathways. Neutrophils were collected from the peritoneal cavity of male Wistar rats four hours after oyster glycogen injection. Afterwards, the neutrophils were incubated with saline or LYSO-7 (1 or 10 μM, 30 min), washed and stimulated with fMLP (10^-7 μM, 1 h). LYSO-7 treatment inhibited gene and protein expression of adhesion molecules, CD62 L and CD18, abolished adhesion of neutrophils to endothelial cells, impaired chemotaxis, blocked the enhancement of intracellular calcium levels, induced the expression of PPARγ as well as PPARβδ and reduced nuclear translocation of nuclear factor κB (NF-κB). Moreover, topical application of LYSO-7 (10 mM) prior to local application of fMLP (10^-7 μM) diminished the in vivo leukocyte-endothelial interactions in the mesentery microcirculation of rats. Together, our data highlight the effectiveness of anti-inflammatory actions of LYSO-7 on neutrophils activated by GPCRs, depending, at least in part, on impaired of NF-κB activation and induction of PPAR expression.

Lymphocytes and monocytes egress peripheral blood within minutes after cessation of steady state exercise: A detailed temporal analysis of leukocyte extravasation

Acute exercise evokes an almost instantaneous lymphocytosis, followed by sustained lymphopenia that occurs within just 30-60 min after exercise cessation. The aim of this study was to characterize the immediate (order of minutes) post-exercise kinetics of lymphocyte and monocyte egress, and to determine whether this egress is associated with heart rate recovery following a single bout of steady state dynamic exercise. Eleven healthy subjects cycled for 30-min at ~70% of their estimated peak power. Blood samples were collected from an intravenous catheter before exercise, during exercise (E) at +15 and +30 min, and during passive recovery (R) at exactly +1, +2, +3, +4, +5 and +10 min after exercise cessation. Complete blood counts and flow cytometry were used to enumerate total monocytes, lymphocytes: CD3+ T-cells, CD4+ T-cells, CD8+ T-cells, NK-cells and γδ T-cells in whole blood. Both lymphocytes and monocytes displayed rapid egress kinetics, by R+3 the total numbers of all cell types examined were significantly lower than E+30. NK-cells egressed more rapidly than other lymphocyte subtypes, followed by CD8+, γδ, and then CD4+ T-cells. Further, the egress of NK-cells, CD4+, and CD8+ T-cells positively correlated with heart rate recovery after exercise cessation. In conclusion, lymphocyte and monocyte egress is rapid and occurs within minutes of exercise recovery, underscoring both the importance of collection time for post exercise blood samples, and the use of intravenous catheters to capture peak cell mobilization. The rate of egress may be dependent on how quickly hemodynamic equilibrium is restored on cessation of exercise and is, therefore, likely to be influenced by individual fitness levels.

Modulation of reactive oxygen species production, apoptosis and cell cycle in pleural exudate cells of carrageenan-induced acute inflammation in rats by rutin

The present study seeks to investigate the effect of rutin, a flavonoid compound in rat models of acute inflammation induced by carrageenan (CAR). Twenty-four female Wistar rats weighing 222-247 g received saline or 2% λ-carrageenan in the pleural cavity and treatment with rutin (80 mg kg^-1) or saline by oral gavage for 21 days prior to the intrapleural induction of CAR. After 4 h of induction, the rats were euthanized, the plasma was prepared from the blood for the analysis of haematological parameters and the pleural exudate was obtained for the analysis of the total cell count, cell viability, reactive oxygen species (ROS) production, apoptosis and cell cycle. The result revealed that rutin exhibited anti-inflammatory effects by modulating the ROS level, apoptosis and cell cycle. This study indicates that rutin may exert a protective effect against ROS-mediated oxidative damage associated with an anti-inflammatory activity in rat models of acute inflammation.

Time and Concentration Dependent Effects of Short Chain Fatty Acids on Lipopolysaccharide- or Tumor Necrosis Factor α-Induced Endothelial Activation

Background and Aim: Endothelial activation is characterized by excessive production of cytokines and chemokines as well as adhesion molecules expression which is involved in the development of atherosclerosis. The aim of our study is to investigate the effects of short chain fatty acids (SCFA) on lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNFα)-induced endothelial activation. Methods and Results: Human umbilical vein endothelial cells (HUVEC) were pre-treated with acetate (10 mM), butyrate (0.1 mM) or propionate (0.3 mM) for 1, 16, or 24 h and then stimulated with LPS (1 or 10 μg/ml) or TNFα (100 pg/ml or 1 ng/ml) for 6, 12, or 24 h. Cytokines in the supernatant were measured by ELISA. HUVEC were pre-treated with acetate (10 mM), butyrate (5 mM) or propionate (10 mM) for 24 h and then stimulated with LPS (1 μg/ml) or TNFα (1 ng/ml) for 8 h. The expression of the adhesion molecules intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was detected by flow cytometry. The human blood mononuclear cell adhesive level to HUVEC monolayer was measured. LPS and TNFα induced a significant increase in the release of interleukin-6 (IL-6) and IL-8. Acetate, butyrate and propionate reduced IL-6 and IL-8 levels and the magnitude was dependent on the incubation times. LPS or TNFα increased ICAM-1 and VCAM-1 expression. Pre-incubation with acetate had no effect. In contrast, butyrate and propionate decreased VCAM-1 expression in TNFα stimulated cells but showed no effects on ICAM-1 expression. Butyrate significantly inhibited the adhesion of mononuclear cells to an endothelial monolayer and propionate was less effective. Conclusion: SCFA, including acetate, butyrate and propionate, influenced LPS- or TNFα-induced endothelial activation by inhibiting the production of IL-6 and IL-8, and reducing the expression of VCAM-1 and subsequent cell adhesion. Results were dependent on the concentrations and pre-incubation time of each SCFA and stimulation time of LPS or TNFα.

Immunological In Vivo and In Vitro Investigations of Aqueous Extract of Stem Bark of Pterocarpus erinaceus Poir (Fabaceae)

BACKGROUND

Macrophages are the first cells to recognize invading foreign bodies and are central to cell mediated and humoral immunity. Therefore, the activation of macrophages is a key event for effective innate and adaptive immunity. Pterocarpus erinaceus has been reported to control infectious diseases, but the mechanism remains to be elucidated. In this study, we demonstrated the immune-modulatory effect of aqueous extract of P. erinaceus using human macrophages and lymphocytes, as well as mice.

METHODS

Hot water was used to extract P. erinaceus from the stem bark. Its effect on lymphocytes was measured by evaluating proliferative response and delayed hypersensitivity. Phagocytic activity of macrophages were measured based on neutral red uptake assay, nitric oxide production and myeloperoxidase and phosphatase acid activity. Hematopoietic and infectious activities were analyzed using the effect on infectious stress and chloramphenicol-induced leucopenic mice model.

RESULTS

Aqueous extract showed stronger stimulatory effects on the neutral red uptake, production of nitric oxide and phosphatase acid activity in lipopolysaccharide-activated macrophages. In addition, aqueous extract significantly stimulated the proliferation of phytohemagglutinin-activated lymphocytes, enhanced delayed hypersensitivity response to erythrocytes and attenuated infection-induced fever. Furthermore, aqueous extract also significantly increased the rate of recovery of white blood cell levels in chloramphenicol-induced leucopenia mice.

CONCLUSIONS

The results suggest that aqueous extract of P. erinaceus stem bark is able to modulate the immune system and has potential effects in clinical conditions when an immune-enhancing and anti-infectious effect is desired.

Neutrophils: Beneficial and Harmful Cells in Septic Arthritis

Septic arthritis is an inflammatory joint disease that is induced by pathogens such as Staphylococcus aureus. Infection of the joint triggers an acute inflammatory response directed by inflammatory mediators including microbial danger signals and cytokines and is accompanied by an influx of leukocytes. The recruitment of these inflammatory cells depends on gradients of chemoattractants including formylated peptides from the infectious agent or dying cells, host-derived leukotrienes, complement proteins and chemokines. Neutrophils are of major importance and play a dual role in the pathogenesis of septic arthritis. On the one hand, these leukocytes are indispensable in the first-line defense to kill invading pathogens in the early stage of disease. However, on the other hand, neutrophils act as mediators of tissue destruction. Since the elimination of inflammatory neutrophils from the site of inflammation is a prerequisite for resolution of the acute inflammatory response, the prolonged stay of these leukocytes at the inflammatory site can lead to irreversible damage to the infected joint, which is known as an important complication in septic arthritis patients. Thus, timely reduction of the recruitment of inflammatory neutrophils to infected joints may be an efficient therapy to reduce tissue damage in septic arthritis.

Impact of developmental exposure to methylphenidate on rat brain's immune privilege and behavior: Control versus ADHD model

Attention deficit hyperactivity disorder (ADHD) is the most prevalent childhood mental disorders that often persists into adulthood. Moreover, methylphenidate (MPH) is the mainstay of medical treatment for this disorder. Yet, not much is known about the neurobiological impact of MPH on control versus ADHD conditions, which is crucial to simultaneously clarify the misuse/abuse versus therapeutic use of this psychostimulant. In the present study, we applied biochemical and behavioral approaches to broadly explore the early-life chronic exposure of two different doses of MPH (1.5 and 5 mg/kg/day) on control and ADHD rats (Wistar Kyoto and Spontaneously Hypertensive rats, respectively). We concluded that the higher dose of MPH promoted blood-brain barrier (BBB) permeability and elicited anxiety-like behavior in both control and ADHD animals. BBB dysfunction triggered by MPH was particularly prominent in control rats, which was characterized by a marked disruption of intercellular junctions, an increase of endothelial vesicles, and an upregulation of adhesion molecules concomitantly with the infiltration of peripheral immune cells into the prefrontal cortex. Moreover, both doses of MPH induced a robust neuroinflammatory and oxidative response in control rats. Curiously, in the ADHD model, the lower dose of MPH (1.5 mg/kg/day) had a beneficial effect since it balanced both immunity and behavior relative to vehicle animals. Overall, the contrasting effects of MPH observed between control and ADHD models support the importance of an appropriate MPH dose regimen for ADHD, and also suggest that MPH misuse negatively affects brain and behavior.

Protective role of FKBP51 in calcium entry-induced endothelial barrier disruption

Pulmonary artery endothelial cells (PAECs) express a cation current, I_SOC (store-operated calcium entry current), which when activated permits calcium entry leading to inter-endothelial cell gap formation. The large molecular weight immunophilin FKBP51 inhibits I_SOC but not other calcium entry pathways in PAECs. However, it is unknown whether FKBP51-mediated inhibition of I_SOC is sufficient to protect the endothelial barrier from calcium entry-induced disruption. The major objective of this study was to determine whether FKBP51-mediated inhibition of I_SOC leads to decreased calcium entry-induced inter-endothelial gap formation and thus preservation of the endothelial barrier. Here, we measured the effects of thapsigargin-induced I_SOC on the endothelial barrier in control and FKBP51 overexpressing PAECs. FKBP51 overexpression decreased actin stress fiber and inter-endothelial cell gap formation in addition to attenuating the decrease in resistance observed with control cells using electric cell-substrate impedance sensing. Finally, the thapsigargin-induced increase in dextran flux was abolished in FKBP51 overexpressing PAECs. We then measured endothelial permeability in perfused lungs of FKBP51 knockout (FKBP51^–/–) mice and observed increased calcium entry-induced permeability compared to wild-type mice. To begin to dissect the mechanism underlying the FKBP51-mediated inhibition of I_SOC, a second goal of this study was to determine the role of the microtubule network. We observed that FKBP51 overexpressing PAECs exhibited increased microtubule polymerization that is critical for inhibition of I_SOC by FKBP51. Overall, we have identified FKBP51 as a novel regulator of endothelial barrier integrity, and these findings are significant as they reveal a protective mechanism for endothelium against calcium entry-induced disruption.

Neutrophils and PMN-MDSC: Their biological role and interaction with stromal cells

Neutrophils and polymorphonucler myeloid-derived suppressor cells (PMN-MDSC) share origin and many morphological and phenotypic features. However, they have different biological role. Neutrophils are one of the major mechanisms of protection against invading pathogens, whereas PMN-MDSC have immune suppressive activity and restrict immune responses in cancer, chronic infectious disease, trauma, sepsis, and many other pathological conditions. Although in healthy adult individuals, PMN-MDSC are not or barely detectable, in patients with cancer and many other diseases they accumulate at various degree and co-exist with neutrophils. Recent advances allow for better distinction of these cells and better understanding of their biological role. Accumulating evidence indicates PMN-MDSC as pathologically activated neutrophils, with important role in regulation of immune responses. In this review, we provide an overview on the definition and characterization of PMN-MDSC and neutrophils, their pathological significance in a variety of diseases, and their interaction with other stromal components.

Emergence of synthetic mRNA: In vitro synthesis of mRNA and its applications in regenerative medicine

The field of gene therapy has evolved over the past two decades after the first introduction of nucleic acid drugs, such as plasmid DNA (pDNA). With the development of in vitro transcription (IVT) methods, synthetic mRNA has become an emerging class of gene therapy. IVT mRNA has several advantages over conventional pDNA for the expression of target proteins. mRNA does not require nuclear localization to mediate protein translation. The intracellular process for protein expression is much simpler and there is no potential risk of insertion mutagenesis. Having these advantages, the level of protein expression is far enhanced as comparable to that of viral expression systems. This makes IVT mRNA a powerful alternative gene expression system for various applications in regenerative medicine. In this review, we highlight the synthesis and preparation of IVT mRNA and its therapeutic applications. The article includes the design and preparation of IVT mRNA, chemical modification of IVT mRNA, and therapeutic applications of IVT mRNA in cellular reprogramming, stem cell engineering, and protein replacement therapy. Finally, future perspectives and challenges of IVT mRNA are discussed.

Potato freeze-thaw solution enhances immune function and antitumor activity in vivo

Although potato extract, derived from various methods, exhibits anticancer, antiviral and anti-parasite activities in vitro and in vivo, the bioactivity of potato solution remains unclear using the freeze-thaw extraction method granted by the State Intellectual Property Office of China. In the present study, a potato freeze-thaw solution (PFTS) was fed to mice with ascites tumor that were pre-treated with cyclophosphamide. The numbers of peripheral white blood cells (WBCs), macrophage phagocytosis, lymphocyte transformation and survival of mice were measured. While mice injected with cyclophosphamide exhibited decreased counts of peripheral WBCs, treatment of the cyclophosphamide-injected mice with PFTS for 10 days significantly increased the number of peripheral WBCs and reversed WBC counts to the normal level, a comparable effect to that of Ganoderma lucidum. In addition, treatment with PFTS for 20 days significantly enhanced peritoneal macrophage phagocytosis and lymphocyte transformation. Lastly, PFTS was noticed to prolong the survival of tumor-bearing mice when compared with that of control mice. Collectively, these data suggested that PFTS, at least in part, enhances immune function and possesses antitumor activity.

Phenotypic Characterization of Human Monocytes following Macronutrient Intake in Healthy Humans

Background

Three subsets of human monocytes in circulation have been identified and their characterization is still ill-defined. Although glucose and lipid intakes have been demonstrated to exert pro-inflammatory effects on mononuclear cells (MNCs) of healthy subjects, characterization of monocytes phenotypes following macronutrient (glucose, protein, and lipid) intake in humans remains to be determined.

Methods

Thirty-six healthy, normal weight volunteers were recruited in the study. Subjects were randomly assigned into three groups, each group consisting of 12 participants. Each group drank equal calories (300 kcal) of either glucose or lipids or whey proteins. Each subject served as his own control by drinking 300 mL of water 1 week before or after the caloric intake. Baseline blood samples were drawn at 0, 1, 2, and 3-h intervals post caloric or water intakes. MNCs were isolated, and the expression levels of different cluster of differentiation (CD) markers (CD86, CD11c, CD169, CD206, CD163, CD36, CD68, CD11b, CD16, and CD14) and IL-6 were measured by RT-qPCR.

Results

Equicaloric intake of either glucose or lipids or whey proteins resulted in different monocyte phenotypes as demonstrated by changes in the expression levels of CD and polarization markers. Whey proteins intake resulted in significant mRNA upregulation in MNCs of CD68 and CD11b at 1, 2, and 3 h post intake while mRNA of IL-6 was significantly inhibited at 1 h. Lipids intake, on the other hand, resulted in mRNA upregulation of CD11b at 2 and 3 h and CD206 at 1, 2, and 3 h. There were no significant changes in the other CD markers measured (CD86, CD163, CD169, CD36, CD16, and CD14) following either whey proteins or lipids intakes. Glucose intake did not alter mRNA expression of any marker tested except CD206 at 3 h.

Conclusion

Macronutrient intake alters the expression levels of polarization markers in MNCs of human subjects. A distinct population of different monocytes phenotypes may result in human circulation following the intake of different macronutrients. Further studies are required to characterize the immunomodulatory effects of macronutrients intake on monocytes phenotypes and their characteristics in humans.

Prophylactic inhibition of neutrophil elastase prevents the development of chronic neuropathic pain in osteoarthritic mice

Background

A subset of osteoarthritis (OA) patients experience joint pain with neuropathic characteristics. Mediators such as neutrophil elastase, a serine proteinase, may be released during acute OA inflammatory flares. We have previously shown that local administration of neutrophil elastase causes joint inflammation and pain via activation of proteinase-activated receptor-2 (PAR2). The aim of this study was to examine the contribution of endogenous neutrophil elastase and PAR2 to the development of joint inflammation, pain, and neuropathy associated with monoiodoacetate (MIA)-induced experimental OA.

Methods

MIA (0.3 mg/10 μl) was injected into the right knee joint of male C57BL/6 mice (20–34 g). Joint inflammation (edema, leukocyte kinetics), neutrophil elastase proteolytic activity, tactile allodynia, and saphenous nerve demyelination were assessed over 14 days post-injection. The effects of inhibiting neutrophil elastase during the early inflammatory phase of MIA (days 0 to 3) were determined using sivelestat (50 mg/kg i.p.) and serpinA1 (10 μg i.p.). Involvement of PAR2 in the development of MIA-induced joint inflammation and pain was studied using the PAR2 antagonist GB83 (5 μg i.p. days 0 to 1) and PAR2 knockout animals.

Results

MIA caused an increase in neutrophil elastase proteolytic activity on day 1 (P < 0.0001), but not on day 14. MIA also generated a transient inflammatory response which peaked on day 1 (P < 0.01) then subsided over the 2-week time course. Joint pain appeared on day 1 and persisted to day 14 (P < 0.0001). By day 14, the saphenous nerve showed signs of demyelination. Early treatment with sivelestat and serpinA1 blocked the proteolytic activity of neutrophil elastase on day 1 (P < 0.001), and caused lasting improvements in joint inflammation, pain, and saphenous nerve damage (P < 0.05). MIA-induced synovitis was reversed by early treatment with GB83 and attenuated in PAR2 knockout mice (P < 0.05). PAR2 knockout mice also showed reduced MIA-induced joint pain (P < 0.0001) and less nerve demyelination (P = 0.81 compared to saline control).

Conclusions

Neutrophil elastase and PAR2 contribute significantly to the development of joint inflammation, pain, and peripheral neuropathy associated with experimental OA, suggesting their potential as therapeutic targets.

Pathobiology of neutrophil-epithelial interactions

Polymorphonuclear neutrophils (PMNs) are innate immune system cells that play an essential role in eradicating invading pathogens. PMN migration to sites of infection/inflammation requires exiting the microcirculation and subsequent crossing of epithelial barriers in mucosa-lined organs such as the lungs and intestines. Although these processes usually occur without significant damage to surrounding host tissues, dysregulated/excessive PMN transmigration and resultant bystander-tissue damage are characteristic of numerous mucosal inflammatory disorders. Mechanisms controlling PMN extravasation have been well characterized, but the molecular details regarding regulation of PMN migration across mucosal epithelia are poorly understood. Given that PMN migration across mucosal epithelia is strongly correlated with disease symptoms in many inflammatory mucosal disorders, enhanced understanding of the mechanisms regulating PMN transepithelial migration should provide insights into clinically relevant tissue-targeted therapies aimed at ameliorating PMN-mediated bystander-tissue damage. This review will highlight current understanding of the molecular interactions between PMNs and mucosal epithelia and the associated functional consequences.

Intravital Imaging of Myeloid Cells: Inflammatory Migration and Resident Patrolling

Myeloid cell recruitment to sites of infection and injury started out as a simple model that has been referred to as the universal concept of leukocyte recruitment. However, as we gain more insight into the different mechanisms, it is becoming clear that each organ and perhaps even each cell has its own unique mechanism of recruitment. Moreover, as the ability to visualize specific cell types in specific organs becomes more accessible, it is also becoming clear that there are resident populations of leukocytes, some within the tissues and others attached to the vasculature of tissues, the latter poised to affect the local environment. In this review, we will first highlight the imaging approaches that have allowed us to gain spectacular insight into locale and function of specific cell types, and then we will discuss what we have learned from this approach as far as myeloid cells are concerned. We will also highlight some of the gaps in our knowledge, which exist almost certainly because of the challenges of being able to visualize certain compartments of the body.

Macrophage exosomes as natural nanocarriers for protein delivery to inflamed brain

Recent work has stimulated interest in the use of exosomes as nanocarriers for delivery of small drugs, RNAs, and proteins to the central nervous system (CNS). To overcome the blood-brain barrier (BBB), exosomes were modified with brain homing peptides that target brain endothelium but likely to increase immune response. Here for the first time we demonstrate that there is no need for such modification to penetrate the BBB in mammals. The naïve macrophage (Mϕ) exosomes can utilize, 1) on the one hand, the integrin lymphocyte function-associated antigen 1 (LFA-1) and intercellular adhesion molecule 1 (ICAM-1), and, 2) on the other hand, the carbohydrate-binding C-type lectin receptors, to interact with brain microvessel endothelial cells comprising the BBB. Notably, upregulation of ICAM-1, a common process in inflammation, promotes Mϕ exosomes uptake in the BBB cells. We further demonstrate in vivo that naïve Mϕ exosomes, after intravenous (IV) administration, cross the BBB and deliver a cargo protein, the brain derived neurotrophic factor (BDNF), to the brain. This delivery is enhanced in the presence of brain inflammation, a condition often present in CNS diseases. Taken together, the findings are of interest to basic science and possible use of Mϕ-derived exosomes as nanocarriers for brain delivery of therapeutic proteins to treat CNS diseases.

Chrysin Attenuates VCAM-1 Expression and Monocyte Adhesion in Lipopolysaccharide-Stimulated Brain Endothelial Cells by Preventing NF-κB Signaling

Adhesion of leukocytes to endothelial cells plays an important role in neuroinflammation. Therefore, suppression of the expression of adhesion molecules in brain endothelial cells may inhibit neuroinflammation. Chrysin (5,7-dihydroxyflavone) is a flavonoid component of propolis, blue passion flowers, and fruits. In the present study, we examined the effects of chrysin on lipopolysaccharide (LPS)-induced expression of vascular cell adhesion molecule-1 (VCAM-1) in mouse cerebral vascular endothelial (bEnd.3) cells. In bEnd.3 cells, LPS increased mRNA expression of VCAM-1 in a time-dependent manner, and chrysin significantly decreased LPS-induced mRNA expression of VCAM-1. Chrysin also reduced VCAM-1 protein expression in a concentration-dependent manner. Furthermore, chrysin blocked adhesion of monocytes to bEnd.3 cells exposed to LPS. Nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase, which are all activated by LPS, were significantly inhibited by chrysin. These results indicate that chrysin inhibits the expression of VCAM-1 in brain endothelial cells by inhibiting NF-κB translocation and MAPK signaling, resulting in the attenuation of leukocyte adhesion to endothelial cells. The anti-inflammatory effects of chrysin suggest a possible therapeutic application of this agent to neurodegenerative diseases, such as multiple sclerosis, septic encephalopathy, and allergic encephalomyelitis.

Time course of VCAM-1 expression in reperfused myocardial infarction in swine and its relation to retention of intracoronary administered bone marrow-derived mononuclear cells

Background

Intracoronary infusion of autologous bone marrow-derived mononuclear cells (BMMNC), after acute myocardial infarction (AMI), has been shown to improve myocardial function. However, therapeutic efficacy is limited, possibly because cell retention rates are low, suggesting that optimization of cell retention might increase therapeutic efficacy. Since retention of injected BMMNC is observed only within infarcted, but not remote, myocardium, we hypothesized that adhesion molecules on activated endothelium following reperfusion are essential. Consequently, we investigated the role of vascular cell adhesion molecule 1 (VCAM-1) in BMMNC retention in swine undergoing reperfused AMI produced by 120 min of percutaneous left circumflex coronary occlusion.

Methods and results

VCAM-1 expression in the infarct and remote region was quantified at 1, 3, 7, 14, and 35 days, post-reperfusion (n≥6 swine per group). Since expression levels were significantly higher at 3 days (2.41±0.62%) than at 7 days (0.98±0.28%; p<0.05), we compared the degree of cell retention at those time points in a follow-up study, in which an average of 43·10⁶ autologous BMMNCs were infused intracoronary at 3, or 7 days, post-reperfusion (n = 6 swine per group) and retention was histologically quantified one hour after intracoronary infusion of autologous BMMNCs. Although VCAM-1 expression correlated with retention of BMMNC within each time point, overall BMMNC retention was similar at day 3 and day 7 (2.3±1.3% vs. 3.1±1.4%, p = 0.72). This was not due to the composition of infused bone marrow cell fractions (analyzed with flow cytometry; n = 5 per group), as cell composition of the infused BMMNC fractions was similar.

Conclusion

These findings suggest that VCAM-1 expression influences to a small degree, but is not the principal determinant of, BMMNC retention.

Monocyte chemoattractant protein-1 polymorphism interaction with spirulina immunomodulatory effects in healthy Korean elderly: A 16 week, double-blind randomized clinical trial

BACKGROUND/OBJECTIVES

Spirulina is a known a functional food related to lipid profiles, immune functions, and antioxidant capacity. Circulating monocyte chemoattractant protein-1 (MCP-1) level is associated with inflammation markers. Single nucleotide polymorphism in the MCP-1 promoter region -2518 have been identified and shown to affect gene transcription. Gene variation may also impact functional food supplementary effects. The current study investigated the interaction of MCP-1 -2518 polymorphism with spirulina supplements on anti-inflammatory capacity in Korean elderly.

SUBJECTS/METHODS

After genotyping, healthy elderly subjects (n = 78) were included in a randomized, double blind, and placebo controlled study. Baseline characteristic, body composition, and dietary intake were measured twice (baseline vs. week 16). For 16 weeks, subjects consumed 8 g either spirulina or placebo daily. Plasma MCP-1, interleukin (IL) -2, IL-6, tumor necrosis factor (TNF)-α, complement (C) 3, immunoglobulin (Ig) G, and Ig A concentrations and lymphocyte proliferation rate (LPR) were analyzed as inflammatory markers.

RESULTS

In the placebo group with A/A genotype, MCP-1 level was significantly increased, but the spirulina group with A/A genotype was unchanged. IL-2 was significantly increased only in subjects with spirulina supplementation. TNF-α was significantly reduced in subjects with the G carrier. C3 was significantly increased in the placebo group, particularly when A/A increased more than G, but not when spirulina was ingested. LPR was significantly different only in subjects with A/A genotype; there was a significant increase in phytohemagglutinin and lipopolysaccharide induced LPR in the spirulina group.

CONCLUSION

In healthy Korean elderly, spirulina supplementation may influence different inflammatory markers by the MCP-1 genotype. These results may be useful for customized dietary guidelines to improve immune function in Koreans.

Heparin-binding protein: a key player in the pathophysiology of organ dysfunction in sepsis

Infectious diseases remain a major health problem, and sepsis and other severe infectious diseases are common causes of morbidity and mortality. There is a need for clinical and laboratory tools to identify patients with severe infections early and to distinguish between bacterial and nonbacterial conditions. Heparin-binding protein (HBP), also known as azurocidin or cationic antimicrobial protein of 37 KDa, is a promising biomarker to distinguish between patients with these conditions. It is biologically plausible that HBP is an early and predictive biomarker because it is prefabricated and rapidly mobilized from migrating neutrophils in response to bacterial infections. HBP induces vascular leakage and oedema formation and has a pro-inflammatory effect on a variety of white blood cells and epithelial cells. The dysregulation of vascular barrier function and cellular inflammatory responses can then lead to organ dysfunction. Indeed, it has been shown that patients with sepsis express elevated levels of HBP in plasma several hours before they develop hypotension or organ dysfunction. HBP has a major role in the pathophysiology of severe bacterial infections and thus represents a potential diagnostic marker and a target for the treatment of sepsis.

Age Increases Monocyte Adhesion on Collagen

Adhesion of monocytes to micro-injuries on arterial walls is an important early step in the occurrence and development of degenerative atherosclerotic lesions. At these injuries, collagen is exposed to the blood stream. We are interested whether age influences monocyte adhesion to collagen under flow, and hence influences the susceptibility to arteriosclerotic lesions. Therefore, we studied adhesion and rolling of human peripheral blood monocytes from old and young individuals on collagen type I coated surface under shear flow. We find that firm adhesion of monocytes to collagen type I is elevated in old individuals. Pre-stimulation by lipopolysaccharide increases the firm adhesion of monocytes homogeneously in older individuals, but heterogeneously in young individuals. Blocking integrin α_x showed that adhesion of monocytes to collagen type I is specific to the main collagen binding integrin α_xβ₂. Surprisingly, we find no significant age-dependent difference in gene expression of integrin α_x or integrin β₂. However, if all integrins are activated from the outside, no differences exist between the age groups. Altered integrin activation therefore causes the increased adhesion. Our results show that the basal increase in integrin activation in monocytes from old individuals increases monocyte adhesion to collagen and therefore the risk for arteriosclerotic plaques.

Differential modulation of innate immune response by epinephrine and estradiol

Background Although it is widely accepted that catecholamines and estrogens influence immunity and have consequences for health, their effect on innate immunity (e.g. monocytes and neutrophils) is still not fully investigated. Materials and methods Our study aimed to analyze the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, monocyte chemoattractant protein (MCP)-1 and IL-8 by whole blood cells following short-term exposure to epinephrine (Epi) and 17β-estradiol (E2) in the presence or absence of lipopolysaccharide (LPS). We also evaluated the in vitro effect of these hormones on expression of β2 integrin (CD11b/CD18) and L-selectin (CD62L) by circulating neutrophils and monocytes in the blood of healthy subjects. Results Epi has shown a potential to modulate the production of pro-inflammatory mediators. Its exposure resulted in significantly increased production of IL-8 in a dose-dependent manner. On the contrary, a dose-dependent suppression of LPS-induced production of IL-1β, IL-8, and MCP-1 by Epi was observed. In neutrophils, a modest rise in CD11b expression was observed after Epi exposure. Simultaneously, Epi suppressed LPS-induced expression of CD11b and CD18. In monocytes, Epi suppressed LPS-induced expression of C11b. E2 inhibited LPS-induced TNF-α production and caused a significant decrease in CD62L expression in both cell populations. No significant changes were observed after double exposure of cells with Epi and E2. Conclusions Thus, our results show that Epi and E2 differentially modulate the innate immune response and have a dual effect on cytokine modulation. The findings suggest that the observed immunoregulatory role of Epi and E2 may influence the outcome in endotoxin responses and can be critical in the regulation of inflammatory responses.

Cholesterol Regulates Monocyte Rolling through CD44 Distribution

Cholesterol is an important risk factor of atherosclerosis, due to its active uptake by monocytes/macrophages. Monocyte recruitment from flowing blood to atherosclerotic foci is the key first step in the development of atherosclerosis. Cholesterol content alters cell membrane stiffness, and lateral lipid and protein diffusion. We hypothesized that cholesterol content will modulate the recruitment of monocytes to inflamed endothelial surface by altering the dynamics of adhesion receptors. We depleted or enriched the cellular cholesterol levels using methyl-β-cyclodextran in freshly isolated human monocytes. We investigated the effect of these changes on the mechanics of monocyte rolling on E-selectin surfaces at 1 dyn/cm² in microchannels. Using imaging flow cytometry and atomic force microscopy, we characterized the distribution of lipid rafts and the E-selectin counterreceptor CD44 on the monocyte surface. We observed that lower levels of cholesterol resulted in the uniform, CD44-mediated rolling of monocytes on the E-selectin-coated surfaces. We also observed that cells depleted of cholesterol had higher membrane fluidity, and more uniform distribution of CD44 counterreceptor, which resulted in smooth motion of the cells compared to cells enriched with cholesterol. This work demonstrates that cholesterol can modulate monocyte adhesion by regulating the receptor mobility, and our results provide insights into the biophysical regulation of inflammation for the better understanding of diseases like atherosclerosis and hypercholesterolemia.

Computational study of cell adhesion and rolling in flow channel by meshfree method

Tethering and rolling of circulating leukocytes on the surface of endothelium are critical steps during an inflammatory response. A soft solid cell model was proposed to study monocytes tethering and rolling behaviors on substrate surface in shear flow. The interactions between monocytes and micro-channel surface were modeled by a coarse-grained molecular adhesive potential. The computational model was implemented in a Lagrange-type meshfree Galerkin formulation to investigate the monocyte tethering and rolling process with different flow rates. From the simulation results, it was found that the flow rate has profound effects on the rolling velocity, contact area and effective stress of monocytes. As the flow rate increased, the rolling velocity would increase linearly, whereas the contact area and average effective stress in monocyte showed nonlinear increase.