Multiple Sclerosis: Microglia, Monocytes, and Macrophage-Mediated Demyelination

This study examined the roles of microglia and monocytes in myelin destruction in patients with early multiple sclerosis (MS). Twenty-two cases were studied; the clinical duration was <9 weeks in 10 cases. Twenty myeloid cell subtypes or categories were identified including 2 cell types not known previously to occur in demyelinating diseases. Commencing myelin breakdown in plaques and in perivascular and subpial tissues occurred in the immediate presence of infiltrating monocytes and was effected by a homogeneous population of IgG-positive Fc receptor-bearing early phagocytes interacting with abnormal myelin. Oligodendrocyte apoptosis was observed in intact myelinated tissue bordering areas of active demyelination. Capillaries in the cerebral cortex plugged by large numbers of monocytes were common in acute cases of MS and in a patient with a neuromyelitis optica variant and extreme systemic recruitment of monocytes. In an MS patient with progressive disease, microglial nodules centered on MHC-II-positive capillaries plugged by monocytes were present in the cerebral cortex. This constitutes a new gray matter lesion in MS.

Systematic Investigation of Polyurethane Biomaterial Surface Roughness on Human Immune Responses in vitro

It has been widely shown that biomaterial surface topography can modulate host immune response, but a fundamental understanding of how different topographies contribute to pro-inflammatory or anti-inflammatory responses is still lacking. To investigate the impact of surface topography on immune response, we undertook a systematic approach by analyzing immune response to eight grades of medical grade polyurethane of increasing surface roughness in three in vitro models of the human immune system. Polyurethane specimens were produced with defined roughness values by injection molding according to the VDI 3400 industrial standard. Specimens ranged from 0.1 μm to 18 μm in average roughness (Ra), which was confirmed by confocal scanning microscopy. Immunological responses were assessed with THP-1-derived macrophages, human peripheral blood mononuclear cells (PBMCs), and whole blood following culture on polyurethane specimens. As shown by the release of pro-inflammatory and anti-inflammatory cytokines in all three models, a mild immune response to polyurethane was observed, however, this was not associated with the degree of surface roughness. Likewise, the cell morphology (cell spreading, circularity, and elongation) in THP-1-derived macrophages and the expression of CD molecules in the PBMC model on T cells (HLA-DR and CD16), NK cells (HLA-DR), and monocytes (HLA-DR, CD16, CD86, and CD163) showed no influence of surface roughness. In summary, this study shows that modifying surface roughness in the micrometer range on polyurethane has no impact on the pro-inflammatory immune response. Therefore, we propose that such modifications do not affect the immunocompatibility of polyurethane, thereby supporting the notion of polyurethane as a biocompatible material.

Myxoma viral serpin, Serp-1, a unique interceptor of coagulation and innate immune pathways

Serpins maintain haemostasis through regulation of serine proteinases in the thrombotic and thrombolytic pathways. Viruses encode serpins that can alter thrombotic and thrombolytic responses producing, in some cases, disseminated intravascular coagulation (DIC). However, it has not been precisely defined how viral serpins induce these profound responses. The rabbit myxoma viral serpin, Serp-1 inhibits urokinase- and tissue-type plasminogen activators (uPA and tPA), plasmin and factor Xa in vitro and exhibits remarkable anti-inflammatory activity in various animal models. The effects of Serp-1 on activation of human platelets, endothelial cells, monocytes and T cells that mediate thrombosis and innate immune responses were therefore examined. We found that Serp-1 attenuated platelet and mononuclear cell adhesion to fibronectin and collagen. Serp-1 similarly inhibited monocyte migration into the peritoneum. Serp-1 inhibition of monocyte migration was lost in uPA receptor (uPAR) deficient mice. Serp-1 bound to the plasma membrane surface and altered uPA activation of endothelial cells (p=0.001), thrombin activation of platelets (p=0.021) and phorbol ester activation of endothelial (p=0.047), monocyte (p=0.011) and Jurkat T cells (p=0.012) as measured by intracellular calcium. Modulation of cellular activation was confirmed by membrane fluidity analysis. Microarray analysis of Serp-1 treated endothelial cells revealed alterations in Inositol 1,4,5-triphosphate receptor type II (ITPR2) a calcium-regulating gene. This study demonstrates the unique capacity ofa viral serpin, Serp-1 to modify adhesion, activation, gene expression and calcium homeostasis in a wide range of cells that regulate coagulation and inflammation. Endothelial cells potentially represent a pivotal regulatory point for Serp-1 anti-inflammatory activity.

The Rho-specific guanine nucleotide exchange factor Plekhg5 modulates cell polarity, adhesion, migration, and podosome organization in macrophages and osteoclasts

Osteoclasts are multinucleated bone-resorbing cells that are formed by fusion of monocyte/macrophage lineage. Osteoclasts and macrophages generate podosomes that are actin-based dynamic organelles implicated in cell adhesion, spreading, migration, and degradation. However, the detailed mechanisms of podosome organization remain unknown. Here, we identified the Rho-specific guanine-nucleotide exchange factor (Rho-GEF) Plekhg5 as an up-regulated gene during differentiation of osteoclasts from macrophages. Knockdown of Plekhg5 with small interfering RNA in both macrophages and osteoclasts induced larger cell formation with impaired cell polarity and resulted in an elongated and flattened shape. In macrophages, Plekhg5 depletion enhanced random migration, but impaired directional migration, adhesion, and matrix degradation. Plekhg5 in osteoclasts affected random migration, podosome organization, and bone resorption. Plekhg5 depletion affected signaling and localization of several Rho downstream effectors. In fact, end-binding protein 1 (EB1), cofilin and vinculin were abnormally localized in Plekhg5-depleted cells, and mDia1 and LIM kinase (LIMK)1 were upregulated in Plekhg5-depleted cells compared with control cells. However, overexpression of Plekhg5 in macrophages induced an increase in its mRNA level, but failed to increase the protein level, indicating that overexpressed Plekhg5 was degraded in macrophages but not HEK293T cells. Thus, Plekhg5 affects cell polarity, migration, adhesion, degradation, and podosome organization in macrophages and osteoclasts.

PPD-induced monocyte mitochondrial damage is associated with a protective effect to develop tuberculosis in BCG vaccinated individuals: A cohort study

Introduction

The mechanisms of mononuclear phagocyte death have been associated with the permissiveness and resistance to mycobacterial replication, but it remains unknown whether or not they help predict the risk of developing TB.

Objective

To describe the factors associated with the induction of monocyte mitochondrial and membrane damage in response to PPD as well as determine if this type of damage might predict the susceptibility of developing active tuberculosis in a cohort of household contacts (HHCs) from Medellin, Colombia from 2005 to 2008.

Methods

The prospective cohort study contains 2060 HHCs patients with pulmonary tuberculosis who were meticulously followed for two years. A survey of the socio-demographic, clinical, epidemiological factors and blood samples were collected. Mononuclear cell cultures were stimulated with or without PPD and the type of monocyte death was determined by the flow of cytometry, an indicator was also used for its analysis. Logistic regression was adjusted by the Generalized Estimations Equations and the survival was estimated with the Kaplan-Meier and Cox regression. Confidence intervals were used for estimating the association.

Results

1,859 out of 2,060 blood samples of the HHCs patients analyzed showed monocyte death. In response to PPD, 83.4% underwent mitochondrial damage while 50.9% had membrane damage. The membrane damage in response to PPD was higher in children under 4 years (OR: 1.57; (95% CI: 1.1 to 2.4) and the HHCs who slept regularly in the same household has an index case of (OR: 1.54; 95% CI: 1.0 to 2.3). After adjustment by age, comorbidities, nutritional status, proximity to index case and overcrowding, the risk of developing active TB among BCG vaccinated HHCs individuals with induction of mitochondrial damage was HR = 0.19 (95% CI: 0.1 to 0.5).

Conclusions

The induction of monocytes mitochondrial damage by PPD stimulation correlates with protection of TB disease development in BCG-vaccinated HHCs. This represents a potential tool to predict susceptibility of developing active disease in this population.

[Morphofunctional changes of dendritic cells induced by sulfated polysaccharides of brown algae]

The effects of various sulfated polysaccharides of brown algae Fucus evanescens, Saccharina cichorioides and Saccharina japonica on the morphofunctional changes of dendritic cells have been investigated using flow cytometry and phase-contrast microscopy. The dendritic cells are characterized by larger sizes, vacuolated cytoplasm, eccentrically located nucleus, and also by the presence of numerous cytoplasmic pseudopodia of various shapes. They express surface markers, indicating their maturation (CD83, CD11c, HLA-DR, CD86). Increased production of immunoregulatory (IL-12) and proinflammatory TNF-a, IL-6) cytokines (by dendritic cells polarizes the development of the Th-1 type immune response.

Monocyte cell membrane-derived nanoghosts for targeted cancer therapy

Core-shell type 'nanoghosts' were synthesized with a drug-loaded biodegradable PLGA core and a monocyte cell membrane-derived shell. The nanoghosts were monodisperse with an average size <200 nm, and showed good serum stability for 120 h. Doxorubicin-loaded nanoghosts showed greater cellular uptake and cytotoxicity compared to non-coated nanoparticle controls in metastatic MCF-7 breast cancer cell lines.

[CHARACTERIZATION OF THE DIFFERENCE IN THE MORPHOLOGY OF DETERGENT RESISTANT MEMBRANES DOMAINS ISOLATED FROM DIFFERENT CELL TYPES BY ATOMIC FORCE MICROSCOPY]

Planar raft and caveolae are specific membrane clusters with high concentration of cholesterol and lipids with saturated fatty acid. These clasters are resistant to detergents and are denoted as detergent resistant membranes domains (DRMs). Their morphology and size have been studied by atomic force microscopy. The size of planar rafts isolated by Librol from monocytes of healthy volunteers was 150.6 ± 68.6 nm--diameters and 5.7 ± 2.9 nm--height, the size of caveolae was 87.3 ± 46.1 nm--diameters and 9.4 ± 5.4 nm--height. Significant difference have been found morphology and size of DRMs isolated from monocytes of healthy volunteers and patients suffering from myocardial infarction as well as between DRMs isolated from endothelial cells. The study of time-dependent changes in the morphology of isolated planar rafts and caveolae has shown that they quickly aggregate during keeping. Therefore, to asses the actual size and morphology of the DRMS, they should be investigated immediately after isolation.

APOE Stabilization by Exercise Prevents Aging Neurovascular Dysfunction and Complement Induction

Aging is the major risk factor for neurodegenerative diseases such as Alzheimer's disease, but little is known about the processes that lead to age-related decline of brain structures and function. Here we use RNA-seq in combination with high resolution histological analyses to show that aging leads to a significant deterioration of neurovascular structures including basement membrane reduction, pericyte loss, and astrocyte dysfunction. Neurovascular decline was sufficient to cause vascular leakage and correlated strongly with an increase in neuroinflammation including up-regulation of complement component C1QA in microglia/monocytes. Importantly, long-term aerobic exercise from midlife to old age prevented this age-related neurovascular decline, reduced C1QA+ microglia/monocytes, and increased synaptic plasticity and overall behavioral capabilities of aged mice. Concomitant with age-related neurovascular decline and complement activation, astrocytic Apoe dramatically decreased in aged mice, a decrease that was prevented by exercise. Given the role of APOE in maintaining the neurovascular unit and as an anti-inflammatory molecule, this suggests a possible link between astrocytic Apoe, age-related neurovascular dysfunction and microglia/monocyte activation. To test this, Apoe-deficient mice were exercised from midlife to old age and in contrast to wild-type (Apoe-sufficient) mice, exercise had little to no effect on age-related neurovascular decline or microglia/monocyte activation in the absence of APOE. Collectively, our data shows that neurovascular structures decline with age, a process that we propose to be intimately linked to complement activation in microglia/monocytes. Exercise prevents these changes, but not in the absence of APOE, opening up new avenues for understanding the complex interactions between neurovascular and neuroinflammatory responses in aging and neurodegenerative diseases such as Alzheimer’s disease.

Ileana Soto, Gareth Howell, and coauthors find that age-related deterioration of the neurovascular unit and increased neuroinflammation in aging mice is prevented by long-term exercise, but not in the absence of apolipoprotein E.

Aging is frequently accompanied with frailty and cognitive decline. In recent years, increasing evidence has linked physical inactivity with the development of dementias such as Alzheimer’s disease. In fact, it is recognized that exercise combats frailty and cognitive decline in older adults, but the biological mechanisms involved are not completely known. Understanding the biological changes that trigger cognitive deterioration during aging and the mechanisms by which exercise improves health and brain function is key to ensuring the quality of life of the elderly population and to reducing risk of dementias such as Alzheimer’s disease. Here, we show that the cerebrovascular system in mice significantly deteriorates with age, and the structure and function of the blood brain barrier is progressively compromised. These age-related neurovascular changes are accompanied by neuroinflammation and deficits in common and spontaneous behaviors in mice. We found, however, that exercise from middle to older age preserves the cerebrovascular health, prevents behavioral deficits and reduces the age-related neuroinflammation in the cortex and hippocampus in aged mice. Mice deficient in Apoe, a gene associated with longevity and Alzheimer’s disease, are resistant to the beneficial effects of exercise, suggesting a possible mediating role for APOE in the maintenance and function of the neurovascular system during aging.

Porphyromonas gingivalis evasion of autophagy and intracellular killing by human myeloid dendritic cells involves DC-SIGN-TLR2 crosstalk

Signaling via pattern recognition receptors (PRRs) expressed on professional antigen presenting cells, such as dendritic cells (DCs), is crucial to the fate of engulfed microbes. Among the many PRRs expressed by DCs are Toll-like receptors (TLRs) and C-type lectins such as DC-SIGN. DC-SIGN is targeted by several major human pathogens for immune-evasion, although its role in intracellular routing of pathogens to autophagosomes is poorly understood. Here we examined the role of DC-SIGN and TLRs in evasion of autophagy and survival of Porphyromonas gingivalis in human monocyte-derived DCs (MoDCs). We employed a panel of P. gingivalis isogenic fimbriae deficient strains with defined defects in Mfa-1 fimbriae, a DC-SIGN ligand, and FimA fimbriae, a TLR2 agonist. Our results show that DC-SIGN dependent uptake of Mfa1+P. gingivalis strains by MoDCs resulted in lower intracellular killing and higher intracellular content of P. gingivalis. Moreover, Mfa1+P. gingivalis was mostly contained within single membrane vesicles, where it survived intracellularly. Survival was decreased by activation of TLR2 and/or autophagy. Mfa1+P. gingivalis strain did not induce significant levels of Rab5, LC3-II, and LAMP1. In contrast, P. gingivalis uptake through a DC-SIGN independent manner was associated with early endosomal routing through Rab5, increased LC3-II and LAMP-1, as well as the formation of double membrane intracellular phagophores, a characteristic feature of autophagy. These results suggest that selective engagement of DC-SIGN by Mfa-1+P. gingivalis promotes evasion of antibacterial autophagy and lysosome fusion, resulting in intracellular persistence in myeloid DCs; however TLR2 activation can overcome autophagy evasion and pathogen persistence in DCs.

Among the most successful of human microbes are intracellular pathogens. By entering the intracellular milieu, these pathogens are protected from harsh environmental factors in the host, including the humoral and cellular immune responses. Porphyromonas gingivalis is an opportunistic pathogen that colonizes the oral mucosa and accesses the bloodstream and distant sites such as the blood vessel walls, brain, placenta and other organs. Still unclear is how P. gingivalis traverses from oral mucosa to these distant sites. Dendritic cells are highly migratory antigen presenting cells that “patrol” the blood, skin, mucosa and all the major organ systems. Capture of microbes by dendritic cells activates a tightly regulated series of events, including directed migration towards the secondary lymphoid organs, where processed antigens are ostensibly presented to T cells. Autophagy is now recognized as an integral component of microbial clearance, antigen processing and presentation by dendritic cells. We report here that P. gingivalis is able to subvert autophagic destruction within dendritic cells. This occurs through its glycoprotein fimbriae, called Mfa-1, which targets the C-type lectin DC-SIGN on dendritic cells. The other major fimbriae on P. gingivalis, FimA, targets TLR2, which promotes autophagic destruction of P. gingivalis. We conclude that DC-SIGN-TLR2 crosstalk determines the intracellular fate of this pathogen within dendritic cells, and may have profound implications for the treatment of many chronic diseases involving low-grade infections.

Besnoitia besnoiti tachyzoites induce monocyte extracellular trap formation

Extracellular trap (ET) formation has been demonstrated as an important novel effector mechanism of polymorphonuclear neutrophils (PMN), eosinophils, mast cells and macrophages acting extracellularly against pathogens. In the present study, we show that tachyzoites of the emerging apicomplexan parasite Besnoitia besnoiti, that have recently been reported as potent inducers of PMN-derived ETosis, also trigger the release of ETs in an additional cell type, namely in monocytes. Fluorescence illustrations as well as scanning electron microscopy analyses (SEM) showed monocyte-promoted ET formation to be rapidly induced upon exposure to viable tachyzoites of B. besnoiti. Classical characteristics of ETs were confirmed by the co-localization of extracellular DNA with histones (H3) or myeloperoxidase (MPO) in parasite-entrapping structures. Monocyte-derived ETs were efficiently abolished by DNase I treatment and significantly reduced by treatments with inhibitors of MPO and NADPH oxidase, thus strengthening the key roles of reactive oxygen species (ROS) and MPO in monocyte ET formation. For comparative reasons, we additionally tested sporozoite stages of the closely related parasite Eimeria bovis for their capacity to induce monocyte-derived ETs and showed that these stages indeed induce ETs. To our best knowledge, we here report for the first time on monocyte ETs against the apicomplexan parasites B. besnoiti and E. bovis. Our results indicate that monocyte-triggered ETs may represent an important effector mechanism of the host early innate immune response against B. besnoiti and add a new cell type to the list of cells capable to release ETs.

Platelets and smooth muscle cells affecting the differentiation of monocytes

Background

Atherosclerosis is characterised by the formation of plaques. Monocytes play a pivotal role in plaque development as they differentiate into foam cells, a component of the lipid core whilst smooth muscle cells (SMC) are the principal cell identified in the cap. Recently, the ability of monocytes to differentiate into a myriad of other cell types has been reported. In lieu of these findings the ability of monocytes to differentiate into SMCs/smooth muscle (SM)-like cells was investigated.

Method and Results

Human monocytes were co-cultured with platelets or human coronary aortic SMCs and then analysed to assess their differentiation into SMCs/SM-like cells. The differentiated cells expressed a number of SMC markers and genes as determined by immunofluorescence staining and quantitative polymerase chain reaction (qPCR). CD array analysis identified marker expression profiles that discriminated them from monocytes, macrophages and foam cells as well as the expression of markers which overlapped with fibroblast and mesenchymal cells. Electron microscopy studies identified microfilaments and increased amounts of rough endoplasmic reticulum indicative of the SM- like cells, fibroblasts.

Conclusions

In the appropriate environmental conditions, monocytes can differentiate into SM-like cells potentially contributing to cap formation and plaque stability. Thus, monocytes may play a dual role in the development of plaque formation and ultimately atherosclerosis.

Biological effects of the aqueous extract of Bridelia grandis stem bark on normal and neoplastic human cells: an in vitro preliminary evaluation

The aim of the work is to investigate the effects of Bridelia grandis (Pierre ex Hutch) stem bark water extract on human HeLa cancer cells and normal monocytes treated in vitro, evaluating the morphological modifications with light and electron microscopy. The phytocomplex obtained from B. grandis caused a significant decrease in the mitotic index of both HeLa cancer cells and normal monocytes. In addition, a reduction of the typical aneuploid-polyploid pattern has been observed in HeLa cells after treatment. Various alterations at fine structural level, both in neoplastic (HeLa cells) and normal (monocytes) cells have been observed. In particular, electron-dense cells containing condensed mitochondria, autophagic vacuoles and dense spherical cytoplasmic inclusions have been observed. The results show that B. grandis water extracts have an antiproliferative effect on human cells, with a different effect on neoplastic and normal cells. The antiproliferative effect is accompanied by the appearance of various subcellular alterations. The morphological alterations observed are likely to represent the condition of 'dark cell' as a possible preliminary phase towards the autophagic and/or apoptotic cell death.

[Dopamine as a possible substance for oncotherapy and for quantitative evaluation of cytosolic G-actin]

Viability, histology and ultrastructure of normal cells and cells of different degrees of malignancy after interaction with dopamine as well as the ability of these cells and isolated G-actin in model experiments to stain by Falck technique were studied. It is shown that dopamine, virtually having no effect on the viability of the "normal" non-tumorigenic transformed cells, noticeably reduces cell viability of slightly tumorigenic cells, causes a significant reduction in viability of attachable cancerous cells and a very significant decrease in cell viability of cancerous cells growing in suspension. The intensity of fluorescence of the cytosole in cells treated with dopamine, has been very high and varied in different cultures, and that of isolated actin directly depended on its concentration. Common to all cell morphological feature of damage from the action of dopamine and the putative substrate of fluorescence was actodopamine filaments network strands (identified on the structure and size), which appears in the cytosole loci, where they were absent in control. The data show that dopamine can be used as an oncotherapeutic remedy and diagnostic tool interacting with G-actin as a cellular target.

Co-culturing monocytes with smooth muscle cells improves cell distribution within a degradable polyurethane scaffold and reduces inflammatory cytokines

Activated monocytes can promote inflammation or wound repair, depending on the nature of the implant environment. Recent work showed that a degradable, polar-hydrophobic-ionic polyurethane (D-PHI) induced an anti-inflammatory monocyte phenotype. In the current study it is hypothesized that wound-healing phenotype monocytes (activated by D-PHI material chemistry) will promote human vascular smooth muscle cells (hVSMC) to attach and migrate into porous D-PHI scaffolds. hVSMC migration is necessary for hVSMC population of the scaffold and tissue formation to occur, and then, once tissue formation is complete, the monocyte should promote contractile phenotype markers in the hVSMC. hVSMC were cultured for up to 28 days with or without monocytes and analyzed for cell viability, attachment (DNA) and migration. Lysates were analyzed for the hVSMC contractile phenotype markers calponin and α-smooth muscle actin (α-SMA) as well as urokinase plasminogen activator (uPA; pro-migration marker) using immunoblotting analysis. Histological staining showed that hVSMC alone remained around the perimeter of the scaffold, whereas co-culture samples had co-localization of monocytes with hVSMC in the pores, a more even cell distribution throughout the scaffold and increased total cell attachment (P<0.05). Co-culture samples had higher cell numbers and more DNA than the addition of both single cell cultures. The water-soluble tetrazolium-1 data suggested that cells were not dying over the 28 day culture period. Calponin, also linked to cell motility, was maintained up to 28 days in the co-culture and hVSMC alone, whereas α-SMA disappeared after 7 days. Co-cultures on D-PHI showed that monocytes were activated to a wound-healing phenotype (low TNF-α, elevated IL-10), while promoting uPA expression. In summary, this study showed that, by co-culturing monocytes with hVSMC, the latter showed increased total cell attachment and infiltration into the D-PHI scaffold compared with hVSMC alone, suggesting that monocytes may promote hVSMC migration, a condition necessary for ultimately achieving uniform tissue formation in porous scaffolds.

Mice spermatogonial stem cells transplantation induces macrophage migration into the seminiferous epithelium and lipid body formation: high-resolution light microscopy and ultrastructural studies

Transplantation of spermatogonial stem cells (SSCs), the male germline stem cells, in experimental animal models has been successfully used to study mechanisms involved in SSC self-renewal and to restore fertility. However, there are still many challenges associated with understanding the recipient immune response for SSCs use in clinical therapies. Here, we have undertaken a detailed structural study of macrophages elicited by SSCs transplantation in mice using both high-resolution light microscopy (HRLM) and transmission electron microscopy (TEM). We demonstrate that SSCs transplantation elicits a rapid and potent recruitment of macrophages into the seminiferous epithelium (SE). Infiltrating macrophages were derived from differentiation of peritubular monocyte-like cells into typical activated macrophages, which actively migrate through the SE, accumulate in the tubule lumen, and direct phagocytosis of differentiating germ cells and spermatozoa. Quantitative TEM analyses revealed increased formation of lipid bodies (LBs), organelles recognized as intracellular platforms for synthesis of inflammatory mediators and key markers of macrophage activation, within both infiltrating macrophages and Sertoli cells. LBs significantly increased in number and size in parallel to the augmented macrophage migration during different times post-transplantation. Our findings suggest that LBs may be involved with immunomodulatory mechanisms regulating the seminiferous tubule niche after SSC transplantation.

The sequestration of hydroxyapatite nanoparticles by human monocyte-macrophages in a compartment that allows free diffusion with the extracellular environment

Calcium phosphate and hydroxyapatite nanoparticles are extensively researched for medical applications, including bone implant materials, DNA and SiRNA delivery vectors and slow release vaccines. Elucidating the mechanisms by which cells internalize nanoparticles is fundamental for their long-term exploitation. In this study, we demonstrate that hydrophilic hydroxyapatite nanoparticles are sequestered within a specialized compartment called SCC (surface-connected compartment). This membrane-bound compartment is an elaborate labyrinth-like structure directly connected to the extracellular space. This continuity is demonstrated by in vivo 2-photon microscopy of ionic calcium using both cell-permeable and cell-impermeable dyes and by 3-D reconstructions from serial block-face SEM of fixed cells. Previously, this compartment was thought to be initiated specifically by exposure of macrophages to hydrophobic nanoparticles. However, we show that the SCC can be triggered by a much wider range of nanoparticles. Furthermore, we demonstrate its formation in A549 human lung epithelial cells, which are considerably less phagocytic than macrophages. EDX shows that extensive amounts of hydroxyapatite nanoparticles can be sequestered in this manner. We propose that SCC formation may be a means to remove large amounts of foreign material from the extracellular space, followed by slow degradation, may be to avoid excessive damage to surrounding cells or tissues.

Differential contributions of monocyte- and platelet-derived microparticles towards thrombin generation and fibrin formation and stability

BACKGROUND

Microparticles (MPs) are sub-micron vesicles shed by activated or apoptotic cells, including platelets and monocytes. Increased circulating MPs are associated with thrombosis; however, their role in thrombogenesis is poorly understood.

OBJECTIVE

To determine how MPs promote thrombin generation and modulate fibrin density and stability.

METHODS

Platelets and monocytes were isolated from healthy donors. Platelets were stimulated with calcium ionophore, thrombin receptor agonist peptide (TRAP) or TRAP/convulxin. Monocytes and human monocytic THP-1 cells were stimulated with lipopolysaccharide (LPS). MPs were isolated, washed by high-speed centrifugation and assessed using the following: transmission electron microscopy (TEM), Nanoparticle Tracking Analysis (NTA), flow cytometry, tissue factor (TF) activity, prothrombinase activity, thrombin generation, and clot formation, density and stability.

RESULTS

MPs from monocytes (M-MPs) and platelets (PMPs) had similar shapes and diameters (100-300 nm). M-MPs had TF activity (16.7 ± 2.4 pm TF per 10(6) MP), supported prothrombinase activity and triggered shorter thrombin generation lag times than buffer controls (5.4 ± 0.5 vs. 84.2 ± 4.8 min, respectively). Compared with controls, M-MPs supported faster fibrin formation (0.24 ± 0.24 vs. 76.7 ± 15.1 mOD min(-1) , respectively), 38% higher fibrin network density and higher clot stability (3.8-fold higher turbidity in the presence of tissue plasminogen activator). In contrast, PMPs did not have TF activity and supported 2.8-fold lower prothrombinase activity than M-MPs. PMPs supported contact-dependent thrombin generation, but did not independently increase fibrin network density or stability. Interestingly, PMPs increased rates of thrombin generation and fibrin formation (1.7- and 1.3-fold, respectively) when mixed with THP-1-derived MPs.

CONCLUSION

MPs from platelets and monocytes differentially modulate clot formation, structure and stability, suggesting unique contributions to thrombosis.

The stimulation of an osteogenic response by classical monocyte activation

The monocyte/macrophage system plays a central role in host defense, wound healing and immune regulation at biomaterial surfaces. Monocytes can be classically and alternatively activated, and can be stimulated differently in response to variations in biomaterial surface properties. In this study, human monocytes, cultured on polystyrene surfaces (Ps), were activated either classically, by lipopolysaccharide (LPS), or alternatively, by interleukin-4 (IL-4). Monocytes were also cultured on anodically oxidized (Ox) and machined (Ma) titanium surfaces, with and without LPS stimulation. Cells were cultured for 1 and 3 days and their conditioned media (CM) were collected. The osteogenic response of hMSCs to the monocyte CM was determined by analyzing the gene expression of key osteogenic markers. The CM from classically activated monocytes increased the hMSCs expression of runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP). Furthermore, CM from monocytes cultured on Ox surface resulted in a modest increase of the expression of bone morphogenetic protein-2 (BMP-2). LPS stimulation of the surface-seeded monocytes overwhelmed the effect of the surface properties and resulted in significant upregulation of BMP-2 and Runx2 for all samples. The results show that human monocytes, cultured on different surfaces and/or under different activation pathways, communicate pro-osteogenic signals to hMSCs. The signals involve regulation of autologous BMP-2 in the hMSCs. The classical activation results in profound and prolonged osteogenic effect compared to the effect of the investigated surface properties.

Cytotoxic and apoptotic effects of the oxidized derivatives of stigmasterol in the U937 human monocytic cell line

Dietary exposure to phytosterols has increased in recent years due to the incorporation of these compounds into cholesterol-lowering products. Previous studies have investigated the cytotoxic effects of the oxidized derivatives of β-sitosterol and determined that phytosterol oxidation products (POP) have a similar but less potent toxicity compared to their cholesterol equivalents. In the present study, the cytotoxicity of the oxidized derivatives of stigmasterol were investigated in the U937 cell line. The stigmasta-5,22-diene-3β,7β-diol (7β-OH), 5,6-epoxystigmasta-22,23-diol (epoxydiol), 5,6,22,23-diepoxystigmastane (diepoxide), and (22R,23R)-stigmast-5-ene-3β,22,23-triol (22R,23R-triol) derivatives were identified as the most cytotoxic, and the mode of cell death was identified as apoptosis in cells incubated with 7β-OH, epoxydiol, and diepoxide stigmasterol. The antioxidants α-tocopherol, γ-tocopherol, and β-carotene did not protect against apoptosis induced by 7β-OH and diepoxide stigmasterol; however, α-tocopherol was found to protect against epoxydiol-induced apoptosis. The cellular antioxidant, glutathione, was depleted and the apoptotic protein, Bcl-2, was down-regulated by the stigmasterol oxides identified as apoptotic.

[Cytotoxicity and its mechanism of zinc oxide nanoparticles on human leukemic monocyte lymphoma cell line U937]

OBJECTIVE

To investigate the cytotoxicity and its mechanism of ZnO nanoparticles on human leukemic monocyte lymphoma cell line U937.

METHODS

Four different size ZnO (10, 30, 60, 500 nm) were carefully characterized. The survival rate and viability were measured by trypan blue assay and MTT assay for each size ZnO particles at different concentrations (12, 120, 240, 600, 1200 µmol/L). The zinc probe, Fluozin-3, was used to detect the intracellular free zinc. Transmission electron microscopy was adopted to observe the cellular ultrastructure and the uptake of ZnO.

RESULTS

All four kinds of ZnO were rod shape, with a purity of > 99.9 wt%, and they were classified as zincite phase crystal and their surface areas were in accordance with the sizes. The viability (ZnO-n10: (97 ± 19)%, (91 ± 4)%, (24 ± 4)%, (15 ± 2)%; ZnO-n30: (111 ± 4)%, (81 ± 3)%, (24 ± 2)%, (27 ± 8)%; ZnO-n60: (105 ± 11)%, (73 ± 20)%, (43 ± 11)%, (28 ± 14)%; ZnO-µm: (88 ± 16)%, (62 ± 7)%, (22 ± 4)%, (13 ± 5)%) of cells exposed to ZnO decreased with the increasing of the concentration of ZnO from 12 to 600 µmol/L (r values were 0.965, 0.979, 0.998, 0.992, and the t values were 19.8, 25.3, 76.3, 40.9, respectively, P < 0.05). The liability (ZnO-n10: (98 ± 1)%, (67 ± 2)%, (59 ± 7)%, (13 ± 13)%, (5 ± 4)%; ZnO-n30: (98 ± 1)%, (97 ± 2)%, (50 ± 3)%, (20 ± 14)%, (7 ± 2)%; ZnO-n60: (97 ± 2)%, (88 ± 5)%, (48 ± 10)%, (12 ± 5)%, (4 ± 1)%; ZnO-µm: (96 ± 1)%, (76 ± 3)%, (58 ± 3)%, (19 ± 5)%, (20 ± 10)%) of cells exposed to ZnO decreased with the increasing of the concentration of ZnO from 12 to 600 µmol/L (r valued at 0.982, 0.956, 0.972, 0.980, and the t valued at 19.3, 12.1, 15.6, 18.5, respectively, P < 0.05). The increase of the zinc concentration showed by the zinc fluorescence probe was 121 ± 11, which was similar to the fluorescence of cells treated with ZnAc(2) (132 ± 14, F = 0.6, P > 0.05) at the Zn-equivalent concentration. There was no statistic difference for the percents of high zinc content cells in total cells exposed to ZnO-n30 (87.6 ± 2.6)% and these exposed to ZnAc(2) (86.9 ± 3.2)% (F = 1.5, P > 0.05).

CONCLUSION

ZnO nanoparticles are highly cytotoxic to U937 cells and the solubilization of ZnO is the main toxicological mechanism.

Haemopoiesis in the head kidney of tilapia, Oreochromis niloticus (Teleostei: Cichlidae): a morphological (optical and ultrastructural) study

The present work focused on the histological and ultrastructural studies on haemopoiesis in the kidney of tilapia, Oreochromis niloticus. Haemopoietic tissue was found mainly in the head kidney and a small amount occurred in the mesonephros. The haemopoiesis of tilapia had the following series: erythropoiesis, granulopoiesis, thrombopoiesis, monopoiesis and lymphoplasmopoiesis. Erythropoiesis includes proerythroblasts, basophilic erythroblasts, polychromatic erythroblasts, acidophilic erythroblasts and young and mature erythrocytes. The proerythroblasts were the largest cells in the erythropoietic series. During the maturation process both the nuclear and cellular size decreased gradually due to the chromatin condensation and the progressive substitution of cytoplasmic matrix with a large amount of haemoglobin. Granulopoietic series consisted of cells with variable shape and size at different stages of maturity from myeloblasts to mature granulocytes. The promyelocytes were the largest cells in the series and were characterised by the appearance of primary (azoruphilic) granules. The maturation process involved the appearance of specific granules in the heterophilic, eosinophilic and basophilic series. It is important to mention that eosinophilic granulocytes were the dominant granulopoietic series in the haemopoietic tissue (Ht) of tilapia. Lymphopoietic series consisted of lymphoblasts, large lymphocytes, small lymphocytes and active and inactive plasma cells. Thrombopoietic series consisted of thromboblasts, prothromboblasts and thrombocytes. Thrombocytes of tilapia were nucleated and possessed a spindle shape. Melanomacrophage centres were dominant among the Ht of the head kidney. Also, monocytes were detected and shown to be large cells with an indented nucleus and cytoplasm containing numerous vesicles of different sizes and a few lysosomes.

HDL interfere with the binding of T cell microparticles to human monocytes to inhibit pro-inflammatory cytokine production

Background

Direct cellular contact with stimulated T cells is a potent mechanism that induces cytokine production in human monocytes in the absence of an infectious agent. This mechanism is likely to be relevant to T cell-mediated inflammatory diseases such as rheumatoid arthritis and multiple sclerosis. Microparticles (MP) generated by stimulated T cells (MP_T) display similar monocyte activating ability to whole T cells, isolated T cell membranes, or solubilized T cell membranes. We previously demonstrated that high-density lipoproteins (HDL) inhibited T cell contact- and MP_T-induced production of IL-1β but not of its natural inhibitor, the secreted form of IL-1 receptor antagonist (sIL-1Ra).

Methodology/Principal Findings

Labeled MP_T were used to assess their interaction with monocytes and T lymphocytes by flow cytometry. Similarly, interactions of labeled HDL with monocytes and MP_T were assessed by flow cytometry. In parallel, the MP_T-induction of IL-1β and sIL-1Ra production in human monocytes and the effect of HDL were assessed in cell cultures. The results show that MP_T, but not MP generated by activated endothelial cells, bond monocytes to trigger cytokine production. MP_T did not bind T cells. The inhibition of IL-1β production by HDL correlated with the inhibition of MP_T binding to monocytes. HDL interacted with MP_T rather than with monocytes suggesting that they bound the activating factor(s) of T cell surface. Furthermore, prototypical pro-inflammatory cytokines and chemokines such as TNF, IL-6, IL-8, CCL3 and CCL4 displayed a pattern of production induced by MP_T and inhibition by HDL similar to IL-1β, whereas the production of CCL2, like that of sIL-1Ra, was not inhibited by HDL.

Conclusions/Significance

HDL inhibit both MP_T binding to monocytes and the MP_T-induced production of some but not all cytokines, shedding new light on the mechanism by which HDL display their anti-inflammatory functions.

Altered mitochondrial membrane potential, mass, and morphology in the mononuclear cells of humans with type 2 diabetes

Mitochondrial membrane hyperpolarization and morphologic changes are important in inflammatory cell activation. Despite the pathophysiologic relevance, no valid and reproducible method for measuring mitochondrial homeostasis in human inflammatory cells is available currently. The purpose of this study was to define and validate reproducible methods for measuring relevant mitochondrial perturbations and to determine whether these methods could discern mitochondrial perturbations in type 2 diabetes mellitus (T2DM), which is a condition associated with altered mitochondrial homeostasis. We employed 5,5',6,6'-tetrachloro-1,1'3,3'-tetraethylbenzamidazol-carboncyanine (JC-1) to estimate mitochondrial membrane potential (Psi(m)) and acridine orange 10-nonyl bromide (NAO) to assess mitochondrial mass in human mononuclear cells isolated from blood. Both assays were reproducible. We validated our findings by electron microscopy and pharmacologic manipulation of Psi(m). We measured JC-1 and NAO fluorescence in the mononuclear cells of 27 T2DM patients and 32 controls. Mitochondria were more polarized (P = 0.02) and mitochondrial mass was lower in T2DM (P = 0.008). Electron microscopy demonstrated diabetic mitochondria were smaller, were more spherical, and occupied less cellular area in T2DM. Mitochondrial superoxide production was higher in T2DM (P = 0.01). Valid and reproducible measurements of mitochondrial homeostasis can be made in human mononuclear cells using these fluorophores. Furthermore, potentially clinically relevant perturbations in mitochondrial homeostasis in T2DM human mononuclear cells can be detected.

The topographical effect of electrospun nanofibrous scaffolds on the in vivo and in vitro foreign body reaction

Topographical cues play an important role in influencing cellular behavior and are considered as significant parameters to be controlled in tissue engineering applications. This work investigated the biocompatibility with regard to scaffold architecture and topographical effect of nanofibrous scaffolds on the in vivo and in vitro foreign body reaction. Random and aligned polycaprolactone (PCL) nanofibers were fabricated by electrospinning technique, with diameters of 313 +/- 5 nm and 506 +/- 24 nm, respectively. Primary monocytes isolated from five human donors were cultured on PCL nanofibers, PCL film, and RGD-coated glass in vitro and cell density and morphology was evaluated at time points of day 0 (2 h), day 3, day 7, and day 10. The in vivo study was carried out by implanting PCL nanofibers and film scaffolds subcutaneously in rats to test the biocompatibility and host response at time points of week 1, week 2, and week 4. The in vitro studies revealed that the initial monocyte adhesion on the aligned fiber scaffold was significantly less (p < 0.001) when compared to the random fiber scaffold. The in vivo study showed that the thicknesses of fibrous capsule on fibrous scaffolds were 7.55 +/- 0.54 microm for aligned fibers and 4.13 +/- 0.31 microm for random fibers, which were significantly thinner than that of film implants 37.7 +/- 0.25 microm (p < 0.001). Additionally, cell infiltration was observed in aligned fibrous scaffolds both in vitro and in vivo, while on random fibers and films, distinct fibrous capsule boundaries were found on the surfaces. These results indicate that aligned electrospun nanofibers may serve as a promising scaffold for tissue engineering by minimizing host response, enhancing tissue-scaffold integration, and eliciting a thinner fibrous capsule.

CD14+ monocytes are vulnerable and functionally impaired under endoplasmic reticulum stress in patients with type 2 diabetes

OBJECTIVE

Although patients with diabetes suffer from increased infections and a higher incidence of cancer due to impaired immune function, details on diabetes-induced decrease in immunity are lacking. We assessed how immune-mediating peripheral blood mononuclear cells (PBMCs) are affected in diabetes.

RESEARCH DESIGN AND METHODS

From 33 patients with type 2 diabetes and 28 healthy volunteers, we obtained PBMCs and investigated their susceptibility to apoptosis and functional alteration.

RESULTS

In a subpopulation of PBMCs, monocytes derived from patients with diabetes were more susceptible to apoptosis than monocytes from healthy volunteers. Monocytes from patients with diabetes had decreased phagocytotic activity and were less responsive to Toll-like receptor (TLR) ligands, although the expression of TLRs did not differ significantly between the two groups. Furthermore, monocytes from patients with diabetes had a distinctly different gene expression profile compared with monocytes from normal volunteers as assessed with DNA microarray analysis. Specifically, quantitative real-time detection PCR measurements showed an elevated expression of the markers of endoplasmic reticulum (ER) stress in diabetic monocytes, and electron microscopic examination of monocytes revealed morphologic alterations in the ER of cells derived from patients with diabetes. Consistently, the ER stress inducer tunicamycin increased apoptosis of otherwise healthy monocytes and attenuated the proinflammatory responses to TLR ligands.

CONCLUSIONS

These data suggest that monocytes comprise a substantially impaired subpopulation of PBMCs in patients with diabetes and that ER stress is involved in these pathologic changes mechanistically. This implies that the affected monocytes should be investigated further to better understand diabetic immunity.

Pro-calcific responses by aortic valve interstitial cells in a novel in vitro model simulating dystrophic calcification

Etiopathogenetic mechanisms in calcific aortic valve stenosis are still poorly understood despite this being the third major cause of heart disease in western world. In prior in vitro cultures simulating metastatic calcification, pro-calcific effects on aortic valve interstitial cells (AVICs) resulted by adding bacterial endotoxin lipopolysaccharide (LPS) at high inorganic phosphate (Pi) levels. Here we accomplished improved in vitro models simulating either metastatic (Pi = 2.6 mM) or dystrophic calcification (Pi = 1.3 mM), in which LPS-stimulated bovine AVICs underwent extra-stimulation with macrophage-cytokine-containing media derived from parallel cultures of allogeneic monocyte/macrophages in turn stimulated with LPS. In dystrophic calcification-like cultures, lower calcium amount was spectrometrically assessed with parallel reduced alkaline phosphatase activity with respect to metastatic calcification-like cultures, with an about three-fold slower progression of mineralization. Hydroxyapatite crystal precipitation was ultrastructurally found to correlate with AVIC degeneration processes culminating with the formation of phthalocyanin-positive lipidic layers (PPLs) at the surface of cells and cell-derived matrix-vesicle-like bodies, acting as calcium nucleators according to a pattern mirroring those we had previously found in in vivo conditions. In conclusion, an in vitro model has been developed enabling reliable simulations of the effects exerted on AVICs by putatively pro- or anti-calcific agents.

Differentiation of activated monocytes into osteoclast-like cells on a hydroxyapatite substrate: an in vitro study

BACKGROUND

Hydroxyapatite surface coatings of dental implants have been introduced to obtain more rapid and complete osteointegration. A possible complication associated with hydroxyapatite implant surface is the release of particles. Those particles may be phagocytosed by monocytes, the first cells to colonize the inflammatory sites. The activated monocytes produce cytokines that could cause osteoclast activation.

METHODOLOGY

In order to establish the biological effect of particles released on monocyte differentiation to an osteoclast phenotype, we have used the murine monocyte/macrophage cell line, RAW 264.7 clone CRL-2278 cultured on a hydroxyapatite substrate. The direct action of hydroxyapatite on monocyte differentiation was examined using tartrate-resistant acid phosphatase (TRAP), immunohistochemistry and transmission electron microscopy (TEM) and Western Blot analysis.

RESULTS

The present study demonstrated that hydroxyapatite substrate might be able to induce a self-production of RANKL cytokine that directly stimulates a different behaviour in terms of phenotype expression from monocyte/macrophage lineage to mature and functional osteoclasts without the addition of exogenous factors.

CONCLUSIONS

These studies were designed to test a model in which osteoclasts could be formed from HA-activated monocytes via positive feedback elicited by RANKL, allowing for identification of innovative targets for therapeutic approaches.

CD 1-reactive leukemic cells in bone marrow: Presence of Langerhans cell marker on leukemic monocytic cells

Langerhans cells originate in bone marrow and probably belong to the monocyte-macrophage lineage. CD1 is a specific marker of Langerhans cells. By immunofluorescence and immunoelectron microscopy, CD1a antigen and myeloid markers (CD11, CD13, CD14, CD15, CD33, HLA-DR) were studied in 53 cases of acute myeloid leukemias (AML) and 3 acute lymphoblastic leukemias (ALL). The 11 ANLL without monocytic component were CD1a negative. 2/5 of acute myelomonocytic leukemias (AML4) and 9/37 of acute monocytic leukemias (AML5) were positive. All 3 ALL were negative. No correlation was found between CD1a and myeloid markers. CD1a+ AML did not differ from CD1a- AML with regard to cytogenetics or response to therapy. The CD1a positive cells may originate from an abnormal proliferation of CD1a positive cells which are present in bone marrow and which may differentiate into Langerhans cell precursors.

Type III secretion system 1 of Vibrio parahaemolyticus induces oncosis in both epithelial and monocytic cell lines

The Vibrio parahaemolyticus type III secretion system 1 (T3SS1) induces cytotoxicity in mammalian epithelial cells. We characterized the cell death phenotype in both epithelial (HeLa) and monocytic (U937) cell lines following infection with V. parahaemolyticus. Using a combination of the wild-type strain and gene knockouts, we confirmed that V. parahaemolyticus strain NY-4 was able to induce cell death in both cell lines via a T3SS1-dependent mechanism. Bacterial contact, but not internalization, was required for T3SS1-induced cytotoxicity. The mechanism of cell death involves formation of a pore structure on the surface of infected HeLa and U937 cells, as demonstrated by cellular swelling, uptake of cell membrane-impermeable dye and protection of cytotoxicity by osmoprotectant (PEG3350). Western blot analysis showed that poly ADP ribose polymerase (PARP) was not cleaved and remained in its full-length active form. This result was evident for seven different V. parahaemolyticus strains. V. parahaemolyticus-induced cytotoxicity was not inhibited by addition of the pan-caspase inhibitor carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone (Z-VAD-FMK) or the caspase-1 inhibitor N-acetyl-tyrosyl-valyl-alanyl-aspartyl-aldehyde (Ac-YVAD-CHO); thus, caspases were not involved in T3SS1-induced cytotoxicity. DNA fragmentation was not evident following infection and autophagic vacuoles were not observed after monodansylcadaverine staining. We conclude that T3SS1 of V. parahaemolyticus strain NY-4 induces a host cell death primarily via oncosis rather than apoptosis, pyroptosis or autophagy.

Validation of an integrated Raman- and angular-scattering microscopy system on heterogeneous bead mixtures and single human immune cells

A microscopy system has been constructed that is capable of simultaneously acquiring both Raman spectra and angle-resolved elastic-scattering patterns in either epi- or transillumination modes with a 7 mum spot size. The benefits and drawbacks of the epi- and transillumination modalities are discussed. Validation studies have been performed on single beads of a few micrometers in size, as well as on ensembles of submicrometer particles. In addition, transilluminated Raman and elastic-scattering spectra were obtained from single granulocytes and peripheral blood monocytes. Both the Raman- and the elastic-scattering channels show clear differences between the two types of immune cells.

Comparative proteomics analysis on differentiation of human promyelocytic leukemia HL-60 cells into granulocyte and monocyte lineages

BACKGROUND AND OBJECTIVE

Human promyelocytic leukemia cell line HL-60 has potential to differentiate into granulocytes and monocytes by different inducers, such as NSC67657 and all-trans retinoic acid (ATRA). However, the mechanism is not clear yet. This study was to induce differentiation of HL-60 cells using ATRA and NSC67657, and compare the protein expression patterns using two-dimensional electrophoresis (2-DE).

METHODS

HL-60 cells were cultured with ATRA and NSC67657 respectively. Cell proliferation was analyzed by MTT assay. Cellular surface specific antigen CD11b/CD14 was detected using flow cytometry (FCM) to assess cell differentiation. The alterations of cell morphology were observed with cellular chemical staining under electron microscope. Total protein was separated by modified 2-DE. The differentially expressed proteins were identified using PD-Quest software and analyzed by MOLDI-TOF MS. ICAT protein with differential expression was verified by reverse transcription-polymerase chain reaction (RT-PCR) and western blot.

RESULTS

The granulocytic and monocytic differentiation of HL-60 cells was induced by ATRA and NSC67657, respectively. The positive rates of both CD11b and CD14 in HL-60 cells were over 90% after 5-day treatment (2 micromol/L ATRA or 10 micromol/L NSC67657); cell morphology also represented characteristics of differentiation. Proteomic analysis showed that 25 proteins were differentially expressed with the same pattern in both differentiation groups, ten were differentially expressed only in monocytic differentiation group and 15 only in granulocytic differentiation group. Among them, ICAT expression was upregulated during NSC67657-induced differentiation of HL-60 cells.

CONCLUSION

A batch of differentially expressed proteins has be found by 2-DE in HL-60 cells with granulocytic and monocytic differentiation, which would contribute to the following functional research on related proteins.

NF-kappaB activity in endothelial cells is modulated by cell substratum interactions and influences chemokine-mediated adhesion of natural killer cells

Because changes in subendothelial matrix composition are associated with alterations of the endothelial immune phenotype, we sought to understand if cytokine-induced NF-kappaB activity and downstream effects depend on substrate adherence of endothelial cells (EC). We compared the upstream phosphorylation cascade, activation of NF-kappaB, and expression/secretion of downstream effects of EC grown on tissue culture polystyrene plates (TCPS) with EC embedded within collagen-based matrices (MEEC). Adhesion of natural killer (NK) cells was quantified in vitro and in vivo. NF-kappaB subunit p65 nuclear levels were significantly lower and p50 significantly higher in cytokine-stimulated MEEC than in EC-TCPS. Despite similar surface expression of TNF-alpha receptors, MEEC had significantly decreased secretion and expression of IL-6, IL-8, MCP-1, VCAM-1, and ICAM-1. Attenuated fractalkine expression and secretion in MEEC (two to threefold lower than in EC-TCPS; p < 0.0002) correlated with 3.7-fold lower NK cell adhesion to EC (6,335 +/- 420 vs. 1,735 +/- 135 cpm; p < 0.0002). Furthermore, NK cell infiltration into sites of EC implantation in vivo was significantly reduced when EC were embedded within matrix. Matrix embedding enables control of EC substratum interaction. This in turn regulates chemokine and surface molecule expression and secretion, in particular of those compounds within NF-kappaB pathways, chemoattraction of NK cells, local inflammation, and tissue repair.

The autophagic induction in Helicobacter pylori-infected macrophage

Helicobacter pylori has developed several mechanisms to evade the intracellular killing after phagocytosis. In this study, we reported that some Taiwanese clinical isolated H. pylori can multiply in human monocytic cells, such as THP-1 or U937 cells, but not in murine macrophage Raw264.7 cells. After internalization, there was a 5- to 10-fold increment of re-cultivable H. pylori from the infected THP-1 cells at 12 hrs post infection. The dividing H. pylori was found in a double-layer vesicle, which is characteristic of autophagosome. The formation of autophagosomes is associated with the multiplication of H. pylori in THP-1 cells. Its modulation with rapamycin or 3-MA affects the level of H. pylori replication. Furthermore, the VacA or CagA mutants of H. pylori have lower levels of multiplication in macrophages. We conclude that H. pylori infection induces autophagosome formation, and these autophagic vesicles were adapted for the multiplication of H. pylori in the host.

Alumina nanoparticles induce expression of endothelial cell adhesion molecules

Nanotechnology is a rapidly growing industry that has elicited much concern because of the lack of available toxicity data. Exposure to ultrafine particles may be a risk for the development of vascular diseases due to dysfunction of the vascular endothelium. Increased endothelial adhesiveness is a critical first step in the development of vascular diseases, such as atherosclerosis. The hypothesis that alumina nanoparticles increase inflammatory markers of the endothelium, measured by the induction of adhesion molecules as well as the adhesion of monocytes to the endothelial monolayer, was tested. Following characterization of alumina nanoparticles by transmission electron microscopy (TEM), electron diffraction, and particle size distribution analysis, endothelial cells were exposed to alumina at various concentrations and times. Both porcine pulmonary artery endothelial cells and human umbilical vein endothelial cells showed increased mRNA and protein expression of VCAM-1, ICAM-1, and ELAM-1. Furthermore, human endothelial cells treated with alumina particles showed increased adhesion of activated monocytes. The alumina particles tended to agglomerate at physiological pH in serum-containing media, which led to a range of particle sizes from nano to micron size during treatment conditions. These data show that alumina nanoparticles can elicit a proinflammatory response and thus present a cardiovascular disease risk.

Mosaic tetraploidy and transient GFI1 mutation in a patient with severe chronic neutropenia

This report presents the case of a 15-year-old male with severe chronic neutropenia, leukopenia, and persistent tetraploid mosaicism in the bone marrow and peripheral blood. His father had mild neutropenia and bone marrow tetraploidy. Flow cytometric analysis of DNA content peripheral blood showed tetraploidy in 20% of granulocytes and 15% of monocytes. Sequence analysis of the ELA2 gene was normal, but the GFI1 gene exhibited transient appearance of single base changes the coding region and promoter. We speculate that an underlying genetic defect, inherited in an autosomal dominant pattern, leads to both disordered mitosis and neutropenia in this kindred.

Hybrid cell death induced by exposure to 2-hydroxyethyl methacrylate (HEMA): an ultrastructural and X-ray microanalytical study

PURPOSE

The aim of this study was to evaluate the ultrastructural characteristics and ionic profile of U937 cells after exposure to 2-hydroxyethyl methacrylate (HEMA) to shed light on the cytotoxicity of this dental adhesive and its relation to mechanisms of cell death.

MATERIALS AND METHODS

U937 human monoblastic cells were incubated in RPMI 1640 culture medium and exposed to HEMA at LD50. Structural changes after 5, 15, 30, 60, and 120 min were observed with transmission electron microscopy. Ionic content of Na, K, Cl, Mg, P and S was evaluated by quantitative electron probe X-ray microanalysis.

RESULTS

Our results in human monoblastic cell line U937 establish that exposure to HEMA at LD50 led to a singular mechanism of cell death characterized by changes in the morphology and ultrastructure of the cells (cell size, blebs, and organelle structure) compatible with apoptosis, but without changes in nuclear ultrastructure. These findings were consistent with our microanalytical data, which revealed a significant increase in intracellular Na and a decrease in K, along with a significant initial decrease in Cl concentration followed later (120 min) by an increase.

CONCLUSION

All three lines of evidence (cell morphology, ultrastructural changes, and ionic profile) showed that HEMA at LD50 led to a hybrid process of cell death. We suggest that apoptosis and necrosis are part of a continuum comprising a single process of cell death.

Accumulation of macrophage-like cells expressing NG2 proteoglycan and Iba1 in ischemic core of rat brain after transient middle cerebral artery occlusion

Although neurons and glia inevitably undergo degeneration in the core of ischemic lesions, many cells, particularly immune cells, infiltrate the core and survive in it. Such infiltrating cells may play certain roles in the regeneration and repair of damaged brain tissues. In this study, we characterized macrophage-like cells that accumulated in the ischemic core of a rat brain whose right middle cerebral artery was transiently occluded for 90 mins. Many of the accumulated macrophage-like cells expressed Iba1, a marker of macrophages/microglia, as well as NG2 chondroitin sulfate proteoglycan (NG2), which has been recognized as a marker of oligodendrocyte progenitor cells. Such macrophage-like cells were termed BINCs (brain Iba1(+)/NG2(+) cells) to distinguish them from NG2(-)/Iba1(+) or NG2(+)/Iba1(-) cells that were also present in the perilesion and the contralateral hemisphere. Electron microscopy showed the localization of NG2 along the plasma membrane of cells that had many phagosomes and irregular-shaped or reniform heterochromatin-rich nuclei, which are characteristics of monocytes/macrophages. Brain Iba1(+)/NG2(+) cells were highly proliferative and their number peaked at 7 days post-reperfusion. An immunoblot analysis of NG2 revealed the presence of two NG2s: one expressed by BINCs with a molecular weight of 300 kDa, and the other found in the contralateral hemisphere with a molecular weight of 290 kDa. Taken the various functions of NG2, BINCs may be involved in not only phagocytosis of degenerated cells but also the healing and regeneration of lesion cores.

A cellular Trojan Horse for delivery of therapeutic nanoparticles into tumors

Destruction of hypoxic regions within tumors, virtually inaccessible to cancer therapies, may well prevent malignant progression. The tumor's recruitment of monocytes into these regions may be exploited for nanoparticle-based delivery. Monocytes containing therapeutic nanoparticles could serve as "Trojan Horses" for nanoparticle transport into these tumor regions. Here we report the demonstration of several key steps toward this therapeutic strategy: phagocytosis of Au nanoshells, and photoinduced cell death of monocytes/macrophages as isolates and within tumor spheroids.

M protein from Streptococcus pyogenes induces tissue factor expression and pro-coagulant activity in human monocytes

Invasive infections caused by the important pathogen Streptococcus pyogenes are often associated with disturbed blood coagulation in the human host, and may in severe cases develop into the life-threatening condition disseminated intravascular coagulation. In this study, the addition of M1 protein to human blood or purified peripheral blood mononuclear cells led to a dose-dependent increase of pro-coagulant activity, which was mediated by an upregulation of tissue factor on monocytes. Analysis of the resulting clots by transmission electron microscopy revealed that the cells were covered with a fibrin network that seemed to originate from the cell surface. Taken together, the results imply an important role for M proteins in the induction of haemostatic disorders in invasive streptococcal infectious diseases.

The Fusarium toxin deoxynivalenol disrupts phenotype and function of monocyte-derived dendritic cells in vivo and in vitro

The trichothecene mycotoxin deoxynivalenol (DON) causes systemic immuno-suppression in pigs and possibly also in humans after chronic dietary exposure. Since the outcome of every immune response is largely controlled by dendritic cells (DC), we hypothesised that a direct influence of DON on DC function might play a role in mediating DON immunotoxicity. To test this hypothesis, a 2x2 factorial design study was performed. Pigs were fed a control diet or a diet containing DON (DON-diet); monocyte-derived DC (MoDC) from these pigs were then treated with DON in vitro or left untreated. Phenotype and function of the MoDC were analysed. In vitro DON-treatment of MoDC from pigs fed the control diet resulted in a down-regulation of CD80/86 and CD40. This was associated with an activation of the mitogen-associated protein kinases ERK1/2 and JNK. The endocytic activity of MoDC was decreased after in vitro DON-exposure while their T cell stimulatory capacity was not altered. MoDC derived from pigs that had been fed the DON-diet failed to up-regulate MHC-II in response to LPS/TNFalpha. Dietary exposure of pigs to DON inhibited endocytosis of FITC-dextran by MoDC, but did not influence T cell stimulatory capacity. ERK1/2 and JNK were constitutively activated in MoDC from pigs fed the DON-diet. If MoDC derived from pigs fed the DON-diet were exposed to DON in vitro, this resulted in an up-regulation of MHC-II and CD80/86, but not CD40. In comparison to untreated MoDC from pigs fed DON-diet, endocytic capacity was further down-regulated, whereas mitogen-activated protein kinase activation was increased. In summary, DON disrupts porcine DC function in vitro and in vivo, which might contribute to the immunosuppressive effects of this mycotoxin.

Serglycin and secretion in human monocytes

The human monocytic cell line U-937 has been widely used as a model system for human monocytes. The subclone U-937-B has been adapted to serum-free conditions. This particular U-937 clone and its parent clone U-937-1 were used to investigate the role of the proteoglycan serglycin in human monocytes. For this purpose cells were treated with hexyl-beta-D-thioxyloside to abrogate proteoglycan expression. U-937-B cells expressed and secreted exclusively chondroitin sulphate proteoglycans, and after treatment with this xyloside they only expressed and released free chondroitin sulphate chains. Western blotting showed that serglycin core protein was present in conditioned medium of control cells, but absent in medium from xyloside-treated cells. Also, serglycin core protein could be detected in the cell fractions of control cells, but not in the cell fractions from xyloside-treated cells. Furthermore, less proteoglycan-associated proteins could be detected in medium from cells incubated with xyloside, suggesting that the absence of secreted sergycin affects the secretion of such proteins. Cells incubated in the presence of xyloside were analyzed by transmission electron microscopy and shown to contain numerous large empty vesicles. The lack of serglycin, the dominant proteoglycan in U-937 monocyte-like cells, consequently, leads to effects on vesicle formation and secretion of some low molecular weight proteins, suggesting that this particular proteoglycan is of importance for secretory processes in human monocytes.

Proteomic analysis of the cellular responses induced in uninfected immune cells by cell-expressed X4 HIV-1 envelope

HIV-1 envelope gp120 and gp41 glycoproteins (Env), expressed at the cell surface, induce uninfected CD4 T-cell death, but the molecular mechanisms leading to this demise are still largely unknown. To better understand these events, we analyzed by a proteomic approach the differential protein expression profile of two types of uninfected immune cells after their coculture for 1-3 days with cells that express, or not, Env. First, umbilical cord blood mononuclear cells (UCBMCs) were used to approach the in vivo situation, i.e., blood uninfected naive cells that encounter infected cells. Second, we used the A2.01/CD4.403 T-cell line expressing wild type CXCR4 and a truncated form of CD4 that still undergoes Env-mediated apoptosis, independently of CD4 signaling. After coculture with cells expressing Env, 35 and 39 proteins presenting an altered expression in UCBMCs and the A2.01/CD4.403 T-cell line, respectively, were identified by mass-spectrometry. Whatever the cell type analyzed, the majority of these proteins are involved in degradation processes, redox homeostasis, metabolism and cytoskeleton dynamics, and linked to mitochondrial functions. This study provides new insights into the events that sequentially occur in bystander T lymphocytes after contact with HIV-infected cells and leading, finally, to apoptotic cell death.

CD34 human hematopoietic progenitor cell line, MUTZ-3, differentiates into functional osteoclasts

OBJECTIVE

CD14(+) monocyte cell lines can differentiate into an osteoclast (OC)-like lineage. However, the identification of human cell lines with stem cell characteristics, capable of differentiating into OCs, would provide a tool for the study of the molecular mechanisms regulating their commitment, differentiation, and function. Since the human acute myeloid leukemia cell line MUTZ-3 contains both CD34(+) stem cell and CD14(+) cell populations, we investigated the capacity of the stem/progenitor CD34(+) population to differentiate into functional OCs.

MATERIALS AND METHODS

Sorted MUTZ-3-CD34(+) and MUTZ-3-CD14(+) cells were cultured in presence of M-CSF, RANK-L, and TNF-alpha to generate OCs. Differentiation was evaluated by TRAP staining and RT-PCR, which assessed the expression of c-fms, RANK, MMP-9, CATK, TRAP, and CTR in -CD34(+)OC and -CD14(+)OC cells. Resorption pit formation was also evaluated. CD34, CD14, M-CSF-R, RANK, and CTR expression was assessed by FACS analysis.

RESULTS

MUTZ-3-CD34(+) differentiated into OCs, displaying the full range of differentiation markers; MMP-9, CATK, TRAP, and RANK mRNA were detected from day 3 of culture, whereas CTR from day 12. Stimulated MUTZ-3-CD34(+) generated functional osteoclasts that formed extensive resorption lacunae on both mineralized surface and bone slices. Surprisingly, in both sorted populations we identified a population M-CSF-R(+)/RANK(+) that at the same time co-expressed CD14 and CD34.

CONCLUSIONS

These findings demonstrate that MUTZ-3 cells constitute an invaluable model to study the expression pattern in different developmental stages of commitment and differentiation. Importantly, the data indicate that the CD14(+)CD34(+)M-CSF-R(+)RANK(+) population represents an intermediate stage of differentiation from CD34 precursors and monocytes to osteoclast.

Neutrophil elastase is associated with serglycin on its way to lysosomes in U937 cells

Mutations in the neutrophil elastase (NE) gene have been postulated to interfere with normal intracellular trafficking of NE as an AP3-interacting membrane integrated protein and to cause severe congenital or cyclic neutropenia in humans. Here, we show that in U937 promonocytes NE is synthesized as a predominantly soluble proenzyme and is completely secreted in the presence of phorbol esters similarly to serglycin. Using chemical cross-linking NE is shown to be associated with serglycin as 34 kDa proenzyme in the trans-Golgi region of these cells indicating that it is delivered to lysosomes associated with serglycin.

Life and death in bovine monocytes: the fate of Mycobacterium avium subsp. paratuberculosis

We previously reported that the number of acid-fast bacilli within Mycobacterium paratuberculosis-infected bovine monocytes increased steadily during an 8-day incubation period in vitro, despite a decrease in the number of viable bacilli as estimated by a radiometric method. In this study, we used differential live/dead staining of bacilli from infected monocytes to show that the percentage of viable bacilli decreased during an 8-day incubation period. We observed poor phagosome-lysosome fusion in monocytes that had ingested viable M. paratuberculosis (30% phagosome-lysosome fusion), while monocytes that ingested heat killed M. paratuberculosis exhibited 94% phagosome-lysosome fusion at 24h after infection. Treatment with the selective Ca(2+)/CaM and PI3 kinase inhibitors (i.e. KN62 and Wortmannin) in combination increased the survival of M. paratuberculosis in bovine monocytes without significantly altering phagosome-lysosome fusion. Scanning electron microscopy suggested that M. paratuberculosis-infected monocytes were less differentiated (smaller and less spreading) than uninfected monocytes at 4 and 8 days of infection. Overall, these data suggest that both multiplication and killing of intracellular M. paratuberculosis occur concomitantly in bovine monocytes. Monocytes in turn may be adversely affected by the bacilli, their products, or factors released from infected monocytes.

Activated CD34-derived Langerhans cells mediate transinfection with human immunodeficiency virus

Langerhans cells (LCs) are a subset of dendritic cells (DCs) that reside within epidermal and mucosal tissue. Because of their location, LCs are potentially the first cells to encounter human immunodeficiency virus (HIV) during sexual transmission. We report that LCs purified from CD34(+)-derived DCs can facilitate the transinfection of target cells but only after activation. Virions were observed in an intracellular compartment that contains several tetraspanins, in addition to the unique LC markers langerin and CD1a. This reveals that the trafficking of HIV within LCs is reminiscent of that which occurs in mature monocyte-derived DCs and that it varies with the activation state of the cell. The observation that activated LCs can mediate transinfection suggests a potential role for these cells in the known increase in HIV transmission associated with sexually transmitted infections that would cause inflammation of the genital lining.