Role of vimentin in regulation of monocyte/macrophage differentiation

Morphine suppresses peripheral responses and transforms brain myeloid gene expression to favor neuropathogenesis in SIV infection

The twin pandemics of opioid abuse and HIV infection can have devastating effects on physiological systems, including on the brain. Our previous work found that morphine increased the viral reservoir in the brains of treated SIV-infected macaques. In this study, we investigated the interaction of morphine and SIV to identify novel host-specific targets using a multimodal approach. We probed systemic parameters and performed single-cell examination of the targets for infection in the brain, microglia and macrophages. Morphine treatment created an immunosuppressive environment, blunting initial responses to infection, which persisted during antiretroviral treatment. Antiretroviral drug concentrations and penetration into the cerebrospinal fluid and brain were unchanged by morphine treatment. Interestingly, the transcriptional signature of both microglia and brain macrophages was transformed to one of a neurodegenerative phenotype. Notably, the expression of osteopontin, a pleiotropic cytokine, was significantly elevated in microglia. This was especially notable in the white matter, which is also dually affected by HIV and opioids. Increased osteopontin expression was linked to numerous HIV neuropathogenic mechanisms, including those that can maintain a viral reservoir. The opioid morphine is detrimental to SIV/HIV infection, especially in the brain.

Identification of Inflammatory Proteomics Networks of Toll-like Receptor 4 through Immunoprecipitation-Based Chemical Cross-Linking Proteomics

Toll-like receptor 4 (TLR4) is a receptor on an immune cell that can recognize the invasion of bacteria through their attachment with bacterial lipopolysaccharides (LPS). Hence, LPS is a pro-immune response stimulus. On the other hand, statins are lipid-lowering drugs and can also lower immune cell responses. We used human embryonic kidney (HEK 293) cells engineered to express HA-tagged TLR-4 upon treatment with LPS, statin, and both statin and LPS to understand the effect of pro- and anti-inflammatory responses. We performed a monoclonal antibody (mAb) directed co-immunoprecipitation (CO-IP) of HA-tagged TLR4 and its interacting proteins in the HEK 293 extracted proteins. We utilized an ETD cleavable chemical cross-linker to capture weak and transient interactions with TLR4 protein. We tryptic digested immunoprecipitated and cross-linked proteins on beads, followed by liquid chromatography–mass spectrometry (LC-MS/MS) analysis of the peptides. Thus, we utilized the label-free quantitation technique to measure the relative expression of proteins between treated and untreated samples. We identified 712 proteins across treated and untreated samples and performed protein network analysis using Ingenuity Pathway Analysis (IPA) software to reveal their protein networks. After filtering and evaluating protein expression, we identified macrophage myristoylated alanine-rich C kinase substrate (MARCKSL1) and creatine kinase proteins as a potential part of the inflammatory networks of TLR4. The results assumed that MARCKSL1 and creatine kinase proteins might be associated with a statin-induced anti-inflammatory response due to possible interaction with the TLR4.

Therapeutic Potential of Human Immature Dental Pulp Stem Cells Observed in Mouse Model for Acquired Aplastic Anemia

Aplastic anemia (AA) is a rare and serious disorder of hematopoietic stem cells (HSCs) that results in the loss of blood cells due to the failure of the bone marrow (BM). Although BM transplantation is used to treat AA, its use is limited by donor availability. In this sense, mesenchymal stem cells (MSCs) can offer a novel therapeutic approach for AA. This is because the MSCs contribute to the hematopoietic niche organization through their repopulating. In our study, we used the human immature dental pulp stem cell (hIDPSC), an MSC-like cell, to explore an alternative therapeutic approach for AA. For this, isogenic C57BL/6 mice were exposed to total body irradiation (TBI) to induce the AA. After 48 h of TBI, the mice were intraperitoneally treated with hIDPSC. The immunohistochemistry analyses confirmed that the hIDPSCs migrated and grafted in the mouse bone marrow (BM) and spleen, providing rapid support to hematopoiesis recovery compared to the group exposed to radiation, but not to those treated with the cells as well as the hematological parameters. Six months after the last hIDPSC transplantation, the BM showed long-term stable hematopoiesis. Our data highlight the therapeutic plasticity and hematoprotective role of hIDPSC for AA and potentially for other hematopoietic failures.

Pathophysiological Role of Vimentin Intermediate Filaments in Lung Diseases

Vimentin intermediate filaments, a type III intermediate filament, are among the most widely studied IFs and are found abundantly in mesenchymal cells. Vimentin intermediate filaments localize primarily in the cytoplasm but can also be found on the cell surface and extracellular space. The cytoplasmic vimentin is well-recognized for its role in providing mechanical strength and regulating cell migration, adhesion, and division. The post-translationally modified forms of Vimentin intermediate filaments have several implications in host-pathogen interactions, cancers, and non-malignant lung diseases. This review will analyze the role of vimentin beyond just the epithelial to mesenchymal transition (EMT) marker highlighting its role as a regulator of host-pathogen interactions and signaling pathways for the pathophysiology of various lung diseases. In addition, we will also examine the clinically relevant anti-vimentin compounds and antibodies that could potentially interfere with the pathogenic role of Vimentin intermediate filaments in lung disease.

Differentially expressed proteins in the interaction of Paracoccidioides lutzii with human monocytes

BACKGROUND

Fungi of the genus Paracoccidioides are the etiological agents of paracoccidioidomycosis, a highly prevalent mycosis in Latin America. Infection in humans occurs by the inhalation of conidia, which later revert to the form of yeast. In this context, macrophages are positioned as an important line of defense, assisting in the recognition and presentation of antigens, as well as producing reactive oxygen species that inhibit fungal spreading.

AIMS

The objective of this study was to identify differentially expressed proteins during the interaction between Paracoccidioides lutzii Pb01 strain and human U937 monocytes.

METHODS

Two-dimensional electrophoresis, combined with mass spectrometry, was used to evaluate the differential proteomic profiles of the fungus P. lutzii (Pb01) interacting with U937 monocytes.

RESULTS

It was possible to identify 25 proteins differentially expressed by Pb01 alone and after interacting with U937 monocytes. Most of these proteins are directly associated with fungal metabolism for energy generation, such as glyceraldehyde-3-phosphate dehydrogenase, and intracellular adaptation to monocytes. Antioxidant proteins involved in the response to oxidative stress, such as peroxiredoxin, cytochrome, and peroxidase, were expressed in greater quantity in the interaction with monocytes, suggesting their association with survival mechanisms inside phagocytic cells. We also identified 12 proteins differentially expressed in monocytes before and after the interaction with the fungus; proteins involved in the reorganization of the cytoskeleton, such as vimentin, and proteins involved in the response to oxidative stress, such as glioxalase 1, were identified.

CONCLUSIONS

The results of this proteomic study of a P. lutzii isolate are novel, mimicking in vitro what occurs in human infections. In addition, the proteins identified may aid to understand fungal-monocyte interactions and the pathogenesis of paracoccidioidomycosis.

Immunoresponsive Tissue-Engineered Oral Mucosal Equivalents Containing Macrophages

Macrophages play a key role in orchestrating the host immune response toward invading organisms or non-self molecules in the oral mucosa. Three-dimensional (3D) oral mucosal equivalents (OME) containing oral fibroblasts and keratinocytes are used extensively to mimic the human oral mucosa where they have been employed to examine innate immune responses to both bacterial and fungal pathogens as well as to biomaterials. Although the presence of immune cells is critical in generating an immune response, very few studies have incorporated leukocytes into OME, and to date, none have contained primary human macrophages. In this study, we report the generation of an immunocompetent OME to investigate immune responses toward bacterial challenge. Primary human monocyte-derived macrophages (MDM) were as responsive to bacterial lipopolysaccharide (LPS) challenge when cultured within a 3D hydrogel in terms of proinflammatory cytokine (IL-6, CXCL8, and TNF-α) gene expression and protein secretion compared with culture as two-dimensional monolayers. MDM were incorporated into a type 1 collagen hydrogel along with oral fibroblasts and the apical surface seeded with oral keratinocytes to generate an MDM-containing OME. Full-thickness MDM-OME displayed a stratified squamous epithelium and a fibroblast-populated connective tissue containing CD68-positive MDM that could be readily isolated to a single-cell population for further analysis by collagenase treatment followed by flow cytometry. When stimulated with LPS, MDM-OME responded with increased proinflammatory cytokine secretion, most notably for TNF-α that increased 12-fold when compared with OME alone. Moreover, this proinflammatory response was inhibited by pretreatment with dexamethasone, showing that MDM-OME are also amenable to drug treatment. Dual-labeled immunofluorescence confocal microscopy revealed that MDM were the sole source of TNF-α production within MDM-OME. These data show functional activity of MDM-OME and illustrate their usefulness for investigations aimed at monitoring the immune response of the oral mucosa to pathogens, biomaterials, and for tissue toxicity and anti-inflammatory drug delivery studies.

Aptamers against mouse and human tumor-infiltrating myeloid cells as reagents for targeted chemotherapy

Local delivery of anticancer agents has the potential to maximize treatment efficacy and minimize the acute and long-term systemic toxicities. Here, we used unsupervised systematic evolution of ligands by exponential enrichment to identify four RNA aptamers that specifically recognized mouse and human myeloid cells infiltrating tumors but not their peripheral or circulating counterparts in multiple mouse models and from patients with head and neck squamous cell carcinoma (HNSCC). The use of these aptamers conjugated to doxorubicin enhanced the accumulation and bystander release of the chemotherapeutic drug in both primary and metastatic tumor sites in breast and fibrosarcoma mouse models. In the 4T1 mammary carcinoma model, these doxorubicin-conjugated aptamers outperformed Doxil, the first clinically approved highly optimized nanoparticle for targeted chemotherapy, promoting tumor regression after just three administrations with no detected changes in weight loss or blood chemistry. These RNA aptamers recognized tumor infiltrating myeloid cells in a variety of mouse tumors in vivo and from human HNSCC ex vivo. This work suggests the use of RNA aptamers for the detection of myeloid-derived suppressor cells in humans and for a targeted delivery of chemotherapy to the tumor microenvironment in multiple malignancies.

Culture of Mycobacterium smegmatis in Different Carbon Sources to Induce In Vitro Cholesterol Consumption Leads to Alterations in the Host Cells after Infection: A Macrophage Proteomics Analysis

During tuberculosis, Mycobacterium uses host macrophage cholesterol as a carbon and energy source. To mimic these conditions, Mycobacterium smegmatis can be cultured in minimal medium (MM) to induce cholesterol consumption in vitro. During cultivation, M. smegmatis consumes MM cholesterol and changes the accumulation of cell wall compounds, such as PIMs, LM, and LAM, which plays an important role in its pathogenicity. These changes lead to cell surface hydrophobicity modifications and H₂O₂ susceptibility. Furthermore, when M. smegmatis infects J774A.1 macrophages, it induces granuloma-like structure formation. The present study aims to assess macrophage molecular disturbances caused by M. smegmatis after cholesterol consumption, using proteomics analyses. Proteins that showed changes in expression levels were analyzed in silico using OmicsBox and String analysis to investigate the canonical pathways and functional networks involved in infection. Our results demonstrate that, after cholesterol consumption, M. smegmatis can induce deregulation of protein expression in macrophages. Many of these proteins are related to cytoskeleton remodeling, immune response, the ubiquitination pathway, mRNA processing, and immunometabolism. The identification of these proteins sheds light on the biochemical pathways involved in the mechanisms of action of mycobacteria infection, and may suggest novel protein targets for the development of new and improved treatments.

Identification of Candidate Biomarkers for Idiopathic Thrombocytopenic Purpura by Bioinformatics Analysis of Microarray Data

Idiopathic Thrombocytopenic Purpura (ITP) is a multifactorial disease with decreased count of platelet that can lead to bruising and bleeding manifestations. This study was intended to identify critical genes associated with chronic ITP. The gene expression profile GSE46922 was downloaded from the Gene Expression Omnibus database to recognize Differentially Expressed Genes (DEGs) by R software. Gene ontology and pathway analyses were performed by DAVID. The biological network was constructed using the Cytoscape. Molecular Complex Detection (MCODE) was applied for detecting module analysis. Transcription factors were identified by the PANTHER classification system database and the gene regulatory network was constructed by Cytoscape. One hundred thirty-two DEGs were screened from comparison newly diagnosed ITP than chronic ITP. Biological process analysis revealed that the DEGs were enriched in terms of positive regulation of autophagy and prohibiting apoptosis in the chronic phase. KEGG pathway analysis showed that the DEGs were enriched in the ErbB signaling pathway, mRNA surveillance pathway, Estrogen signaling pathway, and Notch signaling pathway. Additionally, the biological network was established, and five modules were extracted from the network. ARRB1, VIM, SF1, BUB3, GRK5, and RHOG were detected as hub genes that also belonged to the modules. SF1 also was identified as a hub-TF gene. To sum up, microarray data analysis could perform a panel of genes that provides new clues for diagnosing chronic ITP.

Giant Intracranial Xanthoma with Cloudy Vision as the First Symptom: A Case Report and Literature Review

A 31-year-old male with mild dizziness complained of cloudy vision in his right eye for 5 days. The visual acuity of both eyes was normal, while the visual contrast sensitivity of both eyes slightly reduced. Fundus examination showed the swollen and radial superficial hemorrhage of his both optic nerves. Brain MRI scan indicated a huge tumor in the right temporal lobe with clear boundary, close to the skull. The midline structure shifted to the left. Blood tests indicated no hyperlipidemia or lipid disorders. The patient then received tumor resection. The size of the tumor was 5.6 cm × 7.5 cm × 10.1 cm. Histology suggested many foam cell accumulations and the tumor was positive for CD34, CD99, Vimentin, β-Catenin and CD68, but negative for EMA, GFAP, IDH-1, Oliga-2, PR, S-100, and CD1a. Three months after surgery, MRI showed the midline structure was back to normal. The swollen and radial superficial hemorrhage of optic nerves had disappeared. The visual acuity and visual field remained normal.

Vimentin regulation of autophagy activation in lung fibroblasts in response to lipopolysaccharide exposure in vitro

Background

The activation and assembly of the NLRP3 inflammasome is dependent on the interaction between NLRP3 and the intermediate filament protein vimentin in an acute respiratory distress syndrome (ARDS) model. We investigated the role of vimentin in this process using human fetal lung (HFL-1) fibroblasts with vimentin transfer genes or gene knockdown and lipopolysaccharide (LPS) intervention.

Methods

HFL-1 cells [con-vector + LPS, vimentin-pCMV3 (VIM-pCMV3), con-siRNA, and vimentin siRNA (VIM-siRNA)] were treated with LPS. An oxidative stress damage assessment, apoptosis analysis, and quantification of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and IL-10 by enzyme linked immunosorbent assay (ELISA) were performed. Immunoblotting was used to reveal the autophagy pathway.

Results

We demonstrated that in response to LPS vimentin expression was lower in the HFL-1 cells with the vimentin gene knocked down. Specifically, an increase in oxidative stress, a decrease in mitochondrial membrane potential, or an increase in calcium ion permeability resulted in an increase in the fibroblast apoptosis rate. In addition, the inflammatory response after vimentin gene knockout was upregulated, as indicated by higher levels of TNF-a, IL-1β, IL-6, and IL-10. Importantly, the mechanism of suppression of vimentin in the lung fibroblasts was caused by a decrease in autophagy, an increase in mitochondrial membrane protein, and a decrease in mitochondrial function, which may contribute to the augmented cellular injury generated during the response to LPS.

Conclusions

This study provides insights into whether vimentin may interfere with the inflammatory cascade by activating the autophagy pathway of mitochondrial lung fibroblasts in the early stage of acute lung injury (ALI).

Tnfaip2/exoc3-driven lipid metabolism is essential for stem cell differentiation and organ homeostasis

Lipid metabolism influences stem cell maintenance and differentiation but genetic factors that control these processes remain to be delineated. Here, we identify Tnfaip2 as an inhibitor of reprogramming of mouse fibroblasts into induced pluripotent stem cells. Tnfaip2 knockout impairs differentiation of embryonic stem cells (ESCs), and knockdown of the planarian para-ortholog, Smed-exoc3, abrogates in vivo tissue homeostasis and regeneration-processes that are driven by somatic stem cells. When stimulated to differentiate, Tnfaip2-deficient ESCs fail to induce synthesis of cellular triacylglycerol (TAG) and lipid droplets (LD) coinciding with reduced expression of vimentin (Vim)-a known inducer of LD formation. Smed-exoc3 depletion also causes a strong reduction of TAGs in planarians. The study shows that Tnfaip2 acts epistatically with and upstream of Vim in impairing cellular reprogramming. Supplementing palmitic acid (PA) and palmitoyl-L-carnitine (the mobilized form of PA) restores the differentiation capacity of Tnfaip2-deficient ESCs and organ maintenance in Smed-exoc3-depleted planarians. Together, these results identify a novel role of Tnfaip2 and exoc3 in controlling lipid metabolism, which is essential for ESC differentiation and planarian organ maintenance.

Assessment of Cellular Uptake Efficiency According to Multiple Inhibitors of Fe3O4-Au Core-Shell Nanoparticles: Possibility to Control Specific Endocytosis in Colorectal Cancer Cells

Magnetite (Fe₃O₄)-gold (Au) core-shell nanoparticles (NPs) have unique magnetic and optical properties. When combined with biological moieties, these NPs can offer new strategies for biomedical applications, such as drug delivery and cancer targeting. Here, we present an effective method for the controllable cellular uptake of magnetic core-shell NP systems combined with biological moieties. Vimentin, which is the structural protein, has been biochemically confirmed to affect phagocytosis potently. In addition, vimentin affects exogenic materials internalization into cells even though under multiple inhibitions of biological moieties. In this study, we demonstrate the cellular internalization performance of Fe₃O₄-Au core-shell NPs with surface modification using a combination of biological moieties. The photofluorescence of vimentin-tagged NPs remained unaffected under multiple inhibition tests, indicating that the NPs were minimally influenced by nystatin, dynasore, cytochalasin D, and even the Muc1 antibody (Ab). Consequently, this result indicates that the Muc1 Ab can target specific molecules and can control specific endocytosis. Besides, we show the possibility of controlling specific endocytosis in colorectal cancer cells.

Immune Assisted Tissue Engineering via Incorporation of Macrophages in Cell-Laden Hydrogels Under Cytokine Stimulation

The function of soft tissues is intricately linked to their connections with the other systems of the body such as circulation, nervous system, and immune system. The presence of resident macrophages in tissues provides a means to control tissue homeostasis and also a way to react to the physical/biological insults and tissue damage. Thus, incorporation of resident macrophage like phenotype-controlled macrophages in engineered tissues can improve their fidelity as model tissues and also improve their rate of integration and facilitate the resolution of inflammation for regenerative medicine applications. Herein, we demonstrate two potential ways to immunoassist the remodeling process of engineered soft tissues in three-dimensional (3-D) gelatin based hydrogels containing fibroblasts and/or endothelial cells: (i) with supplementation of interleukin-4 (IL-4) in the presence of macrophages and (ii) in tri-culture via naive monocytes or differentiated macrophages. The presence of IL-4 had a proliferative effect on fibroblasts, with a significant boosting effect on proliferation and cytokine secretion in the presence of differentiated macrophages with an upregulation of activin, interleukin-1 receptor antagonist (IL-1RA), tumor necrosis factor alpha (TNF-α), and interleukin-1 beta (IL-1β), creating a more stimulating microenvironment. The addition of IL-4 in endothelial cell/macrophage co-culture configuration improved the organization of the sprout-like structures, with a boost in proliferation at day 1 and with an upregulation of IL-6 and IL-1RA at the earliest stage in the presence of differentiated macrophages creating a favorable microenvironment for angiogenesis. In tri-culture conditions, the presence of monocytes or macrophages resulted in a denser tissue-like structure with highly remodeled hydrogels. The presence of differentiated macrophages had a boosting effect on the angiogenic secretory microenvironment, such as IL-6 and IL-8, without any additional cytokine supplementation. The presence of fibroblasts in combination with endothelial cells also had a significant effect on the secretion of angiopoietin. Our results demonstrate that incorporation of macrophages in a resident macrophage function and their phenotype control have significant effects on the maturation and cytokine microenvironment of 3-D multiple cell type-laden hydrogels, which can be harnessed for better integration of implantable systems and for more physiologically relevant in vitro tissue models with an immune component.

Intermediate filaments in cardiomyopathy

Intermediate filament (IF) proteins are critical regulators in health and disease. The discovery of hundreds of mutations in IF genes and posttranslational modifications has been linked to a plethora of human diseases, including, among others, cardiomyopathies, muscular dystrophies, progeria, blistering diseases of the epidermis, and neurodegenerative diseases. The major IF proteins that have been linked to cardiomyopathies and heart failure are the muscle-specific cytoskeletal IF protein desmin and the nuclear IF protein lamin, as a subgroup of the known desminopathies and laminopathies, respectively. The studies so far, both with healthy and diseased heart, have demonstrated the importance of these IF protein networks in intracellular and intercellular integration of structure and function, mechanotransduction and gene activation, cardiomyocyte differentiation and survival, mitochondrial homeostasis, and regulation of metabolism. The high coordination of all these processes is obviously of great importance for the maintenance of proper, life-lasting, and continuous contraction of this highly organized cardiac striated muscle and consequently a healthy heart. In this review, we will cover most known information on the role of IFs in the above processes and how their deficiency or disruption leads to cardiomyopathy and heart failure.

Development of an Off-the-Shelf Tissue-Engineered Sinus Valve for Transcatheter Pulmonary Valve Replacement: a Proof-of-Concept Study

Tissue-engineered heart valves with self-repair and regeneration properties may overcome the problem of long-term degeneration of currently used artificial prostheses. The aim of this study was the development and in vivo proof-of-concept of next-generation off-the-shelf tissue-engineered sinus valve (TESV) for transcatheter pulmonary valve replacement (TPVR). Transcatheter implantation of off-the-shelf TESVs was performed in a translational sheep model for up to 16 weeks. Transapical delivery of TESVs was successful and showed good acute and short-term performance (up to 8 weeks), which then worsened over time most likely due to a non-optimized in vitro valve design. Post-mortem analyses confirmed the remodelling potential of the TESVs, with host cell infiltration, polymer degradation, and collagen and elastin deposition. TESVs proved to be suitable as TPVR in a preclinical model, with encouraging short-term performance and remodelling potential. Future studies will enhance the clinical translation of such approach by improving the valve design to ensure long-term functionality.

Down-regulation of pseudogene Vimentin 2p is associated with poor outcome in de novo acute myeloid leukemia

OBJECTIVES

This study was intended to investigate the expression status of Vimentin 2p (VIM 2p), a pseudogene of Vimentin, and further analyze its clinical significance in AML patients.

METHODS

Real-time quantitative PCR (RQ-PCR) was employed to explore the expression status of VIM 2p in 128 patients with de novo AML and 36 healthy controls.

RESULTS

The expression level of VIM 2p was significantly decreased compared with healthy controls (P< 0.001). The patients with low VIM 2p expression were identified in 93 of 128 (73%) of AML patients. No significant differences could be observed in sex, age, blood parameters, FAB/WHO subtypes, karyotype risks and ten gene mutations (FLT3-ITD, NPM1, C-KIT, IDH1/IDH2, DNMT3 A, C/EBPA, N/K-RAS and U2AF1) between VIM 2p low-expressed and high-expressed patients (P> 0.05). Patients with low VIM 2p expression had significantly shorter overall survival (OS) than those with high VIM 2p expression in whole AML cases (median 7 vs. 13 months, respectively, P= 0.032), besides cytogenetically normal AML (CN-AML) and non-M3 AML cohort (P= 0.042 and 0.045, respectively).

CONCLUSIONS

These findings indicate that VIM 2p down-regulation is a common event in AML and may be associated with poor clinical outcome.

Candida albicans Modifies the Protein Composition and Size Distribution of THP-1 Macrophage-Derived Extracellular Vesicles

The effectiveness of macrophages in the response to systemic candidiasis is crucial to an effective clearance of the pathogen. The secretion of proteins, mRNAs, noncoding RNAs and lipids through extracellular vesicles (EVs) is one of the mechanisms of communication between immune cells. EVs change their cargo to mediate different responses, and may play a role in the response against infections. Thus we have undertaken the first quantitative proteomic analysis on the protein composition of THP-1 macrophage-derived EVs during the interaction with Candida albicans. This study revealed changes in EVs sizes and in protein composition, and allowed the identification and quantification of 717 proteins. Of them, 133 proteins changed their abundance due to the interaction. The differentially abundant proteins were involved in functions relating to immune response, signaling, or cytoskeletal reorganization. THP-1-derived EVs, both from control and from Candida-infected macrophages, had similar effector functions on other THP-1-differenciated macrophages, activating ERK and p38 kinases, and increasing both the secretion of proinflammatory cytokines and the candidacidal activity; while in THP-1 nondifferenciated monocytes, only EVs from infected macrophages increased significantly the TNF-α secretion. Our findings provide new information on the role of macrophage-derived EVs in response to C. albicans infection and in macrophages communication.

Transcriptome profiling of the antiviral immune response in Atlantic cod macrophages

A study was conducted to determine the transcriptome response of Atlantic cod (Gadus morhua) macrophages to the viral mimic, polyriboinosinic polyribocytidylic acid (pIC), using a 20K Atlantic cod microarray platform and qPCR. We identified 285 significantly up-regulated and 161 significantly down-regulated probes in cod macrophages 24 h after pIC stimulation. A subset of 26 microarray-identified transcripts was subjected to qPCR validation using samples treated with pIC or phosphate-buffered saline (control) over time (3, 6, 12, 24, 48 h), and 77% of them showed a significant response to pIC. The microarray and qPCR analyses in this study showed that pIC induced the expression of cod macrophage transcripts involved in RLR- and TLR-dependent pathogen recognition (e.g. tlr3, tlr7, mda5 and lgp2), as well as signal transducers (e.g. stat1 and nfkbia) and transcription activators (e.g. irf7 and irf10) in the MyD88-independent and dependent signalling pathways. Several immune effectors (e.g. isg15s, viperin, herc4, mip2 and ccl13) were significantly up-regulated in pIC-stimulated cod macrophages. The expression of some transcripts (e.g. irf7, irf10, viperin) was significantly up-regulated by pIC as early as 12 h. All pIC-induced transcripts had peak expression at either 24 h (e.g. tlr7, irf7, mip2) or 48 h (e.g. tlr3, lgp2, stat1). This study suggests possible roles of both vertebrate-conserved (e.g. tlr3 as an up-regulated gene) and fish-specific (tlr22g as a down-regulated gene) receptors in dsRNA recognition, and the importance of conserved and potentially fish-specific interferon stimulated genes in cod macrophages.

Downregulation of vimentin in macrophages infected with live Mycobacterium tuberculosis is mediated by Reactive Oxygen Species

Mycobacterium tuberculosis persists primarily in macrophages after infection and manipulates the host defence pathways in its favour. 2D gel electrophoresis results showed that vimentin, an intermediate filament protein, is downregulated in macrophages infected with live Mycobacterium tuberculosis H37Rv when compared to macrophages infected with heat- killed H37Rv. The downregulation was confirmed by Western blot and quantitative RT-PCR. Besides, the expression of vimentin in avirulent strain, Mycobacterium tuberculosis H37Ra- infected macrophages was similar to the expression in heat-killed H37Rv- infected macrophages. Increased expression of vimentin in H2O2- treated live H37Rv-infected macrophages and decreased expression of vimentin both in NAC and DPI- treated heat-killed H37Rv-infected macrophages showed that vimentin expression is positively regulated by ROS. Ectopic expression of ESAT-6 in macrophages decreased both the level of ROS and the expression of vimentin which implies that Mycobacterium tuberculosis-mediated downregulation of vimentin is at least in part due to the downregulation of ROS by the pathogen. Interestingly, the incubation of macrophages with anti-vimentin antibody increased the ROS production and decreased the survival of H37Rv. In addition, we also showed that the pattern of phosphorylation of vimentin in macrophages by PKA/PKC is different from monocytes, emphasizing a role for vimentin phosphorylation in macrophage differentiation.

Role of c-Myb in chondrogenesis

The Myb locus encodes the c-Myb transcription factor involved in controlling a broad variety of cellular processes. Recently, it has been shown that c-Myb may play a specific role in hard tissue formation; however, all of these results were gathered from an analysis of intramembranous ossification. To investigate a possible role of c-Myb in endochondral ossification, we carried out our study on the long bones of mouse limbs during embryonic development. Firstly, the c-myb expression pattern was analyzed by in situ hybridization during endochondral ossification of long bones. c-myb positive areas were found in proliferating as well as hypertrophic zones of the growth plate. At early embryonic stages, localized expression was also observed in the perichondrium and interdigital areas. The c-Myb protein was found in proliferating chondrocytes and in the perichondrium of the forelimb bones (E14.5-E17.5). Furthermore, protein was detected in pre-hypertrophic as well as hypertrophic chondrocytes. Gain-of-function and loss-of-function approaches were used to test the effect of altered c-myb expression on chondrogenesis in micromass cultures established from forelimb buds of mouse embryos. A loss-of-function approach using c-myb specific siRNA decreased nodule formation, as well as downregulated the level of Sox9 expression, a major marker of chondrogenesis. Transient c-myb overexpression markedly increased the formation of cartilage nodules and the production of extracellular matrix as detected by intense staining with Alcian blue. Moreover, the expression of early chondrogenic genes such as Sox9, Col2a1 and activity of a Col2-LUC reporter were increased in the cells overexpressing c-myb while late chondrogenic markers such as Col10a1 and Mmp13 were not significantly changed or were downregulated. Taken together, the results of this study demonstrate that the c-Myb transcription factor is involved in the regulation and promotion of endochondral bone formation.

Myosin II Activity Softens Cells in Suspension

The cellular cytoskeleton is crucial for many cellular functions such as cell motility and wound healing, as well as other processes that require shape change or force generation. Actin is one cytoskeleton component that regulates cell mechanics. Important properties driving this regulation include the amount of actin, its level of cross-linking, and its coordination with the activity of specific molecular motors like myosin. While studies investigating the contribution of myosin activity to cell mechanics have been performed on cells attached to a substrate, we investigated mechanical properties of cells in suspension. To do this, we used multiple probes for cell mechanics including a microfluidic optical stretcher, a microfluidic microcirculation mimetic, and real-time deformability cytometry. We found that nonadherent blood cells, cells arrested in mitosis, and naturally adherent cells brought into suspension, stiffen and become more solidlike upon myosin inhibition across multiple timescales (milliseconds to minutes). Our results hold across several pharmacological and genetic perturbations targeting myosin. Our findings suggest that myosin II activity contributes to increased whole-cell compliance and fluidity. This finding is contrary to what has been reported for cells attached to a substrate, which stiffen via active myosin driven prestress. Our results establish the importance of myosin II as an active component in modulating suspended cell mechanics, with a functional role distinctly different from that for substrate-adhered cells.

Proteomic and systems biology analysis of the monocyte response to Coxiella burnetii infection

Coxiella burnetii is an obligate intracellular bacterial pathogen and the causative agent of Q fever. Chronic Q fever can produce debilitating fatigue and C. burnetii is considered a significant bioterror threat. C. burnetii occupies the monocyte phagolysosome and although prior work has explained features of the host-pathogen interaction, many aspects are still poorly understood. We have conducted a proteomic investigation of human Monomac I cells infected with the Nine Mile Phase II strain of C. burnetii and used the results as a framework for a systems biology model of the host response. Our principal methodology was multiplex differential 2D gel electrophoresis using ZDyes, a new generation of covalently linked fluorescent protein detection dyes under development at Montana State University. The 2D gel analysis facilitated the detection of changes in posttranslational modifications on intact proteins in response to infection. The systems model created from our data a framework for the design of experiments to seek a deeper understanding of the host-pathogen interactions.

Nuclear factor of activated T-cells 1 increases sensitivity of v-myb transformed monoblasts to all-trans retinoic acid

Nuclear factors of activated T-cells (NFATs) are important regulators of the cytokine gene expression in activated T-cells. In the last decade, NFATs have been shown to regulate cell cycle, differentiation and apoptosis in cells of various origins revealing their importance for cell homeostasis. In this study, we investigated the effects of NFAT1 on proliferation and differentiation of v-myb-transformed BM2 monoblasts. In contrast to many other leukemic cell lines, BM2 cells do not respond to retinoic acid. However, once overexpressing NFAT1, they became sensitive to all-trans retinoic acid (ATRA). The ATRA-treated BM2NFAT1 cells differentiated along monocyte/macrophage pathway as evidenced by changes in cell morphology, adherence, phagocytic and non-specific esterase activities, reactive oxygen species production, and vimentin expression. Furthermore, overexpressed NFAT1 either alone or in combination with the ATRA-driven signalling pathway deregulated cyclin A and retinoic acid receptor proteins in BM2 cells. Data presented in this study indicate that the NFAT1 and ATRA signalling pathways synergize in control of proliferation and differentiation of BM2 monoblasts.

Molecular and biological characterization of Streptococcal SpyA-mediated ADP-ribosylation of intermediate filament protein vimentin

The Gram-positive bacterial pathogen Streptococcus pyogenes produces a C3 family ADP-ribosyltransferase designated SpyA (S. pyogenes ADP-ribosyltransferase). Our laboratory has identified a number of eukaryotic protein targets for SpyA, prominent among which are the cytoskeletal proteins actin and vimentin. Because vimentin is an unusual target for modification by bacterial ADP-ribosyltransferases, we quantitatively compared the activity of SpyA on vimentin and actin. Vimentin was the preferred substrate for SpyA (k(cat), 58.5 ± 3.4 min(-1)) relative to actin (k(cat), 10.1 ± 0.6 min(-1)), and vimentin was modified at a rate 9.48 ± 1.95-fold greater than actin. We employed tandem mass spectrometry analysis to identify sites of ADP-ribosylation on vimentin. The primary sites of modification were Arg-44 and -49 in the head domain, with several additional secondary sites identified. Because the primary sites are located in a domain of vimentin known to be important for the regulation of polymerization by phosphorylation, we investigated the effects of SpyA activity on vimentin polymerization, utilizing an in vitro NaCl-induced filamentation assay. SpyA inhibited vimentin filamentation, whereas a catalytic site mutant of SpyA had no effect. Additionally, we demonstrated that expression of SpyA in HeLa cells resulted in collapse of the vimentin cytoskeleton, whereas expression in RAW 264.7 cells impeded vimentin reorganization upon stimulation of this macrophage-like cell line with LPS. We conclude that SpyA modification of vimentin occurs in an important regulatory region of the head domain and has significant functional effects on vimentin assembly.

c-Myb regulates matrix metalloproteinases 1/9, and cathepsin D: implications for matrix-dependent breast cancer cell invasion and metastasis

Background

The c-Myb transcription factor is essential for the maintenance of stem-progenitor cells in bone marrow, colon epithelia, and neurogenic niches. c-Myb malfunction contributes to several types of malignancies including breast cancer. However, the function of c-Myb in the metastatic spread of breast tumors remains unexplored. In this study, we report a novel role of c-Myb in the control of specific proteases that regulate the matrix-dependent invasion of breast cancer cells.

Results

Ectopically expressed c-Myb enhanced migration and ability of human MDA-MB-231 and mouse 4T1 mammary cancer cells to invade Matrigel but not the collagen I matrix in vitro. c-Myb strongly increased the expression/activity of cathepsin D and matrix metalloproteinase (MMP) 9 and significantly downregulated MMP1. The gene coding for cathepsin D was suggested as the c-Myb-responsive gene and downstream effector of the migration-promoting function of c-Myb. Finally, we demonstrated that c-Myb delayed the growth of mammary tumors in BALB/c mice and affected the metastatic potential of breast cancer cells in an organ-specific manner.

Conclusions

This study identified c-Myb as a matrix-dependent regulator of invasive behavior of breast cancer cells.

Extensive viral mimicry of 22 AIDS-related autoantigens by HIV-1 proteins and pathway analysis of 561 viral/human homologues suggest an initial treatable autoimmune component of AIDS

HIV-1 viral proteins, particularly the env protein, are homologous to 22 AIDS autoantigens, suggesting their creation by antiviral antibodies subsequently targeting human homologues. They include antibodies to T-cell receptors, CD4 and CD95, complement components, IgG, TNF and other immune-related proteins. Autoantibodies may compromise the immune system via knockdown of these key proteins, and autoimmune attack on the immune system itself, as supported by immune activation in early stages of infection and during the transition to AIDS. Over 500 human proteins contain pentapeptides or longer consensi, identical to viral peptides. Such homology explains the extensive viral/human interactome, likely related to the ability of viral homologues to compete with human counterparts as binding partners. Pathway analysis of these homologous proteins revealed their involvement in immune-related networks (e.g. natural killer cell toxicity/toll, T-cell/B-cell receptor signalling/antigen processing) and viral and bacterial entry and defence pathways (phagosome/lysosome pathways, DNA sensing/NOD/RIG-1 pathways) relevant to AIDS pathogenesis. At its inception, AIDS may have an autoimmune component selectively targeting the immune system. Immunosuppressive therapy or antibody removal, which has already achieved some success, might be therapeutically beneficial, particularly if targeted at removal of the culpable antibodies, via affinity dialysis.

SpyA, a C3-like ADP-ribosyltransferase, contributes to virulence in a mouse subcutaneous model of Streptococcus pyogenes infection

Streptococcus pyogenes is an important human pathogen with an expansive repertoire of verified and putative virulence factors. Here we demonstrate that a mutant deficient in the production of the streptococcal ADP-ribosyltransferase SpyA generates lesions of reduced size in a subcutaneous mouse infection model. At early stages of infection, when the difference in lesion size is first established, inflamed tissue isolated from lesions of mice infected with spyA mutant bacteria has higher levels of mRNA encoding the chemokines CXCL1 and CCL2 than does tissue isolated from mice infected with wild-type bacteria. In addition, at these early times, the mRNA levels for the gene encoding the intermediate filament vimentin are higher in the mutant-infected tissue. As wound resolution progresses, mRNA levels of the gene encoding matrix metallopeptidase 2 are lower in mutant-infected tissue. Furthermore, we demonstrate that the spyA mutant is internalized more efficiently than wild-type bacteria by HeLa cells. We conclude that SpyA contributes to streptococcal pathogenesis in the mouse subcutaneous infection model. Our observations suggest that the presence of SpyA delays wound healing in this model.

Morphological characterization of pecteneal hyalocytes in the developing quail retina

The periphery of the vitreous body contains a population of cells termed hyalocytes. Despite the existence for more than one century of publications devoted to the pecten oculi, a convoluted coil of blood vessels that seems to be the primary source of nutrients for the avian avascular retina, little information can be found concerning the pecteneal hyalocytes. These cells are situated on the inner limiting membrane in close relationship with the convolute blood vessels. To characterize the origin and macrophagic activity of pecteneal hyalocytes, we have analysed two different stages of quail eye development using histochemistry and immunohistochemistry. Pecteneal hyalocytes express the QH1 epitope and cKit, confirming that these cells belong to the haematopoietic system. They also express vimentin, an intermediate filament protein present in cells of mesenchymal origin and very important for differentiation of fully active macrophages. However, similarly as described in porcine hyalocytes, pecteneal hyalocytes express the glial fibrillary acidic protein, a recognized neuroglial marker. Pecteneal hyalocytes did not express other neuroglial markers, such as glutamine synthetase or S100. Acidic phosphatase was activated and Lep100 was found in secondary lysosomes, confirming phagocytic activity of pecteneal hyalocytes during ocular development. Pecteneal hyalocytes strongly react with RCA-I, WFA, WGA, PNA, SNA, LEA and SBA lectins, whereas other avian macrophages from thymus and the bursa of Fabricius did not bind PNA, SNA and LEA lectins. Interestingly, WGA lectin reacts with all kinds of avian macrophages, including pecteneal hyalocytes, probably reflecting the specific binding of WGA to components of the phagocytic and endocytic pathways. In conclusion, pecteneal hyalocytes are a special subtype of blood-borne macrophages that express markers not specifically associated with the haematopoietic system.

An appraisal of intermediate filament expression in adult and developing pancreas: vimentin is expressed in alpha cells of rat and mouse embryos

Intermediate filaments are frequently used in studies of developmental biology as markers of cell differentiation. To assess whether they can be useful to identify differentiating pancreatic endocrine cells, we examined the pattern of expression of nestin, cytokeratin 20, and vimentin on acetone-fixed cryosections of rat adult and developing pancreas. We also studied vimentin expression in mouse embryonic pancreas at E19. Cytokeratin 20 was found in all pancreatic epithelial cell lineages during the entire development of the rat gland and in the adult animals. Under our experimental conditions, therefore, cytokeratin 20 is not an exclusive marker of rat duct cells. Nestin was detected exclusively in stromal cells either in the adult or developing rat pancreas. Vimentin was observed within cells located in the primitive ducts of rat pancreas starting from E12.5. Their number rapidly increased, reaching its highest level in newborn animals. Vimentin was also spotted in alpha cells starting from E12.5 but disappeared soon after birth, likely identifying immature or recently differentiated alpha cells. In addition, vimentin was observed in duct and alpha cells of mouse developing pancreas showing that its expression in such cells is not an event restricted to the rat. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Reduced nitric oxide production and iNOS mRNA expression in IFN-gamma-stimulated chicken macrophages transfected with iNOS siRNAs

Utilizing RNA interference technology with siRNA in the HD11 macrophage cell line, we determined how the inhibition or knock-down of the iNOS (inducible nitric oxide synthase) gene affected IFN-gamma-induced macrophage production of nitric oxide (NO) and mRNA expression of genes involved in this biological pathway in the chicken. Chicken macrophages produce NO when stimulated with recombinant chicken IFN-gamma, however, when transfected with iNOS siRNAs, the production of NO is significantly decreased. We observed a 14-28% reduction in NO production by IFN-gamma-stimulated HD11 cells at 48h after initial siRNA transfection compared to non-transfected IFN-gamma-stimulated macrophages. Significant knock-down of iNOS mRNA expression (15 to 50-fold lower) was observed for each of four iNOS siRNAs, when compared to non-transfected IFN-gamma-stimulated macrophages and to those treated with a negative control siRNA. The IFN-gamma-stimulated chicken macrophages transfected with iNOS siRNAs did not show altered levels of mRNA expression for genes involved in IFN-gamma signaling and iNOS pathways (IL-1beta, IL-6, IFN-gamma, TGF-beta4, or SOCS-3) suggesting that the observed decrease in NO production is a direct result of siRNA mediated knock-down of iNOS, rather than IFN-gamma-induced changes in the other genes tested.

Proteome of monocyte priming by lipopolysaccharide, including changes in interleukin-1beta and leukocyte elastase inhibitor

BACKGROUND

Monocytes can be primed in vitro by lipopolysaccharide (LPS) for release of cytokines, for enhanced killing of cancer cells, and for enhanced release of microbicidal oxygen radicals like superoxide and peroxide. We investigated the proteins involved in regulating priming, using 2D gel proteomics.

RESULTS

Monocytes from 4 normal donors were cultured for 16 h in chemically defined medium in Teflon bags +/- LPS and +/- 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), a serine protease inhibitor. LPS-primed monocytes released inflammatory cytokines, and produced increased amounts of superoxide. AEBSF blocked priming for enhanced superoxide, but did not affect cytokine release, showing that AEBSF was not toxic. After staining large-format 2D gels with Sypro ruby, we compared the monocyte proteome under the four conditions for each donor. We found 30 protein spots that differed significantly in response to LPS or AEBSF, and these proteins were identified by ion trap mass spectrometry.

CONCLUSION

We identified 19 separate proteins that changed in response to LPS or AEBSF, including ATP synthase, coagulation factor XIII, ferritin, coronin, HN ribonuclear proteins, integrin alpha IIb, pyruvate kinase, ras suppressor protein, superoxide dismutase, transketolase, tropomyosin, vimentin, and others. Interestingly, in response to LPS, precursor proteins for interleukin-1beta appeared; and in response to AEBSF, there was an increase in elastase inhibitor. The increase in elastase inhibitor provides support for our hypothesis that priming requires an endogenous serine protease.

Retinoic acid enhances differentiation of v-myb-transformed monoblasts induced by okadaic acid

Differentiation of various leukemic cells can be induced by liganded retinoic acid receptors and protein phosphatase inhibitors. In this study, we explored the effects of okadaic acid (OA), the phosphatase inhibitor, and retinoic acid (RA) in v-myb-transformed monoblasts BM2. OA induced differentiation of BM2 monoblasts into macrophage-like cells, as documented by analyses of cell morphology, cell cycle, phagocytic activity, non-specific esterase activity, production of reactive oxygen species and expression of vimentin and Mo-1. In contrast to many other leukemic cell lines, BM2 cells do not respond to retinoic acid. However, once exposed to OA and RA simultaneously, BM2 cells differentiate along monocyte/macrophage pathway more efficiently. We conclude that RA enhances differentiation of v-myb-transformed monoblasts induced by protein phosphorylation.