Lipopolysaccharide (LPS)-induced macrophage activation and signal transduction in the absence of Src-family kinases Hck, Fgr, and Lyn

The tyrosine kinase Src promotes phosphorylation of the kinase TBK1 to facilitate type I interferon production after viral infection

Various pattern recognition receptors (PRRs) are activated in response to viral infection to stimulate the production of type I interferons (IFNs). However, central to the responses of all of these receptors is their activation of the kinase TBK1, which stimulates transcription by IFN regulatory factor 3 (IRF3). We investigated the mechanism by which the kinase activity of TBK1 is stimulated in response to viral infection. We found that the tyrosine kinase Src promoted the phosphorylation of TBK1 on Tyr¹⁷⁹ upon viral infection of RAW264.7 macrophages. Mutation of Tyr¹⁷⁹ to alanine resulted in impaired autophosphorylation of TBK1 at Ser¹⁷², which is required for TBK1 activation. The TBK1 Y179A mutant failed to rescue type I IFN production by virally infected RAW264.7 macrophages deficient in TBK1. Pharmacological inhibition of Src with AZD0530 and clustered regularly interspaced short palindromic repeats/Cas9-mediated knockout of Src demonstrated that Src was critical for activating the TBK1-IRF3 pathway and stimulating type I IFN production. However, Src did not directly bind to recombinant TBK1 in vitro but instead bound to the proline-X-X-proline motifs within key PRR adaptor proteins, such as TRIF, MAVS, and STING, which formed complexes with TBK1 after PRR engagement. Together, our data suggest that Src is the major tyrosine kinase that primes TBK1 for autophosphorylation and activation, thus providing mechanistic insights into the regulation of TBK1 activity by various PRRs as part of the innate antiviral response.

Cellular subtype expression and activation of CaMKII regulate the fate of atherosclerotic plaque

BACKGROUND AND AIMS

Atherosclerosis is a degenerative process of the arterial wall implicating activation of macrophages and proliferation of vascular smooth muscle cells. Calcium-calmodulin dependent kinase type II (CaMKII) in vascular smooth muscle cells (VSMCs) regulates proliferation, while in macrophages, this kinase governs diapedesis, infiltration and release of extracellular matrix enzymes. We aimed at understanding the possible role of CaMKII in atherosclerosis plaques to regulate plaque evolution towards stability or instability.

METHODS

Clinically defined stable and unstable plaques obtained from patients undergoing carotid end arteriectomy were processed for evaluation of CaMKs protein expression, activity and localization.

RESULTS

The larger content of CaMKII was found in CD14+myeloid cells that were more abundant in unstable rather than stable plaques. To test the biological effect of activated CD14+myeloid cells, VSMCs were exposed to the conditioned medium (CM) of macrophages extracted from carotid plaques. CM induced attenuation of CaMKs expression and activity in VSMCs, leading to the reduction of VSMCs proliferation. This appears to be due to the CaMKII dependent release of cytokines.

CONCLUSIONS

These results indicate a pivotal role of CaMKs in atherosclerosis by regulating activated myeloid cells on VSMCs activity. CaMKII could represent a possible target for therapeutic strategies based on macrophages specific inhibition for the stabilization of arteriosclerotic lesions.

In Vitro Analysis of the Immunomodulating Effects of Allium Hookeri on Lymphocytes, Macrophages, and Tumour Cells

The present study investigated the effects of ethanol extracts of Allium hookeri (leaf, root, and fermented root) on parameters of innate immunity, tumour cell viability and antioxidant effect in vitro. Innate immunity was measured by spleen lymphocyte proliferation, nitric oxide production by chicken macrophage HD11 cells and suppressive effect on tumour cell viability was assessed using chicken RP9 cells. Free radical scavenging capacity as a measure of antioxidant capacity was determined by 0.15 mM of DPPH solution. In vitro culture of chicken spleen lymphocytes with ethanol extract of Allium hookeri (62.5–500 µg/mL) significantly induced higher proliferation compared with media control. Stimulation of macrophages with ethanol extract of Allium hookeri (62.5–500 µg/mL) showed increased Nitric oxide production. Tumor cells growth was significantly inhibited by extracts of Allium hookeri at 15.6–125 µg/mL compared with medium control and all extracts exhibited greater than 80% scavenging activity at 1000 µg/mL compared with ethanol vehicle control. Above all, fermented root extracts showed strongest effects on antioxidant activity compared to leaf and root extracts.

Identification of stable reference genes for lipopolysaccharide-stimulated macrophage gene expression studies

Gene expression studies which utilize lipopolysaccharide (LPS)-stimulated macrophages to model immune signaling are widely used for elucidating the mechanisms of inflammation-related disease. When expression levels of target genes are quantified using Real-Time quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR), they are analyzed in comparison to reference genes, which should have stable expression. Judicious selection of reference genes is, therefore, critical to interpretation of qRT-PCR results. Ideal reference genes must be identified for each experimental system and demonstrated to remain constant under the experimental conditions. In this study, we evaluated the stability of eight common reference genes: Beta-2-microglobulin (B2M), Cyclophilin A/Peptidylprolyl isomerase A, glyceraldehyde-3-phosphatedehydrogenase (GAPDH), Hypoxanthine Phosphoribosyltransferase 1, Large Ribosomal Protein P0, TATA box binding protein, Ubiquitin C (UBC), and Ribosomal protein L13A. Expression stability of each gene was tested under different conditions of LPS stimulation and compared to untreated controls. Reference gene stabilities were analyzed using C_t value comparison, NormFinder, and geNorm. We found that UBC, closely followed by B2M, is the most stable gene, while the commonly used reference gene GAPDH is the least stable. Thus, for improved accuracy in evaluating gene expression levels, we propose the use of UBC to normalize PCR data from LPS-stimulated macrophages.

Polysaccharide of Danggui Buxue Tang, an Ancient Chinese Herbal Decoction, Induces Expression of Pro-inflammatory Cytokines Possibly Via Activation of NFκB Signaling in Cultured RAW 264.7 Cells

Danggui Buxue Tang (DBT) is an ancient Chinese herbal decoction containing two herbs, Astragali Radix (AR) and Angelicae Sinensis Radix (ASR): this herbal decoction serves as dietary supplement for women during menopause. DBT has been known to modulate immune responses, and its polysaccharide is proposed to be one of the active components. However, the polysaccharide-induced signaling in immune activation is not revealed. Here, we are identifying that the immune activation, triggered by DBT, could be mediated by polysaccharide. In cultured macrophages (RAW 264.7 cells), the application of polysaccharide-enriched extract of DBT significantly increased the expressions of mRNA and protein levels of interleukin-1β, interleukin-6 and tumor necrosis factor. The induction was much stronger than the polysaccharide extract generated singly from AR, or from ASR, or from their simple mixture. The induced cytokine release in cultured macrophage was revealed to be triggered by activation of nuclear factor-kappa B (NF-κB) signaling, including (i) degradation of IkBα; (ii) translocation of NF-κB p65 from cytosol to nuclei; and (iii) activation of NF-κB transcriptional elements. These results verified the possible role of DBT polysaccharide in modulating immune responses. Copyright © 2016 John Wiley & Sons, Ltd.

Molecular topology: a strategy to identify novel compounds against ulcerative colitis

In the present paper, a strategy to identify novel compounds against ulcerative colitis (UC) by molecular topology (MT) is presented. Several quantitative structure-activity relationship (QSAR) models based on molecular topology have been developed to predict inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha ([Formula: see text]) mediated anti-ulcerative colitis (UC) activity and protective activity against a dextran sulfate sodium (DSS)-induced UC model. Each one has been used for the screening of four previously selected compounds as potential therapeutic agents for UC: alizarin-3-methyliminodiacetic acid (AMA), Calcein, (+)-dibenzyl-L-tartrate, and Ro 41-0960. These four compounds were then tested in vitro and in vivo and confirmed AMA and Ro 41-0960 as the best lead candidates for further development against UC.

Use of electrospinning and dynamic air focusing to create three-dimensional cell culture scaffolds in microfluidic devices

Organs-on-a-chip has emerged as a powerful tool for pharmacological and physiological studies. A key part in the construction of such a model is the ability to pattern or culture cells in a biomimetic fashion. Most of the reported cells-on-a-chip models integrate cells on a flat surface, which does not accurately represent the extracellular matrix that they experience in vivo. Electrospinning, a technique used to generate sub-micron diameter polymer fibers, has been used as an in vitro cell culture substrate and for tissue engineering applications. Electrospinning of fibers directly into a fully sealed fluidic channel using a conventional setup has not been possible due to issues of confining the fibers into a discrete network. In this work, a dynamic focusing method was developed, with this approach enabling direct deposition of electrospun fibers into a fully sealed fluidic channel, to act as a matrix for cell culture and subsequent studies under continuous flowing conditions. Scanning electron microscopy of electrospun polycaprolactone fibers shows that this method enables the formation of fibrous layers on the inner wall of a 3D-printed fluidic device (mean fiber size = 1.6 ± 0.6 μm and average pore size = 113 ± 19 μm(2)). Cells were able to be cultured in this 3D scaffold without the addition of adhesion proteins. Media was pumped through the channel at high flow rates (up to 400 μL min(-1)) during a dynamic cell culture process and both the fibers and the cells were found to be strongly adherent. A PDMS fluidic device was also prepared (from a 3D printed mold) and coated with polycaprolactone fibers. The PDMS device enables optical detection and confocal imaging of cultured cells on the fibers. Finally, macrophages were cultured in the devices to study how the fibrous scaffold can affect cell behavior. It was found that under lipopolysaccharide stimulation, macrophages cultured on PCL fibers inside of a channel secreted significantly more cytokines than those cultured on a thin layer of PCL in a channel or directly on the inner channel wall. Overall, this study represents a new approach for in vitro cell studies, where electrospinning can be used to easily and quickly create 3D scaffolds that can improve the culture conditions in microfluidic devices.

Implication of G i proteins and Src tyrosine kinases in endotoxin-induced signal transduction events and mediator production

Previous studies have suggested that heterotrimeric G proteins and tyrosine kinases may be involved in lipopolysaccharide (LPS) signaling events. Signal transduction pathways activated by LPS were examined in human promonocytic THP-1 cells. We hypothesized that Gi proteins and Src tyrosine kinase differentially affect mitogen-activated protein (MAP) kinases (MAPK) and nuclear factor kappa (NF- B) activation. Post-receptor coupling to G i proteins were examined using pertussis toxin (PTx), which inhibits G i receptor-coupling. The involvement of the Src family of tyrosine kinases was examined using the selective Src tyrosine kinase inhibitor pyrazolopyrimidine-2 (PP2). Pretreatment of THP-1 cells with PTx attenuated LPS-induced activation of c-Jun-N-terminal kinase (JNK) and p38 kinase, and production of tumor necrosis factor-alpha (TNF-) and thromboxane B2 (TxB2). Pretreatment with PP2 inhibited TNF- and TxB2 production, but had no effect on p38 kinase or JNK signaling. Therefore, the G i-coupled signaling pathways and Src tyrosine kinase-coupled signaling pathways are necessary for LPS-induced TNF- and TxB2 production, but differ in their effects on MAPK activation. Neither PTx nor PP2 inhibited LPS-induced activation of interleukin receptor activated kinase (IRAK) or inhibitedtranslocation of NF- B. However, PP2 inhibitedLPS-inducedNF-B transactivation of a luciferase reporter gene construct in a concentration-dependent manner. Thus, LPS induction of Src tyrosine kinases may be essential in downstream NF- B transactivation of genes following DNA binding. PTx had no effect on NF- B activation of the reporter construct. These data suggest upstream divergence in signaling through G i pathways leading to MAPK activation and other signaling events leading to I B degradation and NF- B DNA binding.

Src is required for migration, phagocytosis, and interferon beta production in Toll-like receptor-engaged macrophages

As an evolutionarily conserved mechanism, innate immunity controls self-nonself discrimination to protect a host from invasive pathogens. Macrophages are major participants of the innate immune system. Through the activation of diverse Toll-like receptors (TLRs), macrophages are triggered to initiate a variety of functions including locomotion, phagocytosis, and secretion of cytokines that requires the participation of tyrosine kinases. Fgr, Hck, and Lyn are myeloid-specific Src family kinases. Despite their constitutively high expression in macrophages, their absence does not impair LPS responsiveness. In contrast, Src, a barely detectable tyrosine kinase in resting macrophages, becomes greatly inducible in response to TLR engagement, implicating its role in macrophage activation. Indeed, silencing Src suppresses the activated TLR-mediated migration, phagocytosis, and interferon-beta (IFN-β) secretion in macrophages. And these physiological defects can be restored by the introduction of siRNA-resistant Src. Notably, the elevated expression and activity of Src is inducible nitric oxide synthase (iNOS)-dependent. Due to (1) iNOS being a NF-κB target, which can be induced by various TLR ligands, (2) Src can mediate NF-κB activation, therefore, there ought to exist a loop of signal amplification that regulates macrophage physiology in response to the engagement of TLRs.

Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages

Chemical mediators of inflammation (CMI) are important in host defense against infection. The reduced capacity of host to induce the secretion of these mediators following infection is one of the factors in host susceptibility to infection. Boron, which has been suggested for its role in infection, is reported in this study to increase lymphocyte proliferation and the secretion of CMI by the lipopolysaccharide (LPS)-stimulated peritoneal macrophages in BALB/c mice. Boron was administered to mice orally as borax at different doses for 10 consecutive days, followed by the stimulation of animals with ovalbumin and isolation of splenocytes for proliferation assay. The lymphocyte subsets were determined by flow cytometry in spleen cell suspension. The mediators of inflammation, TNF-α, IL-6, IL-1β and nitric oxide (NO), were measured in culture supernatant of LPS-primed macrophages isolated from borax treated mice. TNF and ILs were measured by ELISA. NO was determined by Griess test. The expression of inducible nitric oxide synthase (iNOS) in macrophages was studied by confocal microscopy. Results showed a significant increase in T and B cell populations, as indicated by an increase in CD4 and CD19, but not CD8, cells. Boron further stimulated the secretion of TNF-α, IL-6, IL-1β, NO and the expression of iNOS by the LPS-primed macrophages. The effect was dose dependent and most significant at a dose level of 4.6 mg/kg b. wt. Taken together, the study concludes that boron at physiological concentration induces lymphocyte proliferation and increases the synthesis and secretion of pro-inflammatory mediators by the LPS-primed macrophages, more specifically the M1 macrophages, possibly acting through Toll-like receptor. The study implicates boron as a regulator of the immune and inflammatory reactions and macrophage polarization, thus playing an important role in augmenting host defense against infection, with possible role in cancer and other diseases.

Large-scale hematopoietic differentiation of human induced pluripotent stem cells provides granulocytes or macrophages for cell replacement therapies

Interleukin-3 (IL-3) is capable of supporting the proliferation of a broad range of hematopoietic cell types, whereas granulocyte colony-stimulating factor (G-CSF) and macrophage CSF (M-CSF) represent critical cytokines in myeloid differentiation. When this was investigated in a pluripotent-stem-cell-based hematopoietic differentiation model, IL-3/G-CSF or IL-3/M-CSF exposure resulted in the continuous generation of myeloid cells from an intermediate myeloid-cell-forming complex containing CD34⁺ clonogenic progenitor cells for more than 2 months. Whereas IL-3/G-CSF directed differentiation toward CD45⁺CD11b⁺CD15⁺CD16⁺CD66b⁺ granulocytic cells of various differentiation stages up to a segmented morphology displaying the capacity of cytokine-directed migration, respiratory burst response, and neutrophil-extracellular-trap formation, exposure to IL-3/M-CSF resulted in CD45⁺CD11b⁺CD14⁺CD163⁺CD68⁺ monocyte/macrophage-type cells capable of phagocytosis and cytokine secretion. Hence, we show here that myeloid specification of human pluripotent stem cells by IL-3/G-CSF or IL-3/M-CSF allows for prolonged and large-scale production of myeloid cells, and thus is suited for cell-fate and disease-modeling studies as well as gene- and cell-therapy applications.

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Myeloid specification of human PSCs by IL-3-/M-CSF, G-CSF, or GM-CSF

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Large-scale and continuous generation of M2-MΦ or granulocytes by M-CSF or G-CSF

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Functional iPSC-derived macrophages or granulocytes similar to in-vivo-derived cells

A Higher Frequency of CD14+ CD169+ Monocytes/Macrophages in Patients with Colorectal Cancer

Objective

Monocytes and macrophages can infiltrate into tumor microenvironment and regulate the progression of tumors. This study aimed at determining the frequency of different subsets of circulating monocytes and tumor infiltrating macrophages (TIMs) in patients with colorectal cancer (CRC).

Methods

The frequency of different subsets of circulating monocytes was characterized in 46 CRC patients and 22 healthy controls (HC) by flow cytometry. The frequency of different subsets of macrophages was analyzed in TIMs from 30 tumor tissues and in lamina propria mononuclear cells (LPMCs) from 12 non-tumor tissues. The concentrations of plasma cytokines and carcinoembryonic antigen (CEA) were determined. The potential association of these measures with the values of clinical parameters was analyzed.

Results

In comparison with that in the HC, the percentages of circulating CD14⁺CD169⁺, CD14⁺CD169⁺CD163⁺ and CD14⁺CD169⁺CD206⁺ monocytes and TIMs CD14⁺CD169⁺ as well as IL-10⁺CD14⁺CD169⁺, but not IL-12⁺ CD14⁺CD169⁺ macrophages were significantly increased, accompanied by higher levels of plasma IL-10 in the CRC patients. The percentages of CD14⁺CD169⁺ circulating monocytes and TIM macrophages were associated with the stage of disease and correlated positively with the levels of plasma IL-10 and CEA in CRC patients.

Conclusion

Our data suggest that an increase in the frequency of CD14⁺CD169⁺ cells may be associated with the development and progression of CRC and is concomitant rise of both, pro-tumor (M2-like, IL-10 producing) and anti-tumor (M1-like, IL-12 producing) monocytes and infiltrating macrophages. The frequency of CD14⁺CD169⁺ circulating monocytes and infiltrating macrophages may serve as a biomarker for evaluating the pathogenic degrees of CRC.

CD14(+) macrophages that accumulate in the colon of African AIDS patients express pro-inflammatory cytokines and are responsive to lipopolysaccharide

Background

Intestinal macrophages are key regulators of inflammatory responses to the gut microbiome and play a central role in maintaining tissue homeostasis and epithelial integrity. However, little is known about the role of these cells in HIV infection, a disease fuelled by intestinal inflammation, a loss of epithelial barrier function and increased microbial translocation (MT).

Methods

Phenotypic and functional characterization of intestinal macrophages was performed for 23 African AIDS patients with chronic diarrhea and/or weight loss and 11 HIV-negative Africans with and without inflammatory bowel disease (IBD). AIDS patients were treated with cotrimoxazole for the prevention of opportunistic infections (OIs). Macrophage phenotype was assessed by flow cytometry and immuno-histochemistry (IHC); production of proinflammatory mediators by IHC and Qiagen PCR Arrays; in vitro secretion of cytokines by the Bio-Plex Suspension Array System. Statistical analyses were performed using Spearman’s correlation and Wilcoxon matched-pair tests. Results between groups were analyzed using the Kruskal-Wallis with Dunn’s post-test and the Mann–Whitney U tests.

Results

None of the study participants had evidence of enteric co-infections as assessed by stool analysis and histology. Compared to healthy HIV-negative controls, the colon of AIDS patients was highly inflamed with increased infiltration of inflammatory cells and increased mRNA expression of proinflammatory cytokine (tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IFN-γ, and IL-18), chemokines (chemokine (C-C motif) ligand (CCL)2 and chemokine (C-X-C) motif ligand (CXCL)10) and transcription factors (TNF receptor-associated factor (TRAF)6 and T-box (TXB)21). IHC revealed significant co-localization of TNF-α and IL-1β with CD68⁺ cells. As in IBD, HIV was associated with a marked increase in macrophages expressing innate response receptors including CD14, the co-receptor for lipopolysaccharide (LPS). The frequency of CD14⁺ macrophages correlated positively with plasma LPS, a marker of MT. Total unfractionated mucosal mononuclear cells (MMC) isolated from the colon of AIDS patients, but not MMC depleted of CD14⁺ cells, secreted increased levels of proinflammatory cytokines ex vivo in response to LPS.

Conclusions

Intestinal macrophages, in the absence of overt OIs, play an important role in driving persistent inflammation in HIV patients with late-stage disease and diarrhea. These results suggest intensified treatment strategies that target inflammatory processes in intestinal macrophages may be highly beneficial in restoring the epithelial barrier and limiting MT in HIV-infected patients.

Splenic Dendritic Cells Survey Red Blood Cells for Missing Self-CD47 to Trigger Adaptive Immune Responses

Sheep red blood cells (SRBCs) have long been used as a model antigen for eliciting systemic immune responses, yet the basis for their adjuvant activity has been unknown. Here, we show that SRBCs failed to engage the inhibitory mouse SIRPα receptor on splenic CD4(+) dendritic cells (DCs), and this failure led to DC activation. Removal of the SIRPα ligand, CD47, from self-RBCs was sufficient to convert them into an adjuvant for adaptive immune responses. DC capture of Cd47(-/-) RBCs and DC activation occurred within minutes in a Src-family-kinase- and CD18-integrin-dependent manner. These findings provide an explanation for the adjuvant mechanism of SRBCs and reveal that splenic DCs survey blood cells for missing self-CD47, a process that might contribute to detecting and mounting immune responses against pathogen-infected RBCs.

Inhibition of myostatin in mice improves insulin sensitivity via irisin-mediated cross talk between muscle and adipose tissues

Background/Objective

In mice, a high fat diet (HFD) induces obesity, insulin resistance and myostatin production. We tested whether inhibition of myostatin in mice can reverse these HFD-induced abnormalities.

Subjects/Methods

C57BL/6 mice were fed a HFD for 16 weeks including the final 4 weeks some mice were treated with an anti-myostatin peptibody. Body composition, the respiratory exchange ratio plus glucose and insulin tolerance tests were examined. Myostatin knock down in C2C12 cells was performed using ShRNA lentivirus. Adipose tissue-derived stem cells were cultured to measure their reponses to conditioned media from C2C12 cells lacking myostatin, or to recombinant myostatin or Irisin. Isolated peritoneal macrophages were treated with myostatin or Irisin to determine if myostatin or Irisin induce inflammatory mechanisms.

Results

In HFD-fed mice, peptibody treatment stimulated muscle growth and improved insulin resistance. The improved glucose and insulin tolerances were confirmed when we found increased muscle expression of p-Akt and the glucose transporter, Glut4. In mice fed the HFD, the peptibody suppressed macrophage infiltration and the expression of proinflammatory cytokines in both muscle and adipocytes. Inhibition of myostatin caused the conversion of white (WAT) to brown adipose tissue (BAT) while stimulating fatty acid oxidation and increasing energy expenditure. The related mechanism is a muscle-to-fat cross talk mediated by Irisin. Myostatin inhibition increased PGC-1α expression and Irisin production in muscle. Irisin then stimulated WAT browning. Irisin also suppresses inflammation and stimulates macrophage polarization from M1 to M2 types.

Concusion

these results uncover a metabolic pathway from an increase in myostatin that suppresses Irisin leading to activation of inflammatory cytokines and insulin resistance. Thus, myostatin is a potential therapeutic target to treat insulin resistance of type II diabetes as well as the shortage of brown/beige fat in obesity.

The Src-Family Kinases Hck and Fgr Regulate Early Lipopolysaccharide-Induced Myeloid Cell Recruitment into the Lung and Their Ability To Secrete Chemokines

Myeloid leukocyte recruitment into the lung in response to environmental cues represents a key factor for the induction of lung damage. We report that Hck- and Fgr-deficient mice show a profound impairment in early recruitment of neutrophils and monocytes in response to bacterial LPS. The reduction in interstitial and airway neutrophil recruitment was not due to a cell-intrinsic migratory defect, because Hck- and Fgr-deficient neutrophils were attracted to the airways by the chemokine CXCL2 as wild type cells. However, early accumulation of chemokines and TNF-α in the airways was reduced in hck(-/-)fgr(-/-) mice. Considering that chemokine and TNF-α release into the airways was neutrophil independent, as suggested by a comparison between control and neutrophil-depleted mice, we examined LPS-induced chemokine secretion by neutrophils and macrophages in wild type and mutant cells. Notably, mutant neutrophils displayed a marked deficit in their capability to release the chemokines CXCL1, CXCL2, CCL3, and CCL4 and TNF-α in response to LPS. However, intracellular accumulation of these chemokines and TNF-α, as well as secretion of a wide array of cytokines, including IL-1α, IL-1β, IL-6, and IL-10, by hck(-/-)fgr(-/-) neutrophils was normal. Intriguingly, secretion of CXCL1, CXCL2, CCL2, CCL3, CCL4, RANTES, and TNF-α, but not IL-1α, IL-1β, IL-6, IL-10, and GM-CSF, was also markedly reduced in bone marrow-derived macrophages. Consistently, the Src kinase inhibitors PP2 and dasatinib reduced chemokine secretion by neutrophils and bone marrow-derived macrophages. These findings identify Src kinases as a critical regulator of chemokine secretion in myeloid leukocytes during lung inflammation.

O-glycans direct selectin ligands to lipid rafts on leukocytes

Palmitoylated cysteines typically target transmembrane proteins to domains enriched in cholesterol and sphingolipids (lipid rafts). P-selectin glycoprotein ligand-1 (PSGL-1), CD43, and CD44 are O-glycosylated proteins on leukocytes that associate with lipid rafts. During inflammation, they transduce signals by engaging selectins as leukocytes roll in venules, and they move to the raft-enriched uropods of polarized cells upon chemokine stimulation. It is not known how these glycoproteins associate with lipid rafts or whether this association is required for signaling or for translocation to uropods. Here, we found that loss of core 1-derived O-glycans in murine C1galt1(-/-) neutrophils blocked raft targeting of PSGL-1, CD43, and CD44, but not of other glycosylated proteins, as measured by resistance to solubilization in nonionic detergent and by copatching with a raft-resident sphingolipid on intact cells. Neuraminidase removal of sialic acids from wild-type neutrophils also blocked raft targeting. C1galt1(-/-) neutrophils or neuraminidase-treated neutrophils failed to activate tyrosine kinases when plated on immobilized anti-PSGL-1 or anti-CD44 F(ab')2. Furthermore, C1galt1(-/-) neutrophils incubated with anti-PSGL-1 F(ab')2 did not generate microparticles. In marked contrast, PSGL-1, CD43, and CD44 moved normally to the uropods of chemokine-stimulated C1galt1(-/-) neutrophils. These data define a role for core 1-derived O-glycans and terminal sialic acids in targeting glycoprotein ligands for selectins to lipid rafts of leukocytes. Preassociation of these glycoproteins with rafts is required for signaling but not for movement to uropods.

Characterization of immunomodulatory activities of honey glycoproteins and glycopeptides

Recent evidence suggests an important role for natural honey in modulating immune response. To identify active components responsible, this study investigated the immunomodulatory properties of glycoproteins and glycopeptides fractionated from Ziziphus honey. Honey proteins/peptides were fractionated by size exclusion chromatography into five peaks with molecular masses in the range of 2-450 kDa. The fractionated proteins exhibited potent, concentration-dependent inhibition of reactive oxygen species production in zymosan-activated human neutrophils (IC50 = 6-14 ng/mL) and murine macrophages (IC50 = 2-9 ng/mL). Honey proteins significantly suppressed the nitric oxide production by LPS-activated murine macrophages (IC50 = 96-450 ng/mL). Moreover, honey proteins inhibited the phagocytosis latex bead macrophages. The production of pro-inflammatory cytokines IL-1β and TNF-α by human monocytic cell line in the presence of honey proteins was analyzed. Honey proteins did not affect the production of IL-1β; however, TNF-α production was significantly suppressed. These findings indicated that honey glycoproteins and glycopeptides significantly interfere with molecules of the innate immune system.

Anti-Inflammatory Effect of By-Products fromHaliotis discus hannaiin RAW 264.7 Cells

Several reports promoted the potential of shellfish due to their ability to act as antioxidant, anti-inflammatory, and antimicrobial agents. Pacific abalone,Haliotis discus hannaiviscera is, reported to possess bioactivities such as antioxidative stress and anti-inflammatory. In this study, anti-inflammatory potential of mucus-secreting glands from shell-shucking waste ofH. discus hannaiwas evaluated using RAW 264.7 mouse macrophage cell model. Results indicated that presence ofH. discus hannaimucosubstance by-products (AM) significantly lowered the nitric oxide (NO) production along the expressional suppression of inflammatory mediators such as cytokines TNF-α, IL-1β, and IL-6 and enzymes iNOS and COX-2. Also, AM was shown to increase expression of anti-inflammatory response mediator HO-1. Presence of AM also scavenged the free radicalsin vitro. In conclusion, by-products ofH. discus hannaiare suggested to possess notable anti-inflammatory potential which promotes the possibility of utilization as functional food ingredient.

Anti-Inflammatory Activity of the Solvent-Partitioned Fractions from Spergularia marina in LPS-Stimulated RAW 264.7 Cells

As a part of ongoing research to elucidate and characterize antioxidant and anti-inflammatory nutraceuticals, solvent-partitioned fractions from Spergularia marina were tested for their ability to scavenge radicals and suppress inflammation. The results of the 2',7'-dichlorofluorescein diacetate assay indicate that solvent-partitioned fractions from S. marina scavenged intracellular radicals in H2O2-stimulated mouse macrophages. The tested fractions decreased the generation of nitric oxide (NO) and the expression of inflammation mediators, namely, inducible nitric oxide synthase (iNOS) and interleukin (IL)-6, by lipopolysaccharide (LPS)-induced mouse macrophages, indicating that S. marina decreases inflammation. Among all tested fractions [i.e., H2O, n-buthanol (n-BuOH), 85% aqueous methanol (aq. MeOH), and n-hexane], the 85% aq. MeOH fraction showed the strongest antioxidant and anti-inflammatory response. The 85% aq. MeOH fraction scavenged 80% of the free radicals produced by H2O2-induced control cells. In addition, NO production was 98% lower in 85% aq. MeOH fraction-treated cells compared to LPS-induced control cells. The mRNA expression of iNOS and IL-6 was also suppressed in 85% aq. MeOH fraction-treated cells. The results of the current study suggest that the phenolic compound components of S. marina are responsible for its antioxidant and anti-inflammatory effects.

c-Src function is necessary and sufficient for triggering microglial cell activation

Microglial cells are the resident macrophages of the central nervous system. Their function is essential for neuronal tissue homeostasis. After inflammatory stimuli, microglial cells become activated changing from a resting and highly ramified cell shape to an amoeboid-like morphology. These morphological changes are associated with the release of proinflammatory cytokines and glutamate, as well as with high phagocytic activity. The acquisition of such phenotype has been associated with activation of cytoplasmic tyrosine kinases, including those of the Src family (SFKs). In this study, using both in vivo and in vitro inflammation models coupled to FRET-based time-lapse microscopy, lentiviruses-mediated shRNA delivery and genetic gain-of-function experiments, we demonstrate that among SFKs c-Src function is necessary and sufficient for triggering microglia proinflammatory signature, glutamate release, microglia-induced neuronal loss, and phagocytosis. c-Src inhibition in retinal neuroinflammation experimental paradigms consisting of intravitreal injection of LPS or ischemia-reperfusion injury significantly reduced microglia activation changing their morphology to a more resting phenotype and prevented neuronal apoptosis. Our data demonstrate an essential role for c-Src in microglial cell activation.

Leukocyte cathepsin C deficiency attenuates atherosclerotic lesion progression by selective tuning of innate and adaptive immune responses

OBJECTIVE

The protein degrading activity of cathepsin C (CatC), combined with its role in leukocyte granule activation, suggests a contribution of this cystein protease in atherosclerosis. However, no experimental data are available to validate this concept.

APPROACH AND RESULTS

CatC gene and protein expression were increased in ruptured versus advanced stable human carotid artery lesions. To assess causal involvement of CatC in plaque progression and stability, we generated LDLr(-/-)//CatC(-/-) chimeras by bone marrow transplantation. CatC(-/-) chimeras presented attenuated plaque burden in carotids, descending aorta, aortic arch and root, at both the early and advanced plaque stage. CatC was abundantly expressed by plaque macrophages and foam cells. CatC expression and activity were dramatically downregulated in plaques of CatC(-/-) chimeras, supporting a hematopoietic origin of plaque CatC. Our studies unveiled an unexpected feedback of CatC deficiency on macrophage activation programs and T helper cell differentiation in as much as that CatC expression was upregulated in M1 macrophages, whereas its deficiency led to combined M2 (in vitro) and Th2 polarization (in vivo).

CONCLUSIONS

Our data implicate CatC has a role in the selective tuning of innate and adaptive immune responses, relevant to a chronic immune disease, such as atherosclerosis.

Co-operation of TLR4 and raft proteins in LPS-induced pro-inflammatory signaling

Toll-like receptor 4 (TLR4) is activated by lipopolysaccharide (LPS), a component of Gram-negative bacteria to induce production of pro-inflammatory mediators aiming at eradication of the bacteria. Dysregulation of the host responses to LPS can lead to a systemic inflammatory condition named sepsis. In a typical scenario, activation of TLR4 is preceded by binding of LPS to CD14 protein anchored in cholesterol- and sphingolipid-rich microdomains of the plasma membrane called rafts. CD14 then transfers the LPS to the TLR4/MD-2 complex which dimerizes and triggers MyD88- and TRIF-dependent production of pro-inflammatory cytokines and type I interferons. The TRIF-dependent signaling is linked with endocytosis of the activated TLR4, which is controlled by CD14. In addition to CD14, other raft proteins like Lyn tyrosine kinase of the Src family, acid sphingomyelinase, CD44, Hsp70, and CD36 participate in the TLR4 signaling triggered by LPS and non-microbial endogenous ligands. In this review, we summarize the current state of the knowledge on the involvement of rafts in TLR4 signaling, with an emphasis on how the raft proteins regulate the TLR4 signaling pathways. CD14-bearing rafts, and possibly CD36-rich rafts, are believed to be preferred sites of the assembly of a multimolecular complex which mediates the endocytosis of activated TLR4.

Activation of c-Src: a hub for exogenous pro-oxidant-mediated activation of Toll-like receptor 4 signaling

To study the role of c-Src kinase in pro-oxidant-induced stimulation of Toll-like receptor 4 (TLR4), we used lipopolysaccharide from Escherichia coli K12 (LPS-EK) and monophosphoryl lipid A, as TLR4-specific agonists and positive controls, and SIN-1 and potassium peroxychromate as pro-oxidant sources. We used the HEK-Blue mTLR4 cell line, which is stably transfected with mouse TLR4 and expresses optimized SEAP reporter under the control of a promoter inducible by NF-κB transcription factor. The level of SEAP released due to TLR4 stimulation was a measure of NF-κB activation. Treatment with either the pro-oxidants or LPS-EK increased SEAP release and TNF-α production in these cells. These treatments also increased intracellular reactive oxygen species accumulation, with an enhanced production of nitric oxide and TBARS to confirm oxidant stress in these cells. Pretreatment with c-Src kinase inhibitors, PP2 and Ca-pY, which act by different mechanisms, decreased these parameters. Pretreatment with SSG, a c-Src activator, enhanced the effects promoted by LPS-EK and pro-oxidants and rescued cells from the PP2- and Ca-pY-induced effects. Curiously, pro-oxidants, but not TLR4 agonist, increased the ratio of TNF-α to IL-10 released, suggesting that pro-oxidants can initiate and maintain an imbalance of TNF-α production over IL-10. To different degrees, both pro-oxidants and TLR4 agonist increased formation of c-Src complexes with TLR4 and IκB-α as coimmunoprecipitates. Both pro-oxidants and TLR4 agonist increased c-Src phosphorylation of the Tyr42 residue in IκB-α, but the pro-oxidant-induced effect was more robust and much longer lasting. Taken together, these studies provide a mechanism whereby c-Src assumes a central role in pro-oxidant-induced NF-κB activation in TLR4 signaling. Pro-oxidant-induced activation of TLR4 through c-Src/NF-κB/IκB-α coupling provides a basis for a molecular dissection of the initiation and maintenance of sterile inflammation that may serve as a "pathophysiologic primer" for many diseases.

In vitro methods of assessing ocular biocompatibility using THP-1-derived macrophages

Macrophages play an important role in the elimination of infections, the removal of debris and in tissue repair after infection and trauma. In vitro models that assess ocular biomaterials for toxicity typically focus on the effects of these materials on epithelial or fibroblast cells. This investigation evaluated known ocular toxins deposited on model materials for their effects on the viability and activation of macrophages. THP-1-derived macrophages were cultured onto silicone films (used as a base biomaterial) deposited with chemical toxins (benzalkonium chloride (BAK), zinc diethyldithiocarbamate (ZDEC) and lipopolysaccharide (LPS)). Utilizing three fluorescent dyes calcein, ethidium homodimer-1 (EthD-1) and annexin V, the viability of macrophages attached to the biomaterial was determined using confocal microscopy. Propidium iodide (PI) staining and alamarBlue® (resazurin) reduction were used to assess cell death and metabolic activity. CD14, CD16, CD33, CD45, and CD54 expression of adherent macrophages, were also evaluated to detect LPS activation of macrophages using flow cytometry. The sensitivity of this test battery was demonstrated as significant toxicity from treated surfaces with ZDEC (0.001-0.01%), and BAK (0.001%-0.1%) was detected. Also, macrophage activation could be detected by measuring CD54 expression after exposure to adsorbed LPS. These in vitro methods will be helpful in determining the toxicity potential of new ocular biomaterials.

A deletion in chromosome 6q is associated with human abdominal aortic aneurysm

Current efforts to identify the genetic contribution to abdominal aortic aneurysm (AAA) have mainly focused on the assessment of germ-line variants such as single-nucleotide polymorphisms. The aim of the present study was to assess the presence of acquired chromosomal aberrations in human AAA. Microarray data of ten biopsies obtained from the site of main AAA dilatation (AAA body) and three control biopsies obtained from the macroscopically non-dilated neck of the AAA (AAA neck) were initially compared with identified chromosomal aneuploidies using the Chromosomal Aberration Region Miner (ChARM) software. A commonly deleted segment of chromosome bands 6 (q22.1-23.2) was predicted within AAA biopsies. This finding was confirmed by quantitative real-time PCR (qPCR)-based DNA copy number assessments of an independent set of six AAA body and neck biopsies which identified a fold copy number change (∆KCt) of -1±0.35, suggesting the loss of one copy of the long interspersed nucleotide element type 1 (LINE-1) mapped to chromosome 6 (q22.1-23.2). The median relative genomic content of LINE-1 DNA was also reduced in AAA body compared with AAA neck biopsies (1.540 compared with 3.159; P=0.031). A gene important for vascular homoeostasis mapped to 6q23.1, connective tissue growth factor (CTGF), was assessed and found to be significantly down-regulated within AAA bodies compared with AAA necks (0.261 compared with 0.627; P=0.031), as determined by reverse transcription qPCR using total RNA as a template. Histology demonstrated marked staining for macrophages within AAA body biopsies. We found in vitro that the median relative genomic content of LINE-1 DNA in aortic vascular smooth muscle cells (AoSMCs) exposed to pro-inflammatory medium was ~1.5 times greater than that measured in control AoSMCs exposed to non-conditioned medium (3.044 compared with 2.040; P=0.015). Our findings suggest that acquired chromosomal aberrations associated with retrotransposon propagation may predispose to sporadic AAA.

Neuroinflammation and endoplasmic reticulum stress are coregulated by cyclo(His-Pro) to prevent LPS neurotoxicity

Many neurological and neurodegenerative diseases are associated with oxidative stress and glial inflammation, all related to endoplasmic reticulum stress. Cyclo(His-Pro) is an endogenous cyclic dipeptide that exerts cytoprotection by interfering with the Nrf2-NF-κB systems, the former presiding the antioxidant and the latter the pro-inflammatory cellular response. Here we investigated whether the cyclic dipeptide inhibits glial inflammation thus reducing the detrimental effect of inflammatory neurotoxins on neurons. We found that systemic administration of cyclo(His-Pro) exerts in vivo anti-inflammatory effects in the central nervous system by down-regulating hepatic and cerebral TNFα expression thereby counteracting LPS-induced gliosis. Mechanistic studies indicated that the cyclic dipeptide-mediated effects are achieved through the activation of Nrf2-driven antioxidant response and the inhibition of the pro-inflammatory NF-κB pathway. Moreover, by up-regulating Bip, cyclo(His-Pro) increases the ER stress sensitivity and triggers the unfolded protein response to alleviate the ER stress. These results unveil a novel potential therapeutic use of cyclo(His-Pro) against neuroinflammatory-related diseases and we might now consider its potential anti-inflammatory role in other neuropathological conditions.

Immune-related chemotactic factors were found in acute coronary syndromes by bioinformatics

DNA microarray data for thrombus-related leukocyte from patients with acute coronary syndrome (ACS) was analyzed to acquire key genes associated with ACS. Microarray data set GSE19339, including four ACS patients' samples and four normal samples, were downloaded from Gene Expression Omnibus database. Raw data was pre-processed and differentially expressed genes (DEGs) were identified by Affy packages of R. The interaction network was established with STRING. DrugBank was retrieved to obtain relevant small molecules. A total of 487 differentially expressed genes were identified as DEGs between normal and disease samples. Among which, ten up-regulated genes belonging to chemokine family (CCL2, CCR1, CXCL3, CXCL2, CCL8, CXCL11, CCL7, IL10, CCL22 and CCL20) were related to inflammatory response. In addition, two inhibitors of CCL2 (L-Mimosine) were retrieved from the DrugBank database. Considering the roles of inflammatory response in the progression of ACS and the functions of the ten up-regulated genes, we speculated that these genes might be related to ACS. Moreover, the inhibitors could provide guidelines for future drug design acting on these genes.

Lyn activity protects mice from DSS colitis and regulates the production of IL-22 from innate lymphoid cells

Intestinal homeostasis requires a complex balance of interactions between diverse resident microbial communities, the intestinal epithelium, and the underlying immune system. We show that the Lyn tyrosine kinase, a critical regulator of immune cell function and pattern-recognition receptor (PRR) responses, has a key role in controlling gastrointestinal inflammation. Lyn⁻/⁻ mice were highly susceptible to dextran sulfate sodium (DSS)-induced colitis, whereas Lyn gain-of-function (Lyn(up)) mice exhibited attenuated colitis during acute and chronic models of disease. Lyn(up) mice were hypersensitive to lipopolysaccharide (LPS), driving enhanced production of cytokines and factors associated with intestinal barrier function, including interleukin (IL)-22. Oral administration of LPS was sufficient to protect antibiotic-treated Lyn(up) but not wild-type mice from DSS, highlighting how Lyn-dependent changes in the nature/magnitude of PRR responses can impact intestinal health. Furthermore, protection from DSS-induced colitis and increased IL-22 production in response to LPS did not depend on the adaptive immune system, with increased innate lymphoid cell-derived IL-22 correlating with Lyn activity in dendritic cells. These data reveal a key role for Lyn in the regulation of innate immune responses and control of intestinal inflammation.

The inducible nitric-oxide synthase (iNOS)/Src axis mediates Toll-like receptor 3 tyrosine 759 phosphorylation and enhances its signal transduction, leading to interferon-β synthesis in macrophages

Double-stranded RNA (dsRNA) induces phosphorylation of Toll-like receptor 3 (TLR3) at tyrosine 759 and subsequently triggers signaling pathways to promote interferon-β (IFN-β) production. In this study, we found that dsRNA stimulation induces biphasic TLR3 Tyr-759 phosphorylation in macrophages. In addition to the immediate TLR3 Tyr-759 phosphorylation, we identified a second wave of Tyr-759 phosphorylation accompanied by an increase of both Src and ifn-β transcription in the later phase of dsRNA stimulation. Interestingly, Src phosphorylated TLR3 Tyr-759 in vitro and in vivo. However, knockdown of Src abolished the late phase of TLR3 Tyr-759 phosphorylation and decreased the nuclear accumulation of interferon regulatory factors 3 and 7 (IRF3 and -7) and IFN-β production. Reintroduction of Src restored all of these molecular changes. Notably, via down-regulation of Src, dsRNA-elicited TLR3 Tyr-759 phosphorylation, the nuclear accumulation of IRF3/IRF7, and IFN-β generation were inhibited in inducible nitric-oxide synthase (iNOS)-null macrophages. TLR3 knockdown destabilized Src and reduced the nuclear level of IRF3/IRF7 and IFN-β production in macrophages exposed to LPS (a TLR4 ligand known to induce Src and IFN-β expression). Ectopic expression of wild type TLR3, but not its 759-phenylalanine mutant, restored Src activity and ifn-β transcription. Taken together, these results suggested an essential role of the iNOS/Src/TLR3 axis in IFN-β production in macrophages.

Tyrosine phosphorylation of Wiskott-Aldrich syndrome protein (WASP) by Hck regulates macrophage function

We have shown previously that tyrosine phosphorylation of Wiskott-Aldrich syndrome protein (WASP) is important for diverse macrophage functions including phagocytosis, chemotaxis, podosome dynamics, and matrix degradation. However, the specific tyrosine kinase mediating WASP phosphorylation is still unclear. Here, we provide evidence that Hck, which is predominantly expressed in leukocytes, can tyrosine phosphorylate WASP and regulates WASP-mediated macrophage functions. We demonstrate that tyrosine phosphorylation of WASP in response to stimulation with CX3CL1 or via Fcγ receptor ligation were severely reduced in Hck(-/-) bone marrow-derived macrophages (BMMs) or in RAW/LR5 macrophages in which Hck expression was silenced using RNA-mediated interference (Hck shRNA). Consistent with reduced WASP tyrosine phosphorylation, phagocytosis, chemotaxis, and matrix degradation are reduced in Hck(-/-) BMMs or Hck shRNA cells. In particular, WASP phosphorylation was primarily mediated by the p61 isoform of Hck. Our studies also show that Hck and WASP are required for passage through a dense three-dimensional matrix and transendothelial migration, suggesting that tyrosine phosphorylation of WASP by Hck may play a role in tissue infiltration of macrophages. Consistent with a role for this pathway in invasion, WASP(-/-) BMMs do not invade into tumor spheroids with the same efficiency as WT BMMs and cells expressing phospho-deficient WASP have reduced ability to promote carcinoma cell invasion. Altogether, our results indicate that tyrosine phosphorylation of WASP by Hck is required for proper macrophage functions.

Jellyfish collagen stimulates production of TNF-α and IL-6 by J774.1 cells through activation of NF-κB and JNK via TLR4 signaling pathway

We previously reported that jellyfish collagen stimulates both the acquired and innate immune responses. In the acquired immune response, jellyfish collagen enhanced immunoglobulin production by lymphocytes in vitro and in vivo. Meanwhile, in the innate immune response jellyfish collagen promoted cytokine production and phagocytotic activity of macrophages. The facts that jellyfish collagen plays several potential roles in stimulating cytokine production by macrophages have further attracted us to uncover its mechanisms. We herein describe that the cytokine production-stimulating activity of jellyfish collagen was canceled by a Toll-like receptor 4 (TLR4) inhibitor. Moreover, jellyfish collagen stimulated phosphorylation of inhibitor of κBα (IκBα), promoted the translocation of nucleus factor-κB (NF-κB), and activated c-Jun N-terminal kinase (JNK). A JNK inhibitor also abrogated the cytokine production-stimulating activity of jellyfish collagen. These results suggest that jellyfish collagen may facilitate cytokine production by macrophages through activation of NF-κB and JNK via the TLR4 signaling pathways.

Requirement and redundancy of the Src family kinases Fyn and Lyn in perforin-dependent killing of Cryptococcus neoformans by NK cells

Natural killer (NK) cells directly recognize and kill fungi, such as the pathogenic fungus Cryptococcus neoformans, via cytolytic mechanisms. However, the precise signaling pathways governing this NK cell microbicidal activity and the implications for fungal recognition are still unknown. Previously, it was reported that NK cell anticryptococcal activity is mediated through a conserved phosphatidylinositol 3-kinase-extracellular signal-regulated kinase 1/2 (PI3K-ERK1/2) pathway. Using YT (a human NK-like cell line) and primary human NK cells, we sought to identify the upstream, receptor-proximal signaling elements that led to fungal cytolysis. We demonstrate that Src family kinases were activated in response to C. neoformans. Furthermore, pharmacologic inhibition with an Src kinase inhibitor blocked C. neoformans-induced downstream activation of PI3K and ERK1/2 and abrogated cryptococcal killing. At the same time, the inhibitor disrupted the polarization of perforin-containing granules toward the NK cell-cryptococcal synapse but had no effect on conjugate formation between the organism and the NK cell. Finally, small interfering RNA (siRNA) double (but not single) knockdown of two Src family kinases, Fyn and Lyn, blocked cryptococcal killing. Together these data demonstrate a mechanism whereby the Src family kinases, Fyn and Lyn, redundantly mediate anticryptococcal activity through the activation of PI3K and ERK1/2, which in turn facilitates killing by inducing the polarization of perforin-containing granules to the NK cell-cryptococcal synapse.

Phagocytosis of bacteria adhering to a biomaterial surface in a surface thermodynamic perspective

Bacterial biofilms can increase the pathogenicity of infection and constitute a major problem in modern health-care, especially on biomaterial implants and devices. Biofilms are difficult to eradicate by the host immune system, even with antibiotics, and have been the number one cause of biomaterial implant and device failure for decades. Therefore, it is important to understand how immune cells interact with adhering pathogens. This study firstly aims to develop a simple method to quantify phagocytosis of six different strains of staphylococci adhering on a surface with phase-contrast-microscopy. Phagocytosis of adhering staphylococci to a glass surface by phagocytes was quantified in a parallel plate flow chamber, and expressed as a phagocytosis rate, accounting for the number of adhering staphylococci initially present and for the duration of phagocytosis. Murine macrophages were more effective in clearing staphylococci from a surface than human phagocytes, which require differentiation from their monocyte or promyelocytic state during an experiment. Direct visualization of internalization of a GFP-modified S. aureus strain inside phagocytes confirmed the validity of the method proposed. As a second aim, the differences in phagocytosis rates observed were investigated on a surface thermodynamic basis using measured contact angles of liquids on macroscopic lawns of staphylococci and phagocytes, confirming that phagocytosis of adhering pathogens can be regarded as a surface phenomenon. In addition, surface thermodynamics revealed that phagocytosis of adhering pathogens is determined by an interplay of physical attraction between pathogens and phagocytes and the influence of chemo-attractants. For future studies, these results will help to place in vitro experiments and murine infection models in better perspective with respect to human ones.

Traditional biochemical assays for studying toll-like receptor 9

Understanding the mechanistic basis of receptor activation and regulation can offer therapeutic targets for disease treatment. Evidence is emerging for a role of the normally foreign responsive Toll-like receptors (TLRs) in the development of autoimmunity through response to self-patterns. Regulatory mechanisms governing this class of receptors are poorly understood, and failures within this system likely contribute to development of autoimmunity. In this article, we review biochemical assays used to study one of the self-pattern responsive TLRs, TLR9, and suggest that these studies are critical for development of new targets for autoimmune therapies.

Molecular mechanisms for survival regulation of chronic myeloid leukemia stem cells

Studies on chronic myeloid leukemia (CML) have served as a paradigm for cancer research and therapy. These studies involve the identification of the first cancer-associated chromosomal abnormality and the subsequent development of tyrosine kinase inhibitors (TKIs) that inhibit BCR-ABL kinase activity in CML. It becomes clear that leukemia stem cells (LSCs) in CML which are resistant to TKIs, and eradication of LSCs appears to be extremely difficult. Therefore, one of the major issues in current CML biology is to understand the biology of LSCs and to investigate why LSCs are insensitive to TKI monotherapy for developing curative therapeutic strategies. Studies from our group and others have revealed that CML LSCs form a hierarchy similar to that seen in normal hematopoiesis, in which a rare stem cell population with limitless self-renewal potential gives rise to progenies that lack such potential. LSCs also possess biological features that are different from those of normal hematopoietic stem cells (HSCs) and are critical for their malignant characteristics. In this review, we summarize the latest progress in CML field, and attempt to understand the molecular mechanisms of survival regulation of LSCs.

Class I phosphoinositide-3-kinases and SRC kinases play a nonredundant role in regulation of adhesion-independent and -dependent neutrophil reactive oxygen species generation

Chemoattractant-induced reactive oxygen species (ROS) generation by adherent neutrophils occurs in two phases: the first is very rapid and transient, and the second one is delayed and lasts up to 30-40 min. We examined the role of phosphoinositide 3-kinases (PI3Ks) and Src-family kinases (SFKs) in these responses using human neutrophils treated with inhibitory compounds or murine neutrophils deficient of PI3Kγ or Hck, Fgr, and Lyn. Our studies show that PI3Kγ is indispensable for the early, fMLF-induced ROS generation and AKT and ERK phosphorylation, but is dispensable for the late response to fMLF. Additionally, the response to TNF, an agonist triggering only the delayed phase of ROS generation, was also unaffected in PI3Kγ-deficient neutrophils. In contrast, inhibition of SFKs by a selective inhibitor in human, or SFK deficiency in murine, neutrophils resulted in the inhibition of both the early and late phase of ROS generation, without affecting the early phase of AKT phosphorylation, but inhibiting the late one. Selective inhibitors of PI3Kα and PI3Kδ markedly reduced both the early and late response to fMLF and TNF in human neutrophils. These findings suggest that class IA PI3Ks may be activated by PI3Kγ via Ras in the early phase of the response and by SFKs in the late phase. The evidence that inhibition of SFKs in human, or SFK deficiency in murine, neutrophils results in suppression of Vav phosphorylation at all time points of the response to fMLF or TNF suggests that SFKs are indispensable for Vav phosphorylation.

Furanodien-6-one from Commiphora erythraea inhibits the NF-κB signalling and attenuates LPS-induced neuroinflammation

We investigated the in vitro anti-inflammatory activity of 1(10),4-furanodien-6-one, one the most active compounds of the hexane extract of Commiphora erythraea (Ehrenb.) Engl., by exposing microglial BV-2 cells to lipopolysaccharide. We showed that furanodien-6-one pre-treatment restored cell viability and ROS to control levels while halving NO generation. Production of pro-inflammatory IL-6, IL-23, IL-17, TGF-β, and INF-γ, significantly induced by LPS, was also markedly reduced by furanodien-6-one treatment. We further showed that furanodien-6-one protects primary neuronal cultures against the inflammatory/toxic insults of LPS-treated BV-2 conditioned media, indicating that furanodien-6-one exerts anti-inflammatory/cytoprotective effects in neuronal cells. We then investigated whether furanodien-6-one exerts anti-inflammatory properties in an in vivo model of microglial activation. In adult mice ip-injected with LPS we found that furanodien-6-one had strong cerebral anti-inflammatory properties by inhibiting liver and brain TNFα as well as IL-1β expression. Results were not unexpected since FTIR-metabolomic analyses showed that furanodien-6-one-treated mice had a reduced dissimilarity to control animals and that the response to LPS treatment was markedly modified by furanodien-6-one. In conclusion our data provide strong evidence of the anti-inflammatory properties of furanodien-6-one that could be exploited to counteract degenerative pathologies based on neuroinflammation.

Comparative study of the effect of LPS on the function of BALB/c and C57BL/6 peritoneal macrophages

OBJECTIVE

Macrophages influence their environment and surrounding immune cells as soon as stimulators affect them. Different sources of macrophages induce different reactions in their neighboring immune cells,which result in non-uniform immunologic outcomes. In this experimental research, we compare the behavior of peritoneal macrophages to lipopolysaccharide (LPS) stimulation from BALB/cmice as an indicator of a type 2 immune response and from C57BL/6 mice as an indicator of a type 1 immune response.

MATERIALS AND METHODS

In this experimental study, peritoneal macrophages prepared from thioglycolate stimulated BALB/c and C57BL/6 micewere treated with 1µg/ml LPS. At different time points after LPS treatment, nitric oxide (NO), interferon gamma (IFN-λ), interleukin 4 (IL-4),transforming growth factor β1(TGF-β1), interleukin 17 (IL-17), and interleukin 10(IL-10) production were measured in the supernatants of all macrophage cultures. Indoleamine 2, 3 dioxygenase (IDO) and phagocytic activitywere analyzed in the different experimental groups. The supernatant effects of LPS-treated macrophages on splenocyte proliferation was assessed by the colorimetric method using a 3-(4,5-Dimethylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reagent.

RESULTS

According to cytokine analysis, different mouse strains show different cytokine patterns in response to LPS. C57BL/6 macrophages produced more IL-17, IL-10, and IFN-λ, while BALB/c macrophages produced more TGF-β1 and IL-4. There was no significant difference in IDO activity between strains (p≤0.05). BALB/c mice produced more NO inthe first 24 hours after LPS treatment,but C57BL/6 produced more NO at 72 hours post-LPS treatment. Macrophages from both strains hada suppressor effect on splenocyte proliferation, but this effect was stronger in BALB/c mice.

CONCLUSION

The results show that macrophages from different genetic backgrounds respond differently to the same stimulus in aspects of type, intensity, and time of response. The consideration of these aspects will enableresearchers to use correct treatment programs for immune-regulation or immunotherapy.

The role of Src kinase in macrophage-mediated inflammatory responses

Src kinase (Src) is a tyrosine protein kinase that regulates cellular metabolism, survival, and proliferation. Many studies have shown that Src plays multiple roles in macrophage-mediated innate immunity, such as phagocytosis, the production of inflammatory cytokines/mediators, and the induction of cellular migration, which strongly implies that Src plays a pivotal role in the functional activation of macrophages. Macrophages are involved in a variety of immune responses and in inflammatory diseases including rheumatoid arthritis, atherosclerosis, diabetes, obesity, cancer, and osteoporosis. Previous studies have suggested roles for Src in macrophage-mediated inflammatory responses; however, recently, new functions for Src have been reported, implying that Src functions in macrophage-mediated inflammatory responses that have not been described. In this paper, we discuss recent studies regarding a number of these newly defined functions of Src in macrophage-mediated inflammatory responses. Moreover, we discuss the feasibility of Src as a target for the development of new pharmaceutical drugs to treat macrophage-mediated inflammatory diseases. We provide insights into recent reports regarding new functions for Src that are related to macrophage-related inflammatory responses and the development of novel Src inhibitors with strong immunosuppressive and anti-inflammatory properties, which could be applied to various macrophage-mediated inflammatory diseases.

Mathematical modeling and stability analysis of macrophage activation in left ventricular remodeling post-myocardial infarction

Background

About 6 million Americans suffer from heart failure and 70% of heart failure cases are caused by myocardial infarction (MI). Following myocardial infarction, increased cytokines induce two major types of macrophages: classically activated macrophages which contribute to extracellular matrix destruction and alternatively activated macrophages which contribute to extracellular matrix construction. Though experimental results have shown the transitions between these two types of macrophages, little is known about the dynamic progression of macrophages activation. Therefore, the objective of this study is to analyze macrophage activation patterns post-MI.

Results

We have collected experimental data from adult C57 mice and built a framework to represent the regulatory relationships among cytokines and macrophages. A set of differential equations were established to characterize the regulatory relationships for macrophage activation in the left ventricle post-MI based on the physical chemistry laws. We further validated the mathematical model by comparing our computational results with experimental results reported in the literature. By applying Lyaponuv stability analysis, the established mathematical model demonstrated global stability in homeostasis situation and bounded response to myocardial infarction.

Conclusions

We have established and validated a mathematical model for macrophage activation post-MI. The stability analysis provided a possible strategy to intervene the balance of classically and alternatively activated macrophages in this study. The results will lay a strong foundation to understand the mechanisms of left ventricular remodelling post-MI.

Abl family kinases regulate FcγR-mediated phagocytosis in murine macrophages

Phagocytosis of Ab-coated pathogens is mediated through FcγRs, which activate intracellular signaling pathways to drive actin cytoskeletal rearrangements. Abl and Arg define a family of nonreceptor tyrosine kinases that regulate actin-dependent processes in a variety of cell types, including those important in the adaptive immune response. Using pharmacological inhibition as well as dominant negative and knockout approaches, we demonstrate a role for the Abl family kinases in phagocytosis by macrophages and define a mechanism whereby Abl kinases regulate this process. Bone marrow-derived macrophages from mice lacking Abl and Arg kinases exhibit inefficient phagocytosis of sheep erythrocytes and zymosan particles. Treatment with the Abl kinase inhibitors imatinib and GNF-2 or overexpression of kinase-inactive forms of the Abl family kinases also impairs particle internalization in murine macrophages, indicating Abl kinase activity is required for efficient phagocytosis. Further, Arg kinase is present at the phagocytic cup, and Abl family kinases are activated by FcγR engagement. The regulation of phagocytosis by Abl family kinases is mediated in part by the spleen tyrosine kinase (Syk). Loss of Abl and Arg expression or treatment with Abl inhibitors reduced Syk phosphorylation in response to FcγR ligation. The link between Abl family kinases and Syk may be direct, as purified Arg kinase phosphorylates Syk in vitro. Further, overexpression of membrane-targeted Syk in cells treated with Abl kinase inhibitors partially rescues the impairment in phagocytosis. Together, these findings reveal that Abl family kinases control the efficiency of phagocytosis in part through the regulation of Syk function.

Tec family kinases in inflammation and disease

Over the last decade, the Tec family of nonreceptor tyrosine kinases (Btk, Tec, Bmx, Itk, and Rlk) have been shown to play a key role in inflammation and bone destruction. Bruton's tyrosine kinase (Btk) has been the most widely studied due to the critical role of this kinase in B-cell development and recent evidence showing that blocking Btk signaling is effective in ameliorating lymphoma progression and experimental arthritis. This review will examine the role of TFK in myeloid cell function and the potential of targeting these kinases as a therapeutic intervention in autoimmune disorders such as rheumatoid arthritis.

Experimental Pneumocystis lung infection promotes M2a alveolar macrophage-derived MMP12 production

Among several bacterial and viral pathogens, the atypical fungal organism Pneumocystis jirovecii has been implicated as a contributor to the pathogenesis of chronic obstructive pulmonary disease (COPD). In a previous study, we reported that Pneumocystis-colonized HIV-positive subjects had worse obstruction of airways and higher sputum levels of macrophage elastase/matrix metalloproteinase 12 (MMP12), a protease strongly associated with the development of COPD. Here, we examined parameters of Pneumocystis-induced MMP12 in the lungs of mice and its role in the lung immune response to murine Pneumocystis. Initial studies demonstrated that P. murina exposure induced Mmp12 mRNA expression in whole lungs and alveolar macrophages (AMs), which was dependent on the presence of CD4+ T cells as well as signal transducer and activator of transcription 6. Mmp12 mRNA expression was upregulated in AMs by interleukin (IL)-4 treatment, but downregulated by interferon (IFN)-γ, indicating preferential expression in alternatively activated (M2a) macrophages. IL-4 treatment induced the 54-kDa proenzyme form of MMP12 and the 22-kDa fully processed and active form, whereas IFN-γ failed to induce either. Despite a reported antimicrobial role in macrophage phagolysosomes, mice deficient in MMP12 were not found to be more susceptible to lung infection with P. murina. Collectively, our data indicate that MMP12 induction is a component of the P. murina-induced M2 response and thus provides insight into the link between Pneumocystis colonization/infection and exacerbations in COPD.

p38 MAPK inhibition suppresses the TLR-hypersensitive phenotype in FANCC- and FANCA-deficient mononuclear phagocytes

Fanconi anemia, complementation group C (FANCC)-deficient hematopoietic stem and progenitor cells are hypersensitive to a variety of inhibitory cytokines, one of which, TNFα, can induce BM failure and clonal evolution in Fancc-deficient mice. FANCC-deficient macrophages are also hypersensitive to TLR activation and produce TNFα in an unrestrained fashion. Reasoning that suppression of inhibitory cytokine production might enhance hematopoiesis, we screened small molecules using TLR agonist-stimulated FANCC- and Fanconi anemia, complementation group A (FANCA)-deficient macrophages containing an NF-κB/AP-1-responsive reporter gene (SEAP). Of the 75 small molecules screened, the p38 MAPK inhibitor BIRB 796 and dasatinib potently suppressed TLR8-dependent expression of the reporter gene. Fanconi anemia (FA) macrophages were hypersensitive to the TLR7/8 activator R848, overproducing SEAP and TNFα in response to all doses of the agonist. Low doses (50nM) of both agents inhibited p38 MAPK-dependent activation of MAPKAPK2 (MK2) and suppressed MK2-dependent TNFα production without substantially influencing TNFα gene transcription. Overproduction of TNFα by primary FA cells was likewise suppressed by these agents and involved inhibition of MK2 activation. Because MK2 is also known to influence production and/or sensitivity to 2 other suppressive factors (MIP-1α and IFNγ) to which FA hematopoietic progenitor cells are uniquely vulnerable, targeting of p38 MAPK in FA hematopoietic cells is a rational objective for preclinical evaluation.