Chemotactic Function Research Articles

Regulation of Dipeptidyl Peptidase IV in the Post-stroke Rat Brain and In Vitro Ischemia: Implications for Chemokine-Mediated Neural Progenitor Cell Migration and Angiogenesis.

Cerebral ischemia evokes abnormal release of proteases in the brain microenvironment that spatiotemporally impact angio-neurogenesis. Dipeptidyl peptidase IV (DPPIV), a cell surface and secreted protease, has been implicated in extracellular matrix remodeling by regulating cell adhesion, migration, and angiogenesis through modifying the functions of the major chemokine stromal-derived factor, SDF1. To elucidate the possible association of DPPIV in ischemic brain, we examined the expression of DPPIV in the post-stroke rat brain and under in vitro ischemia by oxygen glucose deprivation (OGD). We further investigated the effects of DPPIV on SDF1 mediated in vitro chemotactic and angiogenic functions. DPPIV protein and mRNA levels were significantly upregulated during repair phase in the ischemic cortex of the rat brain, specifically in neurons, astrocytes, and endothelial cells. In vitro exposure of Neuro-2a neuronal cells and rat brain endothelial cells to OGD resulted in upregulation of DPPIV. In vitro functional analysis showed that DPPIV decreases the SDF1-mediated angiogenic potential of rat brain endothelial cells and inhibits the migration of Neuro-2a and neural progenitor cells. Western blot analyses revealed decreased levels of phosphorylated ERK1/2 and AKT in the presence of DPPIV. DPPIV inhibitor restored the effects of SDF1. Proteome profile array screening further revealed that DPPIV decreases matrix metalloproteinase-9, a key downstream effector of ERK-AKT signaling pathways. Overall, delayed induction of DPPIV in response to ischemia/reperfusion suggests that DPPIV may play an important role in endogenous brain tissue remodeling and repair processes. This may be mediated through modulation of SDF1-mediated cell migration and angiogenesis.

Association of Canine Osteosarcoma and Monocyte Phenotype and Chemotactic Function.

BackgroundMonocytes/macrophages are likely key cells in immune modulation in dogs with osteosarcoma (OSA). Increased peripheral monocyte counts are negatively correlated with shorter disease‐free intervals in dogs with OSA. Understanding the monocyte/macrophage's modulatory role in dogs with OSA can direct further studies in immunotherapy development for OSA.Hypothesis/ObjectivesThat OSA evades the immune response by down‐regulating monocyte chemokine receptor expression and migratory function, and suppresses host immune responses.AnimalsEighteen dogs with OSA that have not received definitive treatment and 14 healthy age‐matched controlsMethodsClinical study—expression of peripheral blood monocyte cell surface receptors, monocyte mRNA expression and cytokine secretion, monocyte chemotaxis, and survival were compared between clinical dogs with OSA and healthy control dogs.ResultsCell surface expression of multiple chemokine receptors is significantly down‐regulated in peripheral blood monocytes of dogs with OSA. The percentage expression of CCR2 (median 58%, range 2–94%) and CXCR2 expression (median 54%, range 2–92%) was higher in control dogs compared to dogs with OSA (CCR2 median 29%, range 3–45%, P = 0.0006; CXCR2 median 23%, range 0.2–52%, P = 0.0007). Prostaglandin E2 (PGE 2) (OSA, median 347.36 pg/mL, range 103.4–1268.5; control, 136.23 pg/mL, range 69.93–542.6, P = .04) and tumor necrosis factor‐alpha (TNF‐α) (P = .02) levels are increased in OSA monocyte culture supernatants compared to controls. Peripheral blood monocytes of dogs with OSA exhibit decreased chemotactic function when compared to control dogs (OSA, median 1.2 directed to random migration, range 0.8–1.25; control, 1.6, range of 0.9–1.8, P = .018).Conclusions and Clinical ImportanceDogs with OSA have decreased monocyte chemokine receptor expression and monocyte chemotaxis, potential mechanisms by which OSA might evade the immune response. Reversal of monocyte dysfunction using immunotherapy could improve survival in dogs with OSA.

Defect of netrophil chemotactic function is one of the etiology of aggressive periodontitis.

Defect of netrophil chemotactic function is one of the etiology of aggressive periodontitis.

Global boundedness in a quasilinear attraction–repulsion chemotaxis model with nonlinear sensitivity

This paper considers the attraction–repulsion chemotaxis model with homogeneous Neumann boundary conditions in a smooth, bounded, convex domain. In this model, when the scaling constant is zero and the chemotactic sensitivity functions are nonlinear, we prove that this system possesses a unique global classical solution that is uniformly bounded under some assumptions; when the scaling constant is one and one of the chemotactic sensitivity functions is nonlinear, we also obtain a unique bounded global classical solution under some assumptions.

Association of Canine Osteosarcoma and Monocyte Phenotype and Chemotactic Function

Association of Canine Osteosarcoma and Monocyte Phenotype and Chemotactic Function

Neutrophil Elastase-Generated Fragment of Vascular Endothelial Growth Factor-A Stimulates Macrophage and Endothelial Progenitor Cell Migration.

Elastase released from neutrophils as part of the innate immune system has been implicated in chronic diseases such as emphysema and cardiovascular disease. We have previously shown that neutrophil elastase targets vascular endothelial growth factor-A (VEGF) for partial degradation to generate a fragment of VEGF (VEGFf) that has distinct activities. Namely, VEGFf binds to VEGF receptor 1 but not to VEGF receptor 2 and shows altered signaling compared to intact VEGF. In the present study we investigated the chemotactic function of VEGF and VEGFf released from cells by neutrophil elastase. We found that endothelial cells migrated in response to intact VEGF but not VEGFf whereas RAW 264.7 macrophages/monocytes and embryonic endothelial progenitor cells were stimulated to migrate by either VEGF or VEGFf. To investigate the role of elastase-mediated release of VEGF from cells/extracellular matrices, a co-culture system was established. High or low VEGF producing cells were co-cultured with macrophages, endothelial or endothelial progenitor cells and treated with neutrophil elastase. Elastase treatment stimulated macrophage and endothelial progenitor cell migration with the response being greater with the high VEGF expressing cells. However, elastase treatment led to decreased endothelial cell migration due to VEGF cleavage to VEGF fragment. These findings suggest that the tissue response to NE-mediated injury might involve the generation of diffusible VEGF fragments that stimulate inflammatory cell recruitment.

Human T Cell Leukemia Virus Type 1 Infection of the Three Monocyte Subsets Contributes to Viral Burden in Humans.

Because the viral DNA burden correlates with disease development, we investigated the contribution of monocyte subsets (classical, intermediate, and nonclassical monocytes) to the total viral burden in 22 human T cell leukemia virus type 1 (HTLV-1)-infected individuals by assessing their infectivity status, frequency, as well as chemotactic and phagocytic functions. All three monocyte subsets sorted from HTLV-1-infected individuals were positive for viral DNA, and the frequency of classical monocytes was lower in the blood of HTLV-1-infected individuals than in that of uninfected individuals, while the expression levels of the chemokine receptors CCR5, CXCR3, and CX3CR1 in classical monocytes were higher in HTLV-1-infected individuals than uninfected individuals; the percentage of intermediate monocytes and their levels of chemokine receptor expression did not differ between HTLV-1-infected and uninfected individuals. However, the capacity of intermediate monocytes to migrate to CCL5, the ligand for CCR5, was higher, and a higher proportion of nonclassical monocytes expressed CCR1, CXCR3, and CX3CR1. The level of viral DNA in the monocyte subsets correlated with the capacity to migrate to CCL2, CCL5, and CX3CL1 for classical monocytes, with lower levels of phagocytosis for intermediate monocytes, and with the level of viral DNA in CD8(+) and CD4(+) T cells for nonclassical monocytes. These data suggest a model whereby HTLV-1 infection augments the number of classical monocytes that migrate to tissues and become infected and the number of infected nonclassical monocytes that transmit virus to CD4(+) and CD8(+) T cells. These results, together with prior findings in a macaque model of HTLV-1 infection, support the notion that infection of monocytes by HTLV-1 is likely a requisite for viral persistence in humans. Monocytes have been implicated in immune regulation and disease progression in patients with HTLV-1-associated inflammatory diseases. We detected HTLV-1 DNA in all three monocyte subsets and found that infection impacts surface receptor expression, migratory function, and subset frequency. The frequency of nonclassical patrolling monocytes is increased in HTLV-1-infected individuals, and they have increased expression of CCR1, CXCR3, and CX3CR1. The viral DNA level in nonclassical monocytes correlated with the viral DNA level in CD4(+) and CD8(+) T cells. Altogether, these data suggest an increased recruitment of classical monocytes to inflammation sites that may result in virus acquisition and, in turn, facilitate virus dissemination and viral persistence. Our findings thus provide new insight into the importance of monocyte infection in viral spread and suggest targeting of monocytes for therapeutic intervention.

CryoEM and computer simulations reveal a novel kinase conformational switch in bacterial chemotaxis signaling.

Chemotactic responses in bacteria require large, highly ordered arrays of sensory proteins to mediate the signal transduction that ultimately controls cell motility. A mechanistic understanding of the molecular events underlying signaling, however, has been hampered by the lack of a high-resolution structural description of the extended array. Here, we report a novel reconstitution of the array, involving the receptor signaling domain, histidine kinase CheA, and adaptor protein CheW, as well as a density map of the core-signaling unit at 11.3 Å resolution, obtained by cryo-electron tomography and sub-tomogram averaging. Extracting key structural constraints from our density map, we computationally construct and refine an atomic model of the core array structure, exposing novel interfaces between the component proteins. Using all-atom molecular dynamics simulations, we further reveal a distinctive conformational change in CheA. Mutagenesis and chemical cross-linking experiments confirm the importance of the conformational dynamics of CheA for chemotactic function.

Systematic Review of the Neurobiological Relevance of Chemokines to Psychiatric Disorders.

Psychiatric disorders are highly prevalent and disabling conditions of increasing public health relevance. Much recent research has focused on the role of cytokines in the pathophysiology of psychiatric disorders; however, the related family of immune proteins designated chemokines has been relatively neglected. Chemokines were originally identified as having chemotactic function on immune cells; however, recent evidence has begun to elucidate novel, brain-specific functions of these proteins of relevance to the mechanisms of psychiatric disorders. A systematic review of both human and animal literature in the PubMed and Google Scholar databases was undertaken. After application of all inclusion and exclusion criteria, 157 references were remained for the review. Some early mechanistic evidence does associate select chemokines with the neurobiological processes, including neurogenesis, modulation of the neuroinflammatory response, regulation of the hypothalamus–pituitary–adrenal axis, and modulation of neurotransmitter systems. This early evidence however does not clearly demonstrate any specificity for a certain psychiatric disorder, but is primarily relevant to mechanisms which are shared across disorders. Notable exceptions include CCL11 that has recently been shown to impair hippocampal function in aging – of distinct relevance to Alzheimer’s disease and depression in the elderly, and pre-natal exposure to CXCL8 that may disrupt early neurodevelopmental periods predisposing to schizophrenia. Pro-inflammatory chemokines, such as CCL2, CCL7, CCL8, CCL12, and CCL13, have been shown to drive chemotaxis of pro-inflammatory cells to the inflamed or injured CNS. Likewise, CX3CL has been implicated in promoting glial cells activation, pro-inflammatory cytokines secretion, expression of ICAM-1, and recruitment of CD4+ T-cells into the CNS during neuroinflammatory processes. With further translational research, chemokines may present novel diagnostic and/or therapeutic targets in psychiatric disorders.

Endothelial LSP1 Modulates Extravascular Neutrophil Chemotaxis by Regulating Nonhematopoietic Vascular PECAM-1 Expression.

During inflammation, leukocyte-endothelial cell interactions generate molecular signals that regulate cell functions. The Ca(2+)- and F-actin-binding leukocyte-specific protein 1 (LSP1) expressed in leukocytes and nonhematopoietic endothelial cells is pivotal in regulating microvascular permeability and leukocyte recruitment. However, cell-specific function of LSP1 during leukocyte recruitment remains elusive. Using intravital microscopy of cremasteric microvasculature of chimeric LSP1-deficient mice, we show that not neutrophil but endothelial LSP1 regulates neutrophil transendothelial migration and extravascular directionality without affecting the speed of neutrophil migration in tissue in response to CXCL2 chemokine gradient. The expression of PECAM-1-sensitive α6β1 integrins on the surface of transmigrated neutrophils was blunted in mice deficient in endothelial LSP1. Functional blocking studies in vivo and in vitro elucidated that α6β1 integrins orchestrated extravascular directionality but not the speed of neutrophil migration. In LSP1-deficient mice, PECAM-1 expression was reduced in endothelial cells, but not in neutrophils. Similarly, LSP1-targeted small interfering RNA silencing in murine endothelial cells mitigated mRNA and protein expression of PECAM-1, but not ICAM-1 or VCAM-1. Overexpression of LSP1 in endothelial cells upregulated PECAM-1 expression. Furthermore, the expression of transcription factor GATA-2 that regulates endothelial PECAM-1 expression was blunted in LSP1-deficient or LSP1-silenced endothelial cells. The present study unravels endothelial LSP1 as a novel cell-specific regulator of integrin α6β1-dependent neutrophil extravascular chemotactic function in vivo, effective through GATA-2-dependent transcriptional regulation of endothelial PECAM-1 expression.

HTLV-1 burden dependent on hijacking monocytes chemotaxis

The HTLV-DNA burden in PBMCs is a risk factor for HAM/TSP and ATL development. We investigated the contribution of monocyte subsets (classical, intermediate and non-classical) to the total viral burden in 23 HTLV-1 infected individuals by assessing their frequency, their chemotactic and phagocytic functions, as well as their infectivity status. Classical monocytes differed between infected and uninfected individuals, their frequency was lower and their expression level of the chemokine receptors CCR5, CXCR3 and CX3CR1 was higher. While the percentage and surface chemokine receptor expression did not differ between HTLV-1 infected and uninfected individuals, intermediate monocytes from HTLV-1 infected individuals had increased migratory capacity to CCL5, the ligand for CCR5. Non-classical monocytes from HTLV-1 infected individuals increased in frequency and expressed high levels of CCR1, CXCR3 and CX3CR1. All three purified monocyte subsets were infected by HTLV-1. The level of viral DNA in monocyte subsets correlated directly with their migration capacity to CCL2, CCL5 and CX3CL1 for the classical subset, with lesser phagocytosis for the intermediate monocytes, and with the level of viral DNA in CD8+ and CD4+T-cells for the non-classical subset. These data suggest a model whereby HTLV-1 infection augments classical monocytes migration to tissues resulting in their infection, and non-classical monocytes frequency, resulting in increased transmission of virus to CD4+ and CD8+T-cells. Our data in humans together with prior animal experiments supports the notion that infection of monocytes in vitro is crucial for viral infectivity and persistence in humans, rendering infected monocytes desirable therapeutic targets.

Modification of β-Defensin-2 by Dicarbonyls Methylglyoxal and Glyoxal Inhibits Antibacterial and Chemotactic Function In Vitro.

BackgroundBeta-defensins (hBDs) provide antimicrobial and chemotactic defense against bacterial, viral and fungal infections. Human β-defensin-2 (hBD-2) acts against gram-negative bacteria and chemoattracts immature dendritic cells, thus regulating innate and adaptive immunity. Immunosuppression due to hyperglycemia underlies chronic infection in Type 2 diabetes. Hyperglycemia also elevates production of dicarbonyls methylgloxal (MGO) and glyoxal (GO).MethodsThe effect of dicarbonyl on defensin peptide structure was tested by exposing recombinant hBD-2 (rhBD-2) to MGO or GO with subsequent analysis by MALDI-TOF MS and LC/MS/MS. Antimicrobial function of untreated rhBD-2 vs. rhBD-2 exposed to dicarbonyl against strains of both gram-negative and gram-positive bacteria in culture was determined by radial diffusion assay. The effect of dicarbonyl on rhBD-2 chemotactic function was determined by chemotaxis assay in CEM-SS cells.ResultsMGO or GO in vitro irreversibly adducts to the rhBD-2 peptide, and significantly reduces antimicrobial and chemotactic functions. Adducts derive from two arginine residues, Arg22 and Arg23 near the C-terminus, and the N-terminal glycine (Gly1). We show by radial diffusion testing on gram-negative E. coli and P. aeruginosa, and gram-positive S. aureus, and a chemotaxis assay for CEM-SS cells, that antimicrobial activity and chemotactic function of rhBD-2 are significantly reduced by MGO.ConclusionsDicarbonyl modification of cationic antimicrobial peptides represents a potential link between hyperglycemia and the clinical manifestation of increased susceptibility to infection, protracted wound healing, and chronic inflammation in undiagnosed and uncontrolled Type 2 diabetes.

The Positively Charged COOH-terminal Glycosaminoglycan-binding CXCL9(74–103) Peptide Inhibits CXCL8-induced Neutrophil Extravasation and Monosodium Urate Crystal-induced Gout in Mice

The ELR(-)CXC chemokine CXCL9 is characterized by a long, highly positively charged COOH-terminal region, absent in most other chemokines. Several natural leukocyte- and fibroblast-derived COOH-terminally truncated CXCL9 forms missing up to 30 amino acids were identified. To investigate the role of the COOH-terminal region of CXCL9, several COOH-terminal peptides were chemically synthesized. These peptides display high affinity for glycosaminoglycans (GAGs) and compete with functional intact chemokines for GAG binding, the longest peptide (CXCL9(74-103)) being the most potent. The COOH-terminal peptide CXCL9(74-103) does not signal through or act as an antagonist for CXCR3, the G protein-coupled CXCL9 receptor, and does not influence neutrophil chemotactic activity of CXCL8 in vitro. Based on the GAG binding data, an anti-inflammatory role for CXCL9(74-103) was further evidenced in vivo. Simultaneous intravenous injection of CXCL9(74-103) with CXCL8 injection in the joint diminished CXCL8-induced neutrophil extravasation. Analogously, monosodium urate crystal-induced neutrophil migration to the tibiofemural articulation, a murine model of gout, is highly reduced by intravenous injection of CXCL9(74-103). These data show that chemokine-derived peptides with high affinity for GAGs may be used as anti-inflammatory peptides; by competing with active chemokines for binding and immobilization on GAGs, these peptides may lower chemokine presentation on the endothelium and disrupt the generation of a chemokine gradient, thereby preventing a chemokine from properly performing its chemotactic function. The CXCL9 peptide may serve as a lead molecule for further development of inhibitors of inflammation based on interference with chemokine-GAG interactions.

Abstract 4144: Extracellular nucleotides and purinergic signaling as novel, underappreciated, pro-metastatic factors for human lung cancer cells

Abstract Background: One of the challenging problems of current radio-chemotherapy is recurrence and metastasis of cancer cells that survive initial treatment. We have proposed that one of the unwanted effects of radio-chemotherapy is release of phospho-sphingolipids in response to treatment and thus induction of pro-metastatic microenvironment in several organs (Mol Cancer Res 2013; 11:793). However, at the same time also intracellular nucleotides such as ATP and UTP are released from damaged (“leaky”) cells exerting chemotactic functions. Hypothesis: Based on these observations that, in addition to phospho-sphingolipids, also nucleotides (e.g., ATP and UTP) are released from damaged cells we hypothesized that these molecules if released into extracellular microenvironment may also direct chemotaxis and metastasis of cancer cells - alone or in synergy with phospho-sphingolipids. Materials and Methods: Several complementary in vitro and in vivo approaches were employed to demonstrate a novel role of extracellular nucleotides (EXN) in a model of metastasis of lung cancer cells. In our studies we employed four large cell and two small cell lung cancer cell lines and a set of nucleotides including ATP, ADP, AMP, UTP, TTP, CTP, and GTP. Real time RT-PCR analysis of the expression of purinergic P1 and P2 receptors as well as chemotaxis, adhesion, proliferation, intracellular calcium flux and cell signaling studies in response to EXN stimulation were performed. Concentrations of ATP and UTP in several organs before and after radio-chemotherapy were measured by colorimetric kits. Purinergic receptor agonists and antagonists, inhibiting all or selected subtypes, were assayed in vitro and in vivo in pro-metastatic assays. Results: We observed that EXN accumulate in in several organs in response to radio-chemotherapy. RT-PCR analysis indicated that most of the P2X, P2Y and adenosine receptor subtypes are expressed in tested lung cancer cell lines. By employing in vitro migration assays, we found that, out of all the nucleotides tested, ATP, AMP and UTP have the strongest chemotactic activity for most of the human lung cancer cell lines correlating with phosphorylation of MAPKp42/44 and AKT. We also observed increased adhesion to fibronectin after stimulation with tested EXN, whereas proliferation was not affected by of EXN. More important, metastasis of lung cancer cells could be inhibited in immune-deficient mice in a presence of specific small molecule inhibitors of nucleotide receptors. Conclusions: Both systemic and local radio-chemotherapy leads to upregulation of EXN release in damaged tissues, and the side effect of such treatment is induction of an unwanted pro-metastatic microenvironment in different organs. Based on this data, EXN are novel pro-metastatic factors and inhibition of their pro-metastatic effects could become an important part of anti-metastatic treatment. Citation Format: Gabriela Schneider, Talita Glaser, Ahmed Abdelbaset Ismail, Henning Ulrich, Mariusz Z. Ratajczak. Extracellular nucleotides and purinergic signaling as novel, underappreciated, pro-metastatic factors for human lung cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4144. doi:10.1158/1538-7445.AM2015-4144

Preoperative serum chemokine (C-C motif) ligand 2 levels and prognosis in colorectal cancer.

Chemokines are cytokines with chemotactic functions in the initiation and maintenance of immune reactions. They have also been shown to regulate other processes such as cancer progression and cancer cell migration. The aim of this study was to determine the prognostic role of serum levels of chemokine (C-C motif) ligand 2 (CCL2) and chemokine (C-C motif) ligand 5 (CCL5) in patients with colorectal cancer. The study included a group of 45 patients with colorectal cancer. The serum concentrations of CCL2 and CCL5 were measured preoperatively. Peripheral blood mononuclear cells (PBMC) from patients' blood were isolated and cultured alone or with cancer cells. The concentrations of chemokines in serum and culture supernatants were measured using the cytometric bead array method. The cut-off points for serum chemokine levels were set based on the receiver-operating characteristic curve analysis at a level of 103.6 pg/ml for CCL2 and of 11933.2 pg/ml for CCL5. The survival analysis and multivariate analysis of prognostic factors were performed. The 5-year survival was 57.5% for the group with low CCL2 levels and 23.87% for the group with high CCL2 levels. For the groups with low and high CCL5 levels, the survival was 18.3% and 49.3%, respectively. For CCL2, the survival of the low-level group was significantly better than that of the highlevel group (P = 0.0028). In the Cox proportional hazard model, radicality of resection (P = 0.001) and CCL2 levels (P = 0.029) were independent prognostic factors. The serum level of CCL2 in patients with colorectal cancer may have prognostic value. One of the possible mechanisms of CCL2 production is the interaction of PBMC with cancer cells.

Expression characteristics of neutrophil and mononuclear-phagocyte related genes mRNA in the stable angina pectoris and acute myocardial infarction stages of coronary artery disease.

ObjectiveTo investigate expression differences of neutrophil and mononuclear phagocyte related gene mRNAs among acute myocardial infarction (AMI), stable angina (SA) and control groups, and then discuss their expression characteristics in the stable angina pectoris (SAP) and AMI stages of coronary artery disease (CAD).MethodsWhole Human Genome Oligo Microarrays were applied to assess the differential expression characteristics of neutrophil and mononuclear phagocyte related mRNAs in patients with AMI (n = 20), SA (n = 20) and controls (n = 20).Results(1) Almost all colony-stimulating factors (CSF) and their receptors related mRNAs was up-regulated in AMI and SA groups compared with the control group, and the expression of granulocyte-macrophage colony stimulating factor receptor (GM-CSFR) and granulocyte colony stimulating factor receptor (G-CSFR) mRNAs in the AMI group was significantly up-regulated compared with the other two groups (P < 0.01). (2) The expression of mRNAs related to monocyte chemoattractant protein-1 (MCP-1), CCR2 (MCP-1 receptor) and CXCR2 (IL-8 receptor) was significantly up-regulated (P < 0.01) in AMI group compared with SA and control groups. IL-8 mRNA expression in the AMI group was clearly higher than the controls (P < 0.05). (3) All mRNAs expression related to opsonic receptors (IgG FcR and C3bR/C4bR) was significantly up-regulated in AMI group compared with SA and control group (P < 0.01), and the SA group showed an upward trend compared with controls. (4) Most pattern recognition receptor (PRR)-related mRNAs expression was up-regulated in AMI group compared with SA and control groups. Most toll-like receptor (TLR) mRNAs expression was significantly up-regulated (P < 0.01) than the SA and control groups; macrophage scavenger receptor (MSR) mRNA was significantly up-regulated in AMI group compared with the control group (P < 0.01), and the SA group showed an upward trend compared with the controls.ConclusionsThe expression of most neutrophil and mononuclear-macrophage function related genes mRNAs was significantly up-regulated by stages during the progression of CAD, suggesting that the adhesive, chemotactic and phagocytic functions of neutrophil and mononuclear-macrophage were strengthened in the occurrence and development of coronary atherosclerosis and AMI. This also showed a stepped upward trend as the disease progressed.

Paracrine Interactions between Adipocytes and Tumor Cells Recruit and Modify Macrophages to the Mammary Tumor Microenvironment: The Role of Obesity and Inflammation in Breast Adipose Tissue.

The relationship between obesity and breast cancer (BC) has focused on serum factors. However, the mammary gland contains adipose tissue (AT) which may enable the crosstalk between adipocytes and tumor cells contributing to tumor macrophage recruitment. We hypothesize that the breast AT (bAT) is inflamed in obese females and plays a major role in breast cancer development. The effects of this interplay on macrophage chemotaxis were examined in vitro, using co-cultures of mouse macrophages, mammary tumor cells and adipocytes. Macrophages were exposed to the adipocyte and tumor paracrine factors leptin, CCL2 and lauric acid (alone or in combinations). In cell supernatants Luminex identified additional molecules with chemotactic and other pro-tumor functions. Focus on the adipokine leptin, which has been shown to have a central role in breast cancer pathogenesis, indicated it modulates macrophage phenotypes and functions. In vivo experiments demonstrate that mammary tumors from obese mice are larger and that bAT from obese tumor-bearers contains higher numbers of macrophages/CLS and hypertrophic adipocytes than bAT from lean tumor-bearers, thus confirming it is more inflamed. Also, bAT distal from the tumor is more inflamed in obese than in lean mice. Our results reveal that bAT plays a role in breast cancer development in obesity.

Cryo-Electron Tomography and Computer Simulations Reveal Distinct CheA Kinase Conformation in Bacterial Chemotaxis Signaling Receptor Complex

Improved sample preparation, data collection, and image processing pipelines have ushered in a new era in cryo-Electron Tomography (CryoET). Electron density maps of large, conformationally heterogeneous assemblies can be determined at subnanometer resolutions and coupled with high resolution structural information and large scale molecular dynamics simulation to gain atomistic understanding of large and complex cellular machinery that is otherwise unattainable. We use such an integrative approach to investigate the signal transduction in bacterial chemotaxis arrays - large transmembrane protein complex assemblies responsible for modulating the motility of bacteria. These arrays are responsible, in part for appropriately biasing the cell's inherent random walk, and also retaining the memory of recent states of the system. Despite recent advances, fundamental questions on how the components of the system work together to transduce the signal from membrane receptor to kinase molecule, and how the individual signaling unit works cohesively to achieve a large gain in signaling remain unanswered. We devised a novel in vitro reconstitution system to build extended signaling arrays on a lipid monolayer using purified protein components, providing an unprecedented number of signaling units in a thin layer (∼150-200nm) ideal for cryoET. The individual subvolumes from 3D tomograms are extracted, aligned, classified and averaged, resulting in a 3D density map of the basic chemotaxis signaling unit comprising the chemoreceptor, the histidine kinase CheA and the cofactor CheW. The density map reveals an unexpected asymmetry among three kinase CheA dimers, indicating distinct CheA conformations within the unit. Large scale all-atom molecular dynamics simulations further point to the specific side chain contacts that mediate the transition of CheA conformations, which we show, through biochemical assays, to fully abrogate chemotactic function if disrupted.

The effect of citrus-derived oil on bovine blood neutrophil function and gene expression in vitro

Research on the use of natural products to treat or prevent microbial invasion as alternatives to antibiotic use is growing. Polymorphonuclear leukocytes (PMNL) play a vital role with regard to the innate immune response that affects severity or duration of mastitis. To our knowledge, effect of cold-pressed terpeneless Valencia orange oil (TCO) on bovine PMNL function has not been elucidated. Therefore, the objective of this study was to investigate the effect of TCO on bovine blood PMNL chemotaxis and phagocytosis capabilities and the expression of genes involved in inflammatory response in vitro. Polymorphonuclear leukocytes were isolated from jugular blood of 12 Holstein cows in mid-lactation and were incubated with 0.0 or 0.01% TCO for 120min at 37°C and 5% CO2, and phagocytosis (2×106 PMNL) and chemotaxis (6×106 PMNL) assays were then performed in vitro. For gene expression, RNA was extracted from incubated PMNL (6×106 PMNL), and gene expression was analyzed using quantitative PCR. The supernatant was stored at −80°C for analysis of tumor necrosis factor-α. Data were analyzed using a general linear mixed model with cow and treatment (i.e., control or TCO) in the model statement. In vitro supplementation of 0.01% of TCO increased the chemotactic ability to IL-8 by 47%; however, migration of PMNL to complement 5a was not altered. Treatment did not affect the production of tumor necrosis factor-α by PMNL. Expression of proinflammatory genes (i.e., SELL, TLR4, IRAK1, TRAF6, and LYZ) coding for proteins was not altered by incubation of PMNL with TCO. However, downregulation of TLR2 [fold change (FC=treatment/control)=−2.14], NFKBIA (FC=1.82), IL1B (FC=−2.16), TNFA (FC=−9.43), and SOD2 (FC=−1.57) was observed for PMNL incubated with TCO when compared with controls. Interestingly, expression of IL10, a well-known antiinflammatory cytokine, was also downregulated (FC=−3.78), whereas expression of IL8 (FC=1.93), a gene coding for the cytokine IL-8 known for its chemotactic function, tended to be upregulated in PMNL incubated with TCO. Incubation of PMNL with TCO enhanced PMNL chemotaxis in vitro. The expression of genes involved in the inflammatory response was primarily downregulated. Results showed that 0.01% TCO did not impair the function of PMNL in vitro. Future studies investigating the use of TCO as an alternative therapy for treatment of mastitis, including dose and duration, for cows during lactation are warranted.

Global existence of solutions for a fully parabolic chemotaxis system with consumption of chemoattractant and logistic source

This paper deals with a fully parabolic chemotaxis system with consumption of chemoattractant and logistic source under homogeneous Neumann boundary conditions in a smooth bounded domain . The functions χ and f are assumed to generalize the chemotactic sensitivity function and logistic source respectively. Under some conditions, we obtain that the corresponding initial-boundary value problem possesses a unique global classical solution that is uniformly bounded.