Chemotaxis Chamber Research Articles

Space and Time in Leukocyte Migration

Dendritic cells (DCs) are an essential component of the mammalian immune system because they link the innate and the adaptive immune responses. They are sentinels that patrol and scan the peripheral tissue where they capture pathogen-derived antigens at the site of infection. After this, they migrate to the secondary lymphoid organs, where they prime naive T lymphocytes by presenting the captured antigens. For migration towards the lymphoid organs, DCs make use of chemoattractant cues. They detect the distribution of the chemoattractant in the tissue and extend cellular protrusions (lamellipodia) to migrate up the chemical gradient in a process called chemotaxis. Although several of the molecular components for DC chemotaxis have been identified, little is known about the mechanisms used by DCs to sense gradients. We used a microfluidic chemotaxis chamber and optical microscopy to elucidate the gradient sensing mechanism of DCs. The microfluidic chemotaxis assay allows us to control with high precision the properties of the gradient in space and time. We will present several novel features of DC migration in response to different spatio-temporal stimulation patterns.

Gnb isoforms control a signaling pathway comprising Rac1, Plcβ2, and Plcβ3 leading to LFA-1 activation and neutrophil arrest in vivo

AbstractChemokines are required for leukocyte recruitment and appropriate host defense and act through G protein-coupled receptors (GPCRs), which induce downstream signaling leading to integrin activation. Although the α and β subunits of the GPCRs are the first intracellular molecules that transduce signals after ligand binding and are therefore indispensable for downstream signaling, relatively little is known about their contribution to lymphocyte function-associated antigen 1 (LFA-1) activation and leukocyte recruitment. We used knockout mice and short hairpin RNA to knock down guanine nucleotide binding protein (GNB) isoforms (GNB1, GNB2, GNB4, and GNB5) in HL60 cells and primary murine hematopoietic cells. Neutrophil function was assessed by using intravital microscopy, flow chamber assays, and chemotaxis and biochemistry studies. We unexpectedly discovered that all expressed GNB isoforms are required for LFA-1 activation. Their downregulation led to a significant impairment of LFA-1 activation, which was demonstrated in vitro and in vivo. Furthermore, we showed that GPCR activation leads to Ras-related C3 botulinum toxin substrate 1 (Rac1)-dependent activation of both phospholipase C β2 (Plcβ2) and Plcβ3. They act nonredundantly to produce inositol triphosphate–mediated intracellular Ca2+ flux and LFA-1 activation that support chemokine-induced arrest in vivo. In a complex inflammatory disease model, Plcβ2-, Plcβ3-, or Rac1-deficient mice were protected from lipopolysaccharide-induced lung injury. Taken together, we demonstrated that all Gnb isoforms are required for chemokine-induced downstream signaling, and Rac1, Plcβ2, and Plcβ3 are critically involved in integrin activation and leukocyte arrest.

Immunomodulatory effects of Santolina chamaecyparissus leaf extracts on human neutrophil functions

Context: Santolina chamaecyparissus L. (Asteraceae) is an aromatic plant wide spread in the Mediterranean region. It is used in folk medicine for its anti-inflammatory properties.Objective: The effects of S. chamaecyparissus aqueous extract (SCAE) and polyphenolic extract (SCPE) on human polymorphonuclear neutrophil (PMN) degranulation, chemotaxis, phagocytosis, and microbicidal capacity were examined in vitro.Materials and methods: Aqueous and polyphenolic extracts were prepared from S. chamaecyparissus leaves. The elastase release was used as a marker for measuring PMN degranulation, while chemotaxis was performed using a 48-microwell chemotaxis chamber. The phagocytosis and the microbicidal capacity were evaluated using fresh cultures of Candida albicans.Results: The treatment of neutrophils with different concentrations (10–200 µg/ml) of SCAE and SCPE caused a significant (p < 0.001) and dose-dependent inhibitory effect on elastase release in fMLP/Cytochalasin B (CB)-stimulated neutrophils. Indeed, 100 µg/ml of SCAE exerted an inhibitory effect of 51.97 ± 6.2%, whereas SCPE at the same concentration abolished completely PMN degranulation. Moreover, both extracts inhibited markedly (p < 0.01) fMLP-induced chemotactic migration. At 200 µg/ml, SCAE and SCPE exerted an inhibitory effect of 54.61 ± 7.3% and 57.71 ± 7.44%, respectively. In addition, a decline in both phagocytosis and microbicidal capacity against Candida albicans was observed when PMNs were exposed to 100 and 200 µg/ml of SCAE or SCPE.Conclusion: The exerted effects on neutrophil functions support the anti-inflammatory activity and show new mechanisms of action and effectiveness of S. chamaecyparissus leaf extracts. This plant may be considered as an interesting source of anti-inflammatory and immunomodulatory agents.

Effects of angular frequency during clinorotation on mesenchymal stem cell morphology and migration.

Aims:To determine the short-term effects of simulated microgravity on mesenchymal stem cell behaviors—as a function of clinorotation speed—using time-lapse microscopy.Background:Ground-based microgravity simulation can reproduce the apparent effects of weightlessness in spaceflight using clinostats that continuously reorient the gravity vector on a specimen, creating a time-averaged nullification of gravity. In this work, we investigated the effects of clinorotation speed on the morphology, cytoarchitecture, and migration behavior of human mesenchymal stem cells (hMSCs).Methods:We compared cell responses at clinorotation speeds of 0, 30, 60, and 75 rpm over 8 h in a recently developed lab-on-chip-based clinostat system. Time-lapse light microscopy was used to visualize changes in cell morphology during and after cessation of clinorotation. Cytoarchitecture was assessed by actin and vinculin staining, and chemotaxis was examined using time-lapse light microscopy of cells in NGF (100 ng/ml) gradients.Results:Among clinorotated groups, cell area distributions indicated a greater inhibition of cell spreading with higher angular frequency (P<0.005), though average cell area at 30 rpm after 8 h became statistically similar to control (P=0.794). Cells at 75 rpm clinorotation remained viable and were able to re-spread after clinorotation. In chemotaxis chambers, clinorotation did not alter migration patterns in elongated cells, but most clinorotated cells exhibited cell retraction, which strongly compromised motility.Conclusions:These results indicate that hMSCs respond to clinorotation by adopting more rounded, less-spread morphologies. The angular frequency-dependence suggests that a cell’s ability to sense the changing gravity vector is governed by the rate of perturbation. For migration studies, cells cultured in clinorotated chemotaxis chambers were generally less motile and exhibited retraction instead of migration.

The cAMP-producing agonist beraprost inhibits human vascular smooth muscle cell migration via exchange protein directly activated by cAMP.

AimsDuring restenosis, vascular smooth muscle cells (VSMCs) migrate from the vascular media to the developing neointima. Preventing VSMC migration is therefore a therapeutic target for restenosis. Drugs, such as prostacyclin analogues, that increase the intracellular concentration of cyclic adenosine monophosphate (cAMP) can inhibit VSMC migration, but the mechanisms via which this occurs are unknown. Two main downstream mediators of cAMP are protein kinase A (PKA) and exchange protein directly activated by cAMP (Epac). This study has examined the effects of the prostacyclin analogue beraprost on VSMC migration and investigated the intracellular pathways involved.Methods and resultsIn a chemotaxis chamber, human saphenous vein VSMC migrated towards a platelet-derived growth-factor-BB (PDGF) chemogradient. Incubation with therapeutically relevant concentrations of cAMP-producing agonist beraprost significantly decreased PDGF-induced migration. Direct activation of either PKA or Epac inhibited migration whereas inhibition of PKA did not prevent the anti-migratory effect of beraprost. Direct activation of Epac also prevented hyperplasia in ex vivo serum-treated human veins. Using fluorescence resonance energy transfer, we demonstrated that beraprost activated Epac but not PKA. The mechanisms of this Epac-mediated effect involved activation of Rap1 with subsequent inhibition of RhoA. Cytoskeletal rearrangement at the leading edge of the cell was consequently inhibited. Interestingly, Epac1 was localized to the leading edge of migrating VSMC.ConclusionsThese results indicate that therapeutically relevant concentrations of beraprost can inhibit VSMC migration via a previously unknown mechanism involving the cAMP mediator Epac. This may provide a novel target that could blunt neointimal formation.

Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to their surrounding area, leading to cell movement and migration. In order to understand the mechanisms that can alter and/or affect cell migration, one can study these forces. In theory, understanding the fundamental mechanisms and forces underlying cell migration holds the promise of effective approaches for treating diseases and promoting cellular transplantation. Unfortunately, modern chemotaxis chambers that have been developed are usually restricted to two dimensions (2D) and have complex diffusion gradients that make the experiment difficult to interpret. To this end, we have developed, and describe in this paper, a direct-viewing chamber for chemotaxis studies, which allows one to overcome modern chemotaxis chamber obstacles able to measure cell forces and specific concentration within the chamber in a 3D environment to study cell 3D migration. More compelling, this approach allows one to successfully model diffusion through 3D collagen matrices and calculate the coefficient of diffusion of a chemoattractant through multiple different concentrations of collagen, while keeping the system simple and user friendly for traction force microscopy (TFM) and digital volume correlation (DVC) analysis.

Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix.

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to their surrounding area, leading to cell movement and migration. In order to understand the mechanisms that can alter and/or affect cell migration, one can study these forces. In theory, understanding the fundamental mechanisms and forces underlying cell migration holds the promise of effective approaches for treating diseases and promoting cellular transplantation. Unfortunately, modern chemotaxis chambers that have been developed are usually restricted to two dimensions (2D) and have complex diffusion gradients that make the experiment difficult to interpret. To this end, we have developed, and describe in this paper, a direct-viewing chamber for chemotaxis studies, which allows one to overcome modern chemotaxis chamber obstacles able to measure cell forces and specific concentration within the chamber in a 3D environment to study cell 3D migration. More compelling, this approach allows one to successfully model diffusion through 3D collagen matrices and calculate the coefficient of diffusion of a chemoattractant through multiple different concentrations of collagen, while keeping the system simple and user friendly for traction force microscopy (TFM) and digital volume correlation (DVC) analysis.

Abstract 445: Beraprost, a Prostacyclin Analogue, Inhibits Human Vascular Smooth Muscle Cell Migration via Activation of Exchange Protein Activated by cAMP (Epac)

Following vein grafting, endothelial damage initiates vascular smooth muscle cell (VSMC) migration to the intima leading to neointimal hyperplasia and restenosis. Inhibition of VSMC migration is therefore a therapeutic target to prevent restenosis. Previous studies have shown that cyclic adenosine monophosphate (cAMP) inhibits VSMC migration although the downstream mediators are unknown. This suggests that cyclic AMP-producing agonists, such as the prostacyclin analogue beraprost which binds to prostanoid receptors, could be used as a potential drug against neointimal formation. We hypothesised that prostacyclin analogues inhibit VSMC migration by activating specific cAMP downstream mediators. The aims of this project were to examine the role of cAMP mediators protein kinase A (PKA) and Exchange protein activated by cAMP (Epac) in this inhibitory effect. Saphenous veins were obtained from patients undergoing coronary artery bypass. VSMCs were primary cultured and migration measured using a chemotaxis chamber. Cell migration stimulated by PDGF was significantly inhibited by 68 ± 5% (n=6) in the presence of a therapeutically relevant concentration of beraprost (1 nM). To examine potential mechanisms of this inhibition, selective activators of PKA and Epac were used. Both Epac and PKA activators significantly inhibited migration towards PDGF. However, fluorescence resonance energy transfer using cells transfected with specific probes revealed that 1 nM beraprost only activates Epac and not PKA in VSMCs (n=4). The downstream mechanisms were further investigated. Pulldown assays demonstrated that beraprost-mediated stimulation of Epac produces subsequent activation of the monomeric G-protein Rap1 and ultimately inhibits RhoA-induced cytoskeleton rearrangement required for migration (n=3). Using siRNA to knockdown Rap1, the inhibition of PDGF-induced migration by beraprost in VSMC cells was shown to be dependent on the Rap1 pathway (n=3). In conclusion, the prostacyclin analogue beraprost inhibits VSMC migration via activation of Epac/Rap1. This may provide a new therapeutic target to prevent neointimal hyperplasia.

Fructus phyllanthi tannin fraction induces apoptosis and inhibits migration and invasion of human lung squamous carcinoma cells in vitro via MAPK/MMP pathways.

Fructus phyllanthi tannin fraction (PTF) from the traditional Tibetan medicine Fructus phyllanthi has been found to inhibit lung and liver carcinoma in mice. In this study we investigated the anticancer mechanisms of PTF in human lung squamous carcinoma cells in vitro. Human lung squamous carcinoma cell line (NCI-H1703), human large-cell lung cancer cell line (NCI-H460), human lung adenocarcinoma cell line (A549) and human fibrosarcoma cell line (HT1080) were tested. Cell viability was detected with MTT assay. Cell migration and invasion were assessed using a wound healing assay and a transwell chemotaxis chambers assay, respectively. Cell apoptosis was analyzed with flow cytometric analysis. The levels of apoptosis-related and metastasis-related proteins were detected by Western blot and immunofluorescence. PTF dose-dependently inhibited the viability of the 3 human lung cancer cells. The IC50 values of PTF in inhibition of NCI-H1703, NCI-H460, and A549 cells were 33, 203, and 94 mg/L, respectively. PTF (15, 30, and 60 mg/L) dose-dependently induced apoptosis of NCI-H1703 cells. Treatment of NCI-H1703 and HT1080 cells with PTF significantly inhibited cell migration, and reduced the number of invasive cells through Matrigel. Furthermore, PTF dose-dependently down-regulated the expression of phosphor-ERK1/2, MMP-2 and MMP-9, up-regulated the expression of phosphor-JNK, but had no significant effect on the expression of ERK1/2 or JNK. PTF induces cell apoptosis and inhibits the migration and invasion of NCI-H1703 cells by decreasing MPPs expression through regulation of the MAPK pathway.

The nucleoside diphosphate kinase-A as a migration suppressor in gastric lymphoma.

87 Background: The nm23-H1 gene encodes the NDPK-A (nucleoside diphosphate kinase A) that contributes variably to the migration of cancer cell. To investigate the role of the NDPK-A in gastric lymphoma, we examined the expression of NDPK-A in two different cancer cell lines of the same gastric lymphoma patient. Methods: The primary cell line of gastric lymphoma, RF-1, was cultured from the primary gastric lymphoma site, and the other cell line RF-48 was metastasized to the peritoneum of the same patient after 6 months. We have generated stable gastric lymphoma transfectants, pIRES-NDPKA-GFP-neo, that constitutively over-express transfected and vector form of NDPK-A, in addition to a reporter, green fluorescent protein(GFP). The transfected gastric lymphoma cell migration assay was performed 24-well modified chemotaxis chambers with FluroBloc membrane. Results: In regard to the migration rate of the gastric lymphoma cell lines, RF-1 vector was 75.8±7.5%, RF-1 transfected was 54.4±12.3%, RF-48 vector was 84.7±15.4%, RF-48 transfected type was 62.3±9.2%, RF-48 migrated better than RF-1, and the vector type migrated better than the transfected type. NDPK-A was presented more in RF-1 than RF-48, and presented more in the transfected type than the vector type, and concerning the migration rate, RF-48 migrated better than RF-1, and the vector type migrated better than the transfected type. Conclusions: In regard to the migration rate of the gastric lymphoma cell lines, RF-1 vector was 75.8±7.5%, RF-1 transfected was 54.4±12.3%, RF-48 vector was 84.7±15.4%, RF-48 transfected type was 62.3±9.2%, RF-48 migrated better than RF-1, and the vector type migrated better than the transfected type. NDPK-A was presented more in RF-1 than RF-48, and presented more in the transfected type than the vector type, and concerning the migration rate, RF-48 migrated better than RF-1, and the vector type migrated better than the transfected type.

Exosomes Secreted By Multiple Myeloma Cell Lines (MMCLs) and Bone Marrow Stromal Cells (BMSCs) Reciprocally Modulate Cell Adhesion and Impact on MM Cell Migration and Bortezomib-Induced Apoptosis

Introduction: In MM pathogenesis, the interaction of plasma cells and the bone marrow microenvironment plays a crucial role. Exosomes are secreted by nearly all cell types, including cancer cells, and have been implicated in intercellular communication, drug resistance and tumor progression. We therefore purified, characterized and studied the influence of exosomes secreted by MMCLs and BMSCs on cell adhesion, bortezomib-induced apoptosis and cell migration.Methods: Exosomes were purified from the supernatants of MMCLs (IM-9, MM.1S, U266, RPMI8226) and M2-10B4 BMSCs after 72h of culture with RPMI1640+10% exosome-depleted FBS by differential centrifugation. Purity and quality of exosomes was confirmed by electron microscopy and western blot for CD63. Exosomal protein concentration per 5x106 cells was quantified by Bradford. CD44 and ICAM1 were evaluated by flow cytometry. Apoptosis was assessed via annexin V/7-AAD-staining. Chemotaxis to M2-10B4 exosomes (100-500μg/ml) was studied using 24-well chemotaxis chambers. Migrated cells were counted by flow cytometry.Results: Exosomes from IM-9 cells were identified by electron microscopy, thereby showing a characteristic saucer-like morphology, ranging in diameter between 30 and 120nm. Both MM cell and M2-10B4 exosomes expressed CD63. Mean exosomal protein concentration was 1.4μg/μl for M2-10B4 and varied for MMCLs between 1.2 and 1.7μg/μl. M2-10B4 cells expressed higher levels of both adhesion molecules CD44 and ICAM-1 when incubated with exosomes from MMCLs compared to basal conditions, however, not reaching statistical significance. Conversely, M2-10B4 exosomes induced a significant increase in CD44 expression on IM-9 cells (p=0.03), reflecting an increased adhesion to components of the extracellular matrix that might contribute to cell-adhesion mediated drug resistance. IM-9 apoptotic cells after 24h with 10nM bortezomib decreased from 72% to 61% in the presence of M2-10B4 exosomes and from 74% to 62% with IM-9 exosomes, suggesting a lower sensitivity to bortezomib. Migration of IM-9 cells slightly increased with 200μg/ml M2-10B4 exosomes and decreased with higher exosome concentrations.Conclusions: Our findings underline the role of M2-10B4 exosomes on adhesion and migration of one representative MMCL (IM-9), and the impact of M2-10B4 and IM-9 exosomes on bortezomib cytotoxicity in this MMCL, suggesting their involvement in a paracrine/autocrine loop modulating treatment response and MM cell survival. DisclosuresNo relevant conflicts of interest to declare.

Prostaglandin E2 switches from a stimulator to an inhibitor of cell migration after epithelial-to-mesenchymal transition

Epithelial–mesenchymal transition (EMT) is critical for embryonic development, and this process is recapitulated in adults during wound healing, tissue regeneration, fibrosis and cancer progression. Cell migration is believed to play a key role in both normal wound repair and in abnormal tissue remodeling. Prostaglandin E2 (PGE2) inhibits fibroblast chemotaxis, but stimulates chemotaxis in airway epithelial cells. The current study was designed to explore the role of PGE2 and its four receptors on airway epithelial cell migration following EMT using both the Boyden blindwell chamber chemotaxis assay and the wound closure assay. EMT in human bronchial epithelial cells (HBECs) was induced by TGF-β1 and a mixture of cytokines (IL-1β, TNF-α, and IFN-γ). PGE2 and selective agonists for all four EP receptors stimulated chemotaxis and wound closure in HBECs. Following EMT, the EP1 and EP3 agonists were without effect, while the EP2 and EP4 agonists inhibited chemotaxis as did PGE2. The effects of the EP2 and EP4 receptors on HBEC and EMT cell migration were further confirmed by blocking the expected signaling pathways. Taken together, these results demonstrate that PGE2 switches from a stimulator to an inhibitor of cell migration following EMT of airway epithelial cells and that this inhibition is mediated by an altered effect of EP2 and EP4 signaling and an apparent loss of the stimulatory effects of EP1 and EP3. Change in the PGE2 modulation of chemotaxis may play a role in repair following injury.

Monocyte chemoattractant protein-1 released from polycaprolactone/chitosan hybrid membrane to promote angiogenesis in vivo

We have fabricated a hybrid membrane composed of polycaprolactone and a natural polysaccharide, chitosan. The incorporation of chitosan enabled heparinization of the material via electrostatic interaction between heparin and chitosan. More importantly, since multiple cytokines have exhibited binding affinity towards heparin, heparinization of the polycaprolactone/chitosan compound also facilitated immobilization of monocyte chemoattractant protein-1, which is a well-reported pro-angiogenic chemokine. Results demonstrated that the heparinized polycaprolactone/chitosan membrane with monocyte chemoattractant protein-1 immobilization was able to release monocyte chemoattractant protein-1 in a controlled and sustained manner. Bioactivity of the released monocyte chemoattractant protein-1 was uncompromised as shown by a chemotaxis chamber assay using isolated rat peripheral blood mononuclear cells. Enhanced local angiogenesis was subsequently observed in vivo after subcutaneous implantation of the heparinized polycaprolactone/chitosan membrane with monocyte chemoattractant protein-1-releasing property and the mechanisms underlying the angiogenic role of monocyte chemoattractant protein-1 were also investigated. We propose that the monocyte chemoattractant protein-1-induced local capillary formation is attributable to increased recruitment of macrophages, particularly the alternatively activated M2 macrophages, which have been implicated in wound healing. Moreover, a direct effect of monocyte chemoattractant protein-1 on angiogenesis was also observed, mainly via monocyte chemoattractant protein-1-stimulated vascular endothelial growth factor expression and activity. In summary, we report here a feasible way to fabricate a polycaprolactone/chitosan hybrid material that could be functionalized with angiogenic signalling agents, such as monocyte chemoattractant protein-1. Implantation of this material promoted angiogenesis and may therefore be developed into scaffold or dressing materials in treating local ischemia injuries or cutaneous wound.

Role of club cell secretory protein on neutrophil migration using a Dunn chemotaxis chamber: Effect on chronic obstructive pulmonary disease?

Role of club cell secretory protein on neutrophil migration using a Dunn chemotaxis chamber: Effect on chronic obstructive pulmonary disease?

Mesenchymal stem cells genetically modified by lentivirus-mediated interleukin-12 inhibit malignant ascites in mice.

The objective of the present study was to investigate the effects of mesenchymal stem cells (MSCs) genetically modified by lentivirus-mediated mouse interleukin-12 (Lenti-mIL-12) in treating malignant ascites in mice. The in vitro chemotactic effect of Lenti-mIL-12-MSC culture supernatant on dendritic cells was investigated using a chemotaxis chamber. Liver cancer H22 and MethA ascites models were constructed. Mice were divided evenly into four groups: Normal saline, MSC, Null and Lenti-mIL-12-MSC. The survival rate, ascites volume and red blood cell number were measured for these groups. The toxicity and side effects of Lenti-mIL-12-MSCs were investigated using visual and microscopy inspections. The results indicated that mIL-12 had a strong chemotactic effect on dendritic cells. mIL-12 was highly expressed in ascites of Lenti-mIL-12-MSC-treated mice. Lenti-mIL-12-MSCs reduced the volume of ascites and the number of red blood cells in ascites and thus increased the survival rate and prolonged the survival duration of the mice. Furthermore, Lenti-mIL-12-MSCs showed no toxicity and side effects on the mice with malignant ascites. In conclusion, the results demonstrated that Lenti-mIL-12-MSCs inhibited the growth of ascites and promoted the survival of tumor-bearing mice, suggesting that Lenti-mIL-12-MSCs exerts a therapeutic effect on malignant ascites by stimulating the immune responses of the mice.

Defining an optimal stromal derived factor-1 presentation for effective recruitment of mesenchymal stem cells in 3D.

In "situ" tissue engineering is a promising approach in regenerative medicine, envisaging to potentiate the physiological tissue repair processes by recruiting the host's own cellular progenitors at the lesion site by means of bioactive materials. Despite numerous works focused the attention in characterizing novel chemoattractant molecules, only few studied the optimal way to present signal in the microenvironment, in order to recruit cells more effectively. In this work, we have analyzed the effects of gradients of stromal derived factor-1 (SDF-1) on the migratory behavior of human mesenchymal stem cells (MSCs). We have characterized the expression of the chemokine-associated receptor, CXCR4, using cytofluorimetric and real-time PCR analyses. Gradients of SDF-1 were created in 3D collagen gels in a chemotaxis chamber. Migration parameters were evaluated using different chemoattractant concentrations. Our results show that cell motion is strongly affected by the spatio-temporal features of SDF-1 gradients. In particular, we demonstrated that the presence of SDF-1 not only influences cell motility but alters the cell state in terms of SDF-1 receptor expression and productions, thus modifying the way cells perceive the signal itself. Our observations highlight the importance of a correct stimulation of MSCs by means of SDF-1 in order to implement on effective cell recruitment. Our results could be useful for the creation of a "cell instructive material" that is capable to communicate with the cells and control and direct tissue regeneration. Biotechnol. Bioeng. 2014;111: 2303-2316. © 2014 Wiley Periodicals, Inc.

MIP-3β/CCL19 is associated with the intrathecal invasion of mononuclear cells in neuroinflammatory and non-neuroinflammatory CNS diseases in dogs.

BackgroundChemokines such as MIP-3β/CCL19 are important factors in the mechanism of cell migration and pathogenesis of central nervous system (CNS) inflammatory reactions. The hypothesis of this study is that CCL19, also known as MIP-3β, is involved in the pathogenesis of inflammatory and non-inflammatory CNS diseases of dogs. Experiments were performed on cerebrospinal fluid (CSF) and serum samples of dogs affected with steroid responsive meningitis-arteritis (SRMA) during the acute phase as well as during treatment. Dogs with SRMA were compared to dogs with presumed meningoencephalomyelitis of unknown origin (MUO), and both groups sub-categorized into dogs receiving no therapy and with patients receiving prednisolone therapy. Idiopathic epilepsy (IE), a group with normal CSF cell count, was used as a control. Additionally, dogs with intervertebral disc disease (IVDD) of varying severity were analyzed. Chemokine concentrations were determined by enzyme linked immunosorbent assay. Migration assays were performed on seven selected CSF samples using a disposable 96-well chemotaxis chamber.ResultsCCL19 was detectable in CSF samples of all dogs. Dogs with untreated SRMA and MUO displayed pronounced CCL19 elevations compared to the control group and patients receiving glucocorticosteroid treatment. CSF cell counts of untreated SRMA and MUO patients were significantly positively correlated with the CCL19 CSF concentration. IVDD patients also had elevated CCL19 concentration compared to controls, but values were considerably lower than in inflammatory CNS diseases. Selected CSF samples displayed chemotactic activity for mononuclear cells in the migration assay.ConclusionsCCL19 CSF concentrations were markedly elevated in patients affected with the neuroinflammatory diseases SRMA and MUO and showed a strong correlation with the CSF cell count. This chemokine may play an important role in the pathogenesis of SRMA and MUO. The elevation of CSF CCL19 in IVDD suggests that it may also be involved in the secondary wave of spinal cord injuries.

Macrophage colony-stimulating factor augments Tie2-expressing monocyte differentiation, angiogenic function, and recruitment in a mouse model of breast cancer.

Reports demonstrate the role of M-CSF (CSF1) in tumor progression in mouse models as well as the prognostic value of macrophage numbers in breast cancer patients. Recently, a subset of CD14+ monocytes expressing the Tie2 receptor, once thought to be predominantly expressed on endothelial cells, has been characterized. We hypothesized that increased levels of CSF1 in breast tumors can regulate differentiation of Tie2- monocytes to a Tie2+ phenotype. We treated CD14+ human monocytes with CSF1 and found a significant increase in CD14+/Tie2+ positivity. To understand if CSF1-induced Tie2 expression on these cells improved their migratory ability, we pre-treated CD14+ monocytes with CSF1 and used Boyden chemotaxis chambers to observe enhanced response to angiopoietin-2 (ANG2), the chemotactic ligand for the Tie2 receptor. We found that CSF1 pre-treatment significantly augmented chemotaxis and that Tie2 receptor upregulation was responsible as siRNA targeting Tie2 receptor abrogated this effect. To understand any augmented angiogenic effect produced by treating these cells with CSF1, we cultured human umbilical vein endothelial cells (HUVECs) with conditioned supernatants from CSF1-pre-treated CD14+ monocytes for a tube formation assay. While supernatants from CSF1-pre-treated TEMs increased HUVEC branching, a neutralizing antibody against the CSF1R abrogated this activity, as did siRNA against the Tie2 receptor. To test our hypothesis in vivo, we treated PyMT tumor-bearing mice with CSF1 and observed an expansion in the TEM population relative to total F4/80+ cells, which resulted in increased angiogenesis. Investigation into the mechanism of Tie2 receptor upregulation on CD14+ monocytes by CSF1 revealed a synergistic contribution from the PI3 kinase and HIF pathways as the PI3 kinase inhibitor LY294002, as well as HIF-1α-deficient macrophages differentiated from the bone marrow of HIF-1αfl/fl/LysMcre mice, diminished CSF1-stimulated Tie2 receptor expression.

Effects of Erythromycin and Rifampicin on Immunomodulatory Gene Expression and Cellular Function in Human Polymorphonuclear Leukocytes

Background: We investigated the effects of two antibiotics, erythromycin and rifampicin, on the immunomodulatory gene expression and cellular function of human polymorphonuclear leukocytes (PMNs). Methods: We used real-time quantitative PCR to examine the expression of immunomodulatory genes. The production of reactive oxygen species (ROS) was determined by fluorescence-activated cell sorting. PMN chemotaxis was analyzed using a KK chemotaxis chamber. Results: Stimulation of PMNs with lipopolysaccharide (LPS) resulted in increases in the mRNA levels of immunomodulatory genes. Rifampicin significantly inhibited the overexpression of TLR2, TLR4, CD14 and IL8Rs. However, erythromycin suppressed only the upregulation of TLR2 and TNFA. Neither antibiotic had an effect on the production of ROS. Rifampicin significantly inhibited PMN chemotaxis, but erythromycin had no effect. Conclusions: Erythromycin and rifampicin may play anti-inflammatory roles by affecting the expression levels of immunomodulatory genes or the chemotaxis of PMNs.

Pulp Fibroblasts Synthesize Functional Complement Proteins Involved in Initiating Dentin–Pulp Regeneration

The complement system is an efficient plasma immune surveillance system that controls tissue injury and infection. Although the liver constitutes the primary circulating complement protein synthesis site, extrahepatic synthesis is known to optimize local tissue inflammatory reaction. Because dentin-pulp regeneration is known to be regulated locally, we investigated activation of the local complement system within the dental pulp and its role in initiating the regeneration process. Membrane attack complex (C5b-9) formation and Gram's staining revealed that complement activation is correlated with the presence of Gram-positive bacteria in carious human teeth. RT-PCR analysis demonstrated that cultured human pulp fibroblasts stimulated with lipoteichoic acid produce all the proteins required for efficient complement activation. This was demonstrated in vitro by C5b-9 formation and C5a active fragment production in the absence of plasma proteins. Finally, the dynamic migration assays performed in μ-Slide chemotaxis chambers and use of a C5aR-specific antagonist (W54011) demonstrated that the activation of complement proteins synthesized by pulp fibroblasts and the subsequent release of C5a specifically induced pulp progenitor cell recruitment. Our study reveals human pulp fibroblasts as the first nonimmune cell type capable of synthesizing all complement proteins. These fibroblasts cells contribute significantly to tissue regeneration by recruiting pulp progenitors via complement activation, which suggests to a potential therapeutic strategy of targeting pulp fibroblasts in dentin-pulp regeneration.