Chemotactic Cell Migration Research Articles

Deubiquitinase Inhibitors Impair Leukemic Cell Migration Through Cofilin Oxidation and Alteration of Actin Reorganization.

Actin networks are dynamically regulated through constant depolymerization and polymerization cycles. Although the fundamental mechanisms that govern these processes have been identified, the nature and role of post-translational modifications (PTMs) of actin and actin regulatory proteins are not completely understood. Here, we employed Actin CytoFRET, a method that we developed for real time detection of fluorescence resonance energy transfer (FRET) signals generated by actin dynamics, to screen a small library of PTM-interfering compounds on a biosensor leukemic T cell line. This strategy led to the identification of small molecule inhibitors of deubiquitinating enzymes (DUBs) as potent inducers of actin polymerization and blockers of chemotactic cell migration. The examination of the underlying mechanism further revealed that the actin depolymerizing protein cofilin represents a major effector of DUB inhibitor (DUBi)-induced actin reorganization. We found that DUB blockade results in the accumulation of polyubiquitinated proteins and ROS production, associated with cofilin oxidation and dephosphorylation on serine 3, which provokes uncontrolled actin polymerization impairing cell migration. Together, our study highlights DUBs as novel regulators of actin dynamics through ROS-dependent cofilin modulation, and shows that DUBi represent attractive novel tools to impede leukemic cell migration.

A Pillar-Free Diffusion Device for Studying Chemotaxis on Supported Lipid Bilayers.

Chemotactic cell migration plays a crucial role in physiological and pathophysiological processes. In tissues, cells can migrate not only through extracellular matrix (ECM), but also along stromal cell surfaces via membrane-bound receptor–ligand interactions to fulfill critical functions. However, there remains a lack of models recapitulating chemotactic migration mediated through membrane-bound interactions. Here, using micro-milling, we engineered a multichannel diffusion device that incorporates a chemoattractant gradient and a supported lipid bilayer (SLB) tethered with membrane-bound factors that mimics stromal cell membranes. The chemoattractant channels are separated by hydrogel barriers from SLB in the cell loading channel, which enable precise control of timing and profile of the chemokine gradients applied on cells interacting with SLB. The hydrogel barriers are formed in pillar-free channels through a liquid pinning process, which eliminates complex cleanroom-based fabrications and distortion of chemoattractant gradient by pillars in typical microfluidic hydrogel barrier designs. As a proof-of-concept, we formed an SLB tethered with ICAM-1, and demonstrated its lateral mobility and different migratory behavior of Jurkat T cells on it from those on immobilized ICAM-1, under a gradient of chemokine CXCL12. Our platform can thus be widely used to investigate membrane-bound chemotaxis such as in cancer, immune, and stem cells.

CXCL12-stimulated lymphocytes produce secondary stimulants that affect the surrounding cell chemotaxis

Chemotactic factors locally secreted from tissues regulate leukocyte migration via cell membrane receptors that induce intracellular signals. It has been suggested that neutrophils stimulated by bacterial peptides secrete a secondary stimulant that enhances the chemotactic cell migration of the surrounding cells. This paracrine mechanism contributes to chemokine-dependent neutrophil migration, however, it has not yet been extensively studied in lymphocytes. In this study, we provide evidence that lymphocytes stimulated by the chemokine, CXCL12, affect the CXCR4-independent chemotactic response of the surrounding cells. We found that CXCR4-expressing lymphocytes or the conditioned medium from CXCL12-stimulated cells promoted CXCR4-deficient cell chemotaxis. In contrast, the conditioned medium from CXCL12-stimulated cells suppressed CCR7 ligand-dependent directionality and the cell migration speed of CXCR4-deficient cells. These results suggest that paracrine factors from CXCL12-stimulated cells navigate surrounding cells to CXCL12 by controlling the responsiveness to CCR7 ligand chemokines and CXCL12.

Microfluidic devices fitted with "flowver" paper pumps generate steady, tunable gradients for extended observation of chemotactic cell migration.

Microfluidics approaches have gained popularity in the field of directed cell migration, enabling control of the extracellular environment and integration with live-cell microscopy; however, technical hurdles remain. Among the challenges are the stability and predictability of the environment, which are especially critical for the observation of fibroblasts and other slow-moving cells. Such experiments require several hours and are typically plagued by the introduction of bubbles and other disturbances that naturally arise in standard microfluidics protocols. Here, we report on the development of a passive pumping strategy, driven by the high capillary pressure and evaporative capacity of paper, and its application to study fibroblast chemotaxis. The paper pumps-flowvers (flow + clover)-are inexpensive, compact, and scalable, and they allow nearly bubble-free operation, with a predictable volumetric flow rate on the order of μl/min, for several hours. To demonstrate the utility of this approach, we combined the flowver pumping strategy with a Y-junction microfluidic device to generate a chemoattractant gradient landscape that is both stable (6+ h) and predictable (by finite-element modeling calculations). Integrated with fluorescence microscopy, we were able to recapitulate previous, live-cell imaging studies of fibroblast chemotaxis to platelet derived growth factor (PDGF), with an order-of-magnitude gain in throughput. The increased throughput of single-cell analysis allowed us to more precisely define PDGF gradient conditions conducive for chemotaxis; we were also able to interpret how the orientation of signaling through the phosphoinositide 3-kinase pathway affects the cells' sensing of and response to conducive gradients.

The osteogenic niche-targeted arsenic nanoparticles prevent colonization of disseminated breast tumor cells in the bone

Up to 70% of patients with late-stage breast cancer have bone metastasis. Current treatment regimens for breast cancer bone metastasis are palliative with no therapeutic cure. Disseminated tumor cells (DTCs) colonize inside the osteogenic niches in the early stage of bone metastasis. Drug delivery into osteogenic niches to inhibit DTC colonization can prevent bone metastasis from entering its late stage and therefore cure bone metastasis. Here, we constructed a 50% DSS6 peptide conjugated nanoparticle to target the osteogenic niche. The osteogenic niche was always located at the endosteum with immature hydroxyapatite. Arsenic-manganese nanocrystals (around 14 nm) were loaded in osteogenic niche-targeted PEG-PLGA nanoparticles with an acidic environment-triggered arsenic release. Arsenic formulations greatly reduced 4T1 cell adhesion to mesenchymal stem cells (MSCs)/preosteoblasts (pre-OBs) and osteogenic differentiation of osteoblastic cells. Arsenic formulations also prevented tumor cell colonization and dormancy via altering the direct interaction between 4T1 cells and MSCs/pre-OBs. The chemotactic migration of 4T1 cells toward osteogenic cells was blocked by arsenic in mimic 3D osteogenic niche. Systemic administration of osteogenic niche-targeted arsenic nanoparticles significantly extended the survival of mice with 4T1 syngeneic bone metastasis. Our findings provide an effective approach for osteogenic niche-specific drug delivery and suggest that bone metastasis can be effectively inhibited by blockage of tumor cell colonization in the bone microenvironment.

Activin A as a Novel Chemokine Induces Migration of L929 Fibroblasts by ERK Signaling in Microfluidic Devices.

Activin A, a member of the transforming growth factor-beta (TGF-β) superfamily, contributes to tissue healing and fibrosis. As the innate tissue cells, fibroblasts also play an important role in wound healing and fibrosis. Herein, this study was aimed to investigate how activin A exhibited regulatory effects on adhesion and migration of fibroblasts. We found that activin A induced the migration of fibroblast cell line L929 cells in transwell chamber and microfluidic device. Activin A also promoted L929 cells adhesion, but did not affect L929 cells viability or proliferation. In addition, activin A induced α-SMA expression and TGF-β1 release, which were factors closely related to tissue fibrosis, but had no effect on IL-6 production, a pro-inflammatory cytokine. Furthermore, activin A elevated calcium levels in L929 cells and increased p-ERK protein levels. Activin A-induced migration of L929 cells was attenuated by ERK inhibitor FR180204. To conclude, these data indicated that activin A as a novel chemokine induced the chemotactic migration of L929 cells via ERK signaling and possessed the pro-fibrosis role. These findings provide a new insight into understanding of activin A in tissue fibrosis.

SAA1/TLR2 axis directs chemotactic migration of hepatic stellate cells responding to injury

SummaryHepatic stellate cells (HSCs) are crucial for liver injury repair and cirrhosis. However, the mechanism of chemotactic recruitment of HSCs into injury loci is still largely unknown. Here, we demonstrate that serum amyloid A1 (SAA1) acts as a chemokine recruiting HSCs toward injury loci signaling via TLR2, a finding proven by gene manipulation studies in cell and mice models. The mechanistic investigations revealed that SAA1/TLR2 axis stimulates the Rac GTPases through PI3K-dependent pathways and induces phosphorylation of MLC (pSer19). Genetic deletion of TLR2 and pharmacological inhibition of PI3K diminished the phosphorylation of MLCpSer19 and migration of HSCs. In brief, SAA1 serves as a hepatic endogenous chemokine for the TLR2 receptor on HSCs, thereby initiating PI3K-dependent signaling and its effector, Rac GTPases, which consequently regulates actin filament remodeling and cell directional migration. Our findings provide novel targets for anti-fibrosis drug development.

Magnetic Helical Hydrogel Motor for Directing T Cell Chemotaxis

AbstractMicro/nanomotors are attracting booming research enthusiasm with their revolutionary potential in biomedicine, sensing, and nanoengineering. Among the motors proposed, magnetic micro/nanomotors are of great interest with their high controllability and field biocompatibility. Yet the fabrication of magnetic actuated especially helical motors requires expensive and complicated instruments, 3D printing or glancing angle deposition, etc. Here, a soft and biocompatible helical poly(vinyl alcohol) (PVA) hydrogel motor via a versatile set‐up is engineered. The obtained helical hydrogel motor offers high capacity for chemokine CXCL12 and superparamagnetic iron oxide (Fe3O4) nanoparticles, which can then allow magnetic manipulation. With a low strength rotating magnetic field, the system is able to perform 3D precision navigation, necessary to steer the robotic system to a model diseased area. The chemokine cues from the hydrogel motor, acting as the synthetic leader cell, then directs immune T cell chemotactic migration. In a previously reported cell manipulating motor system, towing or pushing a single/two cell was demonstrated, with limited efficiency. This motor platform represents a novel approach for directing endogenous cell chemotaxis and organizing immune response.

AWP1 Restrains the Aggressive Behavior of Breast Cancer Cells Induced by TNF-α

TNF-α plays a crucial role in cancer initiation and progression by enhancing cancer cell proliferation, survival, and migration. Even though the known functional role of AWP1 (zinc finger AN1 type-6, ZFAND6) is as a key mediator of TNF-α signaling, its potential role in the TNF-α-dependent responses of cancer cells remains unclear. In our current study, we found that an AWP1 knockdown using short hairpin RNAs increases the migratory potential of non-aggressive MCF-7 breast cancer cells with no significant alteration of their proliferation in response to TNF-α. A CRISPR/Cas9-mediated AWP1 knockout in MCF-7 cells led to mesenchymal cell type morphological changes and an accelerated motility. TNF-α administration further increased this migratory capacity of these AWP1-depleted cells through the activation of NF-κB accompanied by increased epithelial-mesenchymal transition-related gene expression. In particular, an AWP1 depletion augmented the expression of Nox1, reactive oxygen species (ROS) generating enzymes, and ROS levels and subsequently promoted the migratory potential of MCF-7 cells mediated by TNF-α. These TNF-α-mediated increases in the chemotactic migration of AWP1 knockout cells were completely abrogated by an NF-κB inhibitor and a ROS scavenger. Our results suggest that a loss-of-function of AWP1 alters the TNF-α response of non-aggressive breast cancer cells by potentiating ROS-dependent NF-κB activation.

SAA1/TLR2 Axis Directs Chemotactic Migration of Hepatic Stellate Cells Responding to Injury

Hepatic stellate cells (HSCs) are crucial for liver injury repair and cirrhosis. However, the mechanism of chemotactic recruitment of HSCs into injury loci is still largely unknown. Here, by using CCl4- and cryoinjury-induced acute liver injury models in C57/BL6 mice, we demonstrate that the injury-induced and hepatocytes secreted an acute phase protein, serum amyloid A (SAA) is a chemokine attracting HSCs into injury loci. The mRNA-based screening and antagonist administration indicated that the toll-like receptor 2 (TLR2) was a chemotactic receptor on HSCs responding to SAA, and further confirmed by TLR2 knockout HSC cell line LX-2 in vitro and in vivo models. On other hand, genetic depletion of SAA in mice impaired the recruitment of HSCs into injured loci. Moreover, SAA/TLR2 axis appeared to be actively involved in the homing of intrasplenically transplanted LX-2 cells in both CCl4- and cryo-injured livers of NOD-SCID-IL2RG−/− mice. The mechanistic study revealed that SAA1/TLR2 axis stimulates the Rac GTPases through PI3K dependent pathway and induces phosphorylation of MLC (pSer19). Genetic deletion of TLR2 and inhibition of PI3K or Rac GTPase diminished the phosphorylation of MLCpSer19 and chemotactic migration. The evidence concluded that the injury induced chemotactic migration of HSCs is directed by SAA1 which serving as a hepatic endogenous chemokine, and the chemotactic receptor on HSCs is TLR2; the SAA1/TLR2 binding initiates PI3K dependent signaling and its effector, Rac GTPases that dynamically regulates actin filaments remodeling and cell directional migration. Our finding provides novel targets for anti-fibrosis drug development.

BNO 1095, a Standardized Dry Extract from the Fruits of Vitex agnus-castus, Impairs Angiogenesis-related Endothelial Cell Functions In Vitro.

BNO 1095, a standardized dry extract from the fruits of Vitex agnus-castus, represents an approved herbal medicinal product for the treatment of premenstrual syndrome. Angiogenesis, the formation of new blood vessels from pre-existing capillaries, plays a major role in physiological situations, such as wound healing or tissue growth in female reproductive organs, but it is also of great importance in pathophysiological conditions such as chronic inflammatory diseases or cancer. Angiogenesis is a highly regulated multi-step process consisting of distinct key events that can be influenced pharmacologically. Few studies suggested anti-angiogenic actions of V.agnus-castus fruit extracts in in vivo and ex vivo models. Here, we provide for the first time profound in vitro data on BNO 1095-derived anti-angiogenic effects focusing on distinct angiogenesis-related endothelial cell functions that are inevitable for the process of new blood vessel formation. We found that V.agnus-castus extract significantly attenuated undirected and chemotactic migration of primary human endothelial cells. Moreover, the extract efficiently inhibited endothelial cell proliferation and reduced the formation of tube-like structures on Matrigel. Of note, the treatment of endothelial cell spheroids almost blocked endothelial sprouting in a 3D collagen gel. Our data present new and detailed insights into the anti-angiogenic actions of BNO 1095 and, therefore, suggest a novel scope of potential therapeutic applications of the extract for which these anti-angiogenic properties are required.

Induction of CXCL10-Mediated Cell Migration by Different Types of Galectins.

Chemokines are an extended group of chemoattractant cytokines responsible for the recruitment of leukocytes into tissues. Among them, interferon-γ-inducible protein 10 (CXCL10) is abundantly expressed following inflammatory stimuli and participates in the trafficking of monocytes and activated T cells into sites of injury. Here, we report that different members of the galectin family of carbohydrate-binding proteins promote the expression and synthesis of CXCL10 independently of interferon-γ. Interestingly, CXCL10 induction was observed when galectins came in contact with stromal fibroblasts isolated from human cornea but not other cell types such as epithelial, monocytic or endothelial cells. Induction of CXCL10 by the tandem repeat galectin-8 was primarily associated with the chemotactic migration of THP-1 monocytic cells, whereas the prototype galectin-1 promoted the CXCL10-dependent migration of Jurkat T cells. These results highlight the potential importance of the galectin signature in dictating the recruitment of specific leukocyte populations into precise tissue locations.

S-Phase Kinase-Associated Protein-2 and Nuclear Factor-kappa Beta as Molecular Targets of Oral Burkitt’s Lymphoma Cell Induced by Quinolinone Derivate-Vesnarinone

Background: 3,4-Dihydro-6-[4-3,4-dimethoxybenzoyl-1-piperazinyl]-2(1H)-quinolinone (vesnarinone), a novel inotropic drug with unique and complex mechanisms of action, is known to show antitumor activity against several human malignancies. In the present study, vesnarinone-induced signal transduction of S-phase kinase-associated protein 2 (Skp2) and Nuclear Factor-kappa Beta (NF-κB) as molecular targets of oral malignant Burkitt’s lymphoma (Raji cells) was evaluated. Materials and Methods: Raji cells were incubated with vesnarinone at concentrations of 0, 1.25x10-2, 2.50x10-2, or 5.0x10-2 Molar. After 24 h, chemotactic cell migration was examined by a Boyden chamber kit. Apoptosis induction was observed by caspase-9 colorimetric assay. To evaluate levels of Skp2, NF-kB, and α-tubulin, Western blot analysis was performed. Results: Vesnarinone markedly suppressed chemotactic cell migration and significantly induced apoptosis by increasing the caspase-9 activity of Raji cells through down regulation of Skp2 and NF-κB. Conclusion: Vesnarinone decreased the expression of Skp2 and NF-κB indicating these molecules may be targeted for the treatment of oral malignant Burkitt’s lymphoma (BL). The results of this work offer a promising therapeutic approach for BL tumors.

Antisense oligonucleotide p45Skp-2 suppresses migratory chemotactic and metastasis of oral malignant Burkitt’s lymphoma cell through down-regulation of MTA-1 and induction of E-cadherin mechanism

Introduction: Burkitt’s lymphoma is a high-grade B-cell neoplasm and one of the most aggressive malignancies of lymphoid origins which found mainly in the paediatric population. The treatment options of this tumour are still limited. However, a new strategy for refractory tumour, phosphorothioate oligonucleotide antisense technique has watched with keen interest. This study was aimed to examine the effect of antisense p45Skp-2 (Skp-2 AS) suppressed migratory chemotactic and metastasis of oral malignant Burkitt’s lymphoma (Raji) cell through down-regulation of MTA-1 and E-cadherin. Methods: True experiment laboratory with post-test control group design was confirmed in this study. The efficiency of Skp-2 AS in the suppression of cell chemotactic migration was examined by Boyden chamber assay. To evaluate the inhibition of cell metastasis was conducted by decreasing MTA-1 expression protein. The expressions of MTA-1, E-cadherin and α-tubulin protein were investigated by Western blot analysis. Results: The results revealed that the number of chemotactic migration of Skp-2 AS treated Raji cell was significantly decreased when compared with that of sense p45Skp-2 (Skp-2 S) and scrambled control (SC) cells (P<0.05) followed by decreased expressions of MTA-1 protein and overexpression of E-cadherin. Interestingly, the expression of α-tubulin protein as an internal control was approximately similar in each transfectant cells. Conclusion: p45Skp-2 have an antitumor activity via suppression of migratory chemotactic activity and metastasis on oral Burkitt’s lymphoma cells through down-regulation of MTA-1 and induction of E-cadherin proteins targeting this molecule could represent a promising new therapeutic approach for this type of cancer.

HIF\u03b1 independent mechanisms in renal carcinoma cells modulate divergent outcomes in fibronectin assembly mediated by hypoxia and CoCl2

Fibronectin (FN) is a core matrix protein that assembles to form a dynamic cellular scaffold, frequently perturbed during oncogenic transformation. Tumor hypoxia, characterized by low oxygen concentrations in the microenvironment of most solid tumors has been shown to accelerate FN assembly in fibroblasts and cancer-associated fibroblasts, cell types that produce abundant amounts of FN protein. Nevertheless, FN matrix regulation in epithelial cancer cells during hypoxia remains less well defined. In this study we investigate the assembly of the FN matrix during hypoxia in renal cancer epithelial cells, the cells of origin of renal cell carcinoma (RCC). We show that hypoxia (1% O2) specifically increases matrix disassembly and increases migratory propensity in renal cancer cells. However, HIFα stabilization using hypoxia mimetics, does not recapitulate the effect of hypoxia on FN matrix reorganization or cell migration. Using a combination of knockdown and inhibitor-based approaches, our work characterizes the signaling events that mediate these two disparate changes on the matrix and explores its functional significance on chemotactic cell migration. Our study systematically reexamines the role of hypoxia mimetics as experimental substitutes for hypoxia and provides new findings on HIFα stabilization and the FN matrix in the context of renal cancer.

EBV-EBNA1 constructs an immunosuppressive microenvironment for nasopharyngeal carcinoma by promoting the chemoattraction of Treg cells

BackgroundNasopharyngeal carcinoma (NPC) is primarily caused by the Epstein-Barr virus (EBV) infection in NPC endemic areas. EBNA1 is an EBV-encoded nuclear antigen, which plays a critical role in the maintenance...

The chemokine X-factor: Structure-function analysis of the CXC motif at CXCR4 and ACKR3

The human chemokine family consists of 46 protein ligands that induce chemotactic cell migration by activating a family of 23 G protein-coupled receptors. The two major chemokine subfamilies, CC and CXC, bind distinct receptor subsets. A sequence motif defining these families, the X position in the CXC motif, is not predicted to make significant contacts with the receptor, but instead links structural elements associated with binding and activation. Here, we use comparative analysis of chemokine NMR structures, structural modeling, and molecular dynamic simulations that suggested the X position reorients the chemokine N terminus. Using CXCL12 as a model CXC chemokine, deletion of the X residue (Pro-10) had little to no impact on the folded chemokine structure but diminished CXCR4 agonist activity as measured by ERK phosphorylation, chemotaxis, and Gi/o-mediated cAMP inhibition. Functional impairment was attributed to over 100-fold loss of CXCR4 binding affinity. Binding to the other CXCL12 receptor, ACKR3, was diminished nearly 500-fold. Deletion of Pro-10 had little effect on CXCL12 binding to the CXCR4 N terminus, a major component of the chemokine-GPCR interface. Replacement of the X residue with the most frequent amino acid at this position (P10Q) had an intermediate effect between WT and P10del in each assay, with ACKR3 having a higher tolerance for this mutation. This work shows that the X residue helps to position the CXCL12 N terminus for optimal docking into the orthosteric pocket of CXCR4 and suggests that the CC/CXC motif contributes directly to receptor selectivity by orienting the chemokine N terminus in a subfamily-specific direction.

Abnormal DNA methylation patterns in patients with infection‑caused leukocytopenia based on methylation microarrays.

The present study aimed to investigate the association between gene methylation and leukocytopenia from the perspective of gene regulation. A total of 30 patients confirmed as having post-infection leukocytopenia at People's Hospital of Xinjiang Uygur Autonomous Region between January 2016 and June 2017 were successively recruited as the leukocytopenia group; 30 patients with post-infection leukocytosis were enrolled as the leukocytosis group. In addition, 30 healthy volunteers who received a health examination at the hospital during the same period were included as the normal control group. In each group, four individuals were randomly selected for whole genome methylation screening. After selection of key methylation sites, the remaining samples in each group were used for verification using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. The levels of serum complement factors C3 and C5 in the leukocytopenia group were significantly lower than those in the other two groups (P<0.05). According to whole-genome DNA methylation detection, 66 and 27 methylation loci may be associated with leukocytopenia and leukocytosis, respectively. Most of these abnormal loci are located on chromosomes 2, 6, 7, 1, 17 and 11. The rates of WW domain containing E3 ubiquitin protein ligase 2 gene methylation at cytosine-phosphate-guanine (CpG)_1, CpG_5/6 and CpG_7 in the leukocytopenia group were higher than in the other two groups (P<0.05); the rate of AKT2 CpG_1 methylation was higher in the leukocytopenia group than in the other two groups (P<0.05); the rate of calcium-binding atopy-related autoantigen 1 gene CpG_2 methylation was higher in the leukocytosis group than in the normal control group (P<0.05); and the rate of NADPH oxidase 5 gene CpG_3 methylation was higher in the leukocytosis group than in the normal control group (P<0.05). Chemotactic factor secretion and cell migration abnormalities, ubiquitination modification disorders and reduced oxidative burst may participate in infection-complicated leukocytopenia. The results of this study shed new light on the molecular biological mechanisms of infection-complicated leukocytopenia and provide novel avenues for diagnosis and treatment.

Interleukin-22 Mediates the Chemotactic Migration of Breast Cancer Cells and Macrophage Infiltration of the Bone Microenvironment by Potentiating S1P/SIPR Signaling.

The interleukin-22 (IL-22) signaling pathway is well known to be involved in the progression of various cancer types but its role in bone metastatic breast cancer remains unclear. We demonstrate using human GEO profiling that bone metastatic breast cancer displays elevated interleukin-22 receptor 1 (IL-22R1) and sphingosine-1-phosphate receptor 1 (S1PR1) expression. Importantly, IL-22 stimuli promoted the expression of IL-22R1 and S1PR1 in aggressive MDA-MB-231 breast cancer cells. IL-22 treatment also increased sphingosine-1-phosphate production in mesenchymal stem cells (MSCs) and induced the sphingosine-1-phosphate (S1P)-mediated chemotactic migration of MDA-MB-231 cells. This effect was inhibited by an S1P antagonist. In addition to the S1PR1 axis, IL-22 stimulated the expression of matrix metalloproteinase-9 (MMP-9), thereby promoting breast cancer cell invasion. Moreover, IL-22 induced IL22R1 and S1PR1 expression in macrophages, myeloid cell, and MCP1 expression in MSCs to facilitate macrophage infiltration. Immunohistochemistry indicated that IL-22R1 and S1PR1 are overexpressed in invasive malignant breast cancers and that this correlates with the MMP-9 levels. Collectively, our present results indicate a potential role of IL-22 in driving the metastasis of breast cancers into the bone microenvironment through the IL22R1-S1PR1 axis.

Impaired Autophagy in the Fibroblasts by Titanium Particles Increased the Release of CX3CL1 and Promoted the Chemotactic Migration of Monocytes.

Aseptic loosening (AL) is the most frequent cause of failure of total hip arthroplasties (THA). Prosthetic wear particle-induced monocyte recruitment to the periprosthetic tissue and subsequent inflammatory response are thought to be the major contribution to AL. Fibroblast is a dominant cell type in interfacial membrane (IFM) which is the main pathological feature of periprosthetic osteolysis in failed THAs. Considering the role of fibroblasts, as sentinel cells, in the synthesis of chemokines and regulation of inflammation, we hypothesize that fibroblasts might be involved in the monocyte recruitment in the pathogenesis of periprosthetic osteolysis associated with particle debris. This study explored the induction of fibroblasts on the monocyte recruitment. The results showed that titanium (Ti) particle-stimulated fibroblasts isolated from IFMs of loosened THAs significantly promoted the chemotactic migration of THP-1 cells by increasing the release of CX3CL1 (C-X3-C motif chemokine ligand 1). Further investigation demonstrated that Ti particle stimulation increased the expression of ADAM10 (ADAM metallopeptidase domain 10) by impairing autophagy in the fibroblasts and in turn increased the cleavage and shedding of CX3CL1. Thus, we propose a new insight to the pathogenesis of aseptic loosening which implies that autophagy-ADAM10-CX3CL1 signaling pathway in fibroblasts can be leveraged to alleviating inflammation caused by monocyte recruitment in aseptic loosening and improving performance of articulation of the joint device.